From 89493fe58c81db19efc16ec220e6fce512ec1cf7 Mon Sep 17 00:00:00 2001 From: Aaron Tomlin Date: Wed, 22 Jul 2026 11:50:48 -0400 Subject: [PATCH] perf trace: Correct default cpumask formatting to hexadecimal Currently, dynamic non-array fields such as 'cpumask_t' are mishandled in 'perf trace', causing the raw length and offset descriptors to be interpreted and displayed as a literal integer (e.g., "cpumask: 524320" instead of the actual mask data). Correct the parsing of dynamic fields that do not have the TEP_FIELD_IS_ARRAY flag set by introducing helper functions format_field__get_raw_data() and format_field__get_cpumask(). Using these helpers, resolve the pointer to the raw bits within the payload and format the cpumask as a zero-padded hexadecimal string by default. Fixes: c5e006cdbd27 ("perf trace: Support tracepoint dynamic char arrays") Signed-off-by: Aaron Tomlin Signed-off-by: Namhyung Kim --- tools/perf/builtin-trace.c | 69 +++++++++++++++++++++++++---- tools/perf/util/evsel.c | 91 ++++++++++++++++++++++++++++++++++++++ tools/perf/util/evsel.h | 6 +++ 3 files changed, 158 insertions(+), 8 deletions(-) diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index 845a9fe47f0b..186978cafab9 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -3207,6 +3207,22 @@ static void bpf_output__fprintf(struct trace *trace, ++trace->nr_events_printed; } +static unsigned char bitmap_byte(const unsigned long *mask, int byte_idx) +{ + unsigned char b_val = 0; + int bit_in_byte; + + for (bit_in_byte = 0; bit_in_byte < 8; bit_in_byte++) { + int b_idx = byte_idx * 8 + bit_in_byte; + int host_w_idx = b_idx / BITS_PER_LONG; + int host_bit_in_word = b_idx % BITS_PER_LONG; + + if (mask[host_w_idx] & (1UL << host_bit_in_word)) + b_val |= (1 << bit_in_byte); + } + return b_val; +} + static size_t trace__fprintf_tp_fields(struct trace *trace, struct perf_sample *sample, struct thread *thread, void *augmented_args, int augmented_args_size) { @@ -3238,17 +3254,54 @@ static size_t trace__fprintf_tp_fields(struct trace *trace, struct perf_sample * syscall_arg.len = 0; syscall_arg.fmt = arg; if (field->flags & TEP_FIELD_IS_ARRAY) { - int offset = field->offset; + void *ptr = format_field__get_raw_data(field, sample, + evsel->needs_swap, + &syscall_arg.len); - if (field->flags & TEP_FIELD_IS_DYNAMIC) { - offset = format_field__intval(field, sample, evsel->needs_swap); - syscall_arg.len = offset >> 16; - offset &= 0xffff; - if (tep_field_is_relative(field->flags)) - offset += field->offset + field->size; + if (!ptr) { + pr_err("Problem processing %s field, skipping...\n", field->name); + continue; + } + val = (uintptr_t)ptr; + } else if ((field->flags & TEP_FIELD_IS_DYNAMIC) && + strstr(field->type, "cpumask")) { + unsigned long *mask = format_field__get_cpumask(field, sample, + evsel->needs_swap, + &syscall_arg.len); + + if (!mask) { + pr_err("Problem processing %s field, skipping...\n", field->name); + continue; } - val = (uintptr_t)(sample->raw_data + offset); + printed += scnprintf(bf + printed, size - printed, "%s", printed ? ", " : ""); + if (trace->show_arg_names) + printed += scnprintf(bf + printed, size - printed, "%s: ", field->name); + + if (syscall_arg.len == 0) { + printed += scnprintf(bf + printed, size - printed, "0"); + } else { + int i; + bool skip_zero = true; + + printed += scnprintf(bf + printed, size - printed, "0x"); + /* Print bytes from most significant to least significant */ + for (i = syscall_arg.len - 1; i >= 0; i--) { + unsigned char b_val = bitmap_byte(mask, i); + + if (skip_zero && b_val == 0 && i > 0) + continue; + + if (skip_zero) { + printed += scnprintf(bf + printed, size - printed, "%x", b_val); + skip_zero = false; + } else { + printed += scnprintf(bf + printed, size - printed, "%02x", b_val); + } + } + } + free(mask); + continue; } else val = format_field__intval(field, sample, evsel->needs_swap); /* diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index a5b0687a3a79..d4cb455f4a7d 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -16,9 +16,11 @@ #include #include #include +#include #include #include +#include #include #include #include @@ -3933,6 +3935,95 @@ void *perf_sample__rawptr(struct perf_sample *sample, const char *name) return sample->raw_data + offset; } +void *format_field__get_raw_data(struct tep_format_field *field, struct + perf_sample *sample, bool needs_swap, + u16 *len_out) +{ + int offset = field->offset; + int size = field->size; + + if (field->flags & TEP_FIELD_IS_DYNAMIC) { + unsigned int dynamic_data; + + if (out_of_bounds(field, field->offset, field->size, sample->raw_size)) + return NULL; + + dynamic_data = format_field__intval(field, sample, needs_swap); + + offset = dynamic_data & 0xffff; + size = (dynamic_data >> 16) & 0xffff; + + if (tep_field_is_relative(field->flags)) + offset += field->offset + field->size; + } + + if (out_of_bounds(field, offset, size, sample->raw_size)) + return NULL; + + *len_out = size; + return sample->raw_data + offset; +} + +unsigned long *format_field__get_cpumask(struct tep_format_field *field, + struct perf_sample *sample, + bool needs_swap, u16 *len_out) +{ + u16 len; + void *ptr = format_field__get_raw_data(field, sample, needs_swap, &len); + unsigned long *mask; + struct perf_env *env; + bool target_is_64; + int target_word_size; + int nr_words; + int bit_idx; + int nbits; + + if (!ptr) + return NULL; + + nbits = len * 8; + mask = bitmap_zalloc(nbits ?: 1); + if (!mask) + return NULL; + + env = evsel__env(sample->evsel); + target_is_64 = env ? perf_env__kernel_is_64_bit(env) : (sizeof(void *) == 8); + target_word_size = target_is_64 ? 8 : 4; + nr_words = len / target_word_size; + + for (bit_idx = 0; bit_idx < nbits; bit_idx++) { + int w_idx = bit_idx / (target_word_size * 8); + int bit_in_word = bit_idx % (target_word_size * 8); + bool set = false; + + if (w_idx >= nr_words) + break; + + if (target_is_64) { + u64 word; + memcpy(&word, (unsigned char *)ptr + w_idx * 8, 8); + if (needs_swap) + word = bswap_64(word); + set = (word & (1ULL << bit_in_word)) != 0; + } else { + u32 word32; + memcpy(&word32, (unsigned char *)ptr + w_idx * 4, 4); + if (needs_swap) + word32 = bswap_32(word32); + set = (word32 & (1U << bit_in_word)) != 0; + } + + if (set) { + int host_w_idx = bit_idx / BITS_PER_LONG; + int host_bit_in_word = bit_idx % BITS_PER_LONG; + mask[host_w_idx] |= (1UL << host_bit_in_word); + } + } + + *len_out = len; + return mask; +} + u64 format_field__intval(struct tep_format_field *field, struct perf_sample *sample, bool needs_swap) { diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h index 42b95933632a..d9ecc6628217 100644 --- a/tools/perf/util/evsel.h +++ b/tools/perf/util/evsel.h @@ -398,6 +398,12 @@ static inline char *perf_sample__strval(struct perf_sample *sample, const char * struct tep_format_field; +void *format_field__get_raw_data(struct tep_format_field *field, + struct perf_sample *sample, + bool needs_swap, u16 *len_out); +unsigned long *format_field__get_cpumask(struct tep_format_field *field, + struct perf_sample *sample, + bool needs_swap, u16 *len_out); u64 format_field__intval(struct tep_format_field *field, struct perf_sample *sample, bool needs_swap); #ifdef HAVE_LIBTRACEEVENT