From 99b863d2e87210c70354a1c75cc5bcc7a3afdc01 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Wed, 1 Jan 2025 12:51:20 +0100 Subject: [PATCH] x86/sev: Disable UBSAN on SEV code that may execute very early MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Clang 14 and older may emit UBSAN instrumentation into code that is inlined into functions marked with __no_sanitize_undefined¹. This may result in faults when the code is executed very early, which may be the case for functions annotated as __head. Now that this requirement is strictly enforced, the build will fail in this case with the following message Absolute reference to symbol '.data' not permitted in .head.text Work around this by disabling UBSAN instrumentation on all SEV core code. ¹ https://lore.kernel.org/r/20250101024348.GA1828419@ax162 [ bp: Add a footnote with Nathan's detailed explanation and a Fixes tag ] Fixes: 3b6f99a94b04 ("x86/boot: Disable UBSAN in early boot code") Signed-off-by: Ard Biesheuvel Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Nathan Chancellor Link: https://lore.kernel.org/r/20250101115119.114584-2-ardb@kernel.org --- arch/x86/coco/sev/Makefile | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/coco/sev/Makefile b/arch/x86/coco/sev/Makefile index 4e375e7305acd..08de375593074 100644 --- a/arch/x86/coco/sev/Makefile +++ b/arch/x86/coco/sev/Makefile @@ -13,3 +13,6 @@ KCOV_INSTRUMENT_core.o := n # With some compiler versions the generated code results in boot hangs, caused # by several compilation units. To be safe, disable all instrumentation. KCSAN_SANITIZE := n + +# Clang 14 and older may fail to respect __no_sanitize_undefined when inlining +UBSAN_SANITIZE := n -- 2.50.1