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Tue, 09 Dec 2025 05:17:51 -0800 (PST) Message-ID: <1c1092e6-aa5d-4bb1-84e5-81151a02cc6f@linaro.org> Date: Tue, 9 Dec 2025 13:17:50 +0000 Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 06/19] coresight: trbe: Refactor syndrome decoding To: Leo Yan Cc: coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Mike Leach , Anshuman Khandual , Yeoreum Yun , Will Deacon , Mark Rutland , Tamas Petz , Tamas Zsoldos , Arnaldo Carvalho de Melo , Namhyung Kim , Jiri Olsa , Ian Rogers , Adrian Hunter , Suzuki K Poulose References: <20251201-trbe_buffer_refactor_v1-1-v1-0-7da32b076b28@arm.com> <20251201-trbe_buffer_refactor_v1-1-v1-6-7da32b076b28@arm.com> <65c84357-0bda-454f-88c3-623b3ff9d29d@arm.com> Content-Language: en-US From: James Clark In-Reply-To: <65c84357-0bda-454f-88c3-623b3ff9d29d@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 02/12/2025 11:06 am, Suzuki K Poulose wrote: > Hi Leo > > A couple of minor nits below. Otherwise looks like a nice cleanup > > > On 01/12/2025 11:21, Leo Yan wrote: >> It gives priority to TRBSR_EL1.EA (external abort); an external abort >> will immediately bail out and return an error. >> >> Next, the syndrome decoding is refactored based on two levels of >> information: the EC (Event Class) bits and the BSC (Trace Buffer Status >> Code) bits. >> >> If TRBSR_EL1.EC==0b000000, the driver continues parsing TRBSR_EL1.BSC to >> identify the specific trace buffer event.  Otherwise, any non-zero >> TRBSR_EL1.EC is treated as an error. >> >> For error cases, the driver prints an error string and dumps registers >> for debugging. > > minor nit: Please avoid describing the code, which cod does well. > Briefly mention what you are doing, giving any additional contexts > that may not be evident from the code. > > e.g: > > "Add support for decoding the syndrome for TRBE, providing a verbose > description of the code for Fatal/unhandled events. > While at it add the new definitions from the latest Arm ARM for > EC and BSC" > > > > >> >> No additional checks are required for wrap mode beyond verifying the >> TRBSR_EL1.WRAP bit, even on units with overwrite errata, as this bit > > >> reliably indicates a buffer wrap. >> >> Signed-off-by: Leo Yan >> --- >>   drivers/hwtracing/coresight/coresight-trbe.c | 60 ++++++++++++++++++ >> +++------- >>   drivers/hwtracing/coresight/coresight-trbe.h |  8 ++-- >>   2 files changed, 51 insertions(+), 17 deletions(-) >> >> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/ >> hwtracing/coresight/coresight-trbe.c >> index >> 9e565122816949b37b8ff5e4ba04cfbc317c6f25..28e2bfa68074f19ccaa4a737d00af577aea818fe 100644 >> --- a/drivers/hwtracing/coresight/coresight-trbe.c >> +++ b/drivers/hwtracing/coresight/coresight-trbe.c >> @@ -643,29 +643,61 @@ static void trbe_enable_hw(struct trbe_buf *buf) >>   static enum trbe_fault_action trbe_get_fault_act(struct >> perf_output_handle *handle, >>                            u64 trbsr) >>   { >> +    const char *err_str; >>       int ec = get_trbe_ec(trbsr); >>       int bsc = get_trbe_bsc(trbsr); >> -    struct trbe_buf *buf = etm_perf_sink_config(handle); >> -    struct trbe_cpudata *cpudata = buf->cpudata; >>       WARN_ON(is_trbe_running(trbsr)); >> -    if (is_trbe_trg(trbsr) || is_trbe_abort(trbsr)) >> -        return TRBE_FAULT_ACT_FATAL; >> -    if ((ec == TRBE_EC_STAGE1_ABORT) || (ec == TRBE_EC_STAGE2_ABORT)) >> -        return TRBE_FAULT_ACT_FATAL; >> +    if (is_trbe_abort(trbsr)) { >> +        err_str = "External abort"; >> +        goto out_fatal; >> +    } >> -    /* >> -     * If the trbe is affected by TRBE_WORKAROUND_OVERWRITE_FILL_MODE, >> -     * it might write data after a WRAP event in the fill mode. >> -     * Thus the check TRBPTR == TRBBASER will not be honored. >> -     */ >> -    if ((is_trbe_wrap(trbsr) && (ec == TRBE_EC_OTHERS) && (bsc == >> TRBE_BSC_FILLED)) && >> -        (trbe_may_overwrite_in_fill_mode(cpudata) || >> -         get_trbe_write_pointer() == get_trbe_base_pointer())) >> +    switch (ec) { >> +    case TRBE_EC_OTHERS: >> +        break; >> +    case TRBE_EC_BUF_MGMT_IMPL: >> +        err_str = "Unexpected implemented management"; > > minor nit: "Unexpected IMPDEF buffer management event" > > > Suzuki > >> +        goto out_fatal; >> +    case TRBE_EC_GP_CHECK_FAULT: >> +        err_str = "Granule Protection Check fault"; >> +        goto out_fatal; >> +    case TRBE_EC_STAGE1_ABORT: >> +        err_str = "Stage 1 data abort"; >> +        goto out_fatal; >> +    case TRBE_EC_STAGE2_ABORT: >> +        err_str = "Stage 2 data abort"; >> +        goto out_fatal; >> +    default: >> +        err_str = "Unknown error code"; >> +        goto out_fatal; >> +    } >> + >> +    switch (bsc) { >> +    case TRBE_BSC_NOT_STOPPED: >> +        break; >> +    case TRBE_BSC_FILLED: >> +        break; >> +    case TRBE_BSC_TRIGGERED: >> +        err_str = "Unexpected trigger status"; >> +        goto out_fatal; >> +    default: >> +        err_str = "Unexpected buffer status code"; >> +        goto out_fatal; >> +    } >> + >> +    if (is_trbe_wrap(trbsr)) >>           return TRBE_FAULT_ACT_WRAP; >>       return TRBE_FAULT_ACT_SPURIOUS; >> + >> +out_fatal: >> +    pr_err_ratelimited("%s on CPU %d [TRBSR=0x%016llx, >> TRBPTR=0x%016llx, TRBLIMITR=0x%016llx]\n", >> +               err_str, smp_processor_id(), trbsr, >> +               read_sysreg_s(SYS_TRBPTR_EL1), >> +               read_sysreg_s(SYS_TRBLIMITR_EL1)); Don't you need to use %p to not leak pointers? >> +    return TRBE_FAULT_ACT_FATAL; >>   } >>   static unsigned long trbe_get_trace_size(struct perf_output_handle >> *handle, >> diff --git a/drivers/hwtracing/coresight/coresight-trbe.h b/drivers/ >> hwtracing/coresight/coresight-trbe.h >> index >> 45202c48accec7c86ba56130e2737bc2d1830fae..d7f7cd763c0c7139cf322b7336ee563073e3bea0 100644 >> --- a/drivers/hwtracing/coresight/coresight-trbe.h >> +++ b/drivers/hwtracing/coresight/coresight-trbe.h >> @@ -35,9 +35,11 @@ static inline bool is_trbe_enabled(void) >>       return trblimitr & TRBLIMITR_EL1_E; >>   } >> -#define TRBE_EC_OTHERS        0 >> -#define TRBE_EC_STAGE1_ABORT    36 >> -#define TRBE_EC_STAGE2_ABORT    37 >> +#define TRBE_EC_OTHERS            0x0 >> +#define TRBE_EC_GP_CHECK_FAULT        0X1e >> +#define TRBE_EC_BUF_MGMT_IMPL        0x1f >> +#define TRBE_EC_STAGE1_ABORT        0x24 >> +#define TRBE_EC_STAGE2_ABORT        0x25 I know some were already defined here, but this should probably be an enum in sysreg. >>   static inline int get_trbe_ec(u64 trbsr) >>   { >> >