From 7c31bb8c95ed269062ff7c7cc4a28b84a2b0f3a6 Mon Sep 17 00:00:00 2001 From: He Kuang Date: Thu, 18 Jun 2015 02:49:10 +0000 Subject: [PATCH] perf probe: Fix failure to probe events on arm Fix failure to probe events on arm, the problem was introduced by commit 5a51fcd1f30c ("perf probe: Skip kernel symbols which is out of .text"). For some architectures, the '_etext' label is not in the .text section (in the .notes section for arm/arm64). Labels out of the .text section are not loaded as symbols and we get a zero value when looking up its addresses, which causes all events to be wrongly skipped. This patch skips checking the text address range when failing to get the address of '_etext' and thus fixes the problem. The problem can be reproduced on arm as follows: # perf probe --add='generic_perform_write' generic_perform_write+0 is out of .text, skip it. Probe point 'generic_perform_write' not found. Error: Failed to add events. After this patch: # perf probe --add='generic_perform_write' Added new event: probe:generic_perform_write (on generic_perform_write) You can now use it in all perf tools, such as: perf record -e probe:generic_perform_write -aR sleep 1 Signed-off-by: He Kuang Acked-by: Masami Hiramatsu Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Wang Nan Link: http://lkml.kernel.org/r/1434595750-129791-1-git-send-email-hekuang@huawei.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/probe-event.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index 076527b639bd..381f23a443c7 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -249,8 +249,12 @@ static void clear_probe_trace_events(struct probe_trace_event *tevs, int ntevs) static bool kprobe_blacklist__listed(unsigned long address); static bool kprobe_warn_out_range(const char *symbol, unsigned long address) { + u64 etext_addr; + /* Get the address of _etext for checking non-probable text symbol */ - if (kernel_get_symbol_address_by_name("_etext", false) < address) + etext_addr = kernel_get_symbol_address_by_name("_etext", false); + + if (etext_addr != 0 && etext_addr < address) pr_warning("%s is out of .text, skip it.\n", symbol); else if (kprobe_blacklist__listed(address)) pr_warning("%s is blacklisted function, skip it.\n", symbol); -- 2.20.1