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| author | Pawan Gupta <pawan.kumar.gupta@linux.intel.com> | 2024-02-26 15:52:33 -0800 |
|---|---|---|
| committer | Dave Hansen <dave.hansen@linux.intel.com> | 2024-02-26 17:06:17 -0800 |
| commit | 8009479ee919b9a91674f48050ccbff64eafedaa (patch) | |
| tree | d35a8f38ef9b110fe1bee90fc300f20c8799997d | |
| parent | 6890cb1ace350b4386c8aee1343dc3b3ddd214da (diff) | |
| download | lwn-8009479ee919b9a91674f48050ccbff64eafedaa.tar.gz lwn-8009479ee919b9a91674f48050ccbff64eafedaa.zip | |
x86/bugs: Use fixed addressing for VERW operand
The macro used for MDS mitigation executes VERW with relative
addressing for the operand. This was necessary in earlier versions of
the series. Now it is unnecessary and creates a problem for backports
on older kernels that don't support relocations in alternatives.
Relocation support was added by commit 270a69c4485d ("x86/alternative:
Support relocations in alternatives"). Also asm for fixed addressing
is much cleaner than relative RIP addressing.
Simplify the asm by using fixed addressing for VERW operand.
[ dhansen: tweak changelog ]
Closes: https://lore.kernel.org/lkml/20558f89-299b-472e-9a96-171403a83bd6@suse.com/
Fixes: baf8361e5455 ("x86/bugs: Add asm helpers for executing VERW")
Reported-by: Nikolay Borisov <nik.borisov@suse.com>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/20240226-verw-arg-fix-v1-1-7b37ee6fd57d%40linux.intel.com
| -rw-r--r-- | arch/x86/include/asm/nospec-branch.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index 2aa52cab1e46..ab19c7f1167b 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -323,7 +323,7 @@ * Note: Only the memory operand variant of VERW clears the CPU buffers. */ .macro CLEAR_CPU_BUFFERS - ALTERNATIVE "", __stringify(verw _ASM_RIP(mds_verw_sel)), X86_FEATURE_CLEAR_CPU_BUF + ALTERNATIVE "", __stringify(verw mds_verw_sel), X86_FEATURE_CLEAR_CPU_BUF .endm #else /* __ASSEMBLY__ */ |