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Commit 9940d67c authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by David S. Miller
Browse files

bpf: support bpf_get_stackid() and bpf_perf_event_output() in tracepoint programs 



needs two wrapper functions to fetch 'struct pt_regs *' to convert
tracepoint bpf context into kprobe bpf context to reuse existing
helper functions

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9fd82b61

include/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -160,6 +160,7 @@ struct bpf_array { 
#define MAX_TAIL_CALL_CNT 32



u64 bpf_tail_call(u64 ctx, u64 r2, u64 index, u64 r4, u64 r5);

u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);

void bpf_fd_array_map_clear(struct bpf_map *map);

bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp);

const struct bpf_func_proto *bpf_get_trace_printk_proto(void);

kernel/bpf/stackmap.c

+1 −1
Original line number Diff line number Diff line
@@ -116,7 +116,7 @@ static struct bpf_map *stack_map_alloc(union bpf_attr *attr) 
	return ERR_PTR(err);

}



static u64 bpf_get_stackid(u64 r1, u64 r2, u64 flags, u64 r4, u64 r5)

u64 bpf_get_stackid(u64 r1, u64 r2, u64 flags, u64 r4, u64 r5)

{

	struct pt_regs *regs = (struct pt_regs *) (long) r1;

	struct bpf_map *map = (struct bpf_map *) (long) r2;

kernel/trace/bpf_trace.c

+41 −1
Original line number Diff line number Diff line
@@ -340,12 +340,52 @@ static struct bpf_prog_type_list kprobe_tl = { 
	.type	= BPF_PROG_TYPE_KPROBE,

};



static u64 bpf_perf_event_output_tp(u64 r1, u64 r2, u64 index, u64 r4, u64 size)

{

	/*

	 * r1 points to perf tracepoint buffer where first 8 bytes are hidden

	 * from bpf program and contain a pointer to 'struct pt_regs'. Fetch it

	 * from there and call the same bpf_perf_event_output() helper

	 */

	u64 ctx = *(long *)r1;



	return bpf_perf_event_output(ctx, r2, index, r4, size);

}



static const struct bpf_func_proto bpf_perf_event_output_proto_tp = {

	.func		= bpf_perf_event_output_tp,

	.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_STACK,

	.arg5_type	= ARG_CONST_STACK_SIZE,

};



static u64 bpf_get_stackid_tp(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)

{

	u64 ctx = *(long *)r1;



	return bpf_get_stackid(ctx, r2, r3, r4, r5);

}



static const struct bpf_func_proto bpf_get_stackid_proto_tp = {

	.func		= bpf_get_stackid_tp,

	.gpl_only	= true,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_PTR_TO_CTX,

	.arg2_type	= ARG_CONST_MAP_PTR,

	.arg3_type	= ARG_ANYTHING,

};



static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id)

{

	switch (func_id) {

	case BPF_FUNC_perf_event_output:

		return &bpf_perf_event_output_proto_tp;

	case BPF_FUNC_get_stackid:

		return NULL;

		return &bpf_get_stackid_proto_tp;

	default:

		return tracing_func_proto(func_id);

	}