[PATCH] x86/sev: Disable GCOV on noinstr object
From: Brendan Jackman
Date: Mon Nov 17 2025 - 06:20:15 EST
With Debian clang version 19.1.7 (3+build5) there are calls to
kasan_check_write() from __sev_es_nmi_complete, which violates noinstr.
Fix it by disabling GCOV for the noinstr object, as has been done for
previous such instrumentation issues.
Signed-off-by: Brendan Jackman <jackmanb@xxxxxxxxxx>
---
Details:
- ❯❯ clang --version
Debian clang version 19.1.7 (3+build5)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/lib/llvm-19/bin
- Compiling from tip/master at 6f85aad74a70d
- Kernel config:
https://gist.githubusercontent.com/bjackman/bbfdf4ec2e1dfd0e18657174f0537e2c/raw/a88dcc6567d14c69445e7928a7d5dfc23ca9f619/gistfile0.txt
Note I also get this error:
vmlinux.o: warning: objtool: set_ftrace_ops_ro+0x3b: relocation to !ENDBR: machine_kexec_prepare+0x810
That one's a total mystery to me. I guess it's better to "fix" the SEV
one independently rather than waiting until I know how to fix them both.
---
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 3b8ae214a6a64de6bb208eb3b7c8bf12007ccc2c..d2ceae587b6c30b2fb17209a7426e7893dea988c 100644
--- a/arch/x86/coco/sev/Makefile
+++ b/arch/x86/coco/sev/Makefile
@@ -8,3 +8,6 @@ UBSAN_SANITIZE_noinstr.o := n
# GCC may fail to respect __no_sanitize_address or __no_kcsan when inlining
KASAN_SANITIZE_noinstr.o := n
KCSAN_SANITIZE_noinstr.o := n
+
+# Clang 19 and older may fail to respect __no_sanitize_address when inlining
+GCOV_PROFILE_noinstr.o := n
---
base-commit: 6f85aad74a70d17919a64ecd93037aa51c08698d
change-id: 20251117-b4-sev-gcov-objtool-2f6cd197cd9c
Best regards,
--
Brendan Jackman <jackmanb@xxxxxxxxxx>