From 0ca59dd948a51c95d5a366d35f897bc5ef9df55d Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Wed, 24 Dec 2008 23:30:02 +0100 Subject: 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 Acked-by: Steven Rostedt Signed-off-by: Ingo Molnar --- arch/x86/include/asm/msr.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'arch/x86/include/asm/msr.h') diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h index c2a812ebde89..b8a1799ea871 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; -- cgit v1.2.3