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authorFrederic Weisbecker <fweisbec@gmail.com>2008-12-24 23:30:02 +0100
committerIngo Molnar <mingo@elte.hu>2008-12-25 09:39:22 +0100
commit0ca59dd948a51c95d5a366d35f897bc5ef9df55d (patch)
treea5b2cdcd127edb7855a7ec1d7f5fdfc5bee49f55
parent3ddeb912f41801fd1968c7880d031702a396e4d0 (diff)
tracing/ftrace: don't trace on early stage of a secondary cpu boot, v3
Impact: fix a crash/hard-reboot on certain configs while enabling cpu runtime On some archs, the boot of a secondary cpu can have an early fragile state. On x86-64, the pda is not initialized on the first stage of a cpu boot but it is needed to get the cpu number and the current task pointer. This data is needed during tracing. As they were dereferenced at this stage, we got a crash while tracing a cpu being enabled at runtime. Some other archs like ia64 can have such kind of issue too. Changes on v2: We dropped the previous solution of a per-arch called function to guess the current state of a cpu. That could slow down the tracing. This patch removes the -pg flag on arch/x86/kernel/cpu/common.c where the low level cpu boot functions exist, on start_secondary() and a helper function used at this stage. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--arch/x86/include/asm/msr.h3
-rw-r--r--arch/x86/kernel/cpu/Makefile5
-rw-r--r--arch/x86/kernel/smpboot.c2
3 files changed, 8 insertions, 2 deletions
diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
index c2a812ebde8..b8a1799ea87 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -85,7 +85,8 @@ static inline void native_write_msr(unsigned int msr,
asm volatile("wrmsr" : : "c" (msr), "a"(low), "d" (high) : "memory");
}
-static inline int native_write_msr_safe(unsigned int msr,
+/* Can be uninlined because referenced by paravirt */
+notrace static inline int native_write_msr_safe(unsigned int msr,
unsigned low, unsigned high)
{
int err;
diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index 82ec6075c05..4ae495a313f 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -2,6 +2,11 @@
# Makefile for x86-compatible CPU details and quirks
#
+# Don't trace early stages of a secondary CPU boot
+ifdef CONFIG_FUNCTION_TRACER
+CFLAGS_REMOVE_common.o = -pg
+endif
+
obj-y := intel_cacheinfo.o addon_cpuid_features.o
obj-y += proc.o capflags.o powerflags.o common.o
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index f71f96fc9e6..f6174d22902 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -287,7 +287,7 @@ static int __cpuinitdata unsafe_smp;
/*
* Activate a secondary processor.
*/
-static void __cpuinit start_secondary(void *unused)
+notrace static void __cpuinit start_secondary(void *unused)
{
/*
* Don't put *anything* before cpu_init(), SMP booting is too