From c5e006cdbd278a8a5185a3a56acdba161cf159ea Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Tue, 15 Oct 2019 08:26:47 -0300 Subject: [PATCH] perf trace: Support tracepoint dynamic char arrays MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Things like: # grep __data_loc /sys/kernel/debug/tracing/events/sched/sched_process_exec/format field:__data_loc char[] filename; offset:8; size:4; signed:1; # That, at that offset (8) and with that size(8) have an integer that contains the real length and offset for the contents of that array. Now this works: # perf trace --max-events 1 -e sched:*exec -a 0.000 sed/19441 sched:sched_process_exec(filename: "/usr/bin/sync", pid: 19441 (sync), old_pid: 19441 (sync)) # As when using the libtraceevent based beautifier: # perf trace --libtraceevent --max-events 1 -e sched:*exec -a 0.000 sync/19463 sched:sched_process_exec(filename=/usr/bin/sync pid=19463 old_pid=19463) # I.e. that 'filename' is implemented as a dynamic char array. Cc: Adrian Hunter Cc: Andi Kleen Cc: David Ahern Cc: Jiri Olsa Cc: Luis Cláudio Gonçalves Cc: Namhyung Kim Link: https://lkml.kernel.org/n/tip-950p0m842fe6n7sxsdwqj5i2@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-trace.c | 19 ++++++++++++++----- tools/perf/trace/beauty/beauty.h | 2 ++ 2 files changed, 16 insertions(+), 5 deletions(-) diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index cdee22dac2b3..907eaf316f5b 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -563,7 +563,7 @@ static size_t syscall_arg__scnprintf_char_array(char *bf, size_t size, struct sy // XXX Hey, maybe for sched:sched_switch prev/next comm fields we can // fill missing comms using thread__set_comm()... // here or in a special syscall_arg__scnprintf_pid_sched_tp... - return scnprintf(bf, size, "\"%-.*s\"", arg->fmt->nr_entries, arg->val); + return scnprintf(bf, size, "\"%-.*s\"", arg->fmt->nr_entries ?: arg->len, arg->val); } #define SCA_CHAR_ARRAY syscall_arg__scnprintf_char_array @@ -1559,7 +1559,7 @@ syscall_arg_fmt__init_array(struct syscall_arg_fmt *arg, struct tep_format_field arg->scnprintf = SCA_PID; else if (strcmp(field->type, "umode_t") == 0) arg->scnprintf = SCA_MODE_T; - else if ((field->flags & TEP_FIELD_IS_ARRAY) && strstarts(field->type, "char")) { + else if ((field->flags & TEP_FIELD_IS_ARRAY) && strstr(field->type, "char")) { arg->scnprintf = SCA_CHAR_ARRAY; arg->nr_entries = field->arraylen; } else if ((strcmp(field->type, "int") == 0 || @@ -2523,10 +2523,19 @@ static size_t trace__fprintf_tp_fields(struct trace *trace, struct evsel *evsel, if (syscall_arg.mask & bit) continue; + syscall_arg.len = 0; syscall_arg.fmt = arg; - if (field->flags & TEP_FIELD_IS_ARRAY) - val = (uintptr_t)(sample->raw_data + field->offset); - else + if (field->flags & TEP_FIELD_IS_ARRAY) { + int offset = field->offset; + + if (field->flags & TEP_FIELD_IS_DYNAMIC) { + offset = format_field__intval(field, sample, evsel->needs_swap); + syscall_arg.len = offset >> 16; + offset &= 0xffff; + } + + val = (uintptr_t)(sample->raw_data + offset); + } else val = format_field__intval(field, sample, evsel->needs_swap); /* * Some syscall args need some mask, most don't and diff --git a/tools/perf/trace/beauty/beauty.h b/tools/perf/trace/beauty/beauty.h index 77ad80a399fd..0dee0cf4fda8 100644 --- a/tools/perf/trace/beauty/beauty.h +++ b/tools/perf/trace/beauty/beauty.h @@ -87,6 +87,7 @@ struct syscall_arg_fmt; /** * @val: value of syscall argument being formatted + * @len: for tracepoint dynamic arrays, if fmt->nr_entries == 0, then its not a fixed array, look at arg->len * @args: All the args, use syscall_args__val(arg, nth) to access one * @augmented_args: Extra data that can be collected, for instance, with eBPF for expanding the pathname for open, etc * @augmented_args_size: augmented_args total payload size @@ -109,6 +110,7 @@ struct syscall_arg { struct thread *thread; struct trace *trace; void *parm; + u16 len; u8 idx; u8 mask; bool show_string_prefix;