From f386c61fe1a1f36f0e434f1b577e6b112698caf7 Mon Sep 17 00:00:00 2001 From: Peter Oberparleiter Date: Sun, 5 Jul 2009 12:08:06 -0700 Subject: [PATCH] gcov: exclude code operating in userspace from profiling Fix for this issue on x86_64: rostedt@goodmis.org wrote: > On bootup of the latest kernel my init segfaults. Debugging it, > I found that vread_tsc (a vsyscall) increments some strange > kernel memory: > > 0000000000000000 : > 0: 55 push %rbp > 1: 48 ff 05 00 00 00 00 incq 0(%rip) > # 8 > 4: R_X86_64_PC32 .bss+0x3c > 8: 48 89 e5 mov %rsp,%rbp > b: 66 66 90 xchg %ax,%ax > e: 48 ff 05 00 00 00 00 incq 0(%rip) > # 15 > 11: R_X86_64_PC32 .bss+0x44 > 15: 66 66 90 xchg %ax,%ax > 18: 48 ff 05 00 00 00 00 incq 0(%rip) > # 1f > 1b: R_X86_64_PC32 .bss+0x4c > 1f: 0f 31 rdtsc > > > Those "incq" is very bad to happen in vsyscall memory, since > userspace can not modify it. You need to make something prevent > profiling of vsyscall memory (like I do with ftrace). Signed-off-by: Peter Oberparleiter Cc: Ingo Molnar Reported-by: Steven Rostedt Tested-by: Steven Rostedt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86/kernel/Makefile | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 6c327b852e23..430d5b24af7b 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -26,6 +26,8 @@ CFLAGS_tsc.o := $(nostackp) CFLAGS_paravirt.o := $(nostackp) GCOV_PROFILE_vsyscall_64.o := n GCOV_PROFILE_hpet.o := n +GCOV_PROFILE_tsc.o := n +GCOV_PROFILE_paravirt.o := n obj-y := process_$(BITS).o signal.o entry_$(BITS).o obj-y += traps.o irq.o irq_$(BITS).o dumpstack_$(BITS).o