Re: [PATCH] x86/perf: Fixed kernel panic during boot on Nano processor.
From: Codyyao-oc <hidden>
Date: 2021-06-30 04:38:35
Also in:
lkml
Dear Mingo and Peter,
Thank you for taking your precious time to read this letter, I am very
graterful.
Last month, I fixed the bug that boot failed on Nano processor which
introduced by
"Fixes: 3a4ac121c2ca ("x86/perf: Add hardware performance events support
for Zhaoxin CPU.")"
with Arjan's help and submitted this patch. But I haven't got back.
Greatly appreciate if you could kindly
check it and reply at your convenience.
Many Thanks!
Cody
On 2021/6/7 上午9:31, Cody Yao-oc wrote:quoted hunk ↗ jump to hunk
From: CodyYao-oc <redacted> Nano processor may not fully support rdpmc instruction, it works well for reading general pmc counter, but will lead to GP(general protection) when accessing fixed pmc counter. Futhermore, family/model information is same between Nano processor and ZX-C processor, it leads to zhaoxin pmu driver is wrongly loaded for Nano processor, which resulting boot kernal fail. To solve this problem, stepping information will be checked to distinguish between Nano processor and ZX-C processor. [https://bugzilla.kernel.org/show_bug.cgi?id=212389] Reported-by: Arjan <redacted> Signed-off-by: CodyYao-oc <redacted> --- arch/x86/events/zhaoxin/core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)diff --git a/arch/x86/events/zhaoxin/core.c b/arch/x86/events/zhaoxin/core.c index 949d845c922b..cef1de251613 100644 --- a/arch/x86/events/zhaoxin/core.c +++ b/arch/x86/events/zhaoxin/core.c@@ -541,7 +541,8 @@ __init int zhaoxin_pmu_init(void) switch (boot_cpu_data.x86) { case 0x06: - if (boot_cpu_data.x86_model == 0x0f || boot_cpu_data.x86_model == 0x19) { + if ((boot_cpu_data.x86_model == 0x0f && boot_cpu_data.x86_stepping >= 0x0e) || + boot_cpu_data.x86_model == 0x19) { x86_pmu.max_period = x86_pmu.cntval_mask >> 1;