Messages in this thread Patch in this message | | | From | wangxu <> | Subject | [PATCH] sample/hw_breakpoint: avoid sample hw_breakpoint recursion for arm/arm64 | Date | Mon, 23 Sep 2019 16:09:35 +0800 |
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From: Wang Xu <wangxu72@huawei.com>
For x86/ppc, hw_breakpoint is triggered after the instruction is executed.
For arm/arm64, which is triggered before the instruction executed. Arm/arm64 skips the instruction by using single step. But it only supports default overflow_handler.
This patch provides a chance to avoid sample hw_breakpoint recursion for arm/arm64 by adding 'struct perf_event_attr.bp_step'.
Signed-off-by: Wang Xu <wangxu72@huawei.com> --- include/linux/perf_event.h | 3 +++ include/uapi/linux/perf_event.h | 3 ++- samples/hw_breakpoint/data_breakpoint.c | 1 + 3 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 61448c1..f270eb7 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1024,6 +1024,9 @@ extern int perf_event_output(struct perf_event *event, return true; if (unlikely(event->overflow_handler == perf_event_output_backward)) return true; + /* avoid sample hw_breakpoint recursion */ + if (unlikely(event->attr.bp_step)) + return true; return false; } diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index bb7b271..95b81c2 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -375,7 +375,8 @@ struct perf_event_attr { ksymbol : 1, /* include ksymbol events */ bpf_event : 1, /* include bpf events */ aux_output : 1, /* generate AUX records instead of events */ - __reserved_1 : 32; + bp_step : 1, + __reserved_1 : 31; union { __u32 wakeup_events; /* wakeup every n events */ diff --git a/samples/hw_breakpoint/data_breakpoint.c b/samples/hw_breakpoint/data_breakpoint.c index c585047..9fe1351 100644 --- a/samples/hw_breakpoint/data_breakpoint.c +++ b/samples/hw_breakpoint/data_breakpoint.c @@ -46,6 +46,7 @@ static int __init hw_break_module_init(void) attr.bp_addr = kallsyms_lookup_name(ksym_name); attr.bp_len = HW_BREAKPOINT_LEN_4; attr.bp_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R; + attr.bp_step = true; sample_hbp = register_wide_hw_breakpoint(&attr, sample_hbp_handler, NULL); if (IS_ERR((void __force *)sample_hbp)) { -- 1.8.5.6
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