perf trace beauty: Always show mmap prot even though PROT_NONE

PROT_NONE is also useful information, so do not omit the mmap prot even
though it is 0. syscall_arg__scnprintf_mmap_prot() could print PROT_NONE
for prot 0.

Before: PROT_NONE is not shown.
$ sudo perf trace -e syscalls:sys_enter_mmap --filter prot==0  -- ls
     0.000 ls/2979231 syscalls:sys_enter_mmap(len: 4220888, flags: PRIVATE|ANONYMOUS)

After: PROT_NONE is displayed.
$ sudo perf trace -e syscalls:sys_enter_mmap --filter prot==0  -- ls
     0.000 ls/2975708 syscalls:sys_enter_mmap(len: 4220888, prot: NONE, flags: PRIVATE|ANONYMOUS)
Signed-off-by: Changbin Du <changbin.du@huawei.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240522033542.1359421-3-changbin.du@huawei.com

tools/perf/builtin-trace.c

@@ -1033,7 +1033,7 @@ static const struct syscall_fmt syscall_fmts[] = {
 #if defined(__s390x__)
 	.alias = "old_mmap",
 #endif
-	  .arg = { [2] = { .scnprintf = SCA_MMAP_PROT,	/* prot */ },
+	  .arg = { [2] = { .scnprintf = SCA_MMAP_PROT, .show_zero = true, /* prot */ },
 		   [3] = { .scnprintf = SCA_MMAP_FLAGS,	/* flags */
 			   .strtoul   = STUL_STRARRAY_FLAGS,
 			   .parm      = &strarray__mmap_flags, },
@@ -1050,7 +1050,7 @@ static const struct syscall_fmt syscall_fmts[] = {
 		   [4] = { .scnprintf = SCA_MOVE_MOUNT_FLAGS, /* flags */ }, }, },
 	{ .name	    = "mprotect",
 	  .arg = { [0] = { .scnprintf = SCA_HEX,	/* start */ },
-		   [2] = { .scnprintf = SCA_MMAP_PROT,	/* prot */ }, }, },
+		   [2] = { .scnprintf = SCA_MMAP_PROT, .show_zero = true, /* prot */ }, }, },
 	{ .name	    = "mq_unlink",
 	  .arg = { [0] = { .scnprintf = SCA_FILENAME, /* u_name */ }, }, },
 	{ .name	    = "mremap",	    .hexret = true,
@@ -1084,7 +1084,7 @@ static const struct syscall_fmt syscall_fmts[] = {
 	  .arg = { [0] = { .scnprintf = SCA_INT,	/* key */ }, }, },
 	{ .name	    = "pkey_mprotect",
 	  .arg = { [0] = { .scnprintf = SCA_HEX,	/* start */ },
-		   [2] = { .scnprintf = SCA_MMAP_PROT,	/* prot */ },
+		   [2] = { .scnprintf = SCA_MMAP_PROT, .show_zero = true, /* prot */ },
 		   [3] = { .scnprintf = SCA_INT,	/* pkey */ }, }, },
 	{ .name	    = "poll", .timeout = true, },
 	{ .name	    = "ppoll", .timeout = true, },