6.7-stable review patch. If anyone has any objections, please let me know.
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From: Vadim Shakirov vadim.shakirov@syntacore.com
[ Upstream commit 682dc133f83e0194796e6ea72eb642df1c03dfbe ]
With parameters CONFIG_RISCV_PMU_LEGACY=y and CONFIG_RISCV_PMU_SBI=n linux kernel crashes when you try perf record:
$ perf record ls [ 46.749286] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 [ 46.750199] Oops [#1] [ 46.750342] Modules linked in: [ 46.750608] CPU: 0 PID: 107 Comm: perf-exec Not tainted 6.6.0 #2 [ 46.750906] Hardware name: riscv-virtio,qemu (DT) [ 46.751184] epc : 0x0 [ 46.751430] ra : arch_perf_update_userpage+0x54/0x13e [ 46.751680] epc : 0000000000000000 ra : ffffffff8072ee52 sp : ff2000000022b8f0 [ 46.751958] gp : ffffffff81505988 tp : ff6000000290d400 t0 : ff2000000022b9c0 [ 46.752229] t1 : 0000000000000001 t2 : 0000000000000003 s0 : ff2000000022b930 [ 46.752451] s1 : ff600000028fb000 a0 : 0000000000000000 a1 : ff600000028fb000 [ 46.752673] a2 : 0000000ae2751268 a3 : 00000000004fb708 a4 : 0000000000000004 [ 46.752895] a5 : 0000000000000000 a6 : 000000000017ffe3 a7 : 00000000000000d2 [ 46.753117] s2 : ff600000028fb000 s3 : 0000000ae2751268 s4 : 0000000000000000 [ 46.753338] s5 : ffffffff8153e290 s6 : ff600000863b9000 s7 : ff60000002961078 [ 46.753562] s8 : ff60000002961048 s9 : ff60000002961058 s10: 0000000000000001 [ 46.753783] s11: 0000000000000018 t3 : ffffffffffffffff t4 : ffffffffffffffff [ 46.754005] t5 : ff6000000292270c t6 : ff2000000022bb30 [ 46.754179] status: 0000000200000100 badaddr: 0000000000000000 cause: 000000000000000c [ 46.754653] Code: Unable to access instruction at 0xffffffffffffffec. [ 46.754939] ---[ end trace 0000000000000000 ]--- [ 46.755131] note: perf-exec[107] exited with irqs disabled [ 46.755546] note: perf-exec[107] exited with preempt_count 4
This happens because in the legacy case the ctr_get_width function was not defined, but it is used in arch_perf_update_userpage.
Also remove extra check in riscv_pmu_ctr_get_width_mask
Signed-off-by: Vadim Shakirov vadim.shakirov@syntacore.com Reviewed-by: Alexandre Ghiti alexghiti@rivosinc.com Reviewed-by: Atish Patra atishp@rivosinc.com Fixes: cc4c07c89aad ("drivers: perf: Implement perf event mmap support in the SBI backend") Link: https://lore.kernel.org/r/20240227170002.188671-3-vadim.shakirov@syntacore.c... Signed-off-by: Palmer Dabbelt palmer@rivosinc.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/perf/riscv_pmu.c | 18 +++++------------- drivers/perf/riscv_pmu_legacy.c | 8 +++++++- 2 files changed, 12 insertions(+), 14 deletions(-)
diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c index 0dda70e1ef90a..c78a6fd6c57f6 100644 --- a/drivers/perf/riscv_pmu.c +++ b/drivers/perf/riscv_pmu.c @@ -150,19 +150,11 @@ u64 riscv_pmu_ctr_get_width_mask(struct perf_event *event) struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu); struct hw_perf_event *hwc = &event->hw;
- if (!rvpmu->ctr_get_width) - /** - * If the pmu driver doesn't support counter width, set it to default - * maximum allowed by the specification. - */ - cwidth = 63; - else { - if (hwc->idx == -1) - /* Handle init case where idx is not initialized yet */ - cwidth = rvpmu->ctr_get_width(0); - else - cwidth = rvpmu->ctr_get_width(hwc->idx); - } + if (hwc->idx == -1) + /* Handle init case where idx is not initialized yet */ + cwidth = rvpmu->ctr_get_width(0); + else + cwidth = rvpmu->ctr_get_width(hwc->idx);
return GENMASK_ULL(cwidth, 0); } diff --git a/drivers/perf/riscv_pmu_legacy.c b/drivers/perf/riscv_pmu_legacy.c index a85fc9a15f039..fa0bccf4edf2e 100644 --- a/drivers/perf/riscv_pmu_legacy.c +++ b/drivers/perf/riscv_pmu_legacy.c @@ -37,6 +37,12 @@ static int pmu_legacy_event_map(struct perf_event *event, u64 *config) return pmu_legacy_ctr_get_idx(event); }
+/* cycle & instret are always 64 bit, one bit less according to SBI spec */ +static int pmu_legacy_ctr_get_width(int idx) +{ + return 63; +} + static u64 pmu_legacy_read_ctr(struct perf_event *event) { struct hw_perf_event *hwc = &event->hw; @@ -111,7 +117,7 @@ static void pmu_legacy_init(struct riscv_pmu *pmu) pmu->ctr_stop = NULL; pmu->event_map = pmu_legacy_event_map; pmu->ctr_get_idx = pmu_legacy_ctr_get_idx; - pmu->ctr_get_width = NULL; + pmu->ctr_get_width = pmu_legacy_ctr_get_width; pmu->ctr_clear_idx = NULL; pmu->ctr_read = pmu_legacy_read_ctr; pmu->event_mapped = pmu_legacy_event_mapped;