From: Like Xu <likexu@xxxxxxxxxxx>
The pmu test check_counter_overflow() always fails with the "./configure
--arch=i386". The cnt.count obtained from the latter run of measure()
(based on fixed counter 0) is not equal to the expected value (based
on gp counter 0) and there is a positive error with a value of 2.
The two extra instructions come from inline wrmsr() and inline rdmsr()
inside the global_disable() binary code block. Specifically, for each msr
access, the i386 code will have two assembly mov instructions before
rdmsr/wrmsr (mark it for fixed counter 0, bit 32), but only one assembly
mov is needed for x86_64 and gp counter 0 on i386.
Fix the expected init cnt.count for fixed counter 0 overflow based on
the same fixed counter 0, not always using gp counter 0.
Signed-off-by: Like Xu <likexu@xxxxxxxxxxx>
---
x86/pmu.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/x86/pmu.c b/x86/pmu.c
index 45ca2c6..057fd4a 100644
--- a/x86/pmu.c
+++ b/x86/pmu.c
@@ -315,6 +315,9 @@ static void check_counter_overflow(void)
if (i == nr_gp_counters) {
cnt.ctr = fixed_events[0].unit_sel;
+ __measure(&cnt, 0);
+ count = cnt.count;
+ cnt.count = 1 - count;
cnt.count &= (1ull << pmu_fixed_counter_width()) - 1;
}
--
2.37.2
