x86: Put back -pg to tsc.o and add no GCOV to vread_tsc_64.o

The commit 44259b1 Author: Andy Lutomirski <[email protected]> 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 <[email protected]> Cc: Thomas Gleixner <[email protected]> Signed-off-by: Steven Rostedt <[email protected]>
mgowda · May 28, 2011 · 89e1be5 · 89e1be5
1 parent f23a5e1
commit 89e1be5
Showing 1 changed file with 2 additions and 0 deletions.
diff --git 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: