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authorArnaldo Carvalho de Melo <acme@redhat.com>2018-10-25 16:09:47 -0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2018-10-30 11:46:23 -0300
commit496fd346b71ffa0ff35623e9ec79df0bad47bd66 (patch)
tree22a59ea1e65a9e20bed3318099a2306b20b3a9c4 /Documentation/features/debug
parent579e5ff629b17744f62473f314768de8b6f1e66c (diff)
downloadlinux-496fd346b71ffa0ff35623e9ec79df0bad47bd66.tar.bz2
perf trace beauty: Allow syscalls to mask an argument before considering it
Take mount's 'flags' arg, to cope with this semantic, as defined in do_mount in fs/namespace.c: /* * Pre-0.97 versions of mount() didn't have a flags word. When the * flags word was introduced its top half was required to have the * magic value 0xC0ED, and this remained so until 2.4.0-test9. * Therefore, if this magic number is present, it carries no * information and must be discarded. */ We need to mask this arg, and then see if it is zero, when we simply don't print the arg name and value. The next patch will use this for mount's 'flag' arg. Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Benjamin Peterson <benjamin@python.org> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Wang Nan <wangnan0@huawei.com> Link: https://lkml.kernel.org/n/tip-btue14k5jemayuykfrwsnh85@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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