[PATCH 5.15 514/731] perf trace: Return error if a system call doesnt exist

[PATCH 5.15 514/731] perf trace: Return error if a system call doesnt exist

[Greg Kroah-Hartman]

From: Leo Yan <leo.yan@linaro.org>

[ Upstream commit d4223e1776c30b2ce8d0e6eaadcbf696e60fca3c ]

When a system call is not detected, the reason is either because the
system call ID is out of scope or failure to find the corresponding path
in the sysfs, trace__read_syscall_info() returns zero.  Finally, without
returning an error value it introduces confusion for the caller.

This patch lets the function trace__read_syscall_info() to return
-EEXIST when a system call doesn't exist.

Fixes: b8b1033fcaa091d8 ("perf trace: Mark syscall ids that are not allocated to avoid unnecessary error messages")
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: bpf@vger.kernel.org
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221121075237.127706-3-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/perf/builtin-trace.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 2bf21194c7b3..aaa465d7f011 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1782,11 +1782,11 @@ static int trace__read_syscall_info(struct trace *trace, int id)
 #endif
 	sc = trace->syscalls.table + id;
 	if (sc->nonexistent)
-		return 0;
+		return -EEXIST;
 
 	if (name == NULL) {
 		sc->nonexistent = true;
-		return 0;
+		return -EEXIST;
 	}
 
 	sc->name = name;
-- 
2.35.1

[PATCH 5.15 515/731] perf trace: Use macro RAW_SYSCALL_ARGS_NUM to replace number

[Greg Kroah-Hartman]

From: Leo Yan <leo.yan@linaro.org>

[ Upstream commit eadcab4c7a66e1df03d32da0db55d89fd9343fcc ]

This patch defines a macro RAW_SYSCALL_ARGS_NUM to replace the open
coded number '6'.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20221121075237.127706-2-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Stable-dep-of: 03e9a5d8eb55 ("perf trace: Handle failure when trace point folder is missed")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/perf/builtin-trace.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index aaa465d7f011..c1db48ff01a5 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -87,6 +87,8 @@
 # define F_LINUX_SPECIFIC_BASE	1024
 #endif
 
+#define RAW_SYSCALL_ARGS_NUM	6
+
 /*
  * strtoul: Go from a string to a value, i.e. for msr: MSR_FS_BASE to 0xc0000100
  */
@@ -107,7 +109,7 @@ struct syscall_fmt {
 		const char *sys_enter,
 			   *sys_exit;
 	}	   bpf_prog_name;
-	struct syscall_arg_fmt arg[6];
+	struct syscall_arg_fmt arg[RAW_SYSCALL_ARGS_NUM];
 	u8	   nr_args;
 	bool	   errpid;
 	bool	   timeout;
@@ -1224,7 +1226,7 @@ struct syscall {
  */
 struct bpf_map_syscall_entry {
 	bool	enabled;
-	u16	string_args_len[6];
+	u16	string_args_len[RAW_SYSCALL_ARGS_NUM];
 };
 
 /*
@@ -1649,7 +1651,7 @@ static int syscall__alloc_arg_fmts(struct syscall *sc, int nr_args)
 {
 	int idx;
 
-	if (nr_args == 6 && sc->fmt && sc->fmt->nr_args != 0)
+	if (nr_args == RAW_SYSCALL_ARGS_NUM && sc->fmt && sc->fmt->nr_args != 0)
 		nr_args = sc->fmt->nr_args;
 
 	sc->arg_fmt = calloc(nr_args, sizeof(*sc->arg_fmt));
@@ -1800,7 +1802,8 @@ static int trace__read_syscall_info(struct trace *trace, int id)
 		sc->tp_format = trace_event__tp_format("syscalls", tp_name);
 	}
 
-	if (syscall__alloc_arg_fmts(sc, IS_ERR(sc->tp_format) ? 6 : sc->tp_format->format.nr_fields))
+	if (syscall__alloc_arg_fmts(sc, IS_ERR(sc->tp_format) ?
+					RAW_SYSCALL_ARGS_NUM : sc->tp_format->format.nr_fields))
 		return -ENOMEM;
 
 	if (IS_ERR(sc->tp_format))
-- 
2.35.1

[PATCH 5.15 516/731] perf trace: Handle failure when trace point folder is missed

[Greg Kroah-Hartman]

From: Leo Yan <leo.yan@linaro.org>

[ Upstream commit 03e9a5d8eb552a1bf692a9c8a5ecd50f4e428006 ]

On Arm64 a case is perf tools fails to find the corresponding trace
point folder for system calls listed in the table 'syscalltbl_arm64',
e.g. the generated system call table contains "lookup_dcookie" but we
cannot find out the matched trace point folder for it.

We need to figure out if there have any issue for the generated system
call table, on the other hand, we need to handle the case when trace
point folder is missed under sysfs, this patch sets the flag
syscall::nonexistent as true and returns the error from
trace__read_syscall_info().

Another problem is for trace__syscall_info(), it returns two different
values if a system call doesn't exist: at the first time calling
trace__syscall_info() it returns NULL when the system call doesn't exist,
later if call trace__syscall_info() again for the same missed system
call, it returns pointer of syscall.  trace__syscall_info() checks the
condition 'syscalls.table[id].name == NULL', but the name will be
assigned in the first invoking even the system call is not found.

So checking system call's name in trace__syscall_info() is not the right
thing to do, this patch simply checks flag syscall::nonexistent to make
decision if a system call exists or not, finally trace__syscall_info()
returns the consistent result (NULL) if a system call doesn't existed.

Fixes: b8b1033fcaa091d8 ("perf trace: Mark syscall ids that are not allocated to avoid unnecessary error messages")
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: bpf@vger.kernel.org
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221121075237.127706-4-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/perf/builtin-trace.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index c1db48ff01a5..2fea9952818f 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1802,13 +1802,19 @@ static int trace__read_syscall_info(struct trace *trace, int id)
 		sc->tp_format = trace_event__tp_format("syscalls", tp_name);
 	}
 
+	/*
+	 * Fails to read trace point format via sysfs node, so the trace point
+	 * doesn't exist.  Set the 'nonexistent' flag as true.
+	 */
+	if (IS_ERR(sc->tp_format)) {
+		sc->nonexistent = true;
+		return PTR_ERR(sc->tp_format);
+	}
+
 	if (syscall__alloc_arg_fmts(sc, IS_ERR(sc->tp_format) ?
 					RAW_SYSCALL_ARGS_NUM : sc->tp_format->format.nr_fields))
 		return -ENOMEM;
 
-	if (IS_ERR(sc->tp_format))
-		return PTR_ERR(sc->tp_format);
-
 	sc->args = sc->tp_format->format.fields;
 	/*
 	 * We need to check and discard the first variable '__syscall_nr'
@@ -2125,11 +2131,8 @@ static struct syscall *trace__syscall_info(struct trace *trace,
 	    (err = trace__read_syscall_info(trace, id)) != 0)
 		goto out_cant_read;
 
-	if (trace->syscalls.table[id].name == NULL) {
-		if (trace->syscalls.table[id].nonexistent)
-			return NULL;
+	if (trace->syscalls.table && trace->syscalls.table[id].nonexistent)
 		goto out_cant_read;
-	}
 
 	return &trace->syscalls.table[id];
 
-- 
2.35.1