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perf intel-pt: Support decoding of guest kernel

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The guest kernel can be found from any guest thread belonging to the guest
machine. The guest machine is associated with the current host process pid.
An idle thread (pid=tid=0) is created as a vehicle from which to find the
guest kernel map.

Decoding guest user space is not supported.

Synthesized samples just need the cpumode set for the guest.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/r/20210218095801.19576-8-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Adrian Hunter 2021-02-18 11:57:57 +02:00 committed by Arnaldo Carvalho de Melo
parent 3035cb6cbd
commit 6e86bfdc4a
1 changed files with 69 additions and 12 deletions
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81
tools/perf/util/intel-pt.c
View file

@ -163,6 +163,9 @@ struct intel_pt_queue {
int switch_state;
pid_t next_tid;
struct thread *thread;
struct machine *guest_machine;
struct thread *unknown_guest_thread;
pid_t guest_machine_pid;
bool exclude_kernel;
bool have_sample;
u64 time;
@ -550,13 +553,59 @@ static void intel_pt_cache_invalidate(struct dso *dso, struct machine *machine,
auxtrace_cache__remove(dso->auxtrace_cache, offset);
}
static inline u8 intel_pt_cpumode(struct intel_pt *pt, uint64_t ip)
static inline bool intel_pt_guest_kernel_ip(uint64_t ip)
{
return ip >= pt->kernel_start ?
/* Assumes 64-bit kernel */
return ip & (1ULL << 63);
}
static inline u8 intel_pt_nr_cpumode(struct intel_pt_queue *ptq, uint64_t ip, bool nr)
{
if (nr) {
return intel_pt_guest_kernel_ip(ip) ?
PERF_RECORD_MISC_GUEST_KERNEL :
PERF_RECORD_MISC_GUEST_USER;
}
return ip >= ptq->pt->kernel_start ?
PERF_RECORD_MISC_KERNEL :
PERF_RECORD_MISC_USER;
}
static inline u8 intel_pt_cpumode(struct intel_pt_queue *ptq, uint64_t from_ip, uint64_t to_ip)
{
/* No support for non-zero CS base */
if (from_ip)
return intel_pt_nr_cpumode(ptq, from_ip, ptq->state->from_nr);
return intel_pt_nr_cpumode(ptq, to_ip, ptq->state->to_nr);
}
static int intel_pt_get_guest(struct intel_pt_queue *ptq)
{
struct machines *machines = &ptq->pt->session->machines;
struct machine *machine;
pid_t pid = ptq->pid <= 0 ? DEFAULT_GUEST_KERNEL_ID : ptq->pid;
if (ptq->guest_machine && pid == ptq->guest_machine_pid)
return 0;
ptq->guest_machine = NULL;
thread__zput(ptq->unknown_guest_thread);
machine = machines__find_guest(machines, pid);
if (!machine)
return -1;
ptq->unknown_guest_thread = machine__idle_thread(machine);
if (!ptq->unknown_guest_thread)
return -1;
ptq->guest_machine = machine;
ptq->guest_machine_pid = pid;
return 0;
}
static int intel_pt_walk_next_insn(struct intel_pt_insn *intel_pt_insn,
uint64_t *insn_cnt_ptr, uint64_t *ip,
uint64_t to_ip, uint64_t max_insn_cnt,
@ -573,19 +622,29 @@ static int intel_pt_walk_next_insn(struct intel_pt_insn *intel_pt_insn,
u64 offset, start_offset, start_ip;
u64 insn_cnt = 0;
bool one_map = true;
bool nr;
intel_pt_insn->length = 0;
if (to_ip && *ip == to_ip)
goto out_no_cache;
cpumode = intel_pt_cpumode(ptq->pt, *ip);
nr = ptq->state->to_nr;
cpumode = intel_pt_nr_cpumode(ptq, *ip, nr);
thread = ptq->thread;
if (!thread) {
if (cpumode != PERF_RECORD_MISC_KERNEL)
if (nr) {
if (cpumode != PERF_RECORD_MISC_GUEST_KERNEL ||
intel_pt_get_guest(ptq))
return -EINVAL;
thread = ptq->pt->unknown_thread;
machine = ptq->guest_machine;
thread = ptq->unknown_guest_thread;
} else {
thread = ptq->thread;
if (!thread) {
if (cpumode != PERF_RECORD_MISC_KERNEL)
return -EINVAL;
thread = ptq->pt->unknown_thread;
}
}
while (1) {
@ -1101,6 +1160,7 @@ static void intel_pt_free_queue(void *priv)
if (!ptq)
return;
thread__zput(ptq->thread);
thread__zput(ptq->unknown_guest_thread);
intel_pt_decoder_free(ptq->decoder);
zfree(&ptq->event_buf);
zfree(&ptq->last_branch);
@ -1315,8 +1375,8 @@ static void intel_pt_prep_b_sample(struct intel_pt *pt,
sample->time = tsc_to_perf_time(ptq->timestamp, &pt->tc);
sample->ip = ptq->state->from_ip;
sample->cpumode = intel_pt_cpumode(pt, sample->ip);
sample->addr = ptq->state->to_ip;
sample->cpumode = intel_pt_cpumode(ptq, sample->ip, sample->addr);
sample->period = 1;
sample->flags = ptq->flags;
@ -1833,10 +1893,7 @@ static int intel_pt_synth_pebs_sample(struct intel_pt_queue *ptq)
else
sample.ip = ptq->state->from_ip;
/* No support for guest mode at this time */
cpumode = sample.ip < ptq->pt->kernel_start ?
PERF_RECORD_MISC_USER :
PERF_RECORD_MISC_KERNEL;
cpumode = intel_pt_cpumode(ptq, sample.ip, 0);
event->sample.header.misc = cpumode | PERF_RECORD_MISC_EXACT_IP;