Commits
Arnaldo Carvalho de Melo committed b843f62ad94
perf symbols: Accept symbols starting at address 0 That is the case of _text on s390, and we have some functions that return an address, using address zero to report problems, oops. This would lead the symbol loading routines to not use "_text" as the reference relocation symbol, or the first symbol for the kernel, but use instead "_stext", that is at the same address on x86_64 and others, but not on s390: [acme@localhost perf-4.11.0-rc6]$ head -15 /proc/kallsyms 0000000000000000 T _text 0000000000000418 t iplstart 0000000000000800 T start 000000000000080a t .base 000000000000082e t .sk8x8 0000000000000834 t .gotr 0000000000000842 t .cmd 0000000000000846 t .parm 000000000000084a t .lowcase 0000000000010000 T startup 0000000000010010 T startup_kdump 0000000000010214 t startup_kdump_relocated 0000000000011000 T startup_continue 00000000000112a0 T _ehead 0000000000100000 T _stext [acme@localhost perf-4.11.0-rc6]$ Which in turn would make 'perf test vmlinux' to fail because it wouldn't find the symbols before "_stext" in kallsyms. Fix it by using the return value only for errors and storing the address, when the symbol is successfully found, in a provided pointer arg. Before this patch: After: [acme@localhost perf-4.11.0-rc6]$ tools/perf/perf test -v 1 1: vmlinux symtab matches kallsyms : --- start --- test child forked, pid 40693 Looking at the vmlinux_path (8 entries long) Using /usr/lib/debug/lib/modules/3.10.0-654.el7.s390x/vmlinux for symbols ERR : 0: _text not on kallsyms ERR : 0x418: iplstart not on kallsyms ERR : 0x800: start not on kallsyms ERR : 0x80a: .base not on kallsyms ERR : 0x82e: .sk8x8 not on kallsyms ERR : 0x834: .gotr not on kallsyms ERR : 0x842: .cmd not on kallsyms ERR : 0x846: .parm not on kallsyms ERR : 0x84a: .lowcase not on kallsyms ERR : 0x10000: startup not on kallsyms ERR : 0x10010: startup_kdump not on kallsyms ERR : 0x10214: startup_kdump_relocated not on kallsyms ERR : 0x11000: startup_continue not on kallsyms ERR : 0x112a0: _ehead not on kallsyms <SNIP warnings> test child finished with -1 ---- end ---- vmlinux symtab matches kallsyms: FAILED! [acme@localhost perf-4.11.0-rc6]$ After: [acme@localhost perf-4.11.0-rc6]$ tools/perf/perf test -v 1 1: vmlinux symtab matches kallsyms : --- start --- test child forked, pid 47160 <SNIP warnings> test child finished with 0 ---- end ---- vmlinux symtab matches kallsyms: Ok [acme@localhost perf-4.11.0-rc6]$ Reported-by: Michael Petlan <mpetlan@redhat.com> Cc: Adrian Hunter <adrian.hunter@intel.com> 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: http://lkml.kernel.org/n/tip-9x9bwgd3btwdk1u51xie93fz@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>