perf trace: Beautify 'move_mount' arguments

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

@@ -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) \

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 */ }, }, },

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:

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

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
 

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);
+}