* [PATCH] x86/shim: don't use 32-bit compare on boolean variable
@ 2018-01-31 15:33 Jan Beulich
2018-01-31 15:36 ` Andrew Cooper
2018-02-01 10:06 ` Roger Pau Monné
0 siblings, 2 replies; 3+ messages in thread
From: Jan Beulich @ 2018-01-31 15:33 UTC (permalink / raw)
To: xen-devel; +Cc: Andrew Cooper
Current upstream gas silently assumes 32-bit operand size for most
operations where the size can't be inferred from an involved register
(my own one doesn't anymore, which is how I've noticed this). It is pure
luck that the 3 bytes following pvh_boot are currently padding ones.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -586,7 +586,7 @@ trampoline_setup:
push %eax /* Magic number. */
call reloc
#ifdef CONFIG_PVH_GUEST
- cmp $0, sym_fs(pvh_boot)
+ cmpb $0, sym_fs(pvh_boot)
je 1f
mov %eax, sym_fs(pvh_start_info_pa)
jmp 2f
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] x86/shim: don't use 32-bit compare on boolean variable
2018-01-31 15:33 [PATCH] x86/shim: don't use 32-bit compare on boolean variable Jan Beulich
@ 2018-01-31 15:36 ` Andrew Cooper
2018-02-01 10:06 ` Roger Pau Monné
1 sibling, 0 replies; 3+ messages in thread
From: Andrew Cooper @ 2018-01-31 15:36 UTC (permalink / raw)
To: Jan Beulich, xen-devel
On 31/01/18 15:33, Jan Beulich wrote:
> Current upstream gas silently assumes 32-bit operand size for most
> operations where the size can't be inferred from an involved register
> (my own one doesn't anymore, which is how I've noticed this). It is pure
> luck that the 3 bytes following pvh_boot are currently padding ones.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper@citrix.com>
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] x86/shim: don't use 32-bit compare on boolean variable
2018-01-31 15:33 [PATCH] x86/shim: don't use 32-bit compare on boolean variable Jan Beulich
2018-01-31 15:36 ` Andrew Cooper
@ 2018-02-01 10:06 ` Roger Pau Monné
1 sibling, 0 replies; 3+ messages in thread
From: Roger Pau Monné @ 2018-02-01 10:06 UTC (permalink / raw)
To: Jan Beulich; +Cc: xen-devel, Andrew Cooper
On Wed, Jan 31, 2018 at 08:33:46AM -0700, Jan Beulich wrote:
> Current upstream gas silently assumes 32-bit operand size for most
> operations where the size can't be inferred from an involved register
> (my own one doesn't anymore, which is how I've noticed this). It is pure
> luck that the 3 bytes following pvh_boot are currently padding ones.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Thanks, Roger.
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^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2018-02-01 10:06 UTC | newest]
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2018-01-31 15:33 [PATCH] x86/shim: don't use 32-bit compare on boolean variable Jan Beulich
2018-01-31 15:36 ` Andrew Cooper
2018-02-01 10:06 ` Roger Pau Monné
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