From: Pawan Gupta Date: Mon, 26 Feb 2024 23:52:33 +0000 (-0800) Subject: x86/bugs: Use fixed addressing for VERW operand X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=8009479ee919b9a91674f48050ccbff64eafedaa;p=linux.git 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 Signed-off-by: Pawan Gupta Signed-off-by: Dave Hansen Link: https://lore.kernel.org/all/20240226-verw-arg-fix-v1-1-7b37ee6fd57d%40linux.intel.com --- diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index 2aa52cab1e463..ab19c7f1167ba 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__ */