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bpf: add support to read sample address in bpf program

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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 <qinteng@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Teng Qin 2018-03-06 10:55:01 -08:00 committed by Daniel Borkmann
parent a366e300ae
commit 95da0cdb72
2 changed files with 17 additions and 4 deletions
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1
include/uapi/linux/bpf_perf_event.h
View File

@ -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__ */

20
kernel/trace/bpf_trace.c
View File

@ -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,