On Tue, Jan 21, 2014 at 09:59:54PM +0000, Stephen Boyd wrote: > On 01/21/14 10:37, Stephen Boyd wrote: > > On 01/21/14 10:07, Will Deacon wrote: > >> Finally, I'd really like to see this get some test coverage, but I don't > >> want to try running mainline on my phone :) Could you give your patches a > >> spin with Vince's perf fuzzer please? > >> > >> https://github.com/deater/perf_event_tests.git > >> > >> (then build the contents of the fuzzer directory and run it for as long as > >> you can). > >> > > Ok. I'll see what I can do. > > Neat. This quickly discovered a problem. Yeah, the fuzzer is good at that! > BUG: using smp_processor_id() in preemptible [00000000] code: perf_fuzzer/70 > caller is krait_pmu_get_event_idx+0x58/0xd8 > CPU: 2 PID: 70 Comm: perf_fuzzer Not tainted 3.13.0-rc7-next-20140108-00041-gb038353c8516-dirty #58 > [<c02165dc>] (unwind_backtrace) from [<c0212ffc>] (show_stack+0x10/0x14) > [<c0212ffc>] (show_stack) from [<c06ad5fc>] (dump_stack+0x6c/0xb8) > [<c06ad5fc>] (dump_stack) from [<c04b0928>] (debug_smp_processor_id+0xc4/0xe8) > [<c04b0928>] (debug_smp_processor_id) from [<c021a19c>] (krait_pmu_get_event_idx+0x58/0xd8) > [<c021a19c>] (krait_pmu_get_event_idx) from [<c021833c>] (validate_event+0x2c/0x54) > [<c021833c>] (validate_event) from [<c02186b4>] (armpmu_event_init+0x264/0x2dc) > [<c02186b4>] (armpmu_event_init) from [<c02b28e4>] (perf_init_event+0x138/0x194) > [<c02b28e4>] (perf_init_event) from [<c02b2c04>] (perf_event_alloc+0x2c4/0x348) > [<c02b2c04>] (perf_event_alloc) from [<c02b37e4>] (SyS_perf_event_open+0x7b8/0x9cc) > [<c02b37e4>] (SyS_perf_event_open) from [<c020ef80>] (ret_fast_syscall+0x0/0x48) > > This is happening because the pmresrn_used mask is per-cpu but > validate_group() is called in preemptible context. It looks like we'll > need to add another unsigned long * field to struct pmu_hw_events just > for Krait purposes? Or we could use the upper 16 bits of the used_mask > bitmap to hold the pmresr_used values? Sounds sort of hacky but it > avoids adding another bitmap for every PMU user and there aren't any > Krait CPUs with more than 5 counters anyway. I'm fine with that approach, but a comment saying what we're doing with those upper bits wouldn't go amiss. > This is the diff for the latter version. I'll let the fuzzer run overnight. Cheers, Will -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
