* [PATCH kvm-unit-tests] x86: fix stack pointer after call
@ 2020-06-25 11:15 Paolo Bonzini
2020-06-25 13:01 ` Thomas Huth
0 siblings, 1 reply; 2+ messages in thread
From: Paolo Bonzini @ 2020-06-25 11:15 UTC (permalink / raw)
To: kvm; +Cc: namit
Since setup_multiboot has a C calling convention, the stack pointer must
be adjusted after the call. Without this change, the bottom of the
percpu area would be 4 bytes below the bottom of the stack.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
x86/cstart.S | 1 +
1 file changed, 1 insertion(+)
diff --git a/x86/cstart.S b/x86/cstart.S
index deb08b7..409cb00 100644
--- a/x86/cstart.S
+++ b/x86/cstart.S
@@ -116,6 +116,7 @@ start:
push %ebx
call setup_multiboot
+ addl $4, %esp
call setup_libcflat
mov mb_cmdline(%ebx), %eax
mov %eax, __args
--
2.26.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH kvm-unit-tests] x86: fix stack pointer after call
2020-06-25 11:15 [PATCH kvm-unit-tests] x86: fix stack pointer after call Paolo Bonzini
@ 2020-06-25 13:01 ` Thomas Huth
0 siblings, 0 replies; 2+ messages in thread
From: Thomas Huth @ 2020-06-25 13:01 UTC (permalink / raw)
To: Paolo Bonzini, kvm; +Cc: namit
On 25/06/2020 13.15, Paolo Bonzini wrote:
> Since setup_multiboot has a C calling convention, the stack pointer must
> be adjusted after the call. Without this change, the bottom of the
> percpu area would be 4 bytes below the bottom of the stack.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> x86/cstart.S | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/x86/cstart.S b/x86/cstart.S
> index deb08b7..409cb00 100644
> --- a/x86/cstart.S
> +++ b/x86/cstart.S
> @@ -116,6 +116,7 @@ start:
>
> push %ebx
> call setup_multiboot
> + addl $4, %esp
> call setup_libcflat
> mov mb_cmdline(%ebx), %eax
> mov %eax, __args
Looks right.
Reviewed-by: Thomas Huth <thuth@redhat.com>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2020-06-25 11:15 [PATCH kvm-unit-tests] x86: fix stack pointer after call Paolo Bonzini
2020-06-25 13:01 ` Thomas Huth
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