Commit d21cb73a authored May 28, 2020 by Arnaldo Carvalho de Melo

perf trace: Grow the syscall table as needed when using libaudit



The audit-libs API doesn't provide a way to figure out what is the
syscall with the greatest number/id, take that into account when using
that method to go on growing the syscall table as we the syscalls go on
appearing on the radar.

With this the libaudit based method is back working, i.e. when building
with:

  $ make NO_SYSCALL_TABLE=1 O=/tmp/build/perf -C tools/perf install-bin
  <SNIP>
  Auto-detecting system features:
  <SNIP>
  ...                      libaudit: [ on  ]
  ...                        libbfd: [ on  ]
  ...                        libcap: [ on  ]
  <SNIP>
  $ ldd ~/bin/perf | grep audit
	libaudit.so.1 => /lib64/libaudit.so.1 (0x00007faef22df000)
  $

perf trace is back working, which makes it functional in arches other
than x86_64, powerpc, arm64 and s390, that provides these generators:

  $ find tools/perf/arch/ -name "*syscalltbl*"
  tools/perf/arch/x86/entry/syscalls/syscalltbl.sh
  tools/perf/arch/arm64/entry/syscalls/mksyscalltbl
  tools/perf/arch/s390/entry/syscalls/mksyscalltbl
  tools/perf/arch/powerpc/entry/syscalls/mksyscalltbl
  $

Example output forcing the libaudit method on x86_64:

  # perf trace -e file,nanosleep sleep 0.001
           ? (         ): sleep/859090  ... [continued]: execve())                                   = 0
       0.045 ( 0.005 ms): sleep/859090 access(filename: 0x8733e850, mode: R)                         = -1 ENOENT (No such file or directory)
       0.055 ( 0.005 ms): sleep/859090 openat(dfd: CWD, filename: 0x8733ba29, flags: RDONLY|CLOEXEC) = 3
       0.079 ( 0.005 ms): sleep/859090 openat(dfd: CWD, filename: 0x87345d20, flags: RDONLY|CLOEXEC) = 3
       0.085 ( 0.002 ms): sleep/859090 read(fd: 3, buf: 0x7ffd9d483f58, count: 832)                  = 832
       0.090 ( 0.002 ms): sleep/859090 read(fd: 3, buf: 0x7ffd9d483b50, count: 784)                  = 784
       0.094 ( 0.002 ms): sleep/859090 read(fd: 3, buf: 0x7ffd9d483b20, count: 32)                   = 32
       0.098 ( 0.002 ms): sleep/859090 read(fd: 3, buf: 0x7ffd9d483ad0, count: 68)                   = 68
       0.109 ( 0.002 ms): sleep/859090 read(fd: 3, buf: 0x7ffd9d483a50, count: 784)                  = 784
       0.113 ( 0.002 ms): sleep/859090 read(fd: 3, buf: 0x7ffd9d483730, count: 32)                   = 32
       0.117 ( 0.002 ms): sleep/859090 read(fd: 3, buf: 0x7ffd9d483710, count: 68)                   = 68
       0.320 ( 0.008 ms): sleep/859090 openat(dfd: CWD, filename: 0x872c3660, flags: RDONLY|CLOEXEC) = 3
       0.372 ( 1.057 ms): sleep/859090 nanosleep(rqtp: 0x7ffd9d484ac0)                               = 0
  #

There are still some limitations when using the libaudit method, that
will be fixed at some point, i.e., this works with the mksyscalltbl
method but not with libaudit's:

  # perf trace -e file,*sleep sleep 0.001
  event syntax error: '*sleep'
                       \___ parser error
  Run 'perf list' for a list of valid events

   Usage: perf trace [<options>] [<command>]
      or: perf trace [<options>] -- <command> [<options>]
      or: perf trace record [<options>] [<command>]
      or: perf trace record [<options>] -- <command> [<options>]

      -e, --event <event>   event/syscall selector. use 'perf list' to list available events
  #

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent a9e8c1f8

tools/perf/builtin-trace.c

+27 −1

Original line number	Diff line number	Diff line
		@@ -1748,12 +1748,26 @@ static int trace__read_syscall_info(struct trace *trace, int id)
		struct syscall *sc;
		const char *name = syscalltbl__name(trace->sctbl, id);

		#ifdef HAVE_SYSCALL_TABLE_SUPPORT
		if (trace->syscalls.table == NULL) {
		trace->syscalls.table = calloc(trace->sctbl->syscalls.max_id + 1, sizeof(*sc));
		if (trace->syscalls.table == NULL)
		return -ENOMEM;
		}
		#else
		if (id > trace->sctbl->syscalls.max_id \|\| (id == 0 && trace->syscalls.table == NULL)) {
		// When using libaudit we don't know beforehand what is the max syscall id
		struct syscall table = realloc(trace->syscalls.table, (id + 1) sizeof(*sc));

		if (table == NULL)
		return -ENOMEM;

		memset(table + trace->sctbl->syscalls.max_id, 0, (id - trace->sctbl->syscalls.max_id) * sizeof(*sc));

		trace->syscalls.table = table;
		trace->sctbl->syscalls.max_id = id;
		}
		#endif
		sc = trace->syscalls.table + id;
		if (sc->nonexistent)
		return 0;
		@@ -2077,8 +2091,20 @@ static struct syscall trace__syscall_info(struct trace trace,

		err = -EINVAL;

		if (id > trace->sctbl->syscalls.max_id)
		#ifdef HAVE_SYSCALL_TABLE_SUPPORT
		if (id > trace->sctbl->syscalls.max_id) {
		#else
		if (id >= trace->sctbl->syscalls.max_id) {
		/*
		* With libaudit we don't know beforehand what is the max_id,
		* so we let trace__read_syscall_info() figure that out as we
		* go on reading syscalls.
		*/
		err = trace__read_syscall_info(trace, id);
		if (err)
		#endif
		goto out_cant_read;
		}

		if ((trace->syscalls.table == NULL \|\| trace->syscalls.table[id].name == NULL) &&
		(err = trace__read_syscall_info(trace, id)) != 0)

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