[PATCH 09/41] perf trace: Beautify 'move_mount' arguments

Arnaldo Carvalho de Melo
2019-05-29T13:37:02Z

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

Use existing beautifiers for the first 4 args (to/from fds, pathnames)
and wire up the recently introduced move_mount flags table generator.

Now it should be possible to just use:

perf trace -e move_mount

As root and see all move_mount syscalls with its args beautified, except
for the filenames, that need work in the augmented_raw_syscalls.c eBPF
helper to pass more than one, see comment in the
augmented_raw_syscalls.c source code, the other args should work in all
cases, i.e. all that is needed can be obtained directly from the
raw_syscalls:sys_enter tracepoint args.

Running without the strace "skin" (.perfconfig setting output formatting
switches to look like strace output + BPF to collect strings, as we
still need to support collecting multiple string args for the same
syscall, like with move_mount):

# cat sys_move_mount.c
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <unistd.h>
#include <sys/syscall.h> /* For SYS_xxx definitions */

#define __NR_move_mount 429

#define MOVE_MOUNT_F_SYMLINKS 0x00000001 /* Follow symlinks on from path */
#define MOVE_MOUNT_F_AUTOMOUNTS 0x00000002 /* Follow automounts on from path */
#define MOVE_MOUNT_F_EMPTY_PATH 0x00000004 /* Empty from path permitted */
#define MOVE_MOUNT_T_SYMLINKS 0x00000010 /* Follow symlinks on to path */
#define MOVE_MOUNT_T_AUTOMOUNTS 0x00000020 /* Follow automounts on to path */
#define MOVE_MOUNT_T_EMPTY_PATH 0x00000040 /* Empty to path permitted */

static inline int sys_move_mount(int from_fd, const char *from_pathname,
int to_fd, const char *to_pathname,
int flags)
{
syscall(__NR_move_mount, from_fd, from_pathname, to_fd, to_pathname, flags);
}

int main(int argc, char *argv[])
{
int flags = 0, from_fd = 0, to_fd = 100;

sys_move_mount(from_fd++, "/foo", to_fd++, "bar", flags);
flags |= MOVE_MOUNT_F_SYMLINKS;
sys_move_mount(from_fd++, "/foo1", to_fd++, "bar1", flags);
flags |= MOVE_MOUNT_F_AUTOMOUNTS;
sys_move_mount(from_fd++, "/foo2", to_fd++, "bar2", flags);
flags |= MOVE_MOUNT_F_EMPTY_PATH;
sys_move_mount(from_fd++, "/foo3", to_fd++, "bar3", flags);
flags |= MOVE_MOUNT_T_SYMLINKS;
sys_move_mount(from_fd++, "/foo4", to_fd++, "bar4", flags);
flags |= MOVE_MOUNT_T_AUTOMOUNTS;
sys_move_mount(from_fd++, "/foo5", to_fd++, "bar5", flags);
flags |= MOVE_MOUNT_T_EMPTY_PATH;
return sys_move_mount(from_fd++, "/foo6", to_fd++, "bar6", flags);
}
# mv ~/.perfconfig ~/.perfconfig.OFF
# perf trace -e move_mount ./sys_move_mount
0.000 ( 0.009 ms): sys_move_mount/28971 move_mount(from_pathname: 0x402010, to_dfd: 100, to_pathname: 0x402015) = -1 ENOENT (No such file or directory)
0.011 ( 0.003 ms): sys_move_mount/28971 move_mount(from_dfd: 1, from_pathname: 0x40201e, to_dfd: 101, to_pathname: 0x402019, flags: F_SYMLINKS) = -1 ENOENT (No such file or directory)
0.016 ( 0.002 ms): sys_move_mount/28971 move_mount(from_dfd: 2, from_pathname: 0x402029, to_dfd: 102, to_pathname: 0x402024, flags: F_SYMLINKS|F_AUTOMOUNTS) = -1 ENOENT (No such file or directory)
0.020 ( 0.002 ms): sys_move_mount/28971 move_mount(from_dfd: 3, from_pathname: 0x402034, to_dfd: 103, to_pathname: 0x40202f, flags: F_SYMLINKS|F_AUTOMOUNTS|F_EMPTY_PATH) = -1 ENOENT (No such file or directory)
0.023 ( 0.002 ms): sys_move_mount/28971 move_mount(from_dfd: 4, from_pathname: 0x40203f, to_dfd: 104, to_pathname: 0x40203a, flags: F_SYMLINKS|F_AUTOMOUNTS|F_EMPTY_PATH|T_SYMLINKS) = -1 ENOENT (No such file or directory)
0.027 ( 0.002 ms): sys_move_mount/28971 move_mount(from_dfd: 5, from_pathname: 0x40204a, to_dfd: 105, to_pathname: 0x402045, flags: F_SYMLINKS|F_AUTOMOUNTS|F_EMPTY_PATH|T_SYMLINKS|T_AUTOMOUNTS) = -1 ENOENT (No such file or directory)
0.031 ( 0.017 ms): sys_move_mount/28971 move_mount(from_dfd: 6, from_pathname: 0x402055, to_dfd: 106, to_pathname: 0x402050, flags: F_SYMLINKS|F_AUTOMOUNTS|F_EMPTY_PATH|T_SYMLINKS|T_AUTOMOUNTS|T_EMPTY_PATH) = -1 ENOENT (No such file or directory)
#

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-83rim8g4k0s4gieieh5nnlck@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/Makefile.perf | 8 +++++++
tools/perf/builtin-trace.c | 6 +++++
.../examples/bpf/augmented_raw_syscalls.c | 11 +++++++++
tools/perf/trace/beauty/Build | 1 +
tools/perf/trace/beauty/beauty.h | 3 +++
tools/perf/trace/beauty/move_mount.c | 24 +++++++++++++++++++
6 files changed, 53 insertions(+)
create mode 100644 tools/perf/trace/beauty/move_mount.c

diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index c706548d5b10..20448d8cc162 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -493,6 +493,12 @@ mount_flags_tbl := $(srctree)/tools/perf/trace/beauty/mount_flags.sh
$(mount_flags_array): $(linux_uapi_dir)/fs.h $(mount_flags_tbl)
$(Q)$(SHELL) '$(mount_flags_tbl)' $(linux_uapi_dir) > $@

+move_mount_flags_array := $(beauty_outdir)/move_mount_flags_array.c
+move_mount_flags_tbl := $(srctree)/tools/perf/trace/beauty/move_mount_flags.sh
+
+$(move_mount_flags_array): $(linux_uapi_dir)/fs.h $(move_mount_flags_tbl)
+ $(Q)$(SHELL) '$(move_mount_flags_tbl)' $(linux_uapi_dir) > $@
+
prctl_option_array := $(beauty_outdir)/prctl_option_array.c
prctl_hdr_dir := $(srctree)/tools/include/uapi/linux/
prctl_option_tbl := $(srctree)/tools/perf/trace/beauty/prctl_option.sh
@@ -638,6 +644,7 @@ prepare: $(OUTPUT)PERF-VERSION-FILE $(OUTPUT)common-cmds.h archheaders $(drm_ioc
$(madvise_behavior_array) \
$(mmap_flags_array) \
$(mount_flags_array) \
+ $(move_mount_flags_array) \
$(perf_ioctl_array) \
$(prctl_option_array) \
$(usbdevfs_ioctl_array) \
@@ -925,6 +932,7 @@ clean:: $(LIBTRACEEVENT)-clean $(LIBAPI)-clean $(LIBBPF)-clean $(LIBSUBCMD)-clea
$(OUTPUT)$(madvise_behavior_array) \
$(OUTPUT)$(mmap_flags_array) \
$(OUTPUT)$(mount_flags_array) \
+ $(OUTPUT)$(move_mount_flags_array) \
$(OUTPUT)$(drm_ioctl_array) \
$(OUTPUT)$(pkey_alloc_access_rights_array) \
$(OUTPUT)$(sndrv_ctl_ioctl_array) \
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index f5b3a1e9c1dd..b76c950e4393 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -775,6 +775,12 @@ static struct syscall_fmt {
.arg = { [0] = { .scnprintf = SCA_FILENAME, /* dev_name */ },
[3] = { .scnprintf = SCA_MOUNT_FLAGS, /* flags */
.mask_val = SCAMV_MOUNT_FLAGS, /* flags */ }, }, },
+ { .name = "move_mount",
+ .arg = { [0] = { .scnprintf = SCA_FDAT, /* from_dfd */ },
+ [1] = { .scnprintf = SCA_FILENAME, /* from_pathname */ },
+ [2] = { .scnprintf = SCA_FDAT, /* to_dfd */ },
+ [3] = { .scnprintf = SCA_FILENAME, /* to_pathname */ },
+ [4] = { .scnprintf = SCA_MOVE_MOUNT_FLAGS, /* flags */ }, }, },
{ .name = "mprotect",
.arg = { [0] = { .scnprintf = SCA_HEX, /* start */ },
[2] = { .scnprintf = SCA_MMAP_PROT, /* prot */ }, }, },
diff --git a/tools/perf/examples/bpf/augmented_raw_syscalls.c b/tools/perf/examples/bpf/augmented_raw_syscalls.c
index b292e763f3c7..8d0c0976696e 100644
--- a/tools/perf/examples/bpf/augmented_raw_syscalls.c
+++ b/tools/perf/examples/bpf/augmented_raw_syscalls.c
@@ -117,6 +117,7 @@ struct augmented_filename {
#define SYS_RENAMEAT2 316
#define SYS_EXECVEAT 322
#define SYS_STATX 332
+#define SYS_MOVE_MOUNT 429

pid_filter(pids_filtered);

@@ -257,6 +258,16 @@ int sys_enter(struct syscall_enter_args *args)
case SYS_LINKAT:
case SYS_MKDIRAT:
case SYS_MKNODAT:
+ // case SYS_MOVE_MOUNT:
+ // For now don't copy move_mount first string arg, as it has two and
+ // 'perf trace's syscall_arg__scnprintf_filename() will use the one
+ // copied here, the first, for both args, duplicating the first and
+ // ignoring the second.
+ //
+ // We need to copy both here and make syscall_arg__scnprintf_filename
+ // skip the first when reading the second, using the size of the first, etc.
+ // Shouldn't be difficult, but now its perf/urgent time, lets wait for
+ // the next devel window.
case SYS_MQ_TIMEDSEND:
case SYS_NAME_TO_HANDLE_AT:
case SYS_NEWFSTATAT:
diff --git a/tools/perf/trace/beauty/Build b/tools/perf/trace/beauty/Build
index 85f328ddf897..d84812c094ba 100644
--- a/tools/perf/trace/beauty/Build
+++ b/tools/perf/trace/beauty/Build
@@ -6,6 +6,7 @@ perf-y += ioctl.o
endif
perf-y += kcmp.o
perf-y += mount_flags.o
+perf-y += move_mount.o
perf-y += pkey_alloc.o
perf-y += arch_prctl.o
perf-y += prctl.o
diff --git a/tools/perf/trace/beauty/beauty.h b/tools/perf/trace/beauty/beauty.h
index 139d485a6f16..dfb84032d8eb 100644
--- a/tools/perf/trace/beauty/beauty.h
+++ b/tools/perf/trace/beauty/beauty.h
@@ -156,6 +156,9 @@ unsigned long syscall_arg__mask_val_mount_flags(struct syscall_arg *arg, unsigne
size_t syscall_arg__scnprintf_mount_flags(char *bf, size_t size, struct syscall_arg *arg);
#define SCA_MOUNT_FLAGS syscall_arg__scnprintf_mount_flags

+size_t syscall_arg__scnprintf_move_mount_flags(char *bf, size_t size, struct syscall_arg *arg);
+#define SCA_MOVE_MOUNT_FLAGS syscall_arg__scnprintf_move_mount_flags
+
size_t syscall_arg__scnprintf_pkey_alloc_access_rights(char *bf, size_t size, struct syscall_arg *arg);
#define SCA_PKEY_ALLOC_ACCESS_RIGHTS syscall_arg__scnprintf_pkey_alloc_access_rights

diff --git a/tools/perf/trace/beauty/move_mount.c b/tools/perf/trace/beauty/move_mount.c
new file mode 100644
index 000000000000..78ed80395406
--- /dev/null
+++ b/tools/perf/trace/beauty/move_mount.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ * trace/beauty/move_mount.c
+ *
+ * Copyright (C) 2019, Red Hat Inc, Arnaldo Carvalho de Melo <acme@redhat.com>
+ */
+
+#include "trace/beauty/beauty.h"
+#include <linux/log2.h>
+
+static size_t move_mount__scnprintf_flags(unsigned long flags, char *bf, size_t size, bool show_prefix)
+{
+#include "trace/beauty/generated/move_mount_flags_array.c"
+ static DEFINE_STRARRAY(move_mount_flags, "MOVE_MOUNT_");
+
+ return strarray__scnprintf_flags(&strarray__move_mount_flags, bf, size, show_prefix, flags);
+}
+
+size_t syscall_arg__scnprintf_move_mount_flags(char *bf, size_t size, struct syscall_arg *arg)
+{
+ unsigned long flags = arg->val;
+
+ return move_mount__scnprintf_flags(flags, bf, size, arg->show_string_prefix);
+}
--
2.20.1