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perf/x86/amd/ibs: Work around erratum #1197
[ Upstream commit 26db2e0c51
]
Erratum #1197 "IBS (Instruction Based Sampling) Register State May be
Incorrect After Restore From CC6" is published in a document:
"Revision Guide for AMD Family 19h Models 00h-0Fh Processors" 56683 Rev. 1.04 July 2021
https://bugzilla.kernel.org/show_bug.cgi?id=206537
Implement the erratum's suggested workaround and ignore IBS samples if
MSRC001_1031 == 0.
Signed-off-by: Kim Phillips <kim.phillips@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210817221048.88063-3-kim.phillips@amd.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
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@ -90,6 +90,7 @@ struct perf_ibs {
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unsigned long offset_mask[1];
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int offset_max;
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unsigned int fetch_count_reset_broken : 1;
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unsigned int fetch_ignore_if_zero_rip : 1;
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struct cpu_perf_ibs __percpu *pcpu;
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struct attribute **format_attrs;
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@ -674,6 +675,10 @@ static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs)
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if (check_rip && (ibs_data.regs[2] & IBS_RIP_INVALID)) {
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regs.flags &= ~PERF_EFLAGS_EXACT;
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} else {
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/* Workaround for erratum #1197 */
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if (perf_ibs->fetch_ignore_if_zero_rip && !(ibs_data.regs[1]))
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goto out;
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set_linear_ip(®s, ibs_data.regs[1]);
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regs.flags |= PERF_EFLAGS_EXACT;
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}
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@ -767,6 +772,9 @@ static __init void perf_event_ibs_init(void)
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if (boot_cpu_data.x86 >= 0x16 && boot_cpu_data.x86 <= 0x18)
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perf_ibs_fetch.fetch_count_reset_broken = 1;
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if (boot_cpu_data.x86 == 0x19 && boot_cpu_data.x86_model < 0x10)
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perf_ibs_fetch.fetch_ignore_if_zero_rip = 1;
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perf_ibs_pmu_init(&perf_ibs_fetch, "ibs_fetch");
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if (ibs_caps & IBS_CAPS_OPCNT) {
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