[PATCH 11/37] perf augmented_raw_syscalls: Add handler for "openat"

From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Ingo Molnar <mingo@kernel.org>, Thomas Gleixner <tglx@linutronix.de>
Cc: "Jiri Olsa" <jolsa@kernel.org>,
	"Namhyung Kim" <namhyung@kernel.org>,
	"Clark Williams" <williams@redhat.com>,
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
	"Arnaldo Carvalho de Melo" <acme@redhat.com>,
	"Adrian Hunter" <adrian.hunter@intel.com>,
	"Luis Cláudio Gonçalves" <lclaudio@redhat.com>
Subject: [PATCH 11/37] perf augmented_raw_syscalls: Add handler for "openat"
Date: Mon, 22 Jul 2019 14:38:13 -0300	[thread overview]
Message-ID: <20190722173839.22898-12-acme@kernel.org> (raw)
In-Reply-To: <20190722173839.22898-1-acme@kernel.org>

From: Arnaldo Carvalho de Melo <acme@redhat.com>

I.e. for a syscall that has its second argument being a string, its
difficult these days to find 'open' being used in the wild :-)

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-yf3kbzirqrukd3fb2sp5qx4p@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-trace.c                      |  1 +
 .../perf/examples/bpf/augmented_raw_syscalls.c  | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 872c9cc982a5..a681b8c2ee4e 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -836,6 +836,7 @@ static struct syscall_fmt {
 	  .arg = { [0] = { .scnprintf = SCA_FDAT,	/* dfd */ },
 		   [2] = { .scnprintf = SCA_OPEN_FLAGS, /* flags */ }, }, },
 	{ .name	    = "openat",
+	  .bpf_prog_name = { .sys_enter = "!syscalls:sys_enter_openat", },
 	  .arg = { [0] = { .scnprintf = SCA_FDAT,	/* dfd */ },
 		   [2] = { .scnprintf = SCA_OPEN_FLAGS, /* flags */ }, }, },
 	{ .name	    = "perf_event_open",
diff --git a/tools/perf/examples/bpf/augmented_raw_syscalls.c b/tools/perf/examples/bpf/augmented_raw_syscalls.c
index c66474a6ccf4..661936f90fe0 100644
--- a/tools/perf/examples/bpf/augmented_raw_syscalls.c
+++ b/tools/perf/examples/bpf/augmented_raw_syscalls.c
@@ -131,6 +131,23 @@ int sys_enter_open(struct syscall_enter_args *args)
 	return perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, augmented_args, len);
 }
 
+SEC("!syscalls:sys_enter_openat")
+int sys_enter_openat(struct syscall_enter_args *args)
+{
+	int key = 0;
+	struct augmented_args_filename *augmented_args = bpf_map_lookup_elem(&augmented_filename_map, &key);
+	const void *filename_arg = (const void *)args->args[1];
+	unsigned int len = sizeof(augmented_args->args);
+
+        if (augmented_args == NULL)
+                return 1; /* Failure: don't filter */
+
+	len += augmented_filename__read(&augmented_args->filename, filename_arg, sizeof(augmented_args->filename.value));
+
+	/* If perf_event_output fails, return non-zero so that it gets recorded unaugmented */
+	return perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, augmented_args, len);
+}
+
 SEC("raw_syscalls:sys_enter")
 int sys_enter(struct syscall_enter_args *args)
 {
-- 
2.21.0

