From: Madhavan Srinivasan Date: Thu, 28 Oct 2021 11:37:13 +0000 (+0530) Subject: perf evsel: Add bitfield_swap() to handle branch_stack endian issue X-Git-Tag: v6.1-rc5~2702^2~22 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=63c12ae2f246dcdc30895ec7c980365a5133433d;p=platform%2Fkernel%2Flinux-starfive.git perf evsel: Add bitfield_swap() to handle branch_stack endian issue The branch_stack struct has bit field definition which produces different bit ordering for big/little endian. Because of this, when branch_stack sample is collected in a BE system and viewed/reported in a LE system, bit fields of the branch stack are not presented properly. To address this issue, a evsel__bitfield_swap_branch_stack() is defined and introduced in evsel__parse_sample. Signed-off-by: Madhavan Srinivasan Acked-by: Jiri Olsa Cc: Athira Jajeev Cc: Kajol Jain Cc: Mark Rutland Cc: Michael Ellerman Cc: Namhyung Kim Cc: Stephane Eranian Link: http://lore.kernel.org/lkml/20211028113714.600549-1-maddy@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo --- diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 96ef6a4..2cfc293 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -2238,6 +2238,54 @@ void __weak arch_perf_parse_sample_weight(struct perf_sample *data, data->weight = *array; } +u64 evsel__bitfield_swap_branch_flags(u64 value) +{ + u64 new_val = 0; + + /* + * branch_flags + * union { + * u64 values; + * struct { + * mispred:1 //target mispredicted + * predicted:1 //target predicted + * in_tx:1 //in transaction + * abort:1 //transaction abort + * cycles:16 //cycle count to last branch + * type:4 //branch type + * reserved:40 + * } + * } + * + * Avoid bswap64() the entire branch_flag.value, + * as it has variable bit-field sizes. Instead the + * macro takes the bit-field position/size, + * swaps it based on the host endianness. + * + * tep_is_bigendian() is used here instead of + * bigendian() to avoid python test fails. + */ + if (tep_is_bigendian()) { + new_val = bitfield_swap(value, 0, 1); + new_val |= bitfield_swap(value, 1, 1); + new_val |= bitfield_swap(value, 2, 1); + new_val |= bitfield_swap(value, 3, 1); + new_val |= bitfield_swap(value, 4, 16); + new_val |= bitfield_swap(value, 20, 4); + new_val |= bitfield_swap(value, 24, 40); + } else { + new_val = bitfield_swap(value, 63, 1); + new_val |= bitfield_swap(value, 62, 1); + new_val |= bitfield_swap(value, 61, 1); + new_val |= bitfield_swap(value, 60, 1); + new_val |= bitfield_swap(value, 44, 16); + new_val |= bitfield_swap(value, 40, 4); + new_val |= bitfield_swap(value, 0, 40); + } + + return new_val; +} + int evsel__parse_sample(struct evsel *evsel, union perf_event *event, struct perf_sample *data) { @@ -2425,6 +2473,8 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event, if (type & PERF_SAMPLE_BRANCH_STACK) { const u64 max_branch_nr = UINT64_MAX / sizeof(struct branch_entry); + struct branch_entry *e; + unsigned int i; OVERFLOW_CHECK_u64(array); data->branch_stack = (struct branch_stack *)array++; @@ -2433,10 +2483,33 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event, return -EFAULT; sz = data->branch_stack->nr * sizeof(struct branch_entry); - if (evsel__has_branch_hw_idx(evsel)) + if (evsel__has_branch_hw_idx(evsel)) { sz += sizeof(u64); - else + e = &data->branch_stack->entries[0]; + } else { data->no_hw_idx = true; + /* + * if the PERF_SAMPLE_BRANCH_HW_INDEX is not applied, + * only nr and entries[] will be output by kernel. + */ + e = (struct branch_entry *)&data->branch_stack->hw_idx; + } + + if (swapped) { + /* + * struct branch_flag does not have endian + * specific bit field definition. And bswap + * will not resolve the issue, since these + * are bit fields. + * + * evsel__bitfield_swap_branch_flags() uses a + * bitfield_swap macro to swap the bit position + * based on the host endians. + */ + for (i = 0; i < data->branch_stack->nr; i++, e++) + e->flags.value = evsel__bitfield_swap_branch_flags(e->flags.value); + } + OVERFLOW_CHECK(array, sz, max_size); array = (void *)array + sz; } diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h index 45476a8..846c827 100644 --- a/tools/perf/util/evsel.h +++ b/tools/perf/util/evsel.h @@ -484,4 +484,17 @@ struct evsel *evsel__leader(struct evsel *evsel); bool evsel__has_leader(struct evsel *evsel, struct evsel *leader); bool evsel__is_leader(struct evsel *evsel); void evsel__set_leader(struct evsel *evsel, struct evsel *leader); + +/* + * Macro to swap the bit-field postition and size. + * Used when, + * - dont need to swap the entire u64 && + * - when u64 has variable bit-field sizes && + * - when presented in a host endian which is different + * than the source endian of the perf.data file + */ +#define bitfield_swap(src, pos, size) \ + ((((src) >> (pos)) & ((1ull << (size)) - 1)) << (63 - ((pos) + (size) - 1))) + +u64 evsel__bitfield_swap_branch_flags(u64 value); #endif /* __PERF_EVSEL_H */