From 9e755756e4a22784abfb001688357745ea8ca97c Mon Sep 17 00:00:00 2001 From: David Ahern Date: Sun, 15 Apr 2012 20:54:15 -0600 Subject: [PATCH] perf report: Fix crash showing warning related to kernel maps While testing https://lkml.org/lkml/2012/4/10/123 I hit this crash: (gdb) bt 0 0x000000000042000f in __cmd_report (rep=0x7fff80cec580) at builtin-report.c:380 1 cmd_report (argc=0, argv=, prefix=) at builtin-report.c:759 2 0x0000000000414513 in run_builtin (p=0x7724a8, argc=3, argv=0x7fff80ceca70) at perf.c:273 3 0x0000000000413d41 in handle_internal_command (argv=0x7fff80ceca70, argc=3) at perf.c:345 4 run_argv (argv=0x7fff80cec880, argcp=0x7fff80cec88c) at perf.c:389 5 main (argc=3, argv=0x7fff80ceca70) at perf.c:487 kernel_map can be NULL, so need to handle it while dumping a warning to user. v2: - fixed RB_EMPTY_ROOT check -- desc takes the altnerative output when RB_EMPTY_ROOT is false. Signed-off-by: David Ahern Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Namhyung Kim Link: http://lkml.kernel.org/r/1334544855-55021-1-git-send-email-dsahern@gmail.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-report.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c index 2e31743..cdae9b2 100644 --- a/tools/perf/builtin-report.c +++ b/tools/perf/builtin-report.c @@ -374,16 +374,23 @@ static int __cmd_report(struct perf_report *rep) (kernel_map->dso->hit && (kernel_kmap->ref_reloc_sym == NULL || kernel_kmap->ref_reloc_sym->addr == 0))) { - const struct dso *kdso = kernel_map->dso; + const char *desc = + "As no suitable kallsyms nor vmlinux was found, kernel samples\n" + "can't be resolved."; + + if (kernel_map) { + const struct dso *kdso = kernel_map->dso; + if (!RB_EMPTY_ROOT(&kdso->symbols[MAP__FUNCTION])) { + desc = "If some relocation was applied (e.g. " + "kexec) symbols may be misresolved."; + } + } ui__warning( "Kernel address maps (/proc/{kallsyms,modules}) were restricted.\n\n" "Check /proc/sys/kernel/kptr_restrict before running 'perf record'.\n\n%s\n\n" "Samples in kernel modules can't be resolved as well.\n\n", - RB_EMPTY_ROOT(&kdso->symbols[MAP__FUNCTION]) ? -"As no suitable kallsyms nor vmlinux was found, kernel samples\n" -"can't be resolved." : -"If some relocation was applied (e.g. kexec) symbols may be misresolved."); + desc); } if (dump_trace) { -- 1.7.10.4