perf mem: Support using -f to override perf.data file ownership

Enable perf mem to use perf.data when it is not owned by current user or
root.

Example:

# perf mem -t load record ls
# chown Yunlong.Song:Yunlong.Song perf.data
# ls -al perf.data
-rw------- 1 Yunlong.Song Yunlong.Song 16392 Apr 2 14:34 perf.data
# id
uid=0(root) gid=0(root) groups=0(root),64(pkcs11)

Before this patch:

# perf mem -D report
File perf.data not owned by current user or root (use -f to override)
# perf mem -D -f report
Error: unknown switch `f'

usage: perf mem [<options>] {record|report}

-t, --type <type> memory operations(load,store) Default load,store
-D, --dump-raw-samples
dump raw samples in ASCII
-U, --hide-unresolved
Only display entries resolved to a symbol
-i, --input <file> input file name
-C, --cpu <cpu> list of cpus to profile
-x, --field-separator <separator>
separator for columns, no spaces will be added
between columns '.' is reserved.

As shown above, the -f option does not work at all.

After this patch:

# perf mem -D report
File perf.data not owned by current user or root (use -f to override)
# perf mem -D -f report
# PID, TID, IP, ADDR, LOCAL WEIGHT, DSRC, SYMBOL
39095 39095 0xffffffff81127e40 0x016ffff887f45148338 8 0x68100142
/proc/kcore:perf_event_aux
39095 39095 0xffffffff8100a3fe 0xffff89007f8cb7d0 6 0x68100142
/proc/kcore:native_sched_clock
39095 39095 0xffffffff81309139 0xffff88bf44c9ded8 6 0x68100142
/proc/kcore:acpi_map_lookup
39095 39095 0xffffffff810f8c4c 0xffff89007f8ccd88 6 0x68100142
/proc/kcore:rcu_nmi_exit
39095 39095 0xffffffff81136346 0xffff88fea995dd50 6 0x68100142
/proc/kcore:unlock_page
39095 39095 0xffffffff812a64a2 0xffff88fea995dcc8 6 0x68100142
/proc/kcore:half_md4_transform
39095 39095 0x7f0cf877c7e9 0x25dfb94 6 0x68100142
/lib64/libc-2.19.so:__readdir64
39095 39095 0x7f0cf87575a3 0x7f0cf9163731 6 0x68100142
/lib64/libc-2.19.so:__strcoll_l
39095 39095 0xffffffff8116910e 0xffffea01c1bfbd50 23 0x68100242
/proc/kcore:page_remove_rmap

As shown above, the -f option really works now.

Signed-off-by: Yunlong Song <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-mem.c

···
 	char const		*input_name;
 	bool			hide_unresolved;
 	bool			dump_raw;
+	bool			force;
 	int			operation;
 	const char		*cpu_list;
 	DECLARE_BITMAP(cpu_bitmap, MAX_NR_CPUS);
···
 	struct perf_data_file file = {
 		.path = input_name,
 		.mode = PERF_DATA_MODE_READ,
+		.force = mem->force,
 	};
 	int err = -EINVAL;
 	int ret;
···
 		   "separator",
 		   "separator for columns, no spaces will be added"
 		   " between columns '.' is reserved."),
+	OPT_BOOLEAN('f', "force", &mem.force, "don't complain, do it"),
 	OPT_END()
 	};
 	const char *const mem_subcommands[] = { "record", "report", NULL };