[PATCH v2 4/4] nmi_backtrace: generate one-line reports for idle cpus

From: Chris Metcalf
Date: Wed Mar 16 2016 - 13:03:10 EST

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When doing an nmi backtrace of many cores, most of which are idle,
the output is a little overwhelming and very uninformative. Suppress
messages for cpus that are idling when they are interrupted and just
emit one line, "NMI backtrace for N skipped: idling at pc 0xNNN".

We do this by grouping all the cpuidle code together into a new
.cpuidle.text section, and then checking the address of the
interrupted PC to see if it lies within that section.

Signed-off-by: Chris Metcalf <cmetcalf@xxxxxxxxxxxx>
---
arch/alpha/kernel/vmlinux.lds.S | 1 +
arch/arc/kernel/vmlinux.lds.S | 1 +
arch/arm/kernel/vmlinux.lds.S | 1 +
arch/arm64/kernel/vmlinux.lds.S | 1 +
arch/arm64/mm/proc.S | 2 ++
arch/avr32/kernel/vmlinux.lds.S | 1 +
arch/blackfin/kernel/vmlinux.lds.S | 1 +
arch/c6x/kernel/vmlinux.lds.S | 1 +
arch/cris/kernel/vmlinux.lds.S | 1 +
arch/frv/kernel/vmlinux.lds.S | 1 +
arch/h8300/kernel/vmlinux.lds.S | 1 +
arch/hexagon/kernel/vmlinux.lds.S | 1 +
arch/ia64/kernel/vmlinux.lds.S | 1 +
arch/m32r/kernel/vmlinux.lds.S | 1 +
arch/m68k/kernel/vmlinux-nommu.lds | 1 +
arch/m68k/kernel/vmlinux-std.lds | 1 +
arch/m68k/kernel/vmlinux-sun3.lds | 1 +
arch/metag/kernel/vmlinux.lds.S | 1 +
arch/microblaze/kernel/vmlinux.lds.S | 1 +
arch/mips/kernel/vmlinux.lds.S | 1 +
arch/mn10300/kernel/vmlinux.lds.S | 1 +
arch/nios2/kernel/vmlinux.lds.S | 1 +
arch/openrisc/kernel/vmlinux.lds.S | 1 +
arch/parisc/kernel/vmlinux.lds.S | 1 +
arch/powerpc/kernel/vmlinux.lds.S | 1 +
arch/s390/kernel/vmlinux.lds.S | 1 +
arch/score/kernel/vmlinux.lds.S | 1 +
arch/sh/kernel/vmlinux.lds.S | 1 +
arch/sparc/kernel/vmlinux.lds.S | 1 +
arch/tile/kernel/entry.S | 2 +-
arch/tile/kernel/vmlinux.lds.S | 1 +
arch/um/kernel/dyn.lds.S | 1 +
arch/um/kernel/uml.lds.S | 1 +
arch/unicore32/kernel/vmlinux.lds.S | 1 +
arch/x86/kernel/process.c | 4 ++--
arch/x86/kernel/vmlinux.lds.S | 1 +
include/asm-generic/vmlinux.lds.h | 6 ++++++
include/linux/cpu.h | 5 +++++
kernel/sched/idle.c | 13 +++++++++++--
lib/nmi_backtrace.c | 16 +++++++++++-----
scripts/mod/modpost.c | 4 ++--
scripts/recordmcount.c | 1 +
scripts/recordmcount.pl | 1 +
43 files changed, 75 insertions(+), 12 deletions(-)

diff --git a/arch/alpha/kernel/vmlinux.lds.S b/arch/alpha/kernel/vmlinux.lds.S
index 647b84c15382..cebecfb76fbf 100644
--- a/arch/alpha/kernel/vmlinux.lds.S
+++ b/arch/alpha/kernel/vmlinux.lds.S
@@ -22,6 +22,7 @@ SECTIONS
HEAD_TEXT
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
*(.fixup)
*(.gnu.warning)
diff --git a/arch/arc/kernel/vmlinux.lds.S b/arch/arc/kernel/vmlinux.lds.S
index 894e696bddaa..65652160cfda 100644
--- a/arch/arc/kernel/vmlinux.lds.S
+++ b/arch/arc/kernel/vmlinux.lds.S
@@ -97,6 +97,7 @@ SECTIONS
_text = .;
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
*(.fixup)
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index 8b60fde5ce48..6c13d570e9c9 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -107,6 +107,7 @@ SECTIONS
IRQENTRY_TEXT
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
*(.gnu.warning)
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index e3928f578891..a5cbecf8a74c 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -104,6 +104,7 @@ SECTIONS
IRQENTRY_TEXT
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
HYPERVISOR_TEXT
IDMAP_TEXT
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index c164d2cb35c0..b1b60fc438f6 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -48,11 +48,13 @@
*
* Idle the processor (wait for interrupt).
*/
+ .pushsection ".cpuidle.text","ax"
ENTRY(cpu_do_idle)
dsb sy // WFI may enter a low-power mode
wfi
ret
ENDPROC(cpu_do_idle)
+ .popsection

#ifdef CONFIG_CPU_PM
/**
diff --git a/arch/avr32/kernel/vmlinux.lds.S b/arch/avr32/kernel/vmlinux.lds.S
index a4589176bed5..17f2730eb497 100644
--- a/arch/avr32/kernel/vmlinux.lds.S
+++ b/arch/avr32/kernel/vmlinux.lds.S
@@ -52,6 +52,7 @@ SECTIONS
KPROBES_TEXT
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
*(.fixup)
*(.gnu.warning)
diff --git a/arch/blackfin/kernel/vmlinux.lds.S b/arch/blackfin/kernel/vmlinux.lds.S
index c9eec84aa258..63a02c342830 100644
--- a/arch/blackfin/kernel/vmlinux.lds.S
+++ b/arch/blackfin/kernel/vmlinux.lds.S
@@ -33,6 +33,7 @@ SECTIONS
#ifndef CONFIG_SCHEDULE_L1
SCHED_TEXT
#endif
+ CPUIDLE_TEXT
LOCK_TEXT
IRQENTRY_TEXT
KPROBES_TEXT
diff --git a/arch/c6x/kernel/vmlinux.lds.S b/arch/c6x/kernel/vmlinux.lds.S
index 5a6e141d1641..9cabd962ab36 100644
--- a/arch/c6x/kernel/vmlinux.lds.S
+++ b/arch/c6x/kernel/vmlinux.lds.S
@@ -70,6 +70,7 @@ SECTIONS
_stext = .;
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
IRQENTRY_TEXT
KPROBES_TEXT
diff --git a/arch/cris/kernel/vmlinux.lds.S b/arch/cris/kernel/vmlinux.lds.S
index 7552c2557506..979586261520 100644
--- a/arch/cris/kernel/vmlinux.lds.S
+++ b/arch/cris/kernel/vmlinux.lds.S
@@ -43,6 +43,7 @@ SECTIONS
HEAD_TEXT
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
*(.fixup)
*(.text.__*)
diff --git a/arch/frv/kernel/vmlinux.lds.S b/arch/frv/kernel/vmlinux.lds.S
index 7e958d829ec9..aa6e573d57da 100644
--- a/arch/frv/kernel/vmlinux.lds.S
+++ b/arch/frv/kernel/vmlinux.lds.S
@@ -63,6 +63,7 @@ SECTIONS
*(.text..tlbmiss)
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
#ifdef CONFIG_DEBUG_INFO
INIT_TEXT
diff --git a/arch/h8300/kernel/vmlinux.lds.S b/arch/h8300/kernel/vmlinux.lds.S
index cb5dfb02c88d..7f11da1b895e 100644
--- a/arch/h8300/kernel/vmlinux.lds.S
+++ b/arch/h8300/kernel/vmlinux.lds.S
@@ -29,6 +29,7 @@ SECTIONS
_stext = . ;
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
#if defined(CONFIG_ROMKERNEL)
*(.int_redirect)
diff --git a/arch/hexagon/kernel/vmlinux.lds.S b/arch/hexagon/kernel/vmlinux.lds.S
index 5f268c1071b3..ec87e67feb19 100644
--- a/arch/hexagon/kernel/vmlinux.lds.S
+++ b/arch/hexagon/kernel/vmlinux.lds.S
@@ -50,6 +50,7 @@ SECTIONS
_text = .;
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
*(.fixup)
diff --git a/arch/ia64/kernel/vmlinux.lds.S b/arch/ia64/kernel/vmlinux.lds.S
index dc506b05ffbd..f89d20c97412 100644
--- a/arch/ia64/kernel/vmlinux.lds.S
+++ b/arch/ia64/kernel/vmlinux.lds.S
@@ -46,6 +46,7 @@ SECTIONS {
__end_ivt_text = .;
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
*(.gnu.linkonce.t*)
diff --git a/arch/m32r/kernel/vmlinux.lds.S b/arch/m32r/kernel/vmlinux.lds.S
index 018e4a711d79..ad1fe56455aa 100644
--- a/arch/m32r/kernel/vmlinux.lds.S
+++ b/arch/m32r/kernel/vmlinux.lds.S
@@ -31,6 +31,7 @@ SECTIONS
HEAD_TEXT
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
*(.fixup)
*(.gnu.warning)
diff --git a/arch/m68k/kernel/vmlinux-nommu.lds b/arch/m68k/kernel/vmlinux-nommu.lds
index 06a763f49fd3..d2c8abf1c8c4 100644
--- a/arch/m68k/kernel/vmlinux-nommu.lds
+++ b/arch/m68k/kernel/vmlinux-nommu.lds
@@ -45,6 +45,7 @@ SECTIONS {
HEAD_TEXT
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
*(.fixup)
. = ALIGN(16);
diff --git a/arch/m68k/kernel/vmlinux-std.lds b/arch/m68k/kernel/vmlinux-std.lds
index d0993594f558..5b5ce1e4d1ed 100644
--- a/arch/m68k/kernel/vmlinux-std.lds
+++ b/arch/m68k/kernel/vmlinux-std.lds
@@ -16,6 +16,7 @@ SECTIONS
HEAD_TEXT
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
*(.fixup)
*(.gnu.warning)
diff --git a/arch/m68k/kernel/vmlinux-sun3.lds b/arch/m68k/kernel/vmlinux-sun3.lds
index 8080469ee6c1..fe5ea1974b16 100644
--- a/arch/m68k/kernel/vmlinux-sun3.lds
+++ b/arch/m68k/kernel/vmlinux-sun3.lds
@@ -16,6 +16,7 @@ SECTIONS
HEAD_TEXT
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
*(.fixup)
*(.gnu.warning)
diff --git a/arch/metag/kernel/vmlinux.lds.S b/arch/metag/kernel/vmlinux.lds.S
index e12055e88bfe..9fc48354d519 100644
--- a/arch/metag/kernel/vmlinux.lds.S
+++ b/arch/metag/kernel/vmlinux.lds.S
@@ -21,6 +21,7 @@ SECTIONS
.text : {
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
diff --git a/arch/microblaze/kernel/vmlinux.lds.S b/arch/microblaze/kernel/vmlinux.lds.S
index be9488d69734..5913c7863067 100644
--- a/arch/microblaze/kernel/vmlinux.lds.S
+++ b/arch/microblaze/kernel/vmlinux.lds.S
@@ -33,6 +33,7 @@ SECTIONS {
EXIT_TEXT
EXIT_CALL
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index 0a93e83cd014..e0fc08cb0c89 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -55,6 +55,7 @@ SECTIONS
.text : {
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
diff --git a/arch/mn10300/kernel/vmlinux.lds.S b/arch/mn10300/kernel/vmlinux.lds.S
index 13c4814c29f8..2d5f1c3f1afb 100644
--- a/arch/mn10300/kernel/vmlinux.lds.S
+++ b/arch/mn10300/kernel/vmlinux.lds.S
@@ -30,6 +30,7 @@ SECTIONS
HEAD_TEXT
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
*(.fixup)
diff --git a/arch/nios2/kernel/vmlinux.lds.S b/arch/nios2/kernel/vmlinux.lds.S
index 326fab40a9de..340c7ab1d8b0 100644
--- a/arch/nios2/kernel/vmlinux.lds.S
+++ b/arch/nios2/kernel/vmlinux.lds.S
@@ -37,6 +37,7 @@ SECTIONS
.text : {
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
IRQENTRY_TEXT
KPROBES_TEXT
diff --git a/arch/openrisc/kernel/vmlinux.lds.S b/arch/openrisc/kernel/vmlinux.lds.S
index 2d69a853b742..6c3cf834b5d8 100644
--- a/arch/openrisc/kernel/vmlinux.lds.S
+++ b/arch/openrisc/kernel/vmlinux.lds.S
@@ -47,6 +47,7 @@ SECTIONS
_stext = .;
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
diff --git a/arch/parisc/kernel/vmlinux.lds.S b/arch/parisc/kernel/vmlinux.lds.S
index 308f29081d46..7e53bf44fdd2 100644
--- a/arch/parisc/kernel/vmlinux.lds.S
+++ b/arch/parisc/kernel/vmlinux.lds.S
@@ -69,6 +69,7 @@ SECTIONS
.text ALIGN(PAGE_SIZE) : {
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index d41fd0af8980..bf423392b20a 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -52,6 +52,7 @@ SECTIONS
/* careful! __ftr_alt_* sections need to be close to .text */
*(.text .fixup __ftr_alt_* .ref.text)
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index 445657fe658c..cbc74fd4a6db 100644
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -25,6 +25,7 @@ SECTIONS
HEAD_TEXT
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
diff --git a/arch/score/kernel/vmlinux.lds.S b/arch/score/kernel/vmlinux.lds.S
index 7274b5c4287e..4117890b1db1 100644
--- a/arch/score/kernel/vmlinux.lds.S
+++ b/arch/score/kernel/vmlinux.lds.S
@@ -40,6 +40,7 @@ SECTIONS
_text = .; /* Text and read-only data */
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
*(.text.*)
diff --git a/arch/sh/kernel/vmlinux.lds.S b/arch/sh/kernel/vmlinux.lds.S
index db88cbf9eafd..989500c17358 100644
--- a/arch/sh/kernel/vmlinux.lds.S
+++ b/arch/sh/kernel/vmlinux.lds.S
@@ -36,6 +36,7 @@ SECTIONS
TEXT_TEXT
EXTRA_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
diff --git a/arch/sparc/kernel/vmlinux.lds.S b/arch/sparc/kernel/vmlinux.lds.S
index f1a2f688b28a..93029a4b5299 100644
--- a/arch/sparc/kernel/vmlinux.lds.S
+++ b/arch/sparc/kernel/vmlinux.lds.S
@@ -45,6 +45,7 @@ SECTIONS
HEAD_TEXT
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
diff --git a/arch/tile/kernel/entry.S b/arch/tile/kernel/entry.S
index 670a3569450f..101de132e363 100644
--- a/arch/tile/kernel/entry.S
+++ b/arch/tile/kernel/entry.S
@@ -50,7 +50,7 @@ STD_ENTRY(smp_nap)
* When interrupted at _cpu_idle_nap, we bump the PC forward 8, and
* as a result return to the function that called _cpu_idle().
*/
-STD_ENTRY(_cpu_idle)
+STD_ENTRY_SECTION(_cpu_idle, .cpuidle.text)
movei r1, 1
IRQ_ENABLE_LOAD(r2, r3)
mtspr INTERRUPT_CRITICAL_SECTION, r1
diff --git a/arch/tile/kernel/vmlinux.lds.S b/arch/tile/kernel/vmlinux.lds.S
index 0e059a0101ea..a92931e8c4f9 100644
--- a/arch/tile/kernel/vmlinux.lds.S
+++ b/arch/tile/kernel/vmlinux.lds.S
@@ -42,6 +42,7 @@ SECTIONS
.text : AT (ADDR(.text) - LOAD_OFFSET) {
HEAD_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
IRQENTRY_TEXT
diff --git a/arch/um/kernel/dyn.lds.S b/arch/um/kernel/dyn.lds.S
index adde088aeeff..4fdbcf958cd5 100644
--- a/arch/um/kernel/dyn.lds.S
+++ b/arch/um/kernel/dyn.lds.S
@@ -68,6 +68,7 @@ SECTIONS
_stext = .;
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
*(.fixup)
*(.stub .text.* .gnu.linkonce.t.*)
diff --git a/arch/um/kernel/uml.lds.S b/arch/um/kernel/uml.lds.S
index 6899195602b7..1840f55ed042 100644
--- a/arch/um/kernel/uml.lds.S
+++ b/arch/um/kernel/uml.lds.S
@@ -28,6 +28,7 @@ SECTIONS
_stext = .;
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
*(.fixup)
/* .gnu.warning sections are handled specially by elf32.em. */
diff --git a/arch/unicore32/kernel/vmlinux.lds.S b/arch/unicore32/kernel/vmlinux.lds.S
index 77e407e49a63..56e788e8ee83 100644
--- a/arch/unicore32/kernel/vmlinux.lds.S
+++ b/arch/unicore32/kernel/vmlinux.lds.S
@@ -37,6 +37,7 @@ SECTIONS
.text : { /* Real text segment */
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT

*(.fixup)
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 9f7c21c22477..d569ae7fde37 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -298,7 +298,7 @@ void arch_cpu_idle(void)
/*
* We use this if we don't have any better idle routine..
*/
-void default_idle(void)
+void __cpuidle default_idle(void)
{
trace_cpu_idle_rcuidle(1, smp_processor_id());
safe_halt();
@@ -413,7 +413,7 @@ static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c)
* with interrupts enabled and no flags, which is backwards compatible with the
* original MWAIT implementation.
*/
-static void mwait_idle(void)
+static __cpuidle void mwait_idle(void)
{
if (!current_set_polling_and_test()) {
trace_cpu_idle_rcuidle(1, smp_processor_id());
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 74e4bf11f562..95f80be7632f 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -98,6 +98,7 @@ SECTIONS
_stext = .;
TEXT_TEXT
SCHED_TEXT
+ CPUIDLE_TEXT
LOCK_TEXT
KPROBES_TEXT
ENTRY_TEXT
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index c4bd0e2c173c..18af5199f97c 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -444,6 +444,12 @@
*(.spinlock.text) \
VMLINUX_SYMBOL(__lock_text_end) = .;

+#define CPUIDLE_TEXT \
+ ALIGN_FUNCTION(); \
+ VMLINUX_SYMBOL(__cpuidle_text_start) = .; \
+ *(.cpuidle.text) \
+ VMLINUX_SYMBOL(__cpuidle_text_end) = .;
+
#define KPROBES_TEXT \
ALIGN_FUNCTION(); \
VMLINUX_SYMBOL(__kprobes_text_start) = .; \
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index d2ca8c38f9c4..0cbe214e8f4b 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -274,6 +274,11 @@ void cpu_startup_entry(enum cpuhp_state state);

void cpu_idle_poll_ctrl(bool enable);

+/* Attach to any functions which should be considered cpuidle. */
+#define __cpuidle __attribute__((__section__(".cpuidle.text")))
+
+bool cpu_in_idle(unsigned long pc);
+
void arch_cpu_idle(void);
void arch_cpu_idle_prepare(void);
void arch_cpu_idle_enter(void);
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 544a7133cbd1..ffca482beab5 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -15,6 +15,9 @@

#include "sched.h"

+/* Linker adds these: start and end of __cpuidle functions */
+extern char __cpuidle_text_start[], __cpuidle_text_end[];
+
/**
* sched_idle_set_state - Record idle state for the current CPU.
* @idle_state: State to record.
@@ -52,7 +55,7 @@ static int __init cpu_idle_nopoll_setup(char *__unused)
__setup("hlt", cpu_idle_nopoll_setup);
#endif

-static inline int cpu_idle_poll(void)
+static int noinline __cpuidle cpu_idle_poll(void)
{
rcu_idle_enter();
trace_cpu_idle_rcuidle(0, smp_processor_id());
@@ -83,7 +86,7 @@ void __weak arch_cpu_idle(void)
*
* To use when the cpuidle framework cannot be used.
*/
-void default_idle_call(void)
+void __cpuidle default_idle_call(void)
{
if (current_clr_polling_and_test()) {
local_irq_enable();
@@ -273,6 +276,12 @@ static void cpu_idle_loop(void)
}
}

+bool cpu_in_idle(unsigned long pc)
+{
+ return pc >= (unsigned long)__cpuidle_text_start &&
+ pc < (unsigned long)__cpuidle_text_end;
+}
+
void cpu_startup_entry(enum cpuhp_state state)
{
/*
diff --git a/lib/nmi_backtrace.c b/lib/nmi_backtrace.c
index 9375c0279b73..ac41f3c84e8d 100644
--- a/lib/nmi_backtrace.c
+++ b/lib/nmi_backtrace.c
@@ -17,6 +17,7 @@
#include <linux/kprobes.h>
#include <linux/nmi.h>
#include <linux/seq_buf.h>
+#include <linux/cpu.h>

#ifdef arch_trigger_cpumask_backtrace
/* For reliability, we're prepared to waste bits here. */
@@ -160,11 +161,16 @@ bool nmi_cpu_backtrace(struct pt_regs *regs)

/* Replace printk to write into the NMI seq */
this_cpu_write(printk_func, nmi_vprintk);
- pr_warn("NMI backtrace for cpu %d\n", cpu);
- if (regs)
- show_regs(regs);
- else
- dump_stack();
+ if (regs != NULL && cpu_in_idle(instruction_pointer(regs))) {
+ pr_warn("NMI backtrace for cpu %d skipped: idling at pc %#lx\n",
+ cpu, instruction_pointer(regs));
+ } else {
+ pr_warn("NMI backtrace for cpu %d\n", cpu);
+ if (regs)
+ show_regs(regs);
+ else
+ dump_stack();
+ }
this_cpu_write(printk_func, printk_func_save);

cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 48958d3cec9e..37afd721ec99 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -887,8 +887,8 @@ static void check_section(const char *modname, struct elf_info *elf,
#define ALL_EXIT_SECTIONS EXIT_SECTIONS, ALL_XXXEXIT_SECTIONS

#define DATA_SECTIONS ".data", ".data.rel"
-#define TEXT_SECTIONS ".text", ".text.unlikely", ".sched.text", \
- ".kprobes.text"
+#define TEXT_SECTIONS ".text", ".text.unlikely", \
+ ".kprobes.text", ".cpuidle.text"
#define OTHER_TEXT_SECTIONS ".ref.text", ".head.text", ".spinlock.text", \
".fixup", ".entry.text", ".exception.text", ".text.*", \
".coldtext"
diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index e167592793a7..9a6ec6ce00b5 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -357,6 +357,7 @@ is_mcounted_section_name(char const *const txtname)
strcmp(".spinlock.text", txtname) == 0 ||
strcmp(".irqentry.text", txtname) == 0 ||
strcmp(".kprobes.text", txtname) == 0 ||
+ strcmp(".cpuidle.text", txtname) == 0 ||
strcmp(".text.unlikely", txtname) == 0;
}

diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 96e2486a6fc4..29cecf9b504f 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -135,6 +135,7 @@ my %text_sections = (
".spinlock.text" => 1,
".irqentry.text" => 1,
".kprobes.text" => 1,
+ ".cpuidle.text" => 1,
".text.unlikely" => 1,
);

--
2.7.2

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