Messages in this thread Patch in this message | | | From | Arnaldo Carvalho de Melo <> | Subject | [PATCH 1/1] perf symbols: Accept zero as the kernel base address | Date | Wed, 12 Jul 2017 16:36:50 -0300 |
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From: Arnaldo Carvalho de Melo <acme@redhat.com>
Which is the case in S/390, where symbols were not being resolved because machine__get_kernel_start was only setting machine->kernel_start when the just successfully loaded kernel symtab had its map->start set to !0, when it was left at (1ULL << 63) assuming a partitioning of the address space for user/kernel, which is not the case in S/390 nor in Sparc.
So just check if map__load() was successfull and set machine->kernel_start to zero, fixing kernel symbol resolution on S/390.
Test performed by Thomas:
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I like this patch. I have done a new build and removed all my debug output to start from scratch. Without your patch I get this:
# Samples: 4 of event 'cpu-clock' # Event count (approx.): 1000000 # # Children Self Command Shared Object Symbol # ........ ........ ....... ................ ........................ 75.00% 0.00% true [unknown] [k] 0x00000000004bedda | ---0x4bedda | |--50.00%--0x42693a | | | --25.00%--0x2a72e0 | 0x2af0ca | 0x3d1003fe4c0 | --25.00%--0x4272bc 0x26fa84
and with your patch (I just rebuilt the perf tool, nothing else and used the same perf.data file as input):
# Samples: 4 of event 'cpu-clock' # Event count (approx.): 1000000 # # Children Self Command Shared Object Symbol # ........ ........ ....... .......................... .................................. 75.00% 0.00% true [kernel.vmlinux] [k] pgm_check_handler | ---pgm_check_handler do_dat_exception handle_mm_fault __handle_mm_fault filemap_map_pages | |--25.00%--rcu_read_lock_held | rcu_lockdep_current_cpu_online | 0x3d1003ff4c0 | --25.00%--lock_release
Looks good to me.... ----
Reported-and-Tested-by: Thomas-Mich Richter <tmricht@linux.vnet.ibm.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Wang Nan <wangnan0@huawei.com> Cc: Zvonko Kosic <zvonko.kosic@de.ibm.com> Link: http://lkml.kernel.org/n/tip-dk0n1uzmbe0tbthrpfqlx6bz@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> --- tools/perf/util/machine.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index 5de2b86b9880..2e9eb6aa3ce2 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -2209,7 +2209,7 @@ int machine__get_kernel_start(struct machine *machine) machine->kernel_start = 1ULL << 63; if (map) { err = map__load(map); - if (map->start) + if (!err) machine->kernel_start = map->start; } return err; -- 2.9.4
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