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Date: Wed, 26 Oct 2016 02:55:08 -0400
From: David Windsor <dwindsor@...il.com>
To: AKASHI Takahiro <takahiro.akashi@...aro.org>
Cc: Elena Reshetova <elena.reshetova@...el.com>, kernel-hardening@...ts.openwall.com, 
	Kees Cook <keescook@...omium.org>, Hans Liljestrand <ishkamiel@...il.com>
Subject: Re: [RFC v2 PATCH 12/13] x86: implementation for HARDENED_ATOMIC

On Wed, Oct 26, 2016 at 1:06 AM, AKASHI Takahiro
<takahiro.akashi@...aro.org> wrote:
> Elena,
>
> On Thu, Oct 20, 2016 at 01:25:30PM +0300, Elena Reshetova wrote:
>> This adds x86-specific code in order to support
>> HARDENED_ATOMIC feature. When overflow is detected
>> in atomic_t or atomic_long_t types, the counter is
>> decremented back by one (to keep it at INT_MAX or
>
> That's fine, but
>
>> LONG_MAX) and issue is reported using BUG().
>> The side effect is that in both legitimate and
>> non-legitimate cases a counter cannot wrap.
>>
>> Signed-off-by: Elena Reshetova <elena.reshetova@...el.com>
>> Signed-off-by: Hans Liljestrand <ishkamiel@...il.com>
>> Signed-off-by: David Windsor <dwindsor@...il.com>
>> ---
>>  arch/x86/Kconfig                   |   1 +
>>  arch/x86/include/asm/atomic.h      | 323 +++++++++++++++++++++++++++++++++++--
>>  arch/x86/include/asm/atomic64_32.h | 201 ++++++++++++++++++++++-
>>  arch/x86/include/asm/atomic64_64.h | 228 +++++++++++++++++++++++++-
>>  arch/x86/include/asm/bitops.h      |   8 +-
>>  arch/x86/include/asm/cmpxchg.h     |  39 +++++
>>  arch/x86/include/asm/local.h       |  89 +++++++++-
>>  arch/x86/include/asm/preempt.h     |   2 +-
>>  arch/x86/include/asm/rmwcc.h       |  82 ++++++++--
>>  arch/x86/include/asm/rwsem.h       |  50 ++++++
>>  arch/x86/kernel/traps.c            |   4 +
>>  arch/x86/lib/atomic64_386_32.S     | 135 ++++++++++++++++
>>  arch/x86/lib/atomic64_cx8_32.S     |  78 ++++++++-
>>  13 files changed, 1194 insertions(+), 46 deletions(-)
>>
>> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
>> index 402eee4..6c36184 100644
>> --- a/arch/x86/Kconfig
>> +++ b/arch/x86/Kconfig
>> @@ -79,6 +79,7 @@ config X86
>>       select HAVE_AOUT                        if X86_32
>>       select HAVE_ARCH_AUDITSYSCALL
>>       select HAVE_ARCH_HARDENED_USERCOPY
>> +     select HAVE_ARCH_HARDENED_ATOMIC
>>       select HAVE_ARCH_HUGE_VMAP              if X86_64 || X86_PAE
>>       select HAVE_ARCH_JUMP_LABEL
>>       select HAVE_ARCH_KASAN                  if X86_64 && SPARSEMEM_VMEMMAP
>> diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h
>> index 14635c5..4a35c9b 100644
>> --- a/arch/x86/include/asm/atomic.h
>> +++ b/arch/x86/include/asm/atomic.h
>> @@ -27,6 +27,17 @@ static __always_inline int atomic_read(const atomic_t *v)
>>  }
>>
>>  /**
>> + * atomic_read_wrap - read atomic variable
>> + * @v: pointer of type atomic_wrap_t
>> + *
>> + * Atomically reads the value of @v.
>> + */
>> +static __always_inline int atomic_read_wrap(const atomic_wrap_t *v)
>> +{
>> +     return ACCESS_ONCE((v)->counter);
>> +}
>> +
>> +/**
>>   * atomic_set - set atomic variable
>>   * @v: pointer of type atomic_t
>>   * @i: required value
>> @@ -39,6 +50,18 @@ static __always_inline void atomic_set(atomic_t *v, int i)
>>  }
>>
>>  /**
>> + * atomic_set_wrap - set atomic variable
>> + * @v: pointer of type atomic_wrap_t
>> + * @i: required value
>> + *
>> + * Atomically sets the value of @v to @i.
>> + */
>> +static __always_inline void atomic_set_wrap(atomic_wrap_t *v, int i)
>> +{
>> +     v->counter = i;
>> +}
>> +
>> +/**
>>   * atomic_add - add integer to atomic variable
>>   * @i: integer value to add
>>   * @v: pointer of type atomic_t
>> @@ -47,12 +70,55 @@ static __always_inline void atomic_set(atomic_t *v, int i)
>>   */
>>  static __always_inline void atomic_add(int i, atomic_t *v)
>>  {
>> -     asm volatile(LOCK_PREFIX "addl %1,%0"
>> +     asm volatile(LOCK_PREFIX "addl %1,%0\n"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  LOCK_PREFIX "subl %1,%0\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +
>>                    : "+m" (v->counter)
>>                    : "ir" (i));
>>  }
>>
>>  /**
>> + * atomic_add_wrap - add integer to atomic variable
>> + * @i: integer value to add
>> + * @v: pointer of type atomic_wrap_t
>> + *
>> + * Atomically adds @i to @v.
>> + */
>> +static __always_inline void atomic_add_wrap(int i, atomic_wrap_t *v)
>> +{
>> +     asm volatile(LOCK_PREFIX "addl %1,%0\n"
>> +                  : "+m" (v->counter)
>> +                  : "ir" (i));
>> +}
>> +
>> +/**
>> + * atomic_add_and_test - add value from variable and test result
>> + * @i: integer value to add
>> + * @v: pointer of type atomic_t
>> + *
>> + * Atomically adds @i from @v and returns
>> + * true if the result is zero, or false for all
>> + * other cases.
>> + */
>> +static __always_inline bool atomic_add_and_test(int i, atomic_t *v)
>> +{
>> +     GEN_BINARY_RMWcc(LOCK_PREFIX "addl", LOCK_PREFIX "subl", v->counter, "er", i, "%0", e);
>> +}
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static __always_inline bool atomic_add_and_test_wrap(int i, atomic_wrap_t *v)
>> +{
>> +     GEN_BINARY_RMWcc_wrap(LOCK_PREFIX "addl", v->counter, "er", i, "%0", e);
>> +}
>> +#endif /* CONFIG_HARDENED_ATOMIC */
>> +
>> +/**
>>   * atomic_sub - subtract integer from atomic variable
>>   * @i: integer value to subtract
>>   * @v: pointer of type atomic_t
>> @@ -61,7 +127,29 @@ static __always_inline void atomic_add(int i, atomic_t *v)
>>   */
>>  static __always_inline void atomic_sub(int i, atomic_t *v)
>>  {
>> -     asm volatile(LOCK_PREFIX "subl %1,%0"
>> +     asm volatile(LOCK_PREFIX "subl %1,%0\n"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  LOCK_PREFIX "addl %1,%0\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +
>> +                  : "+m" (v->counter)
>> +                  : "ir" (i));
>> +}
>> +
>> +/**
>> + * atomic_sub_wrap - subtract integer from atomic variable
>> + * @i: integer value to subtract
>> + * @v: pointer of type atomic_wrap_t
>> + *
>> + * Atomically subtracts @i from @v.
>> + */
>> +static __always_inline void atomic_sub_wrap(int i, atomic_wrap_t *v)
>> +{
>> +     asm volatile(LOCK_PREFIX "subl %1,%0\n"
>>                    : "+m" (v->counter)
>>                    : "ir" (i));
>>  }
>> @@ -77,7 +165,21 @@ static __always_inline void atomic_sub(int i, atomic_t *v)
>>   */
>>  static __always_inline bool atomic_sub_and_test(int i, atomic_t *v)
>>  {
>> -     GEN_BINARY_RMWcc(LOCK_PREFIX "subl", v->counter, "er", i, "%0", e);
>> +     GEN_BINARY_RMWcc(LOCK_PREFIX "subl", LOCK_PREFIX "addl", v->counter, "er", i, "%0", e);
>> +}
>> +
>> +/**
>> + * atomic_sub_and_test_wrap - subtract value from variable and test result
>> + * @i: integer value to subtract
>> + * @v: pointer of type atomic_wrap_t
>> + *
>> + * Atomically subtracts @i from @v and returns
>> + * true if the result is zero, or false for all
>> + * other cases.
>> + */
>> +static __always_inline bool atomic_sub_and_test_wrap(int i, atomic_wrap_t *v)
>> +{
>> +     GEN_BINARY_RMWcc_wrap(LOCK_PREFIX "subl", v->counter, "er", i, "%0", e);
>>  }
>>
>>  /**
>> @@ -88,7 +190,27 @@ static __always_inline bool atomic_sub_and_test(int i, atomic_t *v)
>>   */
>>  static __always_inline void atomic_inc(atomic_t *v)
>>  {
>> -     asm volatile(LOCK_PREFIX "incl %0"
>> +     asm volatile(LOCK_PREFIX "incl %0\n"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  LOCK_PREFIX "decl %0\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +
>> +                  : "+m" (v->counter));
>> +}
>> +
>> +/**
>> + * atomic_inc_wrap - increment atomic variable
>> + * @v: pointer of type atomic_wrap_t
>> + *
>> + * Atomically increments @v by 1.
>> + */
>> +static __always_inline void atomic_inc_wrap(atomic_wrap_t *v)
>> +{
>> +     asm volatile(LOCK_PREFIX "incl %0\n"
>>                    : "+m" (v->counter));
>>  }
>>
>> @@ -100,7 +222,27 @@ static __always_inline void atomic_inc(atomic_t *v)
>>   */
>>  static __always_inline void atomic_dec(atomic_t *v)
>>  {
>> -     asm volatile(LOCK_PREFIX "decl %0"
>> +     asm volatile(LOCK_PREFIX "decl %0\n"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  LOCK_PREFIX "incl %0\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +
>> +                  : "+m" (v->counter));
>> +}
>> +
>> +/**
>> + * atomic_dec_wrap - decrement atomic variable
>> + * @v: pointer of type atomic_wrap_t
>> + *
>> + * Atomically decrements @v by 1.
>> + */
>> +static __always_inline void atomic_dec_wrap(atomic_wrap_t *v)
>> +{
>> +     asm volatile(LOCK_PREFIX "decl %0\n"
>>                    : "+m" (v->counter));
>>  }
>>
>> @@ -114,9 +256,16 @@ static __always_inline void atomic_dec(atomic_t *v)
>>   */
>>  static __always_inline bool atomic_dec_and_test(atomic_t *v)
>>  {
>> -     GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", e);
>> +     GEN_UNARY_RMWcc(LOCK_PREFIX "decl", LOCK_PREFIX "incl", v->counter, "%0", e);
>>  }
>>
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static __always_inline bool atomic_dec_and_test_wrap(atomic_wrap_t *v)
>> +{
>> +     GEN_UNARY_RMWcc_wrap(LOCK_PREFIX "decl", v->counter, "%0", e);
>> +}
>> +#endif /* CONFIG_HARDENED_ATOMIC */
>> +
>>  /**
>>   * atomic_inc_and_test - increment and test
>>   * @v: pointer of type atomic_t
>> @@ -127,7 +276,20 @@ static __always_inline bool atomic_dec_and_test(atomic_t *v)
>>   */
>>  static __always_inline bool atomic_inc_and_test(atomic_t *v)
>>  {
>> -     GEN_UNARY_RMWcc(LOCK_PREFIX "incl", v->counter, "%0", e);
>> +     GEN_UNARY_RMWcc(LOCK_PREFIX "incl", LOCK_PREFIX "decl", v->counter, "%0", e);
>> +}
>> +
>> +/**
>> + * atomic_inc_and_test_wrap - increment and test
>> + * @v: pointer of type atomic_wrap_t
>> + *
>> + * Atomically increments @v by 1
>> + * and returns true if the result is zero, or false for all
>> + * other cases.
>> + */
>> +static __always_inline int atomic_inc_and_test_wrap(atomic_wrap_t *v)
>> +{
>> +     GEN_UNARY_RMWcc_wrap(LOCK_PREFIX "incl", v->counter, "%0", e);
>>  }
>>
>>  /**
>> @@ -141,9 +303,16 @@ static __always_inline bool atomic_inc_and_test(atomic_t *v)
>>   */
>>  static __always_inline bool atomic_add_negative(int i, atomic_t *v)
>>  {
>> -     GEN_BINARY_RMWcc(LOCK_PREFIX "addl", v->counter, "er", i, "%0", s);
>> +     GEN_BINARY_RMWcc(LOCK_PREFIX "addl", LOCK_PREFIX "subl", v->counter, "er", i, "%0", s);
>>  }
>>
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static __always_inline bool atomic_add_negative_wrap(int i, atomic_wrap_t *v)
>> +{
>> +     GEN_BINARY_RMWcc_wrap(LOCK_PREFIX "addl", v->counter, "er", i, "%0", s);
>> +}
>> +#endif /* CONFIG_HARDENED_ATOMIC */
>> +
>>  /**
>>   * atomic_add_return - add integer and return
>>   * @i: integer value to add
>> @@ -153,6 +322,18 @@ static __always_inline bool atomic_add_negative(int i, atomic_t *v)
>>   */
>>  static __always_inline int atomic_add_return(int i, atomic_t *v)
>>  {
>> +     return i + xadd_check_overflow(&v->counter, i);
>> +}
>
> If overflow, should this function still return i + v->counter?
> (The caller would die anyway, though.)
>

Yes, because in the non-overflow case, xadd_check_overflow() would
return the previous value of v->counter.  This gets added to i and
returned, which is correct and guaranteed to not result in an overflow
(if it did, the checks in xadd_check_overflow() would kill the
process, as you noted).

In the overflow case, the caller gets killed anyway: before
xadd_check_overflow() can return, do_trap() calls
hardened_atomic_overflow() which calls BUG(), so the return statement
won't finish executing.

One thing to note about the pattern of using i +
xadd_check_overflow(): there's a potential TOCTOU issue if i can be
modified after xadd_check_overflow() returns, but before the
expression (i + xadd_check_overflow()) is evaluated.  In areas where i
is shared between threads, we might want to make (i +
xadd_check_overflow()) a critical section.

>> +
>> +/**
>> + * atomic_add_return_wrap - add integer and return
>> + * @i: integer value to add
>> + * @v: pointer of type atomic_wrap_t
>> + *
>> + * Atomically adds @i to @v and returns @i + @v
>> + */
>> +static __always_inline int atomic_add_return_wrap(int i, atomic_wrap_t *v)
>> +{
>>       return i + xadd(&v->counter, i);
>>  }
>>
>> @@ -168,8 +349,26 @@ static __always_inline int atomic_sub_return(int i, atomic_t *v)
>>       return atomic_add_return(-i, v);
>>  }
>>
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static __always_inline int atomic_sub_return_wrap(int i, atomic_wrap_t *v)
>> +{
>> +     return atomic_add_return_wrap(-i, v);
>> +}
>> +#endif /* CONFIG_HARDENED_ATOMIC */
>> +
>>  #define atomic_inc_return(v)  (atomic_add_return(1, v))
>> +static __always_inline int atomic_inc_return_wrap(atomic_wrap_t *v)
>> +{
>> +     return atomic_add_return_wrap(1, v);
>> +}
>> +
>>  #define atomic_dec_return(v)  (atomic_sub_return(1, v))
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static __always_inline int atomic_dec_return_wrap(atomic_wrap_t *v)
>> +{
>> +     return atomic_sub_return_wrap(1, v);
>> +}
>> +#endif /* CONFIG_HARDENED_ATOMIC */
>>
>>  static __always_inline int atomic_fetch_add(int i, atomic_t *v)
>>  {
>
> and atomic_fetch_add/sub() should do
>
>         return xadd_check_overflow((+/-)i, v);
>
>> @@ -186,11 +385,21 @@ static __always_inline int atomic_cmpxchg(atomic_t *v, int old, int new)
>>       return cmpxchg(&v->counter, old, new);
>>  }
>>
>> +static __always_inline int atomic_cmpxchg_wrap(atomic_wrap_t *v, int old, int new)
>> +{
>> +     return cmpxchg(&v->counter, old, new);
>> +}
>> +
>>  static inline int atomic_xchg(atomic_t *v, int new)
>>  {
>>       return xchg(&v->counter, new);
>>  }
>>
>> +static inline int atomic_xchg_wrap(atomic_wrap_t *v, int new)
>> +{
>> +     return xchg(&v->counter, new);
>> +}
>> +
>>  #define ATOMIC_OP(op)                                                        \
>>  static inline void atomic_##op(int i, atomic_t *v)                   \
>>  {                                                                    \
>> @@ -236,12 +445,25 @@ ATOMIC_OPS(xor, ^)
>>   */
>>  static __always_inline int __atomic_add_unless(atomic_t *v, int a, int u)
>>  {
>> -     int c, old;
>> +     int c, old, new;
>>       c = atomic_read(v);
>>       for (;;) {
>>               if (unlikely(c == (u)))
>>                       break;
>> -             old = atomic_cmpxchg((v), c, c + (a));
>> +
>> +             asm volatile("addl %2,%0\n"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                          "jno 0f\n"
>> +                          "subl %2,%0\n"
>> +                          "int $4\n0:\n"
>> +                          _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +
>> +                          : "=r" (new)
>> +                          : "0" (c), "ir" (a));
>> +
>> +             old = atomic_cmpxchg((v), c, new);
>>               if (likely(old == c))
>>                       break;
>>               c = old;
>> @@ -250,6 +472,87 @@ static __always_inline int __atomic_add_unless(atomic_t *v, int a, int u)
>>  }
>>
>>  /**
>> + * __atomic_add_unless__wrap - add unless the number is already a given value
>> + * @v: pointer of type atomic_wrap_t
>> + * @a: the amount to add to v...
>> + * @u: ...unless v is equal to u.
>> + *
>> + * Atomically adds @a to @v, so long as @v was not already @u.
>> + * Returns the old value of @v.
>> + */
>> +static __always_inline int __atomic_add_unless_wrap(atomic_wrap_t *v,
>> +                                                 int a, int u)
>> +{
>> +     int c, old, new;
>> +     c = atomic_read_wrap(v);
>> +     for (;;) {
>> +             if (unlikely(c == (u)))
>> +                     break;
>> +
>> +             asm volatile("addl %2,%0\n"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                          "jno 0f\n"
>> +                          "subl %2,%0\n"
>> +                          "int $4\n0:\n"
>> +                          _ASM_EXTABLE(0b, 0b)
>> +#endif
>
> Is this a mistake? We don't need a check here.
>

Yes, this appears to be a mistake.

>> +
>> +                          : "=r" (new)
>> +                          : "0" (c), "ir" (a));
>> +
>> +             old = atomic_cmpxchg_wrap((v), c, new);
>> +             if (likely(old == c))
>> +                     break;
>> +             c = old;
>> +     }
>> +     return c;
>> +}
>> +
>> +/**
>> ++ * atomic_inc_not_zero_hint - increment if not null
>> ++ * @v: pointer of type atomic_t
>> ++ * @hint: probable value of the atomic before the increment
>> ++ *
>> ++ * This version of atomic_inc_not_zero() gives a hint of probable
>> ++ * value of the atomic. This helps processor to not read the memory
>> ++ * before doing the atomic read/modify/write cycle, lowering
>> ++ * number of bus transactions on some arches.
>> ++ *
>> ++ * Returns: 0 if increment was not done, 1 otherwise.
>> ++ */
>> +#define atomic_inc_not_zero_hint atomic_inc_not_zero_hint
>> +static inline int atomic_inc_not_zero_hint(atomic_t *v, int hint)
>> +{
>> +     int val, c = hint, new;
>> +
>> +     /* sanity test, should be removed by compiler if hint is a constant */
>> +     if (!hint)
>> +             return __atomic_add_unless(v, 1, 0);
>> +
>> +     do {
>> +             asm volatile("incl %0\n"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                          "jno 0f\n"
>> +                          "decl %0\n"
>> +                          "int $4\n0:\n"
>> +                          _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +
>> +                          : "=r" (new)
>> +                          : "0" (c));
>> +
>> +             val = atomic_cmpxchg((v), c, new);
>> +             if (val == c)
>> +                     return 1;
>> +             c = val;
>> +     } while (c);
>> +
>> +     return 0;
>> +}
>> +
>> +/**
>>   * atomic_inc_short - increment of a short integer
>>   * @v: pointer to type int
>>   *
>> diff --git a/arch/x86/include/asm/atomic64_32.h b/arch/x86/include/asm/atomic64_32.h
>> index 71d7705..7c88320 100644
>> --- a/arch/x86/include/asm/atomic64_32.h
>> +++ b/arch/x86/include/asm/atomic64_32.h
>> @@ -11,6 +11,14 @@ typedef struct {
>>       u64 __aligned(8) counter;
>>  } atomic64_t;
>>
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +typedef struct {
>> +     u64 __aligned(8) counter;
>> +} atomic64_wrap_t;
>> +#else
>> +typedef atomic64_t atomic64_wrap_t;
>> +#endif
>> +
>>  #define ATOMIC64_INIT(val)   { (val) }
>>
>>  #define __ATOMIC64_DECL(sym) void atomic64_##sym(atomic64_t *, ...)
>> @@ -36,21 +44,31 @@ typedef struct {
>>       ATOMIC64_DECL_ONE(sym##_386)
>>
>>  ATOMIC64_DECL_ONE(add_386);
>> +ATOMIC64_DECL_ONE(add_wrap_386);
>>  ATOMIC64_DECL_ONE(sub_386);
>> +ATOMIC64_DECL_ONE(sub_wrap_386);
>>  ATOMIC64_DECL_ONE(inc_386);
>> +ATOMIC64_DECL_ONE(inc_wrap_386);
>>  ATOMIC64_DECL_ONE(dec_386);
>> +ATOMIC64_DECL_ONE(dec_wrap_386);
>>  #endif
>>
>>  #define alternative_atomic64(f, out, in...) \
>>       __alternative_atomic64(f, f, ASM_OUTPUT2(out), ## in)
>>
>>  ATOMIC64_DECL(read);
>> +ATOMIC64_DECL(read_wrap);
>>  ATOMIC64_DECL(set);
>> +ATOMIC64_DECL(set_wrap);
>>  ATOMIC64_DECL(xchg);
>>  ATOMIC64_DECL(add_return);
>> +ATOMIC64_DECL(add_return_wrap);
>>  ATOMIC64_DECL(sub_return);
>> +ATOMIC64_DECL(sub_return_wrap);
>>  ATOMIC64_DECL(inc_return);
>> +ATOMIC64_DECL(inc_return_wrap);
>>  ATOMIC64_DECL(dec_return);
>> +ATOMIC64_DECL(dec_return_wrap);
>>  ATOMIC64_DECL(dec_if_positive);
>>  ATOMIC64_DECL(inc_not_zero);
>>  ATOMIC64_DECL(add_unless);
>> @@ -76,6 +94,21 @@ static inline long long atomic64_cmpxchg(atomic64_t *v, long long o, long long n
>>  }
>>
>>  /**
>> + * atomic64_cmpxchg_wrap - cmpxchg atomic64 variable
>> + * @p: pointer to type atomic64_wrap_t
>> + * @o: expected value
>> + * @n: new value
>> + *
>> + * Atomically sets @v to @n if it was equal to @o and returns
>> + * the old value.
>> + */
>> +
>> +static inline long long atomic64_cmpxchg_wrap(atomic64_wrap_t *v, long long o, long long n)
>> +{
>> +     return cmpxchg64(&v->counter, o, n);
>> +}
>> +
>> +/**
>>   * atomic64_xchg - xchg atomic64 variable
>>   * @v: pointer to type atomic64_t
>>   * @n: value to assign
>> @@ -95,6 +128,25 @@ static inline long long atomic64_xchg(atomic64_t *v, long long n)
>>  }
>>
>>  /**
>> + * atomic64_xchg_wrap - xchg atomic64 variable
>> + * @v: pointer to type atomic64_wrap_t
>> + * @n: value to assign
>> + *
>> + * Atomically xchgs the value of @v to @n and returns
>> + * the old value.
>> + */
>> +static inline long long atomic64_xchg_wrap(atomic64_wrap_t *v, long long n)
>> +{
>> +     long long o;
>> +     unsigned high = (unsigned)(n >> 32);
>> +     unsigned low = (unsigned)n;
>> +     alternative_atomic64(xchg, "=&A" (o),
>> +                          "S" (v), "b" (low), "c" (high)
>> +                          : "memory");
>> +     return o;
>> +}
>> +
>> +/**
>>   * atomic64_set - set atomic64 variable
>>   * @v: pointer to type atomic64_t
>>   * @i: value to assign
>> @@ -111,6 +163,22 @@ static inline void atomic64_set(atomic64_t *v, long long i)
>>  }
>>
>>  /**
>> + * atomic64_set_wrap - set atomic64 variable
>> + * @v: pointer to type atomic64_wrap_t
>> + * @n: value to assign
>> + *
>> + * Atomically sets the value of @v to @n.
>> + */
>> +static inline void atomic64_set_wrap(atomic64_wrap_t *v, long long i)
>> +{
>> +     unsigned high = (unsigned)(i >> 32);
>> +     unsigned low = (unsigned)i;
>> +     alternative_atomic64(set, /* no output */,
>> +                          "S" (v), "b" (low), "c" (high)
>> +                          : "eax", "edx", "memory");
>> +}
>> +
>> +/**
>>   * atomic64_read - read atomic64 variable
>>   * @v: pointer to type atomic64_t
>>   *
>> @@ -121,7 +189,20 @@ static inline long long atomic64_read(const atomic64_t *v)
>>       long long r;
>>       alternative_atomic64(read, "=&A" (r), "c" (v) : "memory");
>>       return r;
>> - }
>> +}
>> +
>> +/**
>> + * atomic64_read_wrap - read atomic64 variable
>> + * @v: pointer to type atomic64_wrap_t
>> + *
>> + * Atomically reads the value of @v and returns it.
>> + */
>> +static inline long long atomic64_read_wrap(const atomic64_wrap_t *v)
>> +{
>> +     long long r;
>> +     alternative_atomic64(read, "=&A" (r), "c" (v) : "memory");
>> +     return r;
>> +}
>>
>>  /**
>>   * atomic64_add_return - add and return
>> @@ -138,6 +219,21 @@ static inline long long atomic64_add_return(long long i, atomic64_t *v)
>>       return i;
>>  }
>>
>> +/**
>> + * atomic64_add_return_wrap - add and return
>> + * @i: integer value to add
>> + * @v: pointer to type atomic64_wrap_t
>> + *
>> + * Atomically adds @i to @v and returns @i + *@v
>> + */
>> +static inline long long atomic64_add_return_wrap(long long i, atomic64_wrap_t *v)
>> +{
>> +     alternative_atomic64(add_return_wrap,
>> +                          ASM_OUTPUT2("+A" (i), "+c" (v)),
>> +                          ASM_NO_INPUT_CLOBBER("memory"));
>> +     return i;
>> +}
>> +
>>  /*
>>   * Other variants with different arithmetic operators:
>>   */
>> @@ -149,6 +245,14 @@ static inline long long atomic64_sub_return(long long i, atomic64_t *v)
>>       return i;
>>  }
>>
>> +static inline long long atomic64_sub_return_wrap(long long i, atomic64_wrap_t *v)
>> +{
>> +     alternative_atomic64(sub_return,
>
> sub_return_wrap?
>
> Thanks,
> -Takahiro AKASHI
>
>> +                          ASM_OUTPUT2("+A" (i), "+c" (v)),
>> +                          ASM_NO_INPUT_CLOBBER("memory"));
>> +     return i;
>> +}
>> +
>>  static inline long long atomic64_inc_return(atomic64_t *v)
>>  {
>>       long long a;
>> @@ -157,6 +261,14 @@ static inline long long atomic64_inc_return(atomic64_t *v)
>>       return a;
>>  }
>>
>> +static inline long long atomic64_inc_return_wrap(atomic64_wrap_t *v)
>> +{
>> +     long long a;
>> +     alternative_atomic64(inc_return_wrap, "=&A" (a),
>> +                          "S" (v) : "memory", "ecx");
>> +     return a;
>> +}
>> +
>>  static inline long long atomic64_dec_return(atomic64_t *v)
>>  {
>>       long long a;
>> @@ -165,6 +277,16 @@ static inline long long atomic64_dec_return(atomic64_t *v)
>>       return a;
>>  }
>>
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static inline long long atomic64_dec_return_wrap(atomic64_wrap_t *v)
>> +{
>> +     long long a;
>> +     alternative_atomic64(dec_return_wrap, "=&A" (a),
>> +                          "S" (v) : "memory", "ecx");
>> +     return a;
>> +}
>> +#endif /* CONFIG_HARDENED_ATOMIC */
>> +
>>  /**
>>   * atomic64_add - add integer to atomic64 variable
>>   * @i: integer value to add
>> @@ -181,6 +303,42 @@ static inline long long atomic64_add(long long i, atomic64_t *v)
>>  }
>>
>>  /**
>> + * atomic64_add_wrap - add integer to atomic64 variable
>> + * @i: integer value to add
>> + * @v: pointer to type atomic64_wrap_t
>> + *
>> + * Atomically adds @i to @v.
>> + */
>> +static inline long long atomic64_add_wrap(long long i, atomic64_wrap_t *v)
>> +{
>> +     __alternative_atomic64(add_wrap, add_return_wrap,
>> +                            ASM_OUTPUT2("+A" (i), "+c" (v)),
>> +                            ASM_NO_INPUT_CLOBBER("memory"));
>> +     return i;
>> +}
>> +
>> +/**
>> + * atomic64_add_and_test - add value from variable and test result
>> + * @i: integer value to add
>> + * @v: pointer to type atomic64_t
>> + *
>> + * Atomically subtracts @i from @v and returns
>> + * true if the result is zero, or false for all
>> + * other cases.
>> + */
>> +static inline int atomic64_add_and_test(long long i, atomic64_t *v)
>> +{
>> +     return atomic64_add_return(i, v) == 0;
>> +}
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static inline int atomic64_add_and_test_wrap(long long i, atomic64_wrap_t *v)
>> +{
>> +     return atomic64_add_return_wrap(i, v) == 0;
>> +}
>> +#endif /* CONFIG_HARDENED_ATOMIC */
>> +
>> +/**
>>   * atomic64_sub - subtract the atomic64 variable
>>   * @i: integer value to subtract
>>   * @v: pointer to type atomic64_t
>> @@ -209,6 +367,13 @@ static inline int atomic64_sub_and_test(long long i, atomic64_t *v)
>>       return atomic64_sub_return(i, v) == 0;
>>  }
>>
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static inline int atomic64_sub_and_test_wrap(long long i, atomic64_wrap_t *v)
>> +{
>> +     return atomic64_sub_return_wrap(i, v) == 0;
>> +}
>> +#endif /* CONFIG_HARDENED_ATOMIC */
>> +
>>  /**
>>   * atomic64_inc - increment atomic64 variable
>>   * @v: pointer to type atomic64_t
>> @@ -222,6 +387,18 @@ static inline void atomic64_inc(atomic64_t *v)
>>  }
>>
>>  /**
>> + * atomic64_inc_wrap - increment atomic64 variable
>> + * @v: pointer to type atomic64_wrap_t
>> + *
>> + * Atomically increments @v by 1.
>> + */
>> +static inline void atomic64_inc_wrap(atomic64_wrap_t *v)
>> +{
>> +     __alternative_atomic64(inc_wrap, inc_return_wrap, /* no output */,
>> +                            "S" (v) : "memory", "eax", "ecx", "edx");
>> +}
>> +
>> +/**
>>   * atomic64_dec - decrement atomic64 variable
>>   * @v: pointer to type atomic64_t
>>   *
>> @@ -246,6 +423,13 @@ static inline int atomic64_dec_and_test(atomic64_t *v)
>>       return atomic64_dec_return(v) == 0;
>>  }
>>
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static inline int atomic64_dec_and_test_wrap(atomic64_wrap_t *v)
>> +{
>> +     return atomic64_dec_return_wrap(v) == 0;
>> +}
>> +#endif /* CONFIG_HARDENED_ATOMIC */
>> +
>>  /**
>>   * atomic64_inc_and_test - increment and test
>>   * @v: pointer to type atomic64_t
>> @@ -259,6 +443,13 @@ static inline int atomic64_inc_and_test(atomic64_t *v)
>>       return atomic64_inc_return(v) == 0;
>>  }
>>
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static inline int atomic64_inc_and_test_wrap(atomic64_wrap_t *v)
>> +{
>> +     return atomic64_inc_return_wrap(v) == 0;
>> +}
>> +#endif /* CONFIG_HARDENED_ATOMIC */
>> +
>>  /**
>>   * atomic64_add_negative - add and test if negative
>>   * @i: integer value to add
>> @@ -273,6 +464,13 @@ static inline int atomic64_add_negative(long long i, atomic64_t *v)
>>       return atomic64_add_return(i, v) < 0;
>>  }
>>
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static inline int atomic64_add_negative_wrap(long long i, atomic64_wrap_t *v)
>> +{
>> +     return atomic64_add_return_wrap(i, v) < 0;
>> +}
>> +#endif /* CONFIG_HARDENED_ATOMIC */
>> +
>>  /**
>>   * atomic64_add_unless - add unless the number is a given value
>>   * @v: pointer of type atomic64_t
>> @@ -292,7 +490,6 @@ static inline int atomic64_add_unless(atomic64_t *v, long long a, long long u)
>>       return (int)a;
>>  }
>>
>> -
>>  static inline int atomic64_inc_not_zero(atomic64_t *v)
>>  {
>>       int r;
>> diff --git a/arch/x86/include/asm/atomic64_64.h b/arch/x86/include/asm/atomic64_64.h
>> index 89ed2f6..d8d3a3d 100644
>> --- a/arch/x86/include/asm/atomic64_64.h
>> +++ b/arch/x86/include/asm/atomic64_64.h
>> @@ -22,6 +22,18 @@ static inline long atomic64_read(const atomic64_t *v)
>>  }
>>
>>  /**
>> + * atomic64_read_wrap - read atomic64 variable
>> + * @v: pointer of type atomic64_wrap_t
>> + *
>> + * Atomically reads the value of @v.
>> + * Doesn't imply a read memory barrier.
>> + */
>> +static inline long atomic64_read_wrap(const atomic64_wrap_t *v)
>> +{
>> +     return ACCESS_ONCE((v)->counter);
>> +}
>> +
>> +/**
>>   * atomic64_set - set atomic64 variable
>>   * @v: pointer to type atomic64_t
>>   * @i: required value
>> @@ -34,6 +46,18 @@ static inline void atomic64_set(atomic64_t *v, long i)
>>  }
>>
>>  /**
>> + * atomic64_set_wrap - set atomic64 variable
>> + * @v: pointer to type atomic64_wrap_t
>> + * @i: required value
>> + *
>> + * Atomically sets the value of @v to @i.
>> + */
>> +static inline void atomic64_set_wrap(atomic64_wrap_t *v, long i)
>> +{
>> +     v->counter = i;
>> +}
>> +
>> +/**
>>   * atomic64_add - add integer to atomic64 variable
>>   * @i: integer value to add
>>   * @v: pointer to type atomic64_t
>> @@ -42,12 +66,55 @@ static inline void atomic64_set(atomic64_t *v, long i)
>>   */
>>  static __always_inline void atomic64_add(long i, atomic64_t *v)
>>  {
>> +     asm volatile(LOCK_PREFIX "addq %1,%0\n"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  LOCK_PREFIX "subq %1,%0\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +
>> +                  : "=m" (v->counter)
>> +                  : "er" (i), "m" (v->counter));
>> +}
>> +
>> +/**
>> + * atomic64_add_wrap - add integer to atomic64 variable
>> + * @i: integer value to add
>> + * @v: pointer to type atomic64_wrap_t
>> + *
>> + * Atomically adds @i to @v.
>> + */
>> +static __always_inline void atomic64_add_wrap(long i, atomic64_wrap_t *v)
>> +{
>>       asm volatile(LOCK_PREFIX "addq %1,%0"
>>                    : "=m" (v->counter)
>>                    : "er" (i), "m" (v->counter));
>>  }
>>
>>  /**
>> + * atomic64_add_and_test - add value from variable and test result
>> + * @i: integer value to add
>> + * @v: pointer to type atomic64_t
>> + *
>> + * Atomically adds @i from @v and returns
>> + * true if the result is zero, or false for all
>> + * other cases.
>> + */
>> +static inline bool atomic64_add_and_test(long i, atomic64_t *v)
>> +{
>> +     GEN_BINARY_RMWcc(LOCK_PREFIX "addq", LOCK_PREFIX "subq", v->counter, "er", i, "%0", e);
>> +}
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static inline bool atomic64_add_and_test_wrap(long i, atomic64_wrap_t *v)
>> +{
>> +     GEN_BINARY_RMWcc_wrap(LOCK_PREFIX "addq", v->counter, "er", i, "%0", e);
>> +}
>> +#endif /* CONFIG_HARDENED_ATMOMIC */
>> +
>> +/**
>>   * atomic64_sub - subtract the atomic64 variable
>>   * @i: integer value to subtract
>>   * @v: pointer to type atomic64_t
>> @@ -56,6 +123,26 @@ static __always_inline void atomic64_add(long i, atomic64_t *v)
>>   */
>>  static inline void atomic64_sub(long i, atomic64_t *v)
>>  {
>> +     asm volatile(LOCK_PREFIX "subq %1,%0\n"
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  LOCK_PREFIX "addq %1,%0\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +                  : "=m" (v->counter)
>> +                  : "er" (i), "m" (v->counter));
>> +}
>> +
>> +/**
>> ++ * atomic64_sub_wrap - subtract the atomic64 variable
>> ++ * @i: integer value to subtract
>> ++ * @v: pointer to type atomic64_wrap_t
>> ++ *
>> ++ * Atomically subtracts @i from @v.
>> ++ */
>> +static inline void atomic64_sub_wrap(long i, atomic64_wrap_t *v)
>> +{
>>       asm volatile(LOCK_PREFIX "subq %1,%0"
>>                    : "=m" (v->counter)
>>                    : "er" (i), "m" (v->counter));
>> @@ -72,7 +159,21 @@ static inline void atomic64_sub(long i, atomic64_t *v)
>>   */
>>  static inline bool atomic64_sub_and_test(long i, atomic64_t *v)
>>  {
>> -     GEN_BINARY_RMWcc(LOCK_PREFIX "subq", v->counter, "er", i, "%0", e);
>> +     GEN_BINARY_RMWcc(LOCK_PREFIX "subq", LOCK_PREFIX "addq", v->counter, "er", i, "%0", e);
>> +}
>> +
>> +/**
>> + * atomic64_sub_and_test_wrap - subtract value from variable and test result
>> + * @i: integer value to subtract
>> + * @v: pointer to type atomic64_wrap_t
>> + *
>> + * Atomically subtracts @i from @v and returns
>> + * true if the result is zero, or false for all
>> + * other cases.
>> + */
>> +static inline bool atomic64_sub_and_test_wrap(long i, atomic64_wrap_t *v)
>> +{
>> +     GEN_BINARY_RMWcc_wrap(LOCK_PREFIX "subq", v->counter, "er", i, "%0", e);
>>  }
>>
>>  /**
>> @@ -83,6 +184,26 @@ static inline bool atomic64_sub_and_test(long i, atomic64_t *v)
>>   */
>>  static __always_inline void atomic64_inc(atomic64_t *v)
>>  {
>> +     asm volatile(LOCK_PREFIX "incq %0\n"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  LOCK_PREFIX "decq %0\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +                  : "=m" (v->counter)
>> +                  : "m" (v->counter));
>> +}
>> +
>> +/**
>> + * atomic64_inc_wrap - increment atomic64 variable
>> + * @v: pointer to type atomic64_wrap_t
>> + *
>> + * Atomically increments @v by 1.
>> + */
>> +static __always_inline void atomic64_inc_wrap(atomic64_wrap_t *v)
>> +{
>>       asm volatile(LOCK_PREFIX "incq %0"
>>                    : "=m" (v->counter)
>>                    : "m" (v->counter));
>> @@ -96,6 +217,26 @@ static __always_inline void atomic64_inc(atomic64_t *v)
>>   */
>>  static __always_inline void atomic64_dec(atomic64_t *v)
>>  {
>> +     asm volatile(LOCK_PREFIX "decq %0\n"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  LOCK_PREFIX "incq %0\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +                  : "=m" (v->counter)
>> +                  : "m" (v->counter));
>> +}
>> +
>> +/**
>> + * atomic64_dec_wrap - decrement atomic64 variable
>> + * @v: pointer to type atomic64_wrap_t
>> + *
>> + * Atomically decrements @v by 1.
>> + */
>> +static __always_inline void atomic64_dec_wrap(atomic64_wrap_t *v)
>> +{
>>       asm volatile(LOCK_PREFIX "decq %0"
>>                    : "=m" (v->counter)
>>                    : "m" (v->counter));
>> @@ -111,8 +252,15 @@ static __always_inline void atomic64_dec(atomic64_t *v)
>>   */
>>  static inline bool atomic64_dec_and_test(atomic64_t *v)
>>  {
>> -     GEN_UNARY_RMWcc(LOCK_PREFIX "decq", v->counter, "%0", e);
>> +     GEN_UNARY_RMWcc(LOCK_PREFIX "decq", LOCK_PREFIX "incq", v->counter, "%0", e);
>> +}
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static inline bool atomic64_dec_and_test_wrap(atomic64_wrap_t *v)
>> +{
>> +     GEN_UNARY_RMWcc_wrap(LOCK_PREFIX "decq", v->counter, "%0", e);
>>  }
>> +#endif /* CONFIG_HARDENED_ATOMIC */
>>
>>  /**
>>   * atomic64_inc_and_test - increment and test
>> @@ -124,8 +272,15 @@ static inline bool atomic64_dec_and_test(atomic64_t *v)
>>   */
>>  static inline bool atomic64_inc_and_test(atomic64_t *v)
>>  {
>> -     GEN_UNARY_RMWcc(LOCK_PREFIX "incq", v->counter, "%0", e);
>> +     GEN_UNARY_RMWcc(LOCK_PREFIX "incq", LOCK_PREFIX "decq", v->counter, "%0", e);
>> +}
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static inline bool atomic64_inc_and_test_wrap(atomic64_wrap_t *v)
>> +{
>> +     GEN_UNARY_RMWcc_wrap(LOCK_PREFIX "incq", v->counter, "%0", e);
>>  }
>> +#endif /* CONFIG_HARDENED_ATOMIC */
>>
>>  /**
>>   * atomic64_add_negative - add and test if negative
>> @@ -138,8 +293,15 @@ static inline bool atomic64_inc_and_test(atomic64_t *v)
>>   */
>>  static inline bool atomic64_add_negative(long i, atomic64_t *v)
>>  {
>> -     GEN_BINARY_RMWcc(LOCK_PREFIX "addq", v->counter, "er", i, "%0", s);
>> +     GEN_BINARY_RMWcc(LOCK_PREFIX "addq", LOCK_PREFIX "subq", v->counter, "er", i, "%0", s);
>> +}
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static inline bool atomic64_add_negative_wrap(long i, atomic64_wrap_t *v)
>> +{
>> +     GEN_BINARY_RMWcc_wrap(LOCK_PREFIX "addq", v->counter, "er", i, "%0", s);
>>  }
>> +#endif /* CONFIG_HARDENED_ATOMIC */
>>
>>  /**
>>   * atomic64_add_return - add and return
>> @@ -150,6 +312,11 @@ static inline bool atomic64_add_negative(long i, atomic64_t *v)
>>   */
>>  static __always_inline long atomic64_add_return(long i, atomic64_t *v)
>>  {
>> +     return i + xadd_check_overflow(&v->counter, i);
>> +}
>> +
>> +static __always_inline long atomic64_add_return_wrap(long i, atomic64_wrap_t *v)
>> +{
>>       return i + xadd(&v->counter, i);
>>  }
>>
>> @@ -158,6 +325,13 @@ static inline long atomic64_sub_return(long i, atomic64_t *v)
>>       return atomic64_add_return(-i, v);
>>  }
>>
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static inline long atomic64_sub_return_wrap(long i, atomic64_wrap_t *v)
>> +{
>> +     return atomic64_add_return_wrap(-i, v);
>> +}
>> +#endif /* CONFIG_HARDENED_ATOMIC */
>> +
>>  static inline long atomic64_fetch_add(long i, atomic64_t *v)
>>  {
>>       return xadd(&v->counter, i);
>> @@ -171,16 +345,29 @@ static inline long atomic64_fetch_sub(long i, atomic64_t *v)
>>  #define atomic64_inc_return(v)  (atomic64_add_return(1, (v)))
>>  #define atomic64_dec_return(v)  (atomic64_sub_return(1, (v)))
>>
>> +#define atomic64_inc_return_wrap(v)  (atomic64_add_return_wrap(1, (v)))
>> +#define atomic64_dec_return_wrap(v)  (atomic64_sub_return_wrap(1, (v)))
>> +
>>  static inline long atomic64_cmpxchg(atomic64_t *v, long old, long new)
>>  {
>>       return cmpxchg(&v->counter, old, new);
>>  }
>>
>> +static inline long atomic64_cmpxchg_wrap(atomic64_wrap_t *v, long old, long new)
>> +{
>> +     return cmpxchg(&v->counter, old, new);
>> +}
>> +
>>  static inline long atomic64_xchg(atomic64_t *v, long new)
>>  {
>>       return xchg(&v->counter, new);
>>  }
>>
>> +static inline long atomic64_xchg_wrap(atomic64_wrap_t *v, long new)
>> +{
>> +     return xchg(&v->counter, new);
>> +}
>> +
>>  /**
>>   * atomic64_add_unless - add unless the number is a given value
>>   * @v: pointer of type atomic64_t
>> @@ -192,11 +379,21 @@ static inline long atomic64_xchg(atomic64_t *v, long new)
>>   */
>>  static inline bool atomic64_add_unless(atomic64_t *v, long a, long u)
>>  {
>> -     long c, old;
>> +     long c, old, new;
>>       c = atomic64_read(v);
>>       for (;;) {
>>               if (unlikely(c == (u)))
>>                       break;
>> +             asm volatile("add %2,%0\n"
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                          "jno 0f\n"
>> +                          "sub %2,%0\n"
>> +                          "int $4\n0:\n"
>> +                          _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +                          : "=r" (new)
>> +                          : "0" (c), "ir" (a));
>> +
>>               old = atomic64_cmpxchg((v), c, c + (a));
>>               if (likely(old == c))
>>                       break;
>> @@ -205,6 +402,27 @@ static inline bool atomic64_add_unless(atomic64_t *v, long a, long u)
>>       return c != (u);
>>  }
>>
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +static inline bool atomic64_add_unless_wrap(atomic64_wrap_t *v, long a, long u)
>> +{
>> +     long c, old, new;
>> +     c = atomic64_read_wrap(v);
>> +     for (;;) {
>> +             if (unlikely(c == (u)))
>> +                     break;
>> +             asm volatile("add %2,%0\n"
>> +                          : "=r" (new)
>> +                          : "0" (c), "ir" (a));
>> +
>> +             old = atomic64_cmpxchg_wrap((v), c, c + (a));
>> +             if (likely(old == c))
>> +                     break;
>> +             c = old;
>> +     }
>> +     return c != (u);
>> +}
>> +#endif /* CONFIG_HARDENED_ATOMIC */
>> +
>>  #define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
>>
>>  /*
>> diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h
>> index 68557f52..e25eb0d 100644
>> --- a/arch/x86/include/asm/bitops.h
>> +++ b/arch/x86/include/asm/bitops.h
>> @@ -50,7 +50,7 @@
>>   * a mask operation on a byte.
>>   */
>>  #define IS_IMMEDIATE(nr)             (__builtin_constant_p(nr))
>> -#define CONST_MASK_ADDR(nr, addr)    BITOP_ADDR((void *)(addr) + ((nr)>>3))
>> +#define CONST_MASK_ADDR(nr, addr)    BITOP_ADDR((volatile void *)(addr) + ((nr)>>3))
>>  #define CONST_MASK(nr)                       (1 << ((nr) & 7))
>>
>>  /**
>> @@ -203,7 +203,7 @@ static __always_inline void change_bit(long nr, volatile unsigned long *addr)
>>   */
>>  static __always_inline bool test_and_set_bit(long nr, volatile unsigned long *addr)
>>  {
>> -     GEN_BINARY_RMWcc(LOCK_PREFIX "bts", *addr, "Ir", nr, "%0", c);
>> +     GEN_BINARY_RMWcc_wrap(LOCK_PREFIX "bts", *addr, "Ir", nr, "%0", c);
>>  }
>>
>>  /**
>> @@ -249,7 +249,7 @@ static __always_inline bool __test_and_set_bit(long nr, volatile unsigned long *
>>   */
>>  static __always_inline bool test_and_clear_bit(long nr, volatile unsigned long *addr)
>>  {
>> -     GEN_BINARY_RMWcc(LOCK_PREFIX "btr", *addr, "Ir", nr, "%0", c);
>> +     GEN_BINARY_RMWcc_wrap(LOCK_PREFIX "btr", *addr, "Ir", nr, "%0", c);
>>  }
>>
>>  /**
>> @@ -302,7 +302,7 @@ static __always_inline bool __test_and_change_bit(long nr, volatile unsigned lon
>>   */
>>  static __always_inline bool test_and_change_bit(long nr, volatile unsigned long *addr)
>>  {
>> -     GEN_BINARY_RMWcc(LOCK_PREFIX "btc", *addr, "Ir", nr, "%0", c);
>> +     GEN_BINARY_RMWcc_wrap(LOCK_PREFIX "btc", *addr, "Ir", nr, "%0", c);
>>  }
>>
>>  static __always_inline bool constant_test_bit(long nr, const volatile unsigned long *addr)
>> diff --git a/arch/x86/include/asm/cmpxchg.h b/arch/x86/include/asm/cmpxchg.h
>> index 9733361..b83f612 100644
>> --- a/arch/x86/include/asm/cmpxchg.h
>> +++ b/arch/x86/include/asm/cmpxchg.h
>> @@ -13,10 +13,14 @@ extern void __xchg_wrong_size(void)
>>       __compiletime_error("Bad argument size for xchg");
>>  extern void __cmpxchg_wrong_size(void)
>>       __compiletime_error("Bad argument size for cmpxchg");
>> +extern void __xadd_check_overflow_wrong_size(void)
>> +     __compiletime_error("Bad argument size for xadd_check_overflow");
>>  extern void __xadd_wrong_size(void)
>>       __compiletime_error("Bad argument size for xadd");
>>  extern void __add_wrong_size(void)
>>       __compiletime_error("Bad argument size for add");
>> +extern void __add_check_overflow_wrong_size(void)
>> +     __compiletime_error("Bad argument size for add_check_overflow");
>>
>>  /*
>>   * Constants for operation sizes. On 32-bit, the 64-bit size it set to
>> @@ -68,6 +72,38 @@ extern void __add_wrong_size(void)
>>               __ret;                                                  \
>>       })
>>
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +#define __xchg_op_check_overflow(ptr, arg, op, lock)                 \
>> +     ({                                                              \
>> +             __typeof__ (*(ptr)) __ret = (arg);                      \
>> +             switch (sizeof(*(ptr))) {                               \
>> +             case __X86_CASE_L:                                      \
>> +                     asm volatile (lock #op "l %0, %1\n"             \
>> +                                   "jno 0f\n"                        \
>> +                                   "mov %0,%1\n"                     \
>> +                                   "int $4\n0:\n"                    \
>> +                                   _ASM_EXTABLE(0b, 0b)              \
>> +                                   : "+r" (__ret), "+m" (*(ptr))     \
>> +                                   : : "memory", "cc");              \
>> +                     break;                                          \
>> +             case __X86_CASE_Q:                                      \
>> +                     asm volatile (lock #op "q %q0, %1\n"            \
>> +                                   "jno 0f\n"                        \
>> +                                   "mov %0,%1\n"                     \
>> +                                   "int $4\n0:\n"                    \
>> +                                   _ASM_EXTABLE(0b, 0b)              \
>> +                                   : "+r" (__ret), "+m" (*(ptr))     \
>> +                                   : : "memory", "cc");              \
>> +                     break;                                          \
>> +             default:                                                \
>> +                     __ ## op ## _check_overflow_wrong_size();       \
>> +             }                                                       \
>> +             __ret;                                                  \
>> +     })
>> +#else
>> +#define __xchg_op_check_overflow(ptr, arg, op, lock) __xchg_op(ptr, arg, op, lock)
>> +#endif
>> +
>>  /*
>>   * Note: no "lock" prefix even on SMP: xchg always implies lock anyway.
>>   * Since this is generally used to protect other memory information, we
>> @@ -166,6 +202,9 @@ extern void __add_wrong_size(void)
>>  #define xadd_sync(ptr, inc)  __xadd((ptr), (inc), "lock; ")
>>  #define xadd_local(ptr, inc) __xadd((ptr), (inc), "")
>>
>> +#define __xadd_check_overflow(ptr, inc, lock)        __xchg_op_check_overflow((ptr), (inc), xadd, lock)
>> +#define xadd_check_overflow(ptr, inc)                __xadd_check_overflow((ptr), (inc), LOCK_PREFIX)
>> +
>>  #define __add(ptr, inc, lock)                                                \
>>       ({                                                              \
>>               __typeof__ (*(ptr)) __ret = (inc);                      \
>> diff --git a/arch/x86/include/asm/local.h b/arch/x86/include/asm/local.h
>> index 7511978..46cfaf0 100644
>> --- a/arch/x86/include/asm/local.h
>> +++ b/arch/x86/include/asm/local.h
>> @@ -10,25 +10,69 @@ typedef struct {
>>       atomic_long_t a;
>>  } local_t;
>>
>> +typedef struct {
>> +     atomic_long_wrap_t a;
>> +} local_wrap_t;
>> +
>>  #define LOCAL_INIT(i)        { ATOMIC_LONG_INIT(i) }
>>
>>  #define local_read(l)        atomic_long_read(&(l)->a)
>> +#define local_read_wrap(l)   atomic_long_read_wrap(&(l)->a)
>>  #define local_set(l, i)      atomic_long_set(&(l)->a, (i))
>> +#define local_set_wrap(l, i) atomic_long_set_wrap(&(l)->a, (i))
>>
>>  static inline void local_inc(local_t *l)
>>  {
>> +     asm volatile(_ASM_INC "%0\n"
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  _ASM_DEC "%0\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +                  : "+m" (l->a.counter));
>> +}
>> +
>> +static inline void local_inc_wrap(local_wrap_t *l)
>> +{
>>       asm volatile(_ASM_INC "%0"
>>                    : "+m" (l->a.counter));
>>  }
>>
>>  static inline void local_dec(local_t *l)
>>  {
>> +     asm volatile(_ASM_DEC "%0\n"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  _ASM_INC "%0\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +                  : "+m" (l->a.counter));
>> +}
>> +
>> +static inline void local_dec_wrap(local_wrap_t *l)
>> +{
>>       asm volatile(_ASM_DEC "%0"
>>                    : "+m" (l->a.counter));
>>  }
>>
>>  static inline void local_add(long i, local_t *l)
>>  {
>> +     asm volatile(_ASM_ADD "%1,%0\n"
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  _ASM_SUB "%1,%0\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +                  : "+m" (l->a.counter)
>> +                  : "ir" (i));
>> +}
>> +
>> +static inline void local_add_wrap(long i, local_wrap_t *l)
>> +{
>>       asm volatile(_ASM_ADD "%1,%0"
>>                    : "+m" (l->a.counter)
>>                    : "ir" (i));
>> @@ -36,6 +80,19 @@ static inline void local_add(long i, local_t *l)
>>
>>  static inline void local_sub(long i, local_t *l)
>>  {
>> +     asm volatile(_ASM_SUB "%1,%0\n"
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  _ASM_ADD "%1,%0\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +                  : "+m" (l->a.counter)
>> +                  : "ir" (i));
>> +}
>> +
>> +static inline void local_sub_wrap(long i, local_wrap_t *l)
>> +{
>>       asm volatile(_ASM_SUB "%1,%0"
>>                    : "+m" (l->a.counter)
>>                    : "ir" (i));
>> @@ -52,7 +109,7 @@ static inline void local_sub(long i, local_t *l)
>>   */
>>  static inline bool local_sub_and_test(long i, local_t *l)
>>  {
>> -     GEN_BINARY_RMWcc(_ASM_SUB, l->a.counter, "er", i, "%0", e);
>> +     GEN_BINARY_RMWcc(_ASM_SUB, _ASM_ADD, l->a.counter, "er", i, "%0", e);
>>  }
>>
>>  /**
>> @@ -65,7 +122,7 @@ static inline bool local_sub_and_test(long i, local_t *l)
>>   */
>>  static inline bool local_dec_and_test(local_t *l)
>>  {
>> -     GEN_UNARY_RMWcc(_ASM_DEC, l->a.counter, "%0", e);
>> +     GEN_UNARY_RMWcc(_ASM_DEC, _ASM_INC, l->a.counter, "%0", e);
>>  }
>>
>>  /**
>> @@ -78,7 +135,7 @@ static inline bool local_dec_and_test(local_t *l)
>>   */
>>  static inline bool local_inc_and_test(local_t *l)
>>  {
>> -     GEN_UNARY_RMWcc(_ASM_INC, l->a.counter, "%0", e);
>> +     GEN_UNARY_RMWcc(_ASM_INC, _ASM_DEC, l->a.counter, "%0", e);
>>  }
>>
>>  /**
>> @@ -92,7 +149,7 @@ static inline bool local_inc_and_test(local_t *l)
>>   */
>>  static inline bool local_add_negative(long i, local_t *l)
>>  {
>> -     GEN_BINARY_RMWcc(_ASM_ADD, l->a.counter, "er", i, "%0", s);
>> +     GEN_BINARY_RMWcc(_ASM_ADD, _ASM_SUB, l->a.counter, "er", i, "%0", s);
>>  }
>>
>>  /**
>> @@ -105,6 +162,28 @@ static inline bool local_add_negative(long i, local_t *l)
>>  static inline long local_add_return(long i, local_t *l)
>>  {
>>       long __i = i;
>> +     asm volatile(_ASM_XADD "%0, %1\n"
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  _ASM_MOV "%0,%1\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +                  : "+r" (i), "+m" (l->a.counter)
>> +                  : : "memory");
>> +     return i + __i;
>> +}
>> +
>> +/**
>> + * local_add_return_wrap - add and return
>> + * @i: integer value to add
>> + * @l: pointer to type local_wrap_t
>> + *
>> + * Atomically adds @i to @l and returns @i + @l
>> + */
>> +static inline long local_add_return_wrap(long i, local_wrap_t *l)
>> +{
>> +     long __i = i;
>>       asm volatile(_ASM_XADD "%0, %1;"
>>                    : "+r" (i), "+m" (l->a.counter)
>>                    : : "memory");
>> @@ -121,6 +200,8 @@ static inline long local_sub_return(long i, local_t *l)
>>
>>  #define local_cmpxchg(l, o, n) \
>>       (cmpxchg_local(&((l)->a.counter), (o), (n)))
>> +#define local_cmpxchg_wrap(l, o, n) \
>> +     (cmpxchg_local(&((l)->a.counter), (o), (n)))
>>  /* Always has a lock prefix */
>>  #define local_xchg(l, n) (xchg(&((l)->a.counter), (n)))
>>
>> diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h
>> index 17f2186..2fa0e84 100644
>> --- a/arch/x86/include/asm/preempt.h
>> +++ b/arch/x86/include/asm/preempt.h
>> @@ -81,7 +81,7 @@ static __always_inline void __preempt_count_sub(int val)
>>   */
>>  static __always_inline bool __preempt_count_dec_and_test(void)
>>  {
>> -     GEN_UNARY_RMWcc("decl", __preempt_count, __percpu_arg(0), e);
>> +    GEN_UNARY_RMWcc("decl", "incl", __preempt_count, __percpu_arg(0), e);
>>  }
>>
>>  /*
>> diff --git a/arch/x86/include/asm/rmwcc.h b/arch/x86/include/asm/rmwcc.h
>> index 661dd30..0375d3f 100644
>> --- a/arch/x86/include/asm/rmwcc.h
>> +++ b/arch/x86/include/asm/rmwcc.h
>> @@ -5,28 +5,80 @@
>>
>>  /* Use asm goto */
>>
>> -#define __GEN_RMWcc(fullop, var, cc, ...)                            \
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +#define __GEN_RMWcc(fullop, fullantiop, var, cc, ...)                        \
>>  do {                                                                 \
>> -     asm_volatile_goto (fullop "; j" #cc " %l[cc_label]"             \
>> +     asm_volatile_goto (fullop                                       \
>> +                     ";jno 0f\n"                                     \
>> +                     fullantiop                                      \
>> +                     ";int $4\n0:\n"                                 \
>> +                     _ASM_EXTABLE(0b, 0b)                            \
>> +                      ";j" #cc " %l[cc_label]"                       \
>>                       : : "m" (var), ## __VA_ARGS__                   \
>>                       : "memory" : cc_label);                         \
>>       return 0;                                                       \
>>  cc_label:                                                            \
>>       return 1;                                                       \
>>  } while (0)
>> +#else
>> +#define __GEN_RMWcc(fullop, fullantiop, var, cc, ...)                        \
>> +do {                                                                 \
>> +     asm_volatile_goto (fullop ";j" #cc " %l[cc_label]"              \
>> +                     : : "m" (var), ## __VA_ARGS__                   \
>> +                     : "memory" : cc_label);                         \
>> +     return 0;                                                       \
>> +cc_label:                                                            \
>> +     return 1;                                                       \
>> +} while (0)
>> +#endif
>>
>> -#define GEN_UNARY_RMWcc(op, var, arg0, cc)                           \
>> -     __GEN_RMWcc(op " " arg0, var, cc)
>> -
>> -#define GEN_BINARY_RMWcc(op, var, vcon, val, arg0, cc)                       \
>> -     __GEN_RMWcc(op " %1, " arg0, var, cc, vcon (val))
>> +#define __GEN_RMWcc_wrap(fullop, var, cc, ...)do {                                                                   \
>> +     asm_volatile_goto (fullop "; j" #cc " %l[cc_label]"             \
>> +                     : : "m" (var), ## __VA_ARGS__                   \
>> +                     : "memory" : cc_label);                         \
>> +     return 0;                                                       \
>> +cc_label:                                                            \
>> +     return 1;                                                       \
>> +} while (0)
>>
>> +#define GEN_UNARY_RMWcc(op, antiop, var, arg0, cc)                   \
>> +     __GEN_RMWcc(op " " arg0, antiop " " arg0, var, cc)
>> +#define GEN_UNARY_RMWcc_wrap(op, var, arg0, cc)                      \
>> +     __GEN_RMWcc_wrap(op " " arg0, var, cc)
>> +#define GEN_BINARY_RMWcc(op, antiop, var, vcon, val, arg0, cc)               \
>> +     __GEN_RMWcc(op " %1, " arg0, antiop " %1, " arg0, var, cc, vcon (val))
>> +#define GEN_BINARY_RMWcc_wrap(op, var, vcon, val, arg0, cc)  \
>> +     __GEN_RMWcc_wrap(op " %1, " arg0, var, cc, vcon (val))
>>  #else /* defined(__GCC_ASM_FLAG_OUTPUTS__) || !defined(CC_HAVE_ASM_GOTO) */
>>
>>  /* Use flags output or a set instruction */
>>
>> -#define __GEN_RMWcc(fullop, var, cc, ...)                            \
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +#define __GEN_RMWcc(fullop, fullantiop, var, cc, ...)                        \
>>  do {                                                                 \
>> +     char c;                                                         \
>> +     asm volatile (fullop                                            \
>> +                     ";jno 0f\n"                                     \
>> +                     fullantiop                                      \
>> +                     ";int $4\n0:\n"                                 \
>> +                     _ASM_EXTABLE(0b, 0b)                            \
>> +                     ";" CC_SET(cc)                          \
>> +                     : "+m" (var), CC_OUT(cc) (c)                    \
>> +                     : __VA_ARGS__ : "memory");                      \
>> +     return c != 0;                                                  \
>> +} while (0)
>> +#else
>> +#define __GEN_RMWcc(fullop, fullantiop, var, cc, ...)                        \
>> +do {                                                                 \
>> +     char c;                                                         \
>> +     asm volatile (fullop ";" CC_SET(cc)                             \
>> +                     : "+m" (var), CC_OUT(cc) (c)                    \
>> +                     : __VA_ARGS__ : "memory");                      \
>> +     return c != 0;                                                  \
>> +} while (0)
>> +#endif
>> +
>> +#define __GEN_RMWcc_wrap(fullop, var, cc, ...)do {                                                                   \
>>       bool c;                                                         \
>>       asm volatile (fullop ";" CC_SET(cc)                             \
>>                       : "+m" (var), CC_OUT(cc) (c)                    \
>> @@ -34,12 +86,14 @@ do {                                                                      \
>>       return c;                                                       \
>>  } while (0)
>>
>> -#define GEN_UNARY_RMWcc(op, var, arg0, cc)                           \
>> -     __GEN_RMWcc(op " " arg0, var, cc)
>> -
>> -#define GEN_BINARY_RMWcc(op, var, vcon, val, arg0, cc)                       \
>> -     __GEN_RMWcc(op " %2, " arg0, var, cc, vcon (val))
>> -
>> +#define GEN_UNARY_RMWcc(op, antiop, var, arg0, cc)                   \
>> +     __GEN_RMWcc(op " " arg0, antiop " " arg0, var, cc)
>> +#define GEN_UNARY_RMWcc_wrap(op, var, arg0, cc)                      \
>> +     __GEN_RMWcc_wrap(op " " arg0, var, cc)
>> +#define GEN_BINARY_RMWcc(op, antiop, var, vcon, val, arg0, cc)               \
>> +     __GEN_RMWcc(op " %2, " arg0, antiop " %2, " arg0, var, cc, vcon (val))
>> +#define GEN_BINARY_RMWcc_wrap(op, var, vcon, val, arg0, cc)  \
>> +     __GEN_RMWcc_wrap(op " %2, " arg0, var, cc, vcon (val))
>>  #endif /* defined(__GCC_ASM_FLAG_OUTPUTS__) || !defined(CC_HAVE_ASM_GOTO) */
>>
>>  #endif /* _ASM_X86_RMWcc */
>> diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h
>> index 3d33a71..4d3f8a5 100644
>> --- a/arch/x86/include/asm/rwsem.h
>> +++ b/arch/x86/include/asm/rwsem.h
>> @@ -64,6 +64,14 @@ static inline void __down_read(struct rw_semaphore *sem)
>>  {
>>       asm volatile("# beginning down_read\n\t"
>>                    LOCK_PREFIX _ASM_INC "(%1)\n\t"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  LOCK_PREFIX _ASM_DEC "(%1)\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +
>>                    /* adds 0x00000001 */
>>                    "  jns        1f\n"
>>                    "  call call_rwsem_down_read_failed\n"
>> @@ -85,6 +93,14 @@ static inline bool __down_read_trylock(struct rw_semaphore *sem)
>>                    "1:\n\t"
>>                    "  mov          %1,%2\n\t"
>>                    "  add          %3,%2\n\t"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  "sub %3,%2\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +
>>                    "  jle          2f\n\t"
>>                    LOCK_PREFIX "  cmpxchg  %2,%0\n\t"
>>                    "  jnz          1b\n\t"
>> @@ -99,12 +115,22 @@ static inline bool __down_read_trylock(struct rw_semaphore *sem)
>>  /*
>>   * lock for writing
>>   */
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +#define ____down_write_undo \
>> +                  "jno 0f\n"\
>> +                  "mov %1,(%2)\n"\
>> +                  "int $4\n0:\n"\
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#else
>> +#define ____down_write_undo
>> +#endif
>>  #define ____down_write(sem, slow_path)                       \
>>  ({                                                   \
>>       long tmp;                                       \
>>       struct rw_semaphore* ret;                       \
>>       asm volatile("# beginning down_write\n\t"       \
>>                    LOCK_PREFIX "  xadd      %1,(%3)\n\t"      \
>> +                  ____down_write_undo                \
>>                    /* adds 0xffff0001, returns the old value */ \
>>                    "  test " __ASM_SEL(%w1,%k1) "," __ASM_SEL(%w1,%k1) "\n\t" \
>>                    /* was the active mask 0 before? */\
>> @@ -166,6 +192,14 @@ static inline void __up_read(struct rw_semaphore *sem)
>>       long tmp;
>>       asm volatile("# beginning __up_read\n\t"
>>                    LOCK_PREFIX "  xadd      %1,(%2)\n\t"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  "mov %1,(%2)\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +
>>                    /* subtracts 1, returns the old value */
>>                    "  jns        1f\n\t"
>>                    "  call call_rwsem_wake\n" /* expects old value in %edx */
>> @@ -184,6 +218,14 @@ static inline void __up_write(struct rw_semaphore *sem)
>>       long tmp;
>>       asm volatile("# beginning __up_write\n\t"
>>                    LOCK_PREFIX "  xadd      %1,(%2)\n\t"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  "mov %1,(%2)\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +
>>                    /* subtracts 0xffff0001, returns the old value */
>>                    "  jns        1f\n\t"
>>                    "  call call_rwsem_wake\n" /* expects old value in %edx */
>> @@ -201,6 +243,14 @@ static inline void __downgrade_write(struct rw_semaphore *sem)
>>  {
>>       asm volatile("# beginning __downgrade_write\n\t"
>>                    LOCK_PREFIX _ASM_ADD "%2,(%1)\n\t"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  LOCK_PREFIX _ASM_SUB "%2,(%1)\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +
>>                    /*
>>                     * transitions 0xZZZZ0001 -> 0xYYYY0001 (i386)
>>                     *     0xZZZZZZZZ00000001 -> 0xYYYYYYYY00000001 (x86_64)
>> diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
>> index bd4e3d4..d67a914 100644
>> --- a/arch/x86/kernel/traps.c
>> +++ b/arch/x86/kernel/traps.c
>> @@ -191,6 +191,10 @@ do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
>>                       tsk->thread.trap_nr = trapnr;
>>                       die(str, regs, error_code);
>>               }
>> +
>> +             if (trapnr == X86_TRAP_OF)
>> +                     hardened_atomic_overflow(regs);
>> +
>>               return 0;
>>       }
>>
>> diff --git a/arch/x86/lib/atomic64_386_32.S b/arch/x86/lib/atomic64_386_32.S
>> index 9b0ca8f..0e8a888 100644
>> --- a/arch/x86/lib/atomic64_386_32.S
>> +++ b/arch/x86/lib/atomic64_386_32.S
>> @@ -45,6 +45,10 @@ BEGIN(read)
>>       movl  (v), %eax
>>       movl 4(v), %edx
>>  RET_ENDP
>> +BEGIN(read_wrap)
>> +     movl  (v), %eax
>> +     movl 4(v), %edx
>> +RET_ENDP
>>  #undef v
>>
>>  #define v %esi
>> @@ -52,6 +56,10 @@ BEGIN(set)
>>       movl %ebx,  (v)
>>       movl %ecx, 4(v)
>>  RET_ENDP
>> +BEGIN(set_wrap)
>> +     movl %ebx,  (v)
>> +     movl %ecx, 4(v)
>> +RET_ENDP
>>  #undef v
>>
>>  #define v  %esi
>> @@ -67,6 +75,18 @@ RET_ENDP
>>  BEGIN(add)
>>       addl %eax,  (v)
>>       adcl %edx, 4(v)
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +     jno 0f
>> +     subl %eax,  (v)
>> +     sbbl %edx, 4(v)
>> +     int $4
>> +0:
>> +     _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +RET_ENDP
>> +BEGIN(add_wrap)
>> +     addl %eax,  (v)
>> +     adcl %edx, 4(v)
>>  RET_ENDP
>>  #undef v
>>
>> @@ -74,6 +94,20 @@ RET_ENDP
>>  BEGIN(add_return)
>>       addl  (v), %eax
>>       adcl 4(v), %edx
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +     into
>> +1234:
>> +     _ASM_EXTABLE(1234b, 2f)
>> +#endif
>> +     movl %eax,  (v)
>> +     movl %edx, 4(v)
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +2:
>> +#endif
>> +RET_ENDP
>> +BEGIN(add_return_wrap)
>> +     addl  (v), %eax
>> +     adcl 4(v), %edx
>>       movl %eax,  (v)
>>       movl %edx, 4(v)
>>  RET_ENDP
>> @@ -83,6 +117,18 @@ RET_ENDP
>>  BEGIN(sub)
>>       subl %eax,  (v)
>>       sbbl %edx, 4(v)
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +     jno 0f
>> +     addl %eax,  (v)
>> +     adcl %edx, 4(v)
>> +     int $4
>> +0:
>> +     _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +RET_ENDP
>> +BEGIN(sub_wrap)
>> +     subl %eax,  (v)
>> +     sbbl %edx, 4(v)
>>  RET_ENDP
>>  #undef v
>>
>> @@ -93,6 +139,23 @@ BEGIN(sub_return)
>>       sbbl $0, %edx
>>       addl  (v), %eax
>>       adcl 4(v), %edx
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +     into
>> +1234:
>> +     _ASM_EXTABLE(1234b, 2f)
>> +#endif
>> +     movl %eax,  (v)
>> +     movl %edx, 4(v)
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +2:
>> +#endif
>> +RET_ENDP
>> +BEGIN(sub_return_wrap)
>> +     negl %edx
>> +     negl %eax
>> +     sbbl $0, %edx
>> +     addl  (v), %eax
>> +     adcl 4(v), %edx
>>       movl %eax,  (v)
>>       movl %edx, 4(v)
>>  RET_ENDP
>> @@ -102,6 +165,19 @@ RET_ENDP
>>  BEGIN(inc)
>>       addl $1,  (v)
>>       adcl $0, 4(v)
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +     jno 0f
>> +     subl $1,  (v)
>> +     sbbl $0, 4(v)
>> +     int $4
>> +0:
>> +     _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +
>> +RET_ENDP
>> +BEGIN(inc_wrap)
>> +     addl $1,  (v)
>> +     adcl $0, 4(v)
>>  RET_ENDP
>>  #undef v
>>
>> @@ -111,6 +187,22 @@ BEGIN(inc_return)
>>       movl 4(v), %edx
>>       addl $1, %eax
>>       adcl $0, %edx
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +     into
>> +1234:
>> +     _ASM_EXTABLE(1234b, 2f)
>> +#endif
>> +     movl %eax,  (v)
>> +     movl %edx, 4(v)
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +2:
>> +#endif
>> +RET_ENDP
>> +BEGIN(inc_return_wrap)
>> +     movl  (v), %eax
>> +     movl 4(v), %edx
>> +     addl $1, %eax
>> +     adcl $0, %edx
>>       movl %eax,  (v)
>>       movl %edx, 4(v)
>>  RET_ENDP
>> @@ -120,6 +212,18 @@ RET_ENDP
>>  BEGIN(dec)
>>       subl $1,  (v)
>>       sbbl $0, 4(v)
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +     jno 0f
>> +     addl $1,  (v)
>> +     adcl $0, 4(v)
>> +     int $4
>> +0:
>> +     _ASM_EXTABLE(0b, 0b)
>> +#endif
>> +RET_ENDP
>> +BEGIN(dec_wrap)
>> +     subl $1,  (v)
>> +     sbbl $0, 4(v)
>>  RET_ENDP
>>  #undef v
>>
>> @@ -129,6 +233,22 @@ BEGIN(dec_return)
>>       movl 4(v), %edx
>>       subl $1, %eax
>>       sbbl $0, %edx
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +     into
>> +1234:
>> +     _ASM_EXTABLE(1234b, 2f)
>> +#endif
>> +     movl %eax,  (v)
>> +     movl %edx, 4(v)
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +2:
>> +#endif
>> +RET_ENDP
>> +BEGIN(dec_return_wrap)
>> +     movl  (v), %eax
>> +     movl 4(v), %edx
>> +     subl $1, %eax
>> +     sbbl $0, %edx
>>       movl %eax,  (v)
>>       movl %edx, 4(v)
>>  RET_ENDP
>> @@ -140,6 +260,11 @@ BEGIN(add_unless)
>>       adcl %edx, %edi
>>       addl  (v), %eax
>>       adcl 4(v), %edx
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +     into
>> +1234:
>> +     _ASM_EXTABLE(1234b, 2f)
>> +#endif
>>       cmpl %eax, %ecx
>>       je 3f
>>  1:
>> @@ -165,6 +290,11 @@ BEGIN(inc_not_zero)
>>  1:
>>       addl $1, %eax
>>       adcl $0, %edx
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +     into
>> +1234:
>> +     _ASM_EXTABLE(1234b, 2f)
>> +#endif
>>       movl %eax,  (v)
>>       movl %edx, 4(v)
>>       movl $1, %eax
>> @@ -183,6 +313,11 @@ BEGIN(dec_if_positive)
>>       movl 4(v), %edx
>>       subl $1, %eax
>>       sbbl $0, %edx
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +     into
>> +1234:
>> +     _ASM_EXTABLE(1234b, 1f)
>> +#endif
>>       js 1f
>>       movl %eax,  (v)
>>       movl %edx, 4(v)
>> diff --git a/arch/x86/lib/atomic64_cx8_32.S b/arch/x86/lib/atomic64_cx8_32.S
>> index db3ae854..5bd864e 100644
>> --- a/arch/x86/lib/atomic64_cx8_32.S
>> +++ b/arch/x86/lib/atomic64_cx8_32.S
>> @@ -22,9 +22,19 @@
>>
>>  ENTRY(atomic64_read_cx8)
>>       read64 %ecx
>> +     /* Pax has pax_force_retaddr here
>> +      * do we want similar? If yes, changes
>> +      * have to be made in more places below */
>>       ret
>>  ENDPROC(atomic64_read_cx8)
>>
>> +ENTRY(atomic64_read_wrap_cx8)
>> +     read64 %ecx
>> +/* do we want smth like the below line?
>> + *   pax_force_retaddr */
>> +     ret
>> +ENDPROC(atomic64_read_wrap_cx8)
>> +
>>  ENTRY(atomic64_set_cx8)
>>  1:
>>  /* we don't need LOCK_PREFIX since aligned 64-bit writes
>> @@ -35,6 +45,17 @@ ENTRY(atomic64_set_cx8)
>>       ret
>>  ENDPROC(atomic64_set_cx8)
>>
>> +ENTRY(atomic64_set_wrap_cx8)
>> +1:
>> +/* we don't need LOCK_PREFIX since aligned 64-bit writes
>> + * are atomic on 586 and newer */
>> +     cmpxchg8b (%esi)
>> +     jne 1b
>> +
>> +     /* pax_force_retaddr */
>> +     ret
>> +ENDPROC(atomic64_set_wrap_cx8)
>> +
>>  ENTRY(atomic64_xchg_cx8)
>>  1:
>>       LOCK_PREFIX
>> @@ -44,8 +65,8 @@ ENTRY(atomic64_xchg_cx8)
>>       ret
>>  ENDPROC(atomic64_xchg_cx8)
>>
>> -.macro addsub_return func ins insc
>> -ENTRY(atomic64_\func\()_return_cx8)
>> +.macro addsub_return func ins insc wrap=""
>> +ENTRY(atomic64_\func\()_return\wrap\()_cx8)
>>       pushl %ebp
>>       pushl %ebx
>>       pushl %esi
>> @@ -61,6 +82,13 @@ ENTRY(atomic64_\func\()_return_cx8)
>>       movl %edx, %ecx
>>       \ins\()l %esi, %ebx
>>       \insc\()l %edi, %ecx
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +.ifb \wrap
>> +     into
>> +2:
>> +     _ASM_EXTABLE(2b, 3f)
>> +.endif
>> +#endif
>>       LOCK_PREFIX
>>       cmpxchg8b (%ebp)
>>       jne 1b
>> @@ -68,19 +96,27 @@ ENTRY(atomic64_\func\()_return_cx8)
>>  10:
>>       movl %ebx, %eax
>>       movl %ecx, %edx
>> +
>> +.ifb \wrap
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +3:
>> +#endif
>> +.endif
>>       popl %edi
>>       popl %esi
>>       popl %ebx
>>       popl %ebp
>>       ret
>> -ENDPROC(atomic64_\func\()_return_cx8)
>> +ENDPROC(atomic64_\func\()_return\wrap\()_cx8)
>>  .endm
>>
>>  addsub_return add add adc
>>  addsub_return sub sub sbb
>> +addsub_return add add adc _wrap
>> +addsub_return sub sub sbb _wrap
>>
>> -.macro incdec_return func ins insc
>> -ENTRY(atomic64_\func\()_return_cx8)
>> +.macro incdec_return func ins insc wrap=""
>> +ENTRY(atomic64_\func\()_return\wrap\()_cx8)
>>       pushl %ebx
>>
>>       read64 %esi
>> @@ -89,6 +125,13 @@ ENTRY(atomic64_\func\()_return_cx8)
>>       movl %edx, %ecx
>>       \ins\()l $1, %ebx
>>       \insc\()l $0, %ecx
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +.ifb \wrap
>> +     into
>> +2:
>> +     _ASM_EXTABLE(2b, 3f)
>> +.endif
>> +#endif
>>       LOCK_PREFIX
>>       cmpxchg8b (%esi)
>>       jne 1b
>> @@ -96,13 +139,21 @@ ENTRY(atomic64_\func\()_return_cx8)
>>  10:
>>       movl %ebx, %eax
>>       movl %ecx, %edx
>> +
>> +.ifb \wrap
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +3:
>> +#endif
>> +.endif
>>       popl %ebx
>>       ret
>> -ENDPROC(atomic64_\func\()_return_cx8)
>> +ENDPROC(atomic64_\func\()_return\wrap\()_cx8)
>>  .endm
>>
>>  incdec_return inc add adc
>>  incdec_return dec sub sbb
>> +incdec_return inc add adc _wrap
>> +incdec_return dec sub sbb _wrap
>>
>>  ENTRY(atomic64_dec_if_positive_cx8)
>>       pushl %ebx
>> @@ -113,6 +164,11 @@ ENTRY(atomic64_dec_if_positive_cx8)
>>       movl %edx, %ecx
>>       subl $1, %ebx
>>       sbb $0, %ecx
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +     into
>> +1234:
>> +     _ASM_EXTABLE(1234b, 2f)
>> +#endif
>>       js 2f
>>       LOCK_PREFIX
>>       cmpxchg8b (%esi)
>> @@ -144,6 +200,11 @@ ENTRY(atomic64_add_unless_cx8)
>>       movl %edx, %ecx
>>       addl %ebp, %ebx
>>       adcl %edi, %ecx
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +     into
>> +1234:
>> +     _ASM_EXTABLE(1234b, 3f)
>> +#endif
>>       LOCK_PREFIX
>>       cmpxchg8b (%esi)
>>       jne 1b
>> @@ -173,6 +234,11 @@ ENTRY(atomic64_inc_not_zero_cx8)
>>       xorl %ecx, %ecx
>>       addl $1, %ebx
>>       adcl %edx, %ecx
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +     into
>> +1234:
>> +     _ASM_EXTABLE(1234b, 3f)
>> +#endif
>>       LOCK_PREFIX
>>       cmpxchg8b (%esi)
>>       jne 1b
>> --
>> 2.7.4
>>

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