perf kvm: Fix subcommand matching error
Currently the 'diff', 'top', 'buildid-list' and 'stat' perf commands use
strncmp() to match subcommands. As a result, matching does not meet
expectation.
For example:
# perf kvm diff1234
# Event 'cycles'
#
# Baseline Delta Abs Shared Object Symbol
# ........ ......... ............. ......
#
# Event 'dummy:HG'
#
# Baseline Delta Abs Shared Object Symbol
# ........ ......... ............. ......
#
# echo $?
0
#
Invalid information should be returned, but success is actually returned.
Solution: Use strstarts() to match subcommands.
After:
# perf kvm diff1234
Usage: perf kvm [<options>] {top|record|report|diff|buildid-list|stat}
-i, --input <file> Input file name
-o, --output <file> Output file name
-v, --verbose be more verbose (show counter open errors, etc)
--guest Collect guest os data
--guest-code Guest code can be found in hypervisor process
--guestkallsyms <file>
file saving guest os /proc/kallsyms
--guestmodules <file>
file saving guest os /proc/modules
--guestmount <directory>
guest mount directory under which every guest os instance has a subdir
--guestvmlinux <file>
file saving guest os vmlinux
--host Collect host os data
# echo $?
129
#
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220808092408.107399-2-yangjihong1@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>