[PATCH v9 4/5] x86/cpuid: fix unbootable VMs by really inlining memcmp() in hypervisor_cpuid_base()
Mauricio Faria de Oliveira <[email protected]>
| Newsgroups | org.xenproject.lists.xen-devel,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <[email protected]> |
Even with __builtin the compiler may decide to use the out of line function
instead of the inline implementation.
The existing code is broken with gcc-14/15 but not gcc-12/13 (Ubuntu 25.10)
and vmlinux no longer boots with CONFIG_PVH if CONFIG_KASAN_GENERIC is set.
For testing purposes, if the size argument is reduced from 12 to 8 then the
compiler decides to use the inline implementation; that shows results vary.
Switch the builtin to the inline implementation to address it.
Fixes: 416a33c9afce ("x86/cpu: fix unbootable VMs by inlining memcmp() in hypervisor_cpuid_base()")
Signed-off-by: Mauricio Faria de Oliveira <[email protected]>
Reviewed-by: Juergen Gross <[email protected]>
---
arch/x86/include/asm/cpuid/api.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/cpuid/api.h b/arch/x86/include/asm/cpuid/api.h
index 82eddfa2347b32b76c2ea9b85f005ca5416ac71f..2d9f3d4d63de6e721f275d9e80d372edbdfedf30 100644
--- a/arch/x86/include/asm/cpuid/api.h
+++ b/arch/x86/include/asm/cpuid/api.h
@@ -204,7 +204,7 @@ static inline u32 cpuid_base_hypervisor(const char *sig, u32 leaves)
* from PVH early boot code before instrumentation is set up
* and memcmp() itself may be instrumented.
*/
- if (!__builtin_memcmp(sig, signature, 12) &&
+ if (!__inline_memcmp(sig, signature, 12) &&
(leaves == 0 || ((eax - base) >= leaves)))
return base;
}
--
2.47.3