From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0509F301715; Wed, 15 Oct 2025 17:35:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760549742; cv=none; b=fgRwV38tqO/0T9yZ8Rpvf8xmDZY7Mxg9Hh3NflsK7VS6OuxIDeFnY43ETyQSDGkEd9DfMBRTazD6/exfqnCEo7gUjVWBVuXv0N9dbU5HQqt9lv69N2UV9xhxPTNsnQ2UOHCQrSxHBT/ZnP+JKw/nGJfwGAn4/DBPXANgfldNTo4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760549742; c=relaxed/simple; bh=tTqMR4smyTGZSNYICBdfzZtBFyl5CRUuN4mDG2upOSM=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=dv8vRqiCZ1wy7xnY4nIoaM7RWi1I98fXeDrSuKsm9sOp0fJ/C+qPc0gjTXTZkYrLr2Y8nFzveFpvDWt+fJJvnzH4uEGRcYsMr2Aq/WYIoIZsiGurptVTycZ1/+uA8EYgO1NDQJXD8NbTKpiqGxWa9Lt99gZLOqAtcbugrKHDfJY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Iwt+tnZu; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Iwt+tnZu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C1FBC116C6; Wed, 15 Oct 2025 17:35:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1760549741; bh=tTqMR4smyTGZSNYICBdfzZtBFyl5CRUuN4mDG2upOSM=; h=Date:From:To:Cc:Subject:References:From; b=Iwt+tnZuUCdDp06sOBgxptMFF+gyekG/SmqEV/yYu/qle45zS/2Gpt1RFJLy2ZTR/ yJnJ0YtlUqHU6TjnlJHHUKH1Z45WBfRPhDcSjpMbh2J4TnPYmT3lJ+Kmg9b7Z15eSx 352oDWYvWfDV33jFanO+tYdTRLUVVExVUIf9SZmJjnoX72XXunTv9Ed1ID5wdUZJxv Qyr+AYmDmaLZa8MUUXi1N8ZTLDPplQt6cGsaytMd/wcSSeEKvHvvdGwABNe1qyqJKq AOds+exHW30OvpOgNPWTnACaa1ZKneKwlPxYJv8cPT8TTnK9+qnmJnsaJUY7Ymcl1h TMRAbbXTY8R3g== Received: from rostedt by gandalf with local (Exim 4.98.2) (envelope-from ) id 1v95Pi-0000000120P-0B31; Wed, 15 Oct 2025 13:35:50 -0400 Message-ID: <20251015173549.890595698@kernel.org> User-Agent: quilt/0.68 Date: Wed, 15 Oct 2025 13:32:25 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Peter Zijlstra , Namhyung Kim , Takaya Saeki , Tom Zanussi , Thomas Gleixner , Ian Rogers , Douglas Raillard , Arnaldo Carvalho de Melo , Jiri Olsa , Adrian Hunter , Ingo Molnar Subject: [PATCH v3 11/13] tracing: Add parsing of flags to the sys_enter_openat trace event References: <20251015173214.760495866@kernel.org> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 From: Steven Rostedt Add some logic to give the openat system call trace event a bit more human readable information: syscalls:sys_enter_openat: dfd: 0xffffff9c, filename: 0x7f0053dc121c "/etc/ld.so.cache", flags: O_RDONLY|O_CLOEXEC, mode: 0000 The above is output from "perf script" and now shows the flags used by the openat system call. Since the output from tracing is in the kernel, it can also remove the mode field when not used (when flags does not contain O_CREATE|O_TMPFILE) touch-1185 [002] ...1. 1291.690154: sys_openat(dfd: 4294967196, filename: 139785545139344 "/usr/lib/locale/locale-archive", flags: O_RDONLY|O_CLOEXEC) touch-1185 [002] ...1. 1291.690504: sys_openat(dfd: 18446744073709551516, filename: 140733603151330 "/tmp/x", flags: O_WRONLY|O_CREAT|O_NOCTTY|O_NONBLOCK, mode: 0666) As system calls have a fixed ABI, their trace events can be extended. This currently only updates the openat system call, but others may be extended in the future. Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_syscalls.c | 192 ++++++++++++++++++++++++++++++++-- 1 file changed, 182 insertions(+), 10 deletions(-) diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c index 3617e5487b8d..6ee26203c8ce 100644 --- a/kernel/trace/trace_syscalls.c +++ b/kernel/trace/trace_syscalls.c @@ -127,6 +127,116 @@ const char *get_syscall_name(int syscall) /* Added to user strings or arrays when max limit is reached */ #define EXTRA "..." +static void get_dynamic_len_ptr(struct syscall_trace_enter *trace, + struct syscall_metadata *entry, + int *offset_p, int *len_p, unsigned char **ptr_p) +{ + unsigned char *ptr; + int offset = *offset_p; + int val; + + /* This arg points to a user space string */ + ptr = (void *)trace->args + sizeof(long) * entry->nb_args + offset; + val = *(int *)ptr; + + /* The value is a dynamic string (len << 16 | offset) */ + ptr = (void *)trace + (val & 0xffff); + *len_p = val >> 16; + offset += 4; + + *ptr_p = ptr; + *offset_p = offset; +} + +static enum print_line_t +sys_enter_openat_print(struct syscall_trace_enter *trace, struct syscall_metadata *entry, + struct trace_seq *s, struct trace_event *event) +{ + unsigned char *ptr; + int offset = 0; + int bits, len; + bool done = false; + static const struct trace_print_flags __flags[] = + { + { O_TMPFILE, "O_TMPFILE" }, + { O_WRONLY, "O_WRONLY" }, + { O_RDWR, "O_RDWR" }, + { O_CREAT, "O_CREAT" }, + { O_EXCL, "O_EXCL" }, + { O_NOCTTY, "O_NOCTTY" }, + { O_TRUNC, "O_TRUNC" }, + { O_APPEND, "O_APPEND" }, + { O_NONBLOCK, "O_NONBLOCK" }, + { O_DSYNC, "O_DSYNC" }, + { O_DIRECT, "O_DIRECT" }, + { O_LARGEFILE, "O_LARGEFILE" }, + { O_DIRECTORY, "O_DIRECTORY" }, + { O_NOFOLLOW, "O_NOFOLLOW" }, + { O_NOATIME, "O_NOATIME" }, + { O_CLOEXEC, "O_CLOEXEC" }, + { -1, NULL } + }; + + trace_seq_printf(s, "%s(", entry->name); + + for (int i = 0; !done && i < entry->nb_args; i++) { + + if (trace_seq_has_overflowed(s)) + goto end; + + if (i) + trace_seq_puts(s, ", "); + + switch (i) { + case 2: + bits = trace->args[2]; + + trace_seq_puts(s, "flags: "); + + /* No need to show mode when not creating the file */ + if (!(bits & (O_CREAT|O_TMPFILE))) + done = true; + + if (!(bits & O_ACCMODE)) { + if (!bits) { + trace_seq_puts(s, "O_RDONLY"); + continue; + } + trace_seq_puts(s, "O_RDONLY|"); + } + + trace_print_flags_seq(s, "|", bits, __flags); + /* + * trace_print_flags_seq() adds a '\0' to the + * buffer, but this needs to append more to the seq. + */ + if (!trace_seq_has_overflowed(s)) + trace_seq_pop(s); + + continue; + case 3: + trace_seq_printf(s, "%s: 0%03o", entry->args[i], + (unsigned int)trace->args[i]); + continue; + } + + trace_seq_printf(s, "%s: %lu", entry->args[i], + trace->args[i]); + + if (!(BIT(i) & entry->user_mask)) + continue; + + get_dynamic_len_ptr(trace, entry, &offset, &len, &ptr); + trace_seq_printf(s, " \"%.*s\"", len, ptr); + } + + trace_seq_putc(s, ')'); +end: + trace_seq_putc(s, '\n'); + + return trace_handle_return(s); +} + static enum print_line_t print_syscall_enter(struct trace_iterator *iter, int flags, struct trace_event *event) @@ -152,6 +262,15 @@ print_syscall_enter(struct trace_iterator *iter, int flags, goto end; } + switch (entry->syscall_nr) { + case __NR_openat: + if (!tr || !(tr->trace_flags & TRACE_ITER_VERBOSE)) + return sys_enter_openat_print(trace, entry, s, event); + break; + default: + break; + } + trace_seq_printf(s, "%s(", entry->name); for (i = 0; i < entry->nb_args; i++) { @@ -179,14 +298,7 @@ print_syscall_enter(struct trace_iterator *iter, int flags, if (!(BIT(i) & entry->user_mask)) continue; - /* This arg points to a user space string */ - ptr = (void *)trace->args + sizeof(long) * entry->nb_args + offset; - val = *(int *)ptr; - - /* The value is a dynamic string (len << 16 | offset) */ - ptr = (void *)ent + (val & 0xffff); - len = val >> 16; - offset += 4; + get_dynamic_len_ptr(trace, entry, &offset, &len, &ptr); if (entry->user_arg_size < 0 || entry->user_arg_is_str) { trace_seq_printf(s, " \"%.*s\"", len, ptr); @@ -269,6 +381,62 @@ print_syscall_exit(struct trace_iterator *iter, int flags, .size = sizeof(_type), .align = __alignof__(_type), \ .is_signed = is_signed_type(_type), .filter_type = FILTER_OTHER } +/* When len=0, we just calculate the needed length */ +#define LEN_OR_ZERO (len ? len - pos : 0) + +static int __init +sys_enter_openat_print_fmt(struct syscall_metadata *entry, char *buf, int len) +{ + int pos = 0; + + pos += snprintf(buf + pos, LEN_OR_ZERO, + "\"dfd: 0x%%08lx, filename: 0x%%08lx \\\"%%s\\\", flags: %%s%%s, mode: 0%%03o\","); + pos += snprintf(buf + pos, LEN_OR_ZERO, + " ((unsigned long)(REC->dfd)),"); + pos += snprintf(buf + pos, LEN_OR_ZERO, + " ((unsigned long)(REC->filename)),"); + pos += snprintf(buf + pos, LEN_OR_ZERO, + " __get_str(__filename_val),"); + pos += snprintf(buf + pos, LEN_OR_ZERO, + " (REC->flags & ~3) && !(REC->flags & 3) ? \"O_RDONLY|\" : \"\", "); + pos += snprintf(buf + pos, LEN_OR_ZERO, + " REC->flags ? __print_flags(REC->flags, \"|\", "); + pos += snprintf(buf + pos, LEN_OR_ZERO, + "{ 0x%x, \"O_WRONLY\" }, ", O_WRONLY); + pos += snprintf(buf + pos, LEN_OR_ZERO, + "{ 0x%x, \"O_RDWR\" }, ", O_RDWR); + pos += snprintf(buf + pos, LEN_OR_ZERO, + "{ 0x%x, \"O_CREAT\" }, ", O_CREAT); + pos += snprintf(buf + pos, LEN_OR_ZERO, + "{ 0x%x, \"O_EXCL\" }, ", O_EXCL); + pos += snprintf(buf + pos, LEN_OR_ZERO, + "{ 0x%x, \"O_NOCTTY\" }, ", O_NOCTTY); + pos += snprintf(buf + pos, LEN_OR_ZERO, + "{ 0x%x, \"O_TRUNC\" }, ", O_TRUNC); + pos += snprintf(buf + pos, LEN_OR_ZERO, + "{ 0x%x, \"O_APPEND\" }, ", O_APPEND); + pos += snprintf(buf + pos, LEN_OR_ZERO, + "{ 0x%x, \"O_NONBLOCK\" }, ", O_NONBLOCK); + pos += snprintf(buf + pos, LEN_OR_ZERO, + "{ 0x%x, \"O_DSYNC\" }, ", O_DSYNC); + pos += snprintf(buf + pos, LEN_OR_ZERO, + "{ 0x%x, \"O_DIRECT\" }, ", O_DIRECT); + pos += snprintf(buf + pos, LEN_OR_ZERO, + "{ 0x%x, \"O_LARGEFILE\" }, ", O_LARGEFILE); + pos += snprintf(buf + pos, LEN_OR_ZERO, + "{ 0x%x, \"O_DIRECTORY\" }, ", O_DIRECTORY); + pos += snprintf(buf + pos, LEN_OR_ZERO, + "{ 0x%x, \"O_NOFOLLOW\" }, ", O_NOFOLLOW); + pos += snprintf(buf + pos, LEN_OR_ZERO, + "{ 0x%x, \"O_NOATIME\" }, ", O_NOATIME); + pos += snprintf(buf + pos, LEN_OR_ZERO, + "{ 0x%x, \"O_CLOEXEC\" }) : \"O_RDONLY\", ", O_CLOEXEC); + + pos += snprintf(buf + pos, LEN_OR_ZERO, + " ((unsigned long)(REC->mode))"); + return pos; +} + static int __init __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len) { @@ -276,8 +444,12 @@ __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len) int i; int pos = 0; - /* When len=0, we just calculate the needed length */ -#define LEN_OR_ZERO (len ? len - pos : 0) + switch (entry->syscall_nr) { + case __NR_openat: + return sys_enter_openat_print_fmt(entry, buf, len); + default: + break; + } pos += snprintf(buf + pos, LEN_OR_ZERO, "\""); for (i = 0; i < entry->nb_args; i++) { -- 2.51.0