Commit 5f8a1615 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Ingo Molnar

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: default avatarMikulas 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.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 5771a8c0
......@@ -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();
......
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