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Subject[RFC v1 09/14] krsi: Add a helper function for bpf_perf_event_output
Date
From: KP Singh <kpsingh@google.com>

This helper is mapped to the existing operation
BPF_FUNC_perf_event_output.

An example usage of this function would be:

#define BUF_SIZE 64;

struct bpf_map_def SEC("maps") perf_map = {
.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
.key_size = sizeof(int),
.value_size = sizeof(u32),
.max_entries = MAX_CPUS,
};

SEC("krsi")
int bpf_prog1(void *ctx)
{
char buf[BUF_SIZE];
int len;
u64 flags = BPF_F_CURRENT_CPU;

/* some logic that fills up buf with len data*/
len = fill_up_buf(buf);
if (len < 0)
return len;
if (len > BU)
return 0;

bpf_perf_event_output(ctx, &perf_map, flags, buf len);
return 0;
}

A sample program that showcases the use of bpf_perf_event_output is
added later.

Signed-off-by: KP Singh <kpsingh@google.com>
---
security/krsi/ops.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)

diff --git a/security/krsi/ops.c b/security/krsi/ops.c
index a61508b7018f..57bd304a03f4 100644
--- a/security/krsi/ops.c
+++ b/security/krsi/ops.c
@@ -111,6 +111,26 @@ static bool krsi_prog_is_valid_access(int off, int size,
return false;
}

+BPF_CALL_5(krsi_event_output, void *, log,
+ struct bpf_map *, map, u64, flags, void *, data, u64, size)
+{
+ if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
+ return -EINVAL;
+
+ return bpf_event_output(map, flags, data, size, NULL, 0, NULL);
+}
+
+static const struct bpf_func_proto krsi_event_output_proto = {
+ .func = krsi_event_output,
+ .gpl_only = true,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_CONST_MAP_PTR,
+ .arg3_type = ARG_ANYTHING,
+ .arg4_type = ARG_PTR_TO_MEM,
+ .arg5_type = ARG_CONST_SIZE_OR_ZERO,
+};
+
static const struct bpf_func_proto *krsi_prog_func_proto(enum bpf_func_id
func_id,
const struct bpf_prog
@@ -121,6 +141,8 @@ static const struct bpf_func_proto *krsi_prog_func_proto(enum bpf_func_id
return &bpf_map_lookup_elem_proto;
case BPF_FUNC_get_current_pid_tgid:
return &bpf_get_current_pid_tgid_proto;
+ case BPF_FUNC_perf_event_output:
+ return &krsi_event_output_proto;
default:
return NULL;
}
--
2.20.1
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