Commit-ID:  8d5da2649d8211e63c5f65ccf8945f2c46a9c0b8
Gitweb:     https://git.kernel.org/tip/8d5da2649d8211e63c5f65ccf8945f2c46a9c0b8
Author:     Arnaldo Carvalho de Melo <a...@redhat.com>
AuthorDate: Tue, 16 Jul 2019 14:55:57 -0300
Committer:  Arnaldo Carvalho de Melo <a...@redhat.com>
CommitDate: Mon, 29 Jul 2019 18:34:41 -0300

perf augmented_raw_syscalls: Support copying two string syscall args

Starting with the renameat and renameat2 syscall, that both receive as
second and fourth parameters a pathname:

  # perf trace -e rename* mv one ANOTHER
  LLVM: dumping 
/home/acme/git/perf/tools/perf/examples/bpf/augmented_raw_syscalls.o
  mv: cannot stat 'one': No such file or directory
  renameat2(AT_FDCWD, "one", AT_FDCWD, "ANOTHER", RENAME_NOREPLACE) = -1 ENOENT 
(No such file or directory)
  #

Since the per CPU scratch buffer map has space for two maximum sized
pathnames, the verifier is satisfied that there will be no overrun.

Cc: Adrian Hunter <adrian.hun...@intel.com>
Cc: Jiri Olsa <jo...@kernel.org>
Cc: Luis Cláudio Gonçalves <lclau...@redhat.com>
Cc: Namhyung Kim <namhy...@kernel.org>
Link: https://lkml.kernel.org/n/tip-x2uboyg5kx2wqeru28820...@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com>
---
 tools/perf/builtin-trace.c                       |  2 ++
 tools/perf/examples/bpf/augmented_raw_syscalls.c | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index a681b8c2ee4e..c64f7c99db15 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -873,9 +873,11 @@ static struct syscall_fmt {
        { .name     = "recvmsg",
          .arg = { [2] = { .scnprintf = SCA_MSG_FLAGS, /* flags */ }, }, },
        { .name     = "renameat",
+         .bpf_prog_name = { .sys_enter = "!syscalls:sys_enter_renameat", },
          .arg = { [0] = { .scnprintf = SCA_FDAT, /* olddirfd */ },
                   [2] = { .scnprintf = SCA_FDAT, /* newdirfd */ }, }, },
        { .name     = "renameat2",
+         .bpf_prog_name = { .sys_enter = "!syscalls:sys_enter_renameat", },
          .arg = { [0] = { .scnprintf = SCA_FDAT, /* olddirfd */ },
                   [2] = { .scnprintf = SCA_FDAT, /* newdirfd */ },
                   [4] = { .scnprintf = SCA_RENAMEAT2_FLAGS, /* flags */ }, }, 
},
diff --git a/tools/perf/examples/bpf/augmented_raw_syscalls.c 
b/tools/perf/examples/bpf/augmented_raw_syscalls.c
index ce308b9a317c..df52d92e1c69 100644
--- a/tools/perf/examples/bpf/augmented_raw_syscalls.c
+++ b/tools/perf/examples/bpf/augmented_raw_syscalls.c
@@ -70,6 +70,7 @@ pid_filter(pids_filtered);
 struct augmented_args_filename {
        struct syscall_enter_args args;
        struct augmented_filename filename;
+       struct augmented_filename filename2;
 };
 
 bpf_map(augmented_filename_map, PERCPU_ARRAY, int, struct 
augmented_args_filename, 1);
@@ -148,6 +149,25 @@ int sys_enter_openat(struct syscall_enter_args *args)
        return perf_event_output(args, &__augmented_syscalls__, 
BPF_F_CURRENT_CPU, augmented_args, len);
 }
 
+SEC("!syscalls:sys_enter_renameat")
+int sys_enter_renameat(struct syscall_enter_args *args)
+{
+       int key = 0;
+       struct augmented_args_filename *augmented_args = 
bpf_map_lookup_elem(&augmented_filename_map, &key);
+       const void *oldpath_arg = (const void *)args->args[1],
+                  *newpath_arg = (const void *)args->args[3];
+       unsigned int len = sizeof(augmented_args->args), oldpath_len;
+
+        if (augmented_args == NULL)
+                return 1; /* Failure: don't filter */
+
+       oldpath_len = augmented_filename__read(&augmented_args->filename, 
oldpath_arg, sizeof(augmented_args->filename.value));
+       len += oldpath_len + augmented_filename__read((void 
*)(&augmented_args->filename) + oldpath_len, newpath_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)
 {

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