| Message ID | 20231006082010.11963-1-alexghiti@rivosinc.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 3fec323339a4a9801a54e8b282eb571965b67b23 |
| Headers | show |
| Series | [-fixes] drivers: perf: Fix panic in riscv SBI mmap support | expand |
Hello: This patch was applied to riscv/linux.git (fixes) by Palmer Dabbelt <palmer@rivosinc.com>: On Fri, 6 Oct 2023 10:20:10 +0200 you wrote: > The following panic can happen when mmap is called before the pmu add > callback which sets the hardware counter index: this happens for example > with the following command `perf record --no-bpf-event -n kill`. > > [ 99.461486] CPU: 1 PID: 1259 Comm: perf Tainted: G E 6.6.0-rc4ubuntu-defconfig #2 > [ 99.461669] Hardware name: riscv-virtio,qemu (DT) > [ 99.461748] epc : pmu_sbi_set_scounteren+0x42/0x44 > [ 99.462337] ra : smp_call_function_many_cond+0x126/0x5b0 > [ 99.462369] epc : ffffffff809f9d24 ra : ffffffff800f93e0 sp : ff60000082153aa0 > [ 99.462407] gp : ffffffff82395c98 tp : ff6000009a218040 t0 : ff6000009ab3a4f0 > [ 99.462425] t1 : 0000000000000004 t2 : 0000000000000100 s0 : ff60000082153ab0 > [ 99.462459] s1 : 0000000000000000 a0 : ff60000098869528 a1 : 0000000000000000 > [ 99.462473] a2 : 000000000000001f a3 : 0000000000f00000 a4 : fffffffffffffff8 > [ 99.462488] a5 : 00000000000000cc a6 : 0000000000000000 a7 : 0000000000735049 > [ 99.462502] s2 : 0000000000000001 s3 : ffffffff809f9ce2 s4 : ff60000098869528 > [ 99.462516] s5 : 0000000000000002 s6 : 0000000000000004 s7 : 0000000000000001 > [ 99.462530] s8 : ff600003fec98bc0 s9 : ffffffff826c5890 s10: ff600003fecfcde0 > [ 99.462544] s11: ff600003fec98bc0 t3 : ffffffff819e2558 t4 : ff1c000004623840 > [ 99.462557] t5 : 0000000000000901 t6 : ff6000008feeb890 > [ 99.462570] status: 0000000200000100 badaddr: 0000000000000000 cause: 0000000000000003 > [ 99.462658] [<ffffffff809f9d24>] pmu_sbi_set_scounteren+0x42/0x44 > [ 99.462979] Code: 1060 4785 97bb 00d7 8fd9 9073 1067 6422 0141 8082 (9002) 0013 > [ 99.463335] Kernel BUG [#2] > > [...] Here is the summary with links: - [-fixes] drivers: perf: Fix panic in riscv SBI mmap support https://git.kernel.org/riscv/c/3fec323339a4 You are awesome, thank you!
diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c index 1f9a35f724f5..0dda70e1ef90 100644 --- a/drivers/perf/riscv_pmu.c +++ b/drivers/perf/riscv_pmu.c @@ -23,7 +23,8 @@ static bool riscv_perf_user_access(struct perf_event *event) return ((event->attr.type == PERF_TYPE_HARDWARE) || (event->attr.type == PERF_TYPE_HW_CACHE) || (event->attr.type == PERF_TYPE_RAW)) && - !!(event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT); + !!(event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT) && + (event->hw.idx != -1); } void arch_perf_update_userpage(struct perf_event *event, diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c index 9a51053b1f99..96c7f670c8f0 100644 --- a/drivers/perf/riscv_pmu_sbi.c +++ b/drivers/perf/riscv_pmu_sbi.c @@ -510,16 +510,18 @@ static void pmu_sbi_set_scounteren(void *arg) { struct perf_event *event = (struct perf_event *)arg; - csr_write(CSR_SCOUNTEREN, - csr_read(CSR_SCOUNTEREN) | (1 << pmu_sbi_csr_index(event))); + if (event->hw.idx != -1) + csr_write(CSR_SCOUNTEREN, + csr_read(CSR_SCOUNTEREN) | (1 << pmu_sbi_csr_index(event))); } static void pmu_sbi_reset_scounteren(void *arg) { struct perf_event *event = (struct perf_event *)arg; - csr_write(CSR_SCOUNTEREN, - csr_read(CSR_SCOUNTEREN) & ~(1 << pmu_sbi_csr_index(event))); + if (event->hw.idx != -1) + csr_write(CSR_SCOUNTEREN, + csr_read(CSR_SCOUNTEREN) & ~(1 << pmu_sbi_csr_index(event))); } static void pmu_sbi_ctr_start(struct perf_event *event, u64 ival) @@ -541,7 +543,8 @@ static void pmu_sbi_ctr_start(struct perf_event *event, u64 ival) if ((hwc->flags & PERF_EVENT_FLAG_USER_ACCESS) && (hwc->flags & PERF_EVENT_FLAG_USER_READ_CNT)) - pmu_sbi_set_scounteren((void *)event); + on_each_cpu_mask(mm_cpumask(event->owner->mm), + pmu_sbi_set_scounteren, (void *)event, 1); } static void pmu_sbi_ctr_stop(struct perf_event *event, unsigned long flag) @@ -551,7 +554,8 @@ static void pmu_sbi_ctr_stop(struct perf_event *event, unsigned long flag) if ((hwc->flags & PERF_EVENT_FLAG_USER_ACCESS) && (hwc->flags & PERF_EVENT_FLAG_USER_READ_CNT)) - pmu_sbi_reset_scounteren((void *)event); + on_each_cpu_mask(mm_cpumask(event->owner->mm), + pmu_sbi_reset_scounteren, (void *)event, 1); ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, hwc->idx, 1, flag, 0, 0, 0); if (ret.error && (ret.error != SBI_ERR_ALREADY_STOPPED) &&
The following panic can happen when mmap is called before the pmu add callback which sets the hardware counter index: this happens for example with the following command `perf record --no-bpf-event -n kill`. [ 99.461486] CPU: 1 PID: 1259 Comm: perf Tainted: G E 6.6.0-rc4ubuntu-defconfig #2 [ 99.461669] Hardware name: riscv-virtio,qemu (DT) [ 99.461748] epc : pmu_sbi_set_scounteren+0x42/0x44 [ 99.462337] ra : smp_call_function_many_cond+0x126/0x5b0 [ 99.462369] epc : ffffffff809f9d24 ra : ffffffff800f93e0 sp : ff60000082153aa0 [ 99.462407] gp : ffffffff82395c98 tp : ff6000009a218040 t0 : ff6000009ab3a4f0 [ 99.462425] t1 : 0000000000000004 t2 : 0000000000000100 s0 : ff60000082153ab0 [ 99.462459] s1 : 0000000000000000 a0 : ff60000098869528 a1 : 0000000000000000 [ 99.462473] a2 : 000000000000001f a3 : 0000000000f00000 a4 : fffffffffffffff8 [ 99.462488] a5 : 00000000000000cc a6 : 0000000000000000 a7 : 0000000000735049 [ 99.462502] s2 : 0000000000000001 s3 : ffffffff809f9ce2 s4 : ff60000098869528 [ 99.462516] s5 : 0000000000000002 s6 : 0000000000000004 s7 : 0000000000000001 [ 99.462530] s8 : ff600003fec98bc0 s9 : ffffffff826c5890 s10: ff600003fecfcde0 [ 99.462544] s11: ff600003fec98bc0 t3 : ffffffff819e2558 t4 : ff1c000004623840 [ 99.462557] t5 : 0000000000000901 t6 : ff6000008feeb890 [ 99.462570] status: 0000000200000100 badaddr: 0000000000000000 cause: 0000000000000003 [ 99.462658] [<ffffffff809f9d24>] pmu_sbi_set_scounteren+0x42/0x44 [ 99.462979] Code: 1060 4785 97bb 00d7 8fd9 9073 1067 6422 0141 8082 (9002) 0013 [ 99.463335] Kernel BUG [#2] To circumvent this, try to enable userspace access to the hardware counter when it is selected in addition to when the event is mapped. And vice-versa when the event is stopped/unmapped. Fixes: cc4c07c89aad ("drivers: perf: Implement perf event mmap support in the SBI backend") Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> --- drivers/perf/riscv_pmu.c | 3 ++- drivers/perf/riscv_pmu_sbi.c | 16 ++++++++++------ 2 files changed, 12 insertions(+), 7 deletions(-)