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| Started by | Alexander Kuleshov <kuleshovmail@gmail.com> |
|---|---|
| First post | 2016-01-23 08:00 +0100 |
| Last post | 2016-01-26 10:40 +0100 |
| Articles | 2 — 2 participants |
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[PATCH] x86/head_64.S: do not use temporary register to check alignment Alexander Kuleshov <kuleshovmail@gmail.com> - 2016-01-23 08:00 +0100
Re: [PATCH] x86/head_64.S: do not use temporary register to check alignment Borislav Petkov <bp@suse.de> - 2016-01-26 10:40 +0100
| From | Alexander Kuleshov <kuleshovmail@gmail.com> |
|---|---|
| Date | 2016-01-23 08:00 +0100 |
| Subject | [PATCH] x86/head_64.S: do not use temporary register to check alignment |
| Message-ID | <qU0l4-7kW-11@gated-at.bofh.it> |
We are using temporary %rax register during checking of kernel address alignment. We can ged rid of it since testl instruction is safe and does not change value of the rbp register. Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com> Suggested-by: Brian Gerst <brgerst@gmail.com> --- arch/x86/kernel/head_64.S | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index ffdc0e8..7c21029 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -76,9 +76,7 @@ startup_64: subq $_text - __START_KERNEL_map, %rbp /* Is the address not 2M aligned? */ - movq %rbp, %rax - andl $~PMD_PAGE_MASK, %eax - testl %eax, %eax + testl $~PMD_PAGE_MASK, %ebp jnz bad_address /* -- 2.7.0.25.gfc10eb5
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| From | Borislav Petkov <bp@suse.de> |
|---|---|
| Date | 2016-01-26 10:40 +0100 |
| Subject | Re: [PATCH] x86/head_64.S: do not use temporary register to check alignment |
| Message-ID | <qV8gq-28S-9@gated-at.bofh.it> |
| In reply to | #1315527 |
On Sat, Jan 23, 2016 at 12:50:28PM +0600, Alexander Kuleshov wrote:
> We are using temporary %rax register during checking of kernel address
> alignment. We can ged rid of it since testl instruction is safe and does
> not change value of the rbp register.
>
> Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
> Suggested-by: Brian Gerst <brgerst@gmail.com>
> ---
> arch/x86/kernel/head_64.S | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
> index ffdc0e8..7c21029 100644
> --- a/arch/x86/kernel/head_64.S
> +++ b/arch/x86/kernel/head_64.S
> @@ -76,9 +76,7 @@ startup_64:
> subq $_text - __START_KERNEL_map, %rbp
>
> /* Is the address not 2M aligned? */
> - movq %rbp, %rax
> - andl $~PMD_PAGE_MASK, %eax
> - testl %eax, %eax
> + testl $~PMD_PAGE_MASK, %ebp
> jnz bad_address
>
> /*
> --
Applied, thanks.
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--
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