From: Thomas Gleixner <[email protected]>
The entries in the .parainstr sections are 8 byte aligned and the
corresponding C struct makes the array offset 16 bytes.
Though the pushed entries are only using 12 bytes. .parainstr_end is
therefore 4 bytes short.
That works by chance because it's only used in a loop:
for (p = start; p < end; p++)
But this falls flat when calculating the number of elements:
n = end - start
That's obviously off by one.
Ensure that the gap is filled and the last entry is occupying 16 bytes.
Cc: Juergen Gross <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
---
arch/x86/include/asm/paravirt.h | 1 +
arch/x86/include/asm/paravirt_types.h | 1 +
2 files changed, 2 insertions(+)
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -743,6 +743,7 @@ extern void default_banner(void);
word 771b; \
.byte ptype; \
.byte 772b-771b; \
+ _ASM_ALIGN; \
.popsection
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -294,6 +294,7 @@ extern struct paravirt_patch_template pv
" .byte " type "\n" \
" .byte 772b-771b\n" \
" .short " clobber "\n" \
+ _ASM_ALIGN "\n" \
".popsection\n"
/* Generate patchable code, with the default asm parameters. */
On 02.09.22 15:06, Peter Zijlstra wrote:
> From: Thomas Gleixner <[email protected]>
>
> The entries in the .parainstr sections are 8 byte aligned and the
> corresponding C struct makes the array offset 16 bytes.
>
> Though the pushed entries are only using 12 bytes. .parainstr_end is
> therefore 4 bytes short.
>
> That works by chance because it's only used in a loop:
>
> for (p = start; p < end; p++)
>
> But this falls flat when calculating the number of elements:
>
> n = end - start
>
> That's obviously off by one.
>
> Ensure that the gap is filled and the last entry is occupying 16 bytes.
>
> Cc: Juergen Gross <[email protected]>
> Signed-off-by: Thomas Gleixner <[email protected]>
> Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Juergen Gross <[email protected]>
Juergen