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Sun, 28 May 2023 04:05:26 -0700 (PDT) Date: Sun, 28 May 2023 19:05:16 +0800 From: Leo Yan To: James Clark Cc: coresight@lists.linaro.org, denik@chromium.org, Suzuki K Poulose , Mike Leach , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , John Garry , Will Deacon , linux-arm-kernel@lists.infradead.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/4] perf cs-etm: Track exception level Message-ID: <20230528110516.GC886420@leoy-yangtze.lan> References: <20230524131958.2139331-1-james.clark@arm.com> <20230524131958.2139331-4-james.clark@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20230524131958.2139331-4-james.clark@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230528_040529_919000_C8E9697B X-CRM114-Status: GOOD ( 38.09 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, May 24, 2023 at 02:19:57PM +0100, James Clark wrote: > Currently we assume all trace belongs to the host machine so when > the decoder should be looking at the guest kernel maps it can crash > because it looks at the host ones instead. > > Avoid one scenario (guest kernel running at EL1) by assigning the > default guest machine to this trace. For userspace trace it's still not > possible to determine guest vs host, but the PIDs should help in this > case. > > Signed-off-by: James Clark > --- > .../perf/util/cs-etm-decoder/cs-etm-decoder.c | 7 +- > tools/perf/util/cs-etm.c | 64 ++++++++++++++----- > tools/perf/util/cs-etm.h | 5 +- > 3 files changed, 56 insertions(+), 20 deletions(-) > > diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c > index 82a27ab90c8b..ac227cd03eb0 100644 > --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c > +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c > @@ -573,12 +573,13 @@ cs_etm_decoder__set_tid(struct cs_etm_queue *etmq, > break; > } > > + if (cs_etm__etmq_set_tid_el(etmq, tid, trace_chan_id, > + elem->context.exception_level)) > + return OCSD_RESP_FATAL_SYS_ERR; > + > if (tid == -1) > return OCSD_RESP_CONT; > > - if (cs_etm__etmq_set_tid(etmq, tid, trace_chan_id)) > - return OCSD_RESP_FATAL_SYS_ERR; > - > /* > * A timestamp is generated after a PE_CONTEXT element so make sure > * to rely on that coming one. > diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c > index a997fe79d458..b9ba19327f26 100644 > --- a/tools/perf/util/cs-etm.c > +++ b/tools/perf/util/cs-etm.c > @@ -14,7 +14,6 @@ > #include > #include > > -#include > #include > > #include "auxtrace.h" > @@ -87,6 +86,8 @@ struct cs_etm_traceid_queue { > union perf_event *event_buf; > struct thread *thread; > struct thread *prev_thread; > + ocsd_ex_level prev_el; > + ocsd_ex_level el; > struct branch_stack *last_branch; > struct branch_stack *last_branch_rb; > struct cs_etm_packet *prev_packet; > @@ -479,6 +480,7 @@ static int cs_etm__init_traceid_queue(struct cs_etm_queue *etmq, > > queue = &etmq->etm->queues.queue_array[etmq->queue_nr]; > tidq->trace_chan_id = trace_chan_id; > + tidq->el = tidq->prev_el = ocsd_EL_unknown; > tidq->thread = machine__findnew_thread(&etm->session->machines.host, -1, > queue->tid); > tidq->prev_thread = machine__idle_thread(&etm->session->machines.host); > @@ -618,6 +620,7 @@ static void cs_etm__packet_swap(struct cs_etm_auxtrace *etm, > tmp = tidq->packet; > tidq->packet = tidq->prev_packet; > tidq->prev_packet = tmp; > + tidq->prev_el = tidq->el; > thread__put(tidq->prev_thread); > tidq->prev_thread = thread__get(tidq->thread); > } > @@ -879,11 +882,34 @@ static bool cs_etm__evsel_is_auxtrace(struct perf_session *session, > return evsel->core.attr.type == aux->pmu_type; > } > > -static u8 cs_etm__cpu_mode(struct cs_etm_queue *etmq, u64 address) > +static struct machine *cs_etm__get_machine(struct cs_etm_auxtrace *etm, > + ocsd_ex_level el) > { > - struct machine *machine; > + /* > + * Not perfect, but assume anything in EL1 is the default guest, and > + * everything else is the host. nHVE and pKVM may not work with this s/nHVE/nVHE ? And it's good to say "if any virtulisation (e.g. pKVM) based on nVHE may not work with this ....". > + * assumption. And distinguishing between guest and host userspaces > + * isn't currently supported either. Neither is multiple guest support. > + * All this does is reduce the likeliness of decode errors where we look > + * into the host kernel maps when it should have been the guest maps. > + */ > + switch (el) { > + case ocsd_EL1: > + return machines__find_guest(&etm->session->machines, > + DEFAULT_GUEST_KERNEL_ID); I share the same concern with Mike that this will break perf for any Armv8 CPUs with nVHE (like Cortex-CA53, etc). You could see CoreSight has trace data "elem->context.vmid", when a guest kernel runs in EL1, can we use "elem->context.vmid" as a guest kernel ID and finally retrieve the corresponding machine pointer? Thanks, Leo > + case ocsd_EL3: > + case ocsd_EL2: > + case ocsd_EL0: > + case ocsd_EL_unknown: > + default: > + return &etm->session->machines.host; > + } > +} > > - machine = &etmq->etm->session->machines.host; > +static u8 cs_etm__cpu_mode(struct cs_etm_queue *etmq, u64 address, > + ocsd_ex_level el) > +{ > + struct machine *machine = cs_etm__get_machine(etmq->etm, el); > > if (address >= machine__kernel_start(machine)) { > if (machine__is_host(machine)) > @@ -893,10 +919,14 @@ static u8 cs_etm__cpu_mode(struct cs_etm_queue *etmq, u64 address) > } else { > if (machine__is_host(machine)) > return PERF_RECORD_MISC_USER; > - else if (perf_guest) > + else { > + /* > + * Can't really happen at the moment because > + * cs_etm__get_machine() will always return > + * machines.host for any non EL1 trace. > + */ > return PERF_RECORD_MISC_GUEST_USER; > - else > - return PERF_RECORD_MISC_HYPERVISOR; > + } > } > } > > @@ -913,11 +943,12 @@ static u32 cs_etm__mem_access(struct cs_etm_queue *etmq, u8 trace_chan_id, > if (!etmq) > return 0; > > - cpumode = cs_etm__cpu_mode(etmq, address); > tidq = cs_etm__etmq_get_traceid_queue(etmq, trace_chan_id); > if (!tidq) > return 0; > > + cpumode = cs_etm__cpu_mode(etmq, address, tidq->el); > + > if (!thread__find_map(tidq->thread, cpumode, address, &al)) > return 0; > > @@ -1296,9 +1327,10 @@ cs_etm__get_trace(struct cs_etm_queue *etmq) > } > > static void cs_etm__set_thread(struct cs_etm_auxtrace *etm, > - struct cs_etm_traceid_queue *tidq, pid_t tid) > + struct cs_etm_traceid_queue *tidq, pid_t tid, > + ocsd_ex_level el) > { > - struct machine *machine = &etm->session->machines.host; > + struct machine *machine = cs_etm__get_machine(etm, el); > > if (tid != -1) { > thread__zput(tidq->thread); > @@ -1308,10 +1340,12 @@ static void cs_etm__set_thread(struct cs_etm_auxtrace *etm, > /* Couldn't find a known thread */ > if (!tidq->thread) > tidq->thread = machine__idle_thread(machine); > + > + tidq->el = el; > } > > -int cs_etm__etmq_set_tid(struct cs_etm_queue *etmq, > - pid_t tid, u8 trace_chan_id) > +int cs_etm__etmq_set_tid_el(struct cs_etm_queue *etmq, pid_t tid, u8 trace_chan_id, > + ocsd_ex_level el) > { > struct cs_etm_traceid_queue *tidq; > > @@ -1319,7 +1353,7 @@ int cs_etm__etmq_set_tid(struct cs_etm_queue *etmq, > if (!tidq) > return -EINVAL; > > - cs_etm__set_thread(etmq->etm, tidq, tid); > + cs_etm__set_thread(etmq->etm, tidq, tid, el); > return 0; > } > > @@ -1389,7 +1423,7 @@ static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq, > struct perf_sample sample = {.ip = 0,}; > > event->sample.header.type = PERF_RECORD_SAMPLE; > - event->sample.header.misc = cs_etm__cpu_mode(etmq, addr); > + event->sample.header.misc = cs_etm__cpu_mode(etmq, addr, tidq->el); > event->sample.header.size = sizeof(struct perf_event_header); > > /* Set time field based on etm auxtrace config. */ > @@ -1448,7 +1482,7 @@ static int cs_etm__synth_branch_sample(struct cs_etm_queue *etmq, > ip = cs_etm__last_executed_instr(tidq->prev_packet); > > event->sample.header.type = PERF_RECORD_SAMPLE; > - event->sample.header.misc = cs_etm__cpu_mode(etmq, ip); > + event->sample.header.misc = cs_etm__cpu_mode(etmq, ip, tidq->prev_el); > event->sample.header.size = sizeof(struct perf_event_header); > > /* Set time field based on etm auxtrace config. */ > diff --git a/tools/perf/util/cs-etm.h b/tools/perf/util/cs-etm.h > index 70cac0375b34..88e9b25a8a9f 100644 > --- a/tools/perf/util/cs-etm.h > +++ b/tools/perf/util/cs-etm.h > @@ -232,10 +232,11 @@ int cs_etm__process_auxtrace_info(union perf_event *event, > struct perf_event_attr *cs_etm_get_default_config(struct perf_pmu *pmu); > > #ifdef HAVE_CSTRACE_SUPPORT > +#include > int cs_etm__get_cpu(u8 trace_chan_id, int *cpu); > int cs_etm__get_pid_fmt(u8 trace_chan_id, u64 *pid_fmt); > -int cs_etm__etmq_set_tid(struct cs_etm_queue *etmq, > - pid_t tid, u8 trace_chan_id); > +int cs_etm__etmq_set_tid_el(struct cs_etm_queue *etmq, pid_t tid, u8 trace_chan_id, > + ocsd_ex_level el); > bool cs_etm__etmq_is_timeless(struct cs_etm_queue *etmq); > void cs_etm__etmq_set_traceid_queue_timestamp(struct cs_etm_queue *etmq, > u8 trace_chan_id); > -- > 2.34.1 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel