From 3d0decc4f49e8645cd6369b02ed076bebd3d61ad Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Fri, 11 Jul 2008 15:09:15 +0200 Subject: [PATCH] x86: fix tsc unification buglet with ftrace and stackprotector Yinghai Lu reported crashes on 64-bit x86: BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 IP: [] hrtick_start_fair+0x89/0x173 [...] And with a long session of debugging and a lot of difficulty, tracked it down to this commit: ---------------> 8fbbc4b45ce3e4c0eeb15004c79c72b6896a79c2 is first bad commit commit 8fbbc4b45ce3e4c0eeb15004c79c72b6896a79c2 Author: Alok Kataria Date: Tue Jul 1 11:43:34 2008 -0700 x86: merge tsc_init and clocksource code <-------------- The problem is that the TSC unification missed these Makefile rules in arch/x86/kernel/Makefile: # Do not profile debug and lowlevel utilities CFLAGS_REMOVE_tsc_64.o = -pg CFLAGS_REMOVE_tsc_32.o = -pg ... CFLAGS_tsc_64.o := $(nostackp) ... which rules make sure that various instrumentation and debugging facilities are disabled for code that might end up in a VDSO - such as the TSC code. Reported-and-bisected-by: Yinghai Lu Signed-off-by: Ingo Molnar Conflicts: Signed-off-by: Ingo Molnar --- arch/x86/kernel/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 59b14c9..4033d8d 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -13,7 +13,7 @@ CPPFLAGS_vmlinux.lds += -U$(UTS_MACHINE) nostackp := $(call cc-option, -fno-stack-protector) CFLAGS_vsyscall_64.o := $(PROFILING) -g0 $(nostackp) CFLAGS_hpet.o := $(nostackp) -CFLAGS_tsc_64.o := $(nostackp) +CFLAGS_tsc.o := $(nostackp) obj-y := process_$(BITS).o signal_$(BITS).o entry_$(BITS).o obj-y += traps_$(BITS).o irq_$(BITS).o -- 2.7.4