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| author |   Josh Poimboeuf <jpoimboe@kernel.org> | 2025-03-21 12:53:32 -0700 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2025-03-22 09:49:26 +0100 |
| commit | 2cbb20b008dba39893f0e296dc8ca312f40a9a0e (patch) | |
| tree | f079da8bb91aecf528cb081d899e70dbaffb4028 /drivers | |
| parent | objtool: Use O_CREAT with explicit mode mask (diff) | |
| download | wireguard-linux-2cbb20b008dba39893f0e296dc8ca312f40a9a0e.tar.xz wireguard-linux-2cbb20b008dba39893f0e296dc8ca312f40a9a0e.zip | |
tracing: Disable branch profiling in noinstr code
CONFIG_TRACE_BRANCH_PROFILING inserts a call to ftrace_likely_update()
for each use of likely() or unlikely(). That breaks noinstr rules if
the affected function is annotated as noinstr.
Disable branch profiling for files with noinstr functions. In addition
to some individual files, this also includes the entire arch/x86
subtree, as well as the kernel/entry, drivers/cpuidle, and drivers/idle
directories, all of which are noinstr-heavy.
Due to the nature of how sched binaries are built by combining multiple
.c files into one, branch profiling is disabled more broadly across the
sched code than would otherwise be needed.
This fixes many warnings like the following:
vmlinux.o: warning: objtool: do_syscall_64+0x40: call to ftrace_likely_update() leaves .noinstr.text section
vmlinux.o: warning: objtool: __rdgsbase_inactive+0x33: call to ftrace_likely_update() leaves .noinstr.text section
vmlinux.o: warning: objtool: handle_bug.isra.0+0x198: call to ftrace_likely_update() leaves .noinstr.text section
...
Reported-by: Ingo Molnar <mingo@kernel.org>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/fb94fc9303d48a5ed370498f54500cc4c338eb6d.1742586676.git.jpoimboe@kernel.org
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/acpi/Makefile | 4 | ||||
| -rw-r--r-- | drivers/cpuidle/Makefile | 3 | ||||
| -rw-r--r-- | drivers/idle/Makefile | 5 |
3 files changed, 11 insertions, 1 deletions
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile index 40208a0f5dfb..797070fc9a3f 100644 --- a/drivers/acpi/Makefile +++ b/drivers/acpi/Makefile @@ -5,6 +5,10 @@ ccflags-$(CONFIG_ACPI_DEBUG) += -DACPI_DEBUG_OUTPUT +ifdef CONFIG_TRACE_BRANCH_PROFILING +CFLAGS_processor_idle.o += -DDISABLE_BRANCH_PROFILING +endif + # # ACPI Boot-Time Table Parsing # diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile index d103342b7cfc..1de9e92c5b0f 100644 --- a/drivers/cpuidle/Makefile +++ b/drivers/cpuidle/Makefile @@ -3,6 +3,9 @@ # Makefile for cpuidle. # +# Branch profiling isn't noinstr-safe +ccflags-$(CONFIG_TRACE_BRANCH_PROFILING) += -DDISABLE_BRANCH_PROFILING + obj-y += cpuidle.o driver.o governor.o sysfs.o governors/ obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o obj-$(CONFIG_DT_IDLE_STATES) += dt_idle_states.o diff --git a/drivers/idle/Makefile b/drivers/idle/Makefile index 0a3c37510079..a34af1ba09bd 100644 --- a/drivers/idle/Makefile +++ b/drivers/idle/Makefile @@ -1,3 +1,6 @@ # SPDX-License-Identifier: GPL-2.0-only -obj-$(CONFIG_INTEL_IDLE) += intel_idle.o +# Branch profiling isn't noinstr-safe +ccflags-$(CONFIG_TRACE_BRANCH_PROFILING) += -DDISABLE_BRANCH_PROFILING + +obj-$(CONFIG_INTEL_IDLE) += intel_idle.o |