From 3b6f99a94b04b389292590840d96342b7dd08941 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Thu, 5 Dec 2024 12:28:09 +0100 Subject: [PATCH] x86/boot: Disable UBSAN in early boot code The early boot code runs from a 1:1 mapping of memory, and may execute before the kernel virtual mapping is even up. This means absolute symbol references cannot be permitted in this code. UBSAN injects references to global data structures into the code, and without -fPIC, those references are emitted as absolute references to kernel virtual addresses. Accessing those will fault before the kernel virtual mapping is up, so UBSAN needs to be disabled in early boot code. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Cc: Linus Torvalds Cc: "H. Peter Anvin" Link: https://lore.kernel.org/r/20241205112804.3416920-13-ardb+git@google.com --- arch/x86/coco/sev/shared.c | 7 ++++--- arch/x86/include/asm/init.h | 2 +- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/x86/coco/sev/shared.c b/arch/x86/coco/sev/shared.c index afb7ffc355fee3..96023bd978cc1e 100644 --- a/arch/x86/coco/sev/shared.c +++ b/arch/x86/coco/sev/shared.c @@ -498,7 +498,7 @@ static const struct snp_cpuid_table *snp_cpuid_get_table(void) * * Return: XSAVE area size on success, 0 otherwise. */ -static u32 snp_cpuid_calc_xsave_size(u64 xfeatures_en, bool compacted) +static u32 __head snp_cpuid_calc_xsave_size(u64 xfeatures_en, bool compacted) { const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table(); u64 xfeatures_found = 0; @@ -576,8 +576,9 @@ static void snp_cpuid_hv(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpui sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_CPUID_HV); } -static int snp_cpuid_postprocess(struct ghcb *ghcb, struct es_em_ctxt *ctxt, - struct cpuid_leaf *leaf) +static int __head +snp_cpuid_postprocess(struct ghcb *ghcb, struct es_em_ctxt *ctxt, + struct cpuid_leaf *leaf) { struct cpuid_leaf leaf_hv = *leaf; diff --git a/arch/x86/include/asm/init.h b/arch/x86/include/asm/init.h index 14d72727d7eecf..0e82ebc5d1e190 100644 --- a/arch/x86/include/asm/init.h +++ b/arch/x86/include/asm/init.h @@ -2,7 +2,7 @@ #ifndef _ASM_X86_INIT_H #define _ASM_X86_INIT_H -#define __head __section(".head.text") +#define __head __section(".head.text") __no_sanitize_undefined struct x86_mapping_info { void *(*alloc_pgt_page)(void *); /* allocate buf for page table */