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authorPeter Oberparleiter <oberpar@linux.vnet.ibm.com>2009-07-05 23:08:06 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-07-07 00:57:03 +0400
commitf386c61fe1a1f36f0e434f1b577e6b112698caf7 (patch)
tree40578bc7a067fdb397c1d6dfcc165a433a7c4933 /fs/sync.c
parent28df30e61b46a33d1f0bb60757747396886ef687 (diff)
downloadlinux-f386c61fe1a1f36f0e434f1b577e6b112698caf7.tar.xz
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 <vread_tsc>: > 0: 55 push %rbp > 1: 48 ff 05 00 00 00 00 incq 0(%rip) > # 8 <vread_tsc+0x8> > 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 <vread_tsc+0x15> > 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 <vread_tsc+0x1f> > 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 <oberpar@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Reported-by: Steven Rostedt <rostedt@goodmis.org> Tested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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