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Date: Wed, 26 Feb 2020 10:11:16 +0800
From: Jason Yan <yanaijie@...wei.com>
To: Christophe Leroy <christophe.leroy@....fr>, <mpe@...erman.id.au>,
<linuxppc-dev@...ts.ozlabs.org>, <diana.craciun@....com>,
<benh@...nel.crashing.org>, <paulus@...ba.org>, <npiggin@...il.com>,
<keescook@...omium.org>, <kernel-hardening@...ts.openwall.com>,
<oss@...error.net>
CC: <linux-kernel@...r.kernel.org>, <zhaohongjiang@...wei.com>
Subject: Re: [PATCH v3 1/6] powerpc/fsl_booke/kaslr: refactor
kaslr_legal_offset() and kaslr_early_init()
在 2020/2/20 21:40, Christophe Leroy 写道:
>
>
> Le 06/02/2020 à 03:58, Jason Yan a écrit :
>> Some code refactor in kaslr_legal_offset() and kaslr_early_init(). No
>> functional change. This is a preparation for KASLR fsl_booke64.
>>
>> Signed-off-by: Jason Yan <yanaijie@...wei.com>
>> Cc: Scott Wood <oss@...error.net>
>> Cc: Diana Craciun <diana.craciun@....com>
>> Cc: Michael Ellerman <mpe@...erman.id.au>
>> Cc: Christophe Leroy <christophe.leroy@....fr>
>> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
>> Cc: Paul Mackerras <paulus@...ba.org>
>> Cc: Nicholas Piggin <npiggin@...il.com>
>> Cc: Kees Cook <keescook@...omium.org>
>> ---
>> arch/powerpc/mm/nohash/kaslr_booke.c | 40 ++++++++++++++--------------
>> 1 file changed, 20 insertions(+), 20 deletions(-)
>>
>> diff --git a/arch/powerpc/mm/nohash/kaslr_booke.c
>> b/arch/powerpc/mm/nohash/kaslr_booke.c
>> index 4a75f2d9bf0e..07b036e98353 100644
>> --- a/arch/powerpc/mm/nohash/kaslr_booke.c
>> +++ b/arch/powerpc/mm/nohash/kaslr_booke.c
>> @@ -25,6 +25,7 @@ struct regions {
>> unsigned long pa_start;
>> unsigned long pa_end;
>> unsigned long kernel_size;
>> + unsigned long linear_sz;
>> unsigned long dtb_start;
>> unsigned long dtb_end;
>> unsigned long initrd_start;
>> @@ -260,11 +261,23 @@ static __init void get_cell_sizes(const void
>> *fdt, int node, int *addr_cells,
>> *size_cells = fdt32_to_cpu(*prop);
>> }
>> -static unsigned long __init kaslr_legal_offset(void *dt_ptr, unsigned
>> long index,
>> - unsigned long offset)
>> +static unsigned long __init kaslr_legal_offset(void *dt_ptr, unsigned
>> long random)
>> {
>> unsigned long koffset = 0;
>> unsigned long start;
>> + unsigned long index;
>> + unsigned long offset;
>> +
>> + /*
>> + * Decide which 64M we want to start
>> + * Only use the low 8 bits of the random seed
>> + */
>> + index = random & 0xFF;
>> + index %= regions.linear_sz / SZ_64M;
>> +
>> + /* Decide offset inside 64M */
>> + offset = random % (SZ_64M - regions.kernel_size);
>> + offset = round_down(offset, SZ_16K);
>> while ((long)index >= 0) {
>> offset = memstart_addr + index * SZ_64M + offset;
>> @@ -289,10 +302,9 @@ static inline __init bool kaslr_disabled(void)
>> static unsigned long __init kaslr_choose_location(void *dt_ptr,
>> phys_addr_t size,
>> unsigned long kernel_sz)
>> {
>> - unsigned long offset, random;
>> + unsigned long random;
>> unsigned long ram, linear_sz;
>> u64 seed;
>> - unsigned long index;
>> kaslr_get_cmdline(dt_ptr);
>> if (kaslr_disabled())
>> @@ -333,22 +345,12 @@ static unsigned long __init
>> kaslr_choose_location(void *dt_ptr, phys_addr_t size
>> regions.dtb_start = __pa(dt_ptr);
>> regions.dtb_end = __pa(dt_ptr) + fdt_totalsize(dt_ptr);
>> regions.kernel_size = kernel_sz;
>> + regions.linear_sz = linear_sz;
>> get_initrd_range(dt_ptr);
>> get_crash_kernel(dt_ptr, ram);
>> - /*
>> - * Decide which 64M we want to start
>> - * Only use the low 8 bits of the random seed
>> - */
>> - index = random & 0xFF;
>> - index %= linear_sz / SZ_64M;
>> -
>> - /* Decide offset inside 64M */
>> - offset = random % (SZ_64M - kernel_sz);
>> - offset = round_down(offset, SZ_16K);
>> -
>> - return kaslr_legal_offset(dt_ptr, index, offset);
>> + return kaslr_legal_offset(dt_ptr, random);
>> }
>> /*
>> @@ -358,8 +360,6 @@ static unsigned long __init
>> kaslr_choose_location(void *dt_ptr, phys_addr_t size
>> */
>> notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size)
>> {
>> - unsigned long tlb_virt;
>> - phys_addr_t tlb_phys;
>> unsigned long offset;
>> unsigned long kernel_sz;
>> @@ -375,8 +375,8 @@ notrace void __init kaslr_early_init(void *dt_ptr,
>> phys_addr_t size)
>> is_second_reloc = 1;
>> if (offset >= SZ_64M) {
>> - tlb_virt = round_down(kernstart_virt_addr, SZ_64M);
>> - tlb_phys = round_down(kernstart_addr, SZ_64M);
>> + unsigned long tlb_virt = round_down(kernstart_virt_addr,
>> SZ_64M);
>> + phys_addr_t tlb_phys = round_down(kernstart_addr, SZ_64M);
>
> That looks like cleanup unrelated to the patch itself.
Hi, Christophe
These two variables is only for the booke32 code, so I moved the
definition here so that I can save a "#ifdef CONFIG_PPC32" for them.
Thanks,
Jason
>
>> /* Create kernel map to relocate in */
>> create_kaslr_tlb_entry(1, tlb_virt, tlb_phys);
>>
>
> Christophe
>
> .
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