From b257fac12f38d7f503b932313d704cee21092350 Mon Sep 17 00:00:00 2001 From: Howard Chu Date: Sun, 25 Aug 2024 00:33:19 +0800 Subject: [PATCH] perf trace: Pretty print buffer data Define TRACE_AUG_MAX_BUF in trace_augment.h data, which is the maximum buffer size we can augment. BPF will include this header too. Print buffer in a way that's different than just printing a string, we print all the control characters in \digits (such as \0 for null, and \10 for newline, LF). For character that has a bigger value than 127, we print the digits instead of the character itself as well. Committer notes: Simplified the buffer scnprintf to avoid using multiple buffers as discussed in the patch review thread. We can't really all 'buf' args to SCA_BUF as we're collecting so far just on the sys_enter path, so we would be printing the previous 'read' arg buffer contents, not what the kernel puts there. So instead of: static int syscall_fmt__cmp(const void *name, const void *fmtp) @@ -1987,8 +1989,6 @@ syscall_arg_fmt__init_array(struct syscall_arg_fmt *arg, struct tep_format_field - else if (strstr(field->type, "char *") && strstr(field->name, "buf")) - arg->scnprintf = SCA_BUF; Do: static const struct syscall_fmt syscall_fmts[] = { + { .name = "write", .errpid = true, + .arg = { [1] = { .scnprintf = SCA_BUF /* buf */, from_user = true, }, }, }, Signed-off-by: Howard Chu Cc: Adrian Hunter Cc: Ian Rogers Cc: Jiri Olsa Cc: Kan Liang Cc: Namhyung Kim Link: https://lore.kernel.org/r/20240815013626.935097-8-howardchu95@gmail.com Link: https://lore.kernel.org/r/20240824163322.60796-6-howardchu95@gmail.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-trace.c | 33 +++++++++++++++++++++++++++++++++ tools/perf/util/trace_augment.h | 6 ++++++ 2 files changed, 39 insertions(+) create mode 100644 tools/perf/util/trace_augment.h diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index 41d36a351bfd..dab6d905015d 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -65,6 +65,7 @@ #include "syscalltbl.h" #include "rb_resort.h" #include "../perf.h" +#include "trace_augment.h" #include #include @@ -864,6 +865,10 @@ static size_t syscall_arg__scnprintf_filename(char *bf, size_t size, { .scnprintf = SCA_FILENAME, \ .from_user = true, } +static size_t syscall_arg__scnprintf_buf(char *bf, size_t size, struct syscall_arg *arg); + +#define SCA_BUF syscall_arg__scnprintf_buf + static size_t syscall_arg__scnprintf_pipe_flags(char *bf, size_t size, struct syscall_arg *arg) { @@ -1387,6 +1392,8 @@ static const struct syscall_fmt syscall_fmts[] = { .arg = { [2] = { .scnprintf = SCA_WAITID_OPTIONS, /* options */ }, }, }, { .name = "waitid", .errpid = true, .arg = { [3] = { .scnprintf = SCA_WAITID_OPTIONS, /* options */ }, }, }, + { .name = "write", .errpid = true, + .arg = { [1] = { .scnprintf = SCA_BUF /* buf */, .from_user = true, }, }, }, }; static int syscall_fmt__cmp(const void *name, const void *fmtp) @@ -1758,6 +1765,32 @@ static size_t syscall_arg__scnprintf_filename(char *bf, size_t size, return 0; } +#define MAX_CONTROL_CHAR 31 +#define MAX_ASCII 127 + +static size_t syscall_arg__scnprintf_buf(char *bf, size_t size, struct syscall_arg *arg) +{ + struct augmented_arg *augmented_arg = arg->augmented.args; + unsigned char *orig = (unsigned char *)augmented_arg->value; + size_t printed = 0; + int consumed; + + if (augmented_arg == NULL) + return 0; + + for (int j = 0; j < augmented_arg->size; ++j) { + bool control_char = orig[j] <= MAX_CONTROL_CHAR || orig[j] >= MAX_ASCII; + /* print control characters (0~31 and 127), and non-ascii characters in \(digits) */ + printed += scnprintf(bf + printed, size - printed, control_char ? "\\%d" : "%c", (int)orig[j]); + } + + consumed = sizeof(*augmented_arg) + augmented_arg->size; + arg->augmented.args = ((void *)arg->augmented.args) + consumed; + arg->augmented.size -= consumed; + + return printed; +} + static bool trace__filter_duration(struct trace *trace, double t) { return t < (trace->duration_filter * NSEC_PER_MSEC); diff --git a/tools/perf/util/trace_augment.h b/tools/perf/util/trace_augment.h new file mode 100644 index 000000000000..57a3e5045937 --- /dev/null +++ b/tools/perf/util/trace_augment.h @@ -0,0 +1,6 @@ +#ifndef TRACE_AUGMENT_H +#define TRACE_AUGMENT_H + +#define TRACE_AUG_MAX_BUF 32 /* for buffer augmentation in perf trace */ + +#endif