From 8009479ee919b9a91674f48050ccbff64eafedaa Mon Sep 17 00:00:00 2001 From: Pawan Gupta Date: Mon, 26 Feb 2024 15:52:33 -0800 Subject: [PATCH] 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 --- arch/x86/include/asm/nospec-branch.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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__ */ -- 2.25.1