From: Kan Liang <[email protected]> LBR call stack only has user callchain. It is output as PERF_SAMPLE_BRANCH_STACK data format. For the kernel callchain, it's still from PERF_SAMPLE_CALLCHAIN. The perf tool has to handle both data sources to construct a complete callstack. For perf report -D option, both lbr and fp information will be displayed.
Signed-off-by: Kan Liang <[email protected]> --- tools/perf/util/evsel.h | 4 +++ tools/perf/util/machine.c | 73 +++++++++++++++++++++++++++++++++++++++++------ tools/perf/util/session.c | 56 ++++++++++++++++++++++++++++++++---- 3 files changed, 118 insertions(+), 15 deletions(-) diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h index 9797909..1bbaa74 100644 --- a/tools/perf/util/evsel.h +++ b/tools/perf/util/evsel.h @@ -368,4 +368,8 @@ for ((_evsel) = list_entry((_leader)->node.next, struct perf_evsel, node); \ (_evsel) && (_evsel)->leader == (_leader); \ (_evsel) = list_entry((_evsel)->node.next, struct perf_evsel, node)) +static inline bool has_branch_callstack(struct perf_evsel *evsel) +{ + return evsel->attr.branch_sample_type & PERF_SAMPLE_BRANCH_CALL_STACK; +} #endif /* __PERF_EVSEL_H */ diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index 9c7d136..a63ae26 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -1451,15 +1451,19 @@ static inline int __thread__resolve_callchain_sample(struct thread *thread, } static int thread__resolve_callchain_sample(struct thread *thread, - struct ip_callchain *chain, - struct symbol **parent, - struct addr_location *root_al, - int max_stack) + struct perf_evsel *evsel, + struct perf_sample *sample, + struct symbol **parent, + struct addr_location *root_al, + int max_stack) { + struct ip_callchain *chain = sample->callchain; u8 cpumode = PERF_RECORD_MISC_USER; int chain_nr = min(max_stack, (int)chain->nr); int i, j, err = 0; int skip_idx __maybe_unused; + u64 ip; + bool lbr = has_branch_callstack(evsel); callchain_cursor_reset(&callchain_cursor); @@ -1468,6 +1472,58 @@ static int thread__resolve_callchain_sample(struct thread *thread, return 0; } + if (lbr) { + for (i = 0; i < chain_nr; i++) { + if (chain->ips[i] == PERF_CONTEXT_USER) + break; + } + + /* LBR only affects the user callchain */ + if (i != chain_nr) { + struct branch_stack *lbr_stack = sample->branch_stack; + int lbr_nr = lbr_stack->nr; + /* + * LBR callstack can only get user call chain information. + * The mix_chain_nr should be kernel call chain number plus + * LBR user call chain number. + * i is kernel call chain number, 1 is PERF_CONTEXT_USER, + * lbr_nr + 1 is the user call chain number. + * For details, please refer to the comments + * in callchain__printf + */ + int mix_chain_nr = i + 1 + lbr_nr + 1; + + if (mix_chain_nr > PERF_MAX_STACK_DEPTH) { + pr_warning("corrupted callchain. skipping...\n"); + return 0; + } + + for (j = 0; j < mix_chain_nr; j++) { + if (callchain_param.order == ORDER_CALLEE) { + if (j < i + 1) + ip = chain->ips[j]; + else if (j > i + 1) + ip = lbr_stack->entries[j - i - 2].from; + else + ip = lbr_stack->entries[0].to; + } else { + if (j < lbr_nr) + ip = lbr_stack->entries[lbr_nr - j - 1].from; + else if (j > lbr_nr) + ip = chain->ips[i + 1 - (j - lbr_nr)]; + else + ip = lbr_stack->entries[0].to; + } + + err = __thread__resolve_callchain_sample(thread, + ip, &cpumode, parent, root_al); + if (err) + goto exit; + } + return 0; + } + } + /* * Based on DWARF debug information, some architectures skip * a callchain entry saved by the kernel. @@ -1475,8 +1531,6 @@ static int thread__resolve_callchain_sample(struct thread *thread, skip_idx = arch_skip_callchain_idx(thread, chain); for (i = 0; i < chain_nr; i++) { - u64 ip; - if (callchain_param.order == ORDER_CALLEE) j = i; else @@ -1489,7 +1543,7 @@ static int thread__resolve_callchain_sample(struct thread *thread, ip = chain->ips[j]; err = __thread__resolve_callchain_sample(thread, - ip, &cpumode, parent, root_al); + ip, &cpumode, parent, root_al); if (err) goto exit; } @@ -1512,8 +1566,9 @@ int thread__resolve_callchain(struct thread *thread, struct addr_location *root_al, int max_stack) { - int ret = thread__resolve_callchain_sample(thread, sample->callchain, - parent, root_al, max_stack); + int ret = thread__resolve_callchain_sample(thread, evsel, + sample, parent, + root_al, max_stack); if (ret) return ret; diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c index f4478ce..794c46b 100644 --- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -557,15 +557,59 @@ int perf_session_queue_event(struct perf_session *s, union perf_event *event, return 0; } -static void callchain__printf(struct perf_sample *sample) +static void callchain__printf(struct perf_evsel *evsel, + struct perf_sample *sample) { unsigned int i; + struct ip_callchain *callchain = sample->callchain; + bool lbr = has_branch_callstack(evsel); - printf("... chain: nr:%" PRIu64 "\n", sample->callchain->nr); + if (lbr) { + struct branch_stack *lbr_stack = sample->branch_stack; + u64 kernel_callchain_nr = callchain->nr; - for (i = 0; i < sample->callchain->nr; i++) + for (i = 0; i < kernel_callchain_nr; i++) { + if (callchain->ips[i] == PERF_CONTEXT_USER) + break; + } + + if ((i != kernel_callchain_nr) && lbr_stack->nr) { + u64 total_nr; + /* + * LBR callstack can only get user call chain information, + * So i is kernel call chain number, 1 is PERF_CONTEXT_USER. + * + * The user call chain is stored in LBR registers. + * LBR are pair registers. The caller is stored in "from" + * register, while the callee is stored in "to" register. + * For example, there is a call stack "A"->"B"->"C"->"D". + * The LBR registers will recorde like "C"->"D", "B"->"C", + * "A"->"B". So only the first "to" register and all "from" + * registers are needed to construct the whole stack. + */ + total_nr = i + 1 + lbr_stack->nr + 1; + kernel_callchain_nr = i + 1; + + printf("... LBR call chain: nr:%" PRIu64 "\n", total_nr); + + for (i = 0; i < kernel_callchain_nr; i++) + printf("..... %2d: %016" PRIx64 "\n", + i, callchain->ips[i]); + + printf("..... %2d: %016" PRIx64 "\n", + (int)(kernel_callchain_nr), lbr_stack->entries[0].to); + for (i = 0; i < lbr_stack->nr; i++) + printf("..... %2d: %016" PRIx64 "\n", + (int)(i + kernel_callchain_nr + 1), lbr_stack->entries[i].from); + } + + } + + printf("... FP chain: nr:%" PRIu64 "\n", callchain->nr); + + for (i = 0; i < callchain->nr; i++) printf("..... %2d: %016" PRIx64 "\n", - i, sample->callchain->ips[i]); + i, callchain->ips[i]); } static void branch_stack__printf(struct perf_sample *sample) @@ -691,9 +735,9 @@ static void dump_sample(struct perf_evsel *evsel, union perf_event *event, sample_type = evsel->attr.sample_type; if (sample_type & PERF_SAMPLE_CALLCHAIN) - callchain__printf(sample); + callchain__printf(evsel, sample); - if (sample_type & PERF_SAMPLE_BRANCH_STACK) + if ((sample_type & PERF_SAMPLE_BRANCH_STACK) && !has_branch_callstack(evsel)) branch_stack__printf(sample); if (sample_type & PERF_SAMPLE_REGS_USER) -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
