Commit-ID: 5f8a16156aa1b2d0223eaee9dacdfb9bc096f610 Gitweb: http://git.kernel.org/tip/5f8a16156aa1b2d0223eaee9dacdfb9bc096f610 Author: Mikulas Patocka <mpatocka@xxxxxxxxxx> AuthorDate: Tue, 11 Jul 2017 07:44:05 -0400 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Sun, 16 Jul 2017 11:05:04 +0200 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@xxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Brian Gerst <brgerst@xxxxxxxxx> Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1707110737530.8746@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- arch/x86/kernel/cpu/amd.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index bb5abe8..3b9e220 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(); -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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