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Date: Mon, 10 Jun 2019 16:52:02 -0700
From: Kees Cook <keescook@...omium.org>
To: Thomas Garnier <thgarnie@...omium.org>
Cc: kernel-hardening@...ts.openwall.com, kristen@...ux.intel.com,
Thomas Garnier <thgarnie@...gle.com>, Pavel Machek <pavel@....cz>,
"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Len Brown <len.brown@...el.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 08/12] x86/acpi: Adapt assembly for PIE support
On Mon, May 20, 2019 at 04:19:33PM -0700, Thomas Garnier wrote:
> From: Thomas Garnier <thgarnie@...gle.com>
>
> Change the assembly code to use only relative references of symbols for the
> kernel to be PIE compatible.
>
> Position Independent Executable (PIE) support will allow to extend the
> KASLR randomization range below 0xffffffff80000000.
>
> Signed-off-by: Thomas Garnier <thgarnie@...gle.com>
Reviewed-by: Kees Cook <keescook@...omium.org>
-Kees
> Acked-by: Pavel Machek <pavel@....cz>
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
> arch/x86/kernel/acpi/wakeup_64.S | 31 ++++++++++++++++---------------
> 1 file changed, 16 insertions(+), 15 deletions(-)
>
> diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
> index 510fa12aab73..e080e943e295 100644
> --- a/arch/x86/kernel/acpi/wakeup_64.S
> +++ b/arch/x86/kernel/acpi/wakeup_64.S
> @@ -14,7 +14,7 @@
> * Hooray, we are in Long 64-bit mode (but still running in low memory)
> */
> ENTRY(wakeup_long64)
> - movq saved_magic, %rax
> + movq saved_magic(%rip), %rax
> movq $0x123456789abcdef0, %rdx
> cmpq %rdx, %rax
> jne bogus_64_magic
> @@ -25,14 +25,14 @@ ENTRY(wakeup_long64)
> movw %ax, %es
> movw %ax, %fs
> movw %ax, %gs
> - movq saved_rsp, %rsp
> + movq saved_rsp(%rip), %rsp
>
> - movq saved_rbx, %rbx
> - movq saved_rdi, %rdi
> - movq saved_rsi, %rsi
> - movq saved_rbp, %rbp
> + movq saved_rbx(%rip), %rbx
> + movq saved_rdi(%rip), %rdi
> + movq saved_rsi(%rip), %rsi
> + movq saved_rbp(%rip), %rbp
>
> - movq saved_rip, %rax
> + movq saved_rip(%rip), %rax
> jmp *%rax
> ENDPROC(wakeup_long64)
>
> @@ -45,7 +45,7 @@ ENTRY(do_suspend_lowlevel)
> xorl %eax, %eax
> call save_processor_state
>
> - movq $saved_context, %rax
> + leaq saved_context(%rip), %rax
> movq %rsp, pt_regs_sp(%rax)
> movq %rbp, pt_regs_bp(%rax)
> movq %rsi, pt_regs_si(%rax)
> @@ -64,13 +64,14 @@ ENTRY(do_suspend_lowlevel)
> pushfq
> popq pt_regs_flags(%rax)
>
> - movq $.Lresume_point, saved_rip(%rip)
> + leaq .Lresume_point(%rip), %rax
> + movq %rax, saved_rip(%rip)
>
> - movq %rsp, saved_rsp
> - movq %rbp, saved_rbp
> - movq %rbx, saved_rbx
> - movq %rdi, saved_rdi
> - movq %rsi, saved_rsi
> + movq %rsp, saved_rsp(%rip)
> + movq %rbp, saved_rbp(%rip)
> + movq %rbx, saved_rbx(%rip)
> + movq %rdi, saved_rdi(%rip)
> + movq %rsi, saved_rsi(%rip)
>
> addq $8, %rsp
> movl $3, %edi
> @@ -82,7 +83,7 @@ ENTRY(do_suspend_lowlevel)
> .align 4
> .Lresume_point:
> /* We don't restore %rax, it must be 0 anyway */
> - movq $saved_context, %rax
> + leaq saved_context(%rip), %rax
> movq saved_context_cr4(%rax), %rbx
> movq %rbx, %cr4
> movq saved_context_cr3(%rax), %rbx
> --
> 2.21.0.1020.gf2820cf01a-goog
>
--
Kees Cook
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