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

diff --git a/arch/x86/Kbuild b/arch/x86/Kbuild
index cf0ad89f5639da8a9eaa502eb1a8b8f2432fa1ba..f7fb3d88c57bd846c3f6cb34e760c652568a808c 100644 (file)
--- a/arch/x86/Kbuild
+++ b/arch/x86/Kbuild
@@ -1,4 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
+
+# Branch profiling isn't noinstr-safe.  Disable it for arch/x86/*
+subdir-ccflags-$(CONFIG_TRACE_BRANCH_PROFILING) += -DDISABLE_BRANCH_PROFILING
+
 obj-$(CONFIG_ARCH_HAS_CC_PLATFORM) += coco/
 
 obj-y += entry/

diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index 96c7bc698e6b628ae3522e656c4882b29d3fc2d7..d14bce0f82cc58ee7bd4eb90439f9954ab0fe533 100644 (file)
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -9,8 +9,6 @@
 
 #define pr_fmt(fmt)    "SEV: " fmt
 
-#define DISABLE_BRANCH_PROFILING
-
 #include <linux/sched/debug.h> /* For show_regs() */
 #include <linux/percpu-defs.h>
 #include <linux/cc_platform.h>

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 22c9ba305ac171a408af47b48edf5587b651c605..368157a7f6d213e043487761d1820a78ae36b217 100644 (file)
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -5,8 +5,6 @@
  *  Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
  */
 
-#define DISABLE_BRANCH_PROFILING
-
 /* cpu_feature_enabled() cannot be used this early */
 #define USE_EARLY_PGTABLE_L5
 

diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index 9dddf19a55716030916eb4d380f72d7360dbd181..0539efd0d216b99db014469e14602178154d9a9a 100644 (file)
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define DISABLE_BRANCH_PROFILING
 #define pr_fmt(fmt) "kasan: " fmt
 
 /* cpu_feature_enabled() cannot be used this early */

diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c
index b56c5c073003d6e72692657603692a300ac58191..7490ff6d83b1bcf4df2c6d7137035f8e7873d5cb 100644 (file)
--- a/arch/x86/mm/mem_encrypt_amd.c
+++ b/arch/x86/mm/mem_encrypt_amd.c
@@ -7,8 +7,6 @@
  * Author: Tom Lendacky <thomas.lendacky@amd.com>
  */
 
-#define DISABLE_BRANCH_PROFILING
-
 #include <linux/linkage.h>
 #include <linux/init.h>
 #include <linux/mm.h>

diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
index e6c7686f443a060cc62fdb6a82d549a1a0c9e9df..4e991dedc1db5959b11b4267eeabc6c2e290a6fc 100644 (file)
--- a/arch/x86/mm/mem_encrypt_identity.c
+++ b/arch/x86/mm/mem_encrypt_identity.c
@@ -7,8 +7,6 @@
  * Author: Tom Lendacky <thomas.lendacky@amd.com>
  */
 
-#define DISABLE_BRANCH_PROFILING
-
 /*
  * Since we're dealing with identity mappings, physical and virtual
  * addresses are the same, so override these defines which are ultimately

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 40208a0f5dfb5767e8c2e717fdeab5f794835bd6..797070fc9a3f42ad9be166a6d96051572ae6593e 100644 (file)
--- 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 d103342b7cfc2120d2981dc1f61be9029aa69c54..1de9e92c5b0fc9fec0ed668209e7b9a4cb4f9736 100644 (file)
--- 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 0a3c37510079797fa114638dd3064bd934c73649..a34af1ba09bdba6632eaff9be28825f8ef15df32 100644 (file)
--- 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

diff --git a/kernel/Makefile b/kernel/Makefile
index 87866b037fbed362221c7ab9da0aac4f8a1bc0a7..434929de17ef2711cb1c8d0e3c7663c44612cce7 100644 (file)
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -21,6 +21,11 @@ ifdef CONFIG_FUNCTION_TRACER
 CFLAGS_REMOVE_irq_work.o = $(CC_FLAGS_FTRACE)
 endif
 
+# Branch profiling isn't noinstr-safe
+ifdef CONFIG_TRACE_BRANCH_PROFILING
+CFLAGS_context_tracking.o += -DDISABLE_BRANCH_PROFILING
+endif
+
 # Prevents flicker of uninteresting __do_softirq()/__local_bh_disable_ip()
 # in coverage traces.
 KCOV_INSTRUMENT_softirq.o := n

diff --git a/kernel/entry/Makefile b/kernel/entry/Makefile
index 095c775e001e279fccf0f64be469c859f7c0edf4..d4b8bd0af79b0d7334041d3ee9b5459b598905c1 100644 (file)
--- a/kernel/entry/Makefile
+++ b/kernel/entry/Makefile
@@ -6,6 +6,9 @@ KASAN_SANITIZE := n
 UBSAN_SANITIZE := n
 KCOV_INSTRUMENT := n
 
+# Branch profiling isn't noinstr-safe
+ccflags-$(CONFIG_TRACE_BRANCH_PROFILING) += -DDISABLE_BRANCH_PROFILING
+
 CFLAGS_REMOVE_common.o  = -fstack-protector -fstack-protector-strong
 CFLAGS_common.o                += -fno-stack-protector
 

diff --git a/kernel/sched/Makefile b/kernel/sched/Makefile
index 976092b7bd4520ebc1a607734520ac342585a120..8ae86371ddcddf836172ee93ca34f2e91b4057a7 100644 (file)
--- a/kernel/sched/Makefile
+++ b/kernel/sched/Makefile
@@ -22,6 +22,11 @@ ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y)
 CFLAGS_core.o := $(PROFILING) -fno-omit-frame-pointer
 endif
 
+# Branch profiling isn't noinstr-safe
+ifdef CONFIG_TRACE_BRANCH_PROFILING
+CFLAGS_build_policy.o += -DDISABLE_BRANCH_PROFILING
+CFLAGS_build_utility.o += -DDISABLE_BRANCH_PROFILING
+endif
 #
 # Build efficiency:
 #

diff --git a/kernel/time/Makefile b/kernel/time/Makefile
index fe0ae82124fe7fd887c84530e4d35482c47e774d..e6e9b85d4db5f8dd5d9b574ef7bb0a281b9daa6d 100644 (file)
--- a/kernel/time/Makefile
+++ b/kernel/time/Makefile
@@ -1,4 +1,10 @@
 # SPDX-License-Identifier: GPL-2.0
+
+# Branch profiling isn't noinstr-safe
+ifdef CONFIG_TRACE_BRANCH_PROFILING
+CFLAGS_sched_clock.o += -DDISABLE_BRANCH_PROFILING
+endif
+
 obj-y += time.o timer.o hrtimer.o sleep_timeout.o
 obj-y += timekeeping.o ntp.o clocksource.o jiffies.o timer_list.o
 obj-y += timeconv.o timecounter.o alarmtimer.o

diff --git a/lib/Makefile b/lib/Makefile
index d5cfc7afbbb8215cdb8d03c26fe7b7be13d75d24..4f3d00a2fd6592eb023322bd6d91310a5e474b61 100644 (file)
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -5,6 +5,11 @@
 
 ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
 
+# Branch profiling isn't noinstr-safe
+ifdef CONFIG_TRACE_BRANCH_PROFILING
+CFLAGS_smp_processor_id.o += -DDISABLE_BRANCH_PROFILING
+endif
+
 # These files are disabled because they produce lots of non-interesting and/or
 # flaky coverage that is not a function of syscall inputs. For example,
 # rbtree can be global and individual rotations don't correlate with inputs.