[PATCH bpf-next 1/2] bpf: add support to read sample address in bpf program
flat view
STALE3157d
From: Teng Qin <hidden>
Date: 2018-03-06 18:56:11
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [security & lsm] (security audit and enforcement using bpf), bpf [tracing], the rest, tracing · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, KP Singh, Matt Bobrowski, Song Liu, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
This commit adds new field "addr" to bpf_perf_event_data which could be read and used by bpf programs attached to perf events. The value of the field is copied from bpf_perf_event_data_kern.addr and contains the address value recorded by specifying sample_type with PERF_SAMPLE_ADDR when calling perf_event_open. Signed-off-by: Teng Qin <redacted> --- include/uapi/linux/bpf_perf_event.h | 1 + kernel/trace/bpf_trace.c | 20 ++++++++++++++++---- 2 files changed, 17 insertions(+), 4 deletions(-)
diff --git a/include/uapi/linux/bpf_perf_event.h b/include/uapi/linux/bpf_perf_event.h
index 8f95303..eb1b9d2 100644
--- a/include/uapi/linux/bpf_perf_event.h
+++ b/include/uapi/linux/bpf_perf_event.h@@ -13,6 +13,7 @@ struct bpf_perf_event_data { bpf_user_pt_regs_t regs; __u64 sample_period; + __u64 addr; }; #endif /* _UAPI__LINUX_BPF_PERF_EVENT_H__ */
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index c0a9e31..c634e09 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c@@ -726,8 +726,7 @@ const struct bpf_prog_ops tracepoint_prog_ops = { static bool pe_prog_is_valid_access(int off, int size, enum bpf_access_type type, struct bpf_insn_access_aux *info) { - const int size_sp = FIELD_SIZEOF(struct bpf_perf_event_data, - sample_period); + const int size_u64 = sizeof(u64); if (off < 0 || off >= sizeof(struct bpf_perf_event_data)) return false;
@@ -738,8 +737,13 @@ static bool pe_prog_is_valid_access(int off, int size, enum bpf_access_type type switch (off) { case bpf_ctx_range(struct bpf_perf_event_data, sample_period): - bpf_ctx_record_field_size(info, size_sp); - if (!bpf_ctx_narrow_access_ok(off, size, size_sp)) + bpf_ctx_record_field_size(info, size_u64); + if (!bpf_ctx_narrow_access_ok(off, size, size_u64)) + return false; + break; + case bpf_ctx_range(struct bpf_perf_event_data, addr): + bpf_ctx_record_field_size(info, size_u64); + if (!bpf_ctx_narrow_access_ok(off, size, size_u64)) return false; break; default:
@@ -766,6 +770,14 @@ static u32 pe_prog_convert_ctx_access(enum bpf_access_type type, bpf_target_off(struct perf_sample_data, period, 8, target_size)); break; + case offsetof(struct bpf_perf_event_data, addr): + *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern, + data), si->dst_reg, si->src_reg, + offsetof(struct bpf_perf_event_data_kern, data)); + *insn++ = BPF_LDX_MEM(BPF_DW, si->dst_reg, si->dst_reg, + bpf_target_off(struct perf_sample_data, addr, 8, + target_size)); + break; default: *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern, regs), si->dst_reg, si->src_reg,
--
2.9.5