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authorMikulas Patocka <mpatocka@redhat.com>2017-07-11 07:44:05 -0400
committerIngo Molnar <mingo@kernel.org>2017-07-16 11:05:04 +0200
commit5f8a16156aa1b2d0223eaee9dacdfb9bc096f610 (patch)
treec6f700537ad052e82cbcd19cea2c108ce07db9b9 /arch
parent5771a8c08880cdca3bfb4a3fc6d309d6bba20877 (diff)
downloadlinux-5f8a16156aa1b2d0223eaee9dacdfb9bc096f610.tar.bz2
x86/cpu: Use indirect call to measure performance in init_amd_k6()
This old piece of code is supposed to measure the performance of indirect calls to determine if the processor is buggy or not, however the compiler optimizer turns it into a direct call. Use the OPTIMIZER_HIDE_VAR() macro to thwart the optimization, so that a real indirect call is generated. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1707110737530.8746@file01.intranet.prod.int.rdu2.redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/amd.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index bb5abe8f5fd4..3b9e220621f8 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -134,6 +134,7 @@ static void init_amd_k6(struct cpuinfo_x86 *c)
n = K6_BUG_LOOP;
f_vide = vide;
+ OPTIMIZER_HIDE_VAR(f_vide);
d = rdtsc();
while (n--)
f_vide();