6.18-stable review patch. If anyone has any objections, please let me know.
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From: Leo Yan leo.yan@arm.com
[ Upstream commit 1fdc2cd347a7bc58acacb6144404ee892cea6c2e ]
If a CPU supports FEAT_TRF, as described in the section K5.5 "Context switching", Arm ARM (ARM DDI 0487 L.a), it defines a flow to prohibit program-flow trace, execute a TSB CSYNC instruction for flushing, followed by clearing TRCPRGCTLR.EN bit.
To restore the state, the reverse sequence is required.
This differs from the procedure described in the section 3.4.1 "The procedure when powering down the PE" of ARM IHI0064H.b, which involves the OS Lock to prevent external debugger accesses and implicitly disables trace.
To be compatible with different ETM versions, explicitly control trace unit using etm4_disable_trace_unit() and etm4_enable_trace_unit() during CPU idle to comply with FEAT_TRF.
As a result, the save states for TRFCR_ELx and trcprgctlr are redundant, remove them.
Fixes: f188b5e76aae ("coresight: etm4x: Save/restore state across CPU low power states") Reviewed-by: Mike Leach mike.leach@linaro.org Tested-by: James Clark james.clark@linaro.org Reviewed-by: Yeoreum Yun yeoreum.yun@arm.com Signed-off-by: Leo Yan leo.yan@arm.com Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com Link: https://lore.kernel.org/r/20251111-arm_coresight_power_management_fix-v6-6-f... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/hwtracing/coresight/coresight-etm4x-core.c | 14 +++++++------- drivers/hwtracing/coresight/coresight-etm4x.h | 3 --- 2 files changed, 7 insertions(+), 10 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index 5e707d082537a..fdda924a2c711 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -1858,9 +1858,11 @@ static int __etm4_cpu_save(struct etmv4_drvdata *drvdata) goto out; }
+ if (!drvdata->paused) + etm4_disable_trace_unit(drvdata); + state = drvdata->save_state;
- state->trcprgctlr = etm4x_read32(csa, TRCPRGCTLR); if (drvdata->nr_pe) state->trcprocselr = etm4x_read32(csa, TRCPROCSELR); state->trcconfigr = etm4x_read32(csa, TRCCONFIGR); @@ -1970,9 +1972,6 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata) { int ret = 0;
- /* Save the TRFCR irrespective of whether the ETM is ON */ - if (drvdata->trfcr) - drvdata->save_trfcr = read_trfcr(); /* * Save and restore the ETM Trace registers only if * the ETM is active. @@ -1994,7 +1993,6 @@ static void __etm4_cpu_restore(struct etmv4_drvdata *drvdata) etm4_cs_unlock(drvdata, csa); etm4x_relaxed_write32(csa, state->trcclaimset, TRCCLAIMSET);
- etm4x_relaxed_write32(csa, state->trcprgctlr, TRCPRGCTLR); if (drvdata->nr_pe) etm4x_relaxed_write32(csa, state->trcprocselr, TRCPROCSELR); etm4x_relaxed_write32(csa, state->trcconfigr, TRCCONFIGR); @@ -2079,13 +2077,15 @@ static void __etm4_cpu_restore(struct etmv4_drvdata *drvdata)
/* Unlock the OS lock to re-enable trace and external debug access */ etm4_os_unlock(drvdata); + + if (!drvdata->paused) + etm4_enable_trace_unit(drvdata); + etm4_cs_lock(drvdata, csa); }
static void etm4_cpu_restore(struct etmv4_drvdata *drvdata) { - if (drvdata->trfcr) - write_trfcr(drvdata->save_trfcr); if (drvdata->state_needs_restore) __etm4_cpu_restore(drvdata); } diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h index 13ec9ecef46f5..b8796b4271025 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x.h +++ b/drivers/hwtracing/coresight/coresight-etm4x.h @@ -866,7 +866,6 @@ struct etmv4_config { * struct etm4_save_state - state to be preserved when ETM is without power */ struct etmv4_save_state { - u32 trcprgctlr; u32 trcprocselr; u32 trcconfigr; u32 trcauxctlr; @@ -980,7 +979,6 @@ struct etmv4_save_state { * at runtime, due to the additional setting of TRFCR_CX when * in EL2. Otherwise, 0. * @config: structure holding configuration parameters. - * @save_trfcr: Saved TRFCR_EL1 register during a CPU PM event. * @save_state: State to be preserved across power loss * @state_needs_restore: True when there is context to restore after PM exit * @skip_power_up: Indicates if an implementation can skip powering up @@ -1037,7 +1035,6 @@ struct etmv4_drvdata { bool lpoverride; u64 trfcr; struct etmv4_config config; - u64 save_trfcr; struct etmv4_save_state *save_state; bool state_needs_restore; bool skip_power_up;