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| author | Mark Rutland <mark.rutland@arm.com> | 2021-06-07 11:46:24 +0200 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2021-06-07 12:35:56 +0200 |
| commit | b5df5b8307b1db6d168ffac29eff3974779bb34b (patch) | |
| tree | 253bdd58b56ea3a2066dabccbb05536620336996 /arch/arm64/kernel/Makefile | |
| parent | arm64: entry: don't instrument entry code with KCOV (diff) | |
| download | linux-b5df5b8307b1db6d168ffac29eff3974779bb34b.tar.xz linux-b5df5b8307b1db6d168ffac29eff3974779bb34b.zip | |
arm64: idle: don't instrument idle code with KCOV
The low-level idle code in arch_cpu_idle() and its callees runs at a
time where 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 factoring these functions into a new idle.c so that we
can disable KCOV for the entire compilation unit, as is done for the
core idle code in kernel/sched/idle.c.
We'd like to keep instrumentation of the rest of process.c, and for the
existing code in cpuidle.c, so a new compilation unit is preferable. The
arch_cpu_idle_dead() function in process.c is a cpu hotplug function
that is safe to instrument, so it is left as-is in process.c.
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/20210607094624.34689-21-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/Makefile | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 787c3c83edd7..de434204d723 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -18,6 +18,7 @@ CFLAGS_syscall.o += -fno-stack-protector # 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 +KCOV_INSTRUMENT_idle.o := n # Object file lists. obj-y := debug-monitors.o entry.o irq.o fpsimd.o \ @@ -27,7 +28,7 @@ obj-y := debug-monitors.o entry.o irq.o fpsimd.o \ return_address.o cpuinfo.o cpu_errata.o \ cpufeature.o alternative.o cacheinfo.o \ smp.o smp_spin_table.o topology.o smccc-call.o \ - syscall.o proton-pack.o idreg-override.o + syscall.o proton-pack.o idreg-override.o idle.o targets += efi-entry.o |