From ab8bf5f2e0321f254590ad81c6e230185d88b4e5 Mon Sep 17 00:00:00 2001 From: Tommi Rantala Date: Fri, 16 Oct 2020 14:47:18 +0300 Subject: perf tools: Fix crash with non-jited bpf progs The addr in PERF_RECORD_KSYMBOL events for non-jited bpf progs points to the bpf interpreter, ie. within kernel text section. When processing the unregister event, this causes unexpected removal of vmlinux_map, crashing perf later in cleanup: # perf record -- timeout --signal=INT 2s /usr/share/bcc/tools/execsnoop PCOMM PID PPID RET ARGS [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.208 MB perf.data (5155 samples) ] perf: tools/include/linux/refcount.h:131: refcount_sub_and_test: Assertion `!(new > val)' failed. Aborted (core dumped) # perf script -D|grep KSYM 0 0xa40 [0x48]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b530 len 0 type 1 flags 0x0 name bpf_prog_f958f6eb72ef5af6 0 0xab0 [0x48]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b530 len 0 type 1 flags 0x0 name bpf_prog_8c42dee26e8cd4c2 0 0xb20 [0x48]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b530 len 0 type 1 flags 0x0 name bpf_prog_f958f6eb72ef5af6 108563691893 0x33d98 [0x58]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b3b0 len 0 type 1 flags 0x0 name bpf_prog_bc5697a410556fc2_syscall__execve 108568518458 0x34098 [0x58]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b3f0 len 0 type 1 flags 0x0 name bpf_prog_45e2203c2928704d_do_ret_sys_execve 109301967895 0x34830 [0x58]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b3b0 len 0 type 1 flags 0x1 name bpf_prog_bc5697a410556fc2_syscall__execve 109302007356 0x348b0 [0x58]: PERF_RECORD_KSYMBOL addr ffffffffa9b6b3f0 len 0 type 1 flags 0x1 name bpf_prog_45e2203c2928704d_do_ret_sys_execve perf: tools/include/linux/refcount.h:131: refcount_sub_and_test: Assertion `!(new > val)' failed. Here the addresses match the bpf interpreter: # grep -e ffffffffa9b6b530 -e ffffffffa9b6b3b0 -e ffffffffa9b6b3f0 /proc/kallsyms ffffffffa9b6b3b0 t __bpf_prog_run224 ffffffffa9b6b3f0 t __bpf_prog_run192 ffffffffa9b6b530 t __bpf_prog_run32 Fix by not allowing vmlinux_map to be removed by PERF_RECORD_KSYMBOL unregister event. Signed-off-by: Tommi Rantala Acked-by: Jiri Olsa Tested-by: Jiri Olsa Link: https://lore.kernel.org/r/20201016114718.54332-1-tommi.t.rantala@nokia.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/symbol.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'tools/perf/util/symbol.c') diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index 6138866665df..0d14abdf3d72 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -515,6 +515,13 @@ void dso__insert_symbol(struct dso *dso, struct symbol *sym) } } +void dso__delete_symbol(struct dso *dso, struct symbol *sym) +{ + rb_erase_cached(&sym->rb_node, &dso->symbols); + symbol__delete(sym); + dso__reset_find_symbol_cache(dso); +} + struct symbol *dso__find_symbol(struct dso *dso, u64 addr) { if (dso->last_find_result.addr != addr || dso->last_find_result.symbol == NULL) { -- cgit v1.2.3