Kemeng Shi 78886f3ed3 perf symbols: Fix arm64 gap between kernel start and module end ... During execution of command 'perf report' in my arm64 virtual machine, this error message is showed: failed to process sample __symbol__inc_addr_samples(860): ENOMEM! sym->name=__this_module, start=0x1477100, addr=0x147dbd8, end=0x80002000, func: 0 The error is caused with path: cmd_report __cmd_report perf_session__process_events __perf_session__process_events ordered_events__flush __ordered_events__flush oe->deliver (ordered_events__deliver_event) perf_session__deliver_event machines__deliver_event perf_evlist__deliver_sample tool->sample (process_sample_event) hist_entry_iter__add iter->add_entry_cb(hist_iter__report_callback) hist_entry__inc_addr_samples symbol__inc_addr_samples __symbol__inc_addr_samples h = annotated_source__histogram(src, evidx) (NULL) annotated_source__histogram failed is caused with path: ... hist_entry__inc_addr_samples symbol__inc_addr_samples symbol__hists annotated_source__alloc_histograms src->histograms = calloc(nr_hists, sizeof_sym_hist) (failed) Calloc failed as the symbol__size(sym) is too huge. As show in error message: start=0x1477100, end=0x80002000, size of symbol is about 2G. This is the same problem as 'perf annotate: Fix s390 gap between kernel end and module start (b9c0a64901)'. Perf gets symbol information from /proc/kallsyms in __dso__load_kallsyms. A part of symbol in /proc/kallsyms from my virtual machine is as follows: #cat /proc/kallsyms | sort ... ffff000001475080 d rpfilter_mt_reg [ip6t_rpfilter] ffff000001475100 d $d [ip6t_rpfilter] ffff000001475100 d __this_module [ip6t_rpfilter] ffff000080080000 t _head ffff000080080000 T _text ffff000080080040 t pe_header ... Take line 'ffff000001475100 d __this_module [ip6t_rpfilter]' as example. The start and end of symbol are both set to ffff000001475100 in dso__load_all_kallsyms. Then symbols__fixup_end will set the end of symbol to next big address to ffff000001475100 in /proc/kallsyms, ffff000080080000 in this example. Then sizeof of symbol will be about 2G and cause the problem. The start of module in my machine is ffff000000a62000 t $x [dm_mod] The start of kernel in my machine is ffff000080080000 t _head There is a big gap between end of module and begin of kernel if a samll amount of memory is used by module. And the last symbol in module will have a large address range as caotaining the big gap. Give that the module and kernel text segment sequence may change in the future, fix this by limiting range of last symbol in module and kernel to 4K in arch arm64. Signed-off-by: Kemeng Shi <shikemeng@huawei.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Hewenliang <hewenliang4@huawei.com> Cc: Hu Shiyuan <hushiyuan@huawei.com> Cc: Ian Rogers <irogers@google.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Richter <tmricht@linux.ibm.com> Link: http://lore.kernel.org/lkml/33fd24c4-0d5a-9d93-9b62-dffa97c992ca@huawei.com [ refreshed the patch on current codebase, added string.h include as strchr() is used ] Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>		2020-04-03 09:37:55 -03:00
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util	perf symbols: Fix arm64 gap between kernel start and module end	2020-04-03 09:37:55 -03:00
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