The patch titled
Subject: x86/kernel: increase kcov coverage under arch/x86/kernel folder
has been added to the -mm mm-nonmm-unstable branch. Its filename is
x86-kernel-increase-kcov-coverage-under-arch-x86-kernel-folder.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/x86-kernel-increase-kcov-coverage-under-arch-x86-kernel-folder.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Pengfei Xu <pengfei.xu@xxxxxxxxx>
Subject: x86/kernel: increase kcov coverage under arch/x86/kernel folder
Date: Mon, 31 Jul 2023 11:04:18 +0800
Currently kcov instrument is disabled for object files under
arch/x86/kernel folder.
For object files under arch/x86/kernel, actually just disabling the kcov
instrument of files:"head32.o or head64.o and sev.o" could achieve
successful booting and provide kcov coverage for object files that do not
disable kcov instrument. The additional kcov coverage collected from
arch/x86/kernel folder helps kernel fuzzing efforts to find bugs.
Link to related improvement discussion is below:
https://groups.google.com/g/syzkaller/c/Dsl-RYGCqs8/m/x-tfpTyFBAAJ Related
ticket is as follow: https://bugzilla.kernel.org/show_bug.cgi?id=198443
Link: https://lkml.kernel.org/r/06c0bb7b5f61e5884bf31180e8c122648c752010.1690771380.git.pengfei.xu@xxxxxxxxx
Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Tested-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Pengfei Xu <pengfei.xu@xxxxxxxxx>
Cc: Aleksandr Nogikh <nogikh@xxxxxxxxxx>
Cc: <heng.su@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxx>,
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Sohil Mehta <sohil.mehta@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/Makefile | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
--- a/arch/x86/kernel/Makefile~x86-kernel-increase-kcov-coverage-under-arch-x86-kernel-folder
+++ a/arch/x86/kernel/Makefile
@@ -33,11 +33,10 @@ KCSAN_SANITIZE := n
KMSAN_SANITIZE_head$(BITS).o := n
KMSAN_SANITIZE_nmi.o := n
-# If instrumentation of this dir is enabled, boot hangs during first second.
-# Probably could be more selective here, but note that files related to irqs,
-# boot, dumpstack/stacktrace, etc are either non-interesting or can lead to
-# non-deterministic coverage.
-KCOV_INSTRUMENT := n
+# If instrumentation of the following files is enabled, boot hangs during
+# first second.
+KCOV_INSTRUMENT_head$(BITS).o := n
+KCOV_INSTRUMENT_sev.o := n
CFLAGS_irq.o := -I $(srctree)/$(src)/../include/asm/trace
_
Patches currently in -mm which might be from pengfei.xu@xxxxxxxxx are
x86-kernel-increase-kcov-coverage-under-arch-x86-kernel-folder.patch
