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authorMark Rutland <mark.rutland@arm.com>2021-06-07 10:46:23 +0100
committerWill Deacon <will@kernel.org>2021-06-07 11:35:56 +0100
commitbf6fa2c0dda751863c3446aa64d733013bec4a19 (patch)
tree0e94d5c49177a4e87f7c05c4335a5982c7a56d40 /arch/arm64/kernel/Makefile
parent6ecbc78c3d06a3e7a4676f348a52f1c533d88464 (diff)
arm64: entry: don't instrument entry code with KCOV
The code in entry-common.c runs at exception entry and return boundaries, where portions of the kernel environment aren't available. For example, RCU may not be watching, and lockdep state may be out-of-sync with the hardware. Due to this, it is not sound to instrument this code. We generally avoid instrumentation by marking the entry functions as `noinstr`, but currently this doesn't inhibit KCOV instrumentation. Prevent this by disabling KCOV for the entire compilation unit. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Marc Zyngier <maz@kernel.org> Cc: James Morse <james.morse@arm.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20210607094624.34689-20-mark.rutland@arm.com Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/kernel/Makefile')
-rw-r--r--arch/arm64/kernel/Makefile5
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 6cc97730790e..787c3c83edd7 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -14,6 +14,11 @@ CFLAGS_REMOVE_return_address.o = $(CC_FLAGS_FTRACE)
CFLAGS_REMOVE_syscall.o = -fstack-protector -fstack-protector-strong
CFLAGS_syscall.o += -fno-stack-protector
+# It's not safe to invoke KCOV when portions of the kernel environment aren't
+# available or are out-of-sync with HW state. Since `noinstr` doesn't always
+# inhibit KCOV instrumentation, disable it for the entire compilation unit.
+KCOV_INSTRUMENT_entry.o := n
+
# Object file lists.
obj-y := debug-monitors.o entry.o irq.o fpsimd.o \
entry-common.o entry-fpsimd.o process.o ptrace.o \