From 89e1be50c68eb5e58b873dce87bbac627ee18d1f Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Fri, 27 May 2011 23:11:24 -0400 Subject: [PATCH] x86: Put back -pg to tsc.o and add no GCOV to vread_tsc_64.o The commit 44259b1abfaa8bb819d25d41d71e8e33e25dd36a Author: Andy Lutomirski x86-64: Move vread_tsc into a new file with sensible options Removed the -pg from tsc.o which caused the function graph tracer to go into an infinite function call recursion as it uses the tsc internally outside its recursion protection, thus tracing the tsc breaks the function graph tracer. This commit also added the file vread_tsc_64.c that gets used by vdso but failed to prevent GCOV from monkeying with it, causing userspace to try to access kernel data when GCOV was enabled. Thanks to Thomas Gleixner for pointing out GCOV as the likely culprit that added strange kernel accesses into the vread_tsc() call. Cc: Author: Andy Lutomirski Cc: Thomas Gleixner Signed-off-by: Steven Rostedt --- arch/x86/kernel/Makefile | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index f5abe3a245b8..90b06d4daee2 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -8,6 +8,7 @@ CPPFLAGS_vmlinux.lds += -U$(UTS_MACHINE) ifdef CONFIG_FUNCTION_TRACER # Do not profile debug and lowlevel utilities +CFLAGS_REMOVE_tsc.o = -pg CFLAGS_REMOVE_rtc.o = -pg CFLAGS_REMOVE_paravirt-spinlocks.o = -pg CFLAGS_REMOVE_pvclock.o = -pg @@ -28,6 +29,7 @@ CFLAGS_paravirt.o := $(nostackp) GCOV_PROFILE_vsyscall_64.o := n GCOV_PROFILE_hpet.o := n GCOV_PROFILE_tsc.o := n +GCOV_PROFILE_vread_tsc_64.o := n GCOV_PROFILE_paravirt.o := n # vread_tsc_64 is hot and should be fully optimized: -- 2.34.1