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Commit 95da0cdb authored by Teng Qin's avatar Teng Qin Committed by Daniel Borkmann
Browse files

bpf: add support to read sample address in bpf program 



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: default avatarTeng Qin <qinteng@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent a366e300

include/uapi/linux/bpf_perf_event.h

+1 −0
Original line number Diff line number Diff line
@@ -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__ */

kernel/trace/bpf_trace.c

+16 −4
Original line number Diff line number Diff line
@@ -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,