bpf: introduce BPF_MAP_TYPE_STACK_TRACE

add new map type to store stack traces and corresponding helper
bpf_get_stackid(ctx, map, flags) - walk user or kernel stack and return id
@ctx: struct pt_regs*
@map: pointer to stack_trace map
@flags: bits 0-7 - numer of stack frames to skip
        bit 8 - collect user stack instead of kernel
        bit 9 - compare stacks by hash only
        bit 10 - if two different stacks hash into the same stackid
                 discard old
        other bits - reserved
Return: >= 0 stackid on success or negative error

stackid is a 32-bit integer handle that can be further combined with
other data (including other stackid) and used as a key into maps.

Userspace will access stackmap using standard lookup/delete syscall commands to
retrieve full stack trace for given stackid.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 21 insertions, 0 deletions

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 2ee0fde1bf96..d3e77da8e9e8 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -83,6 +83,7 @@ enum bpf_map_type {
         BPF_MAP_TYPE_PERF_EVENT_ARRAY,
         BPF_MAP_TYPE_PERCPU_HASH,
         BPF_MAP_TYPE_PERCPU_ARRAY,
+        BPF_MAP_TYPE_STACK_TRACE,
 };
 
 enum bpf_prog_type {
@@ -272,6 +273,20 @@ enum bpf_func_id {
          */
         BPF_FUNC_perf_event_output,
         BPF_FUNC_skb_load_bytes,
+
+        /**
+         * bpf_get_stackid(ctx, map, flags) - walk user or kernel stack and return id
+         * @ctx: struct pt_regs*
+         * @map: pointer to stack_trace map
+         * @flags: bits 0-7 - numer of stack frames to skip
+         *         bit 8 - collect user stack instead of kernel
+         *         bit 9 - compare stacks by hash only
+         *         bit 10 - if two different stacks hash into the same stackid
+         *                  discard old
+         *         other bits - reserved
+         * Return: >= 0 stackid on success or negative error
+         */
+        BPF_FUNC_get_stackid,
         __BPF_FUNC_MAX_ID,
 };
 
@@ -294,6 +309,12 @@ enum bpf_func_id {
 /* BPF_FUNC_skb_set_tunnel_key and BPF_FUNC_skb_get_tunnel_key flags. */
 #define BPF_F_TUNINFO_IPV6              (1ULL << 0)
 
+/* BPF_FUNC_get_stackid flags. */
+#define BPF_F_SKIP_FIELD_MASK           0xffULL
+#define BPF_F_USER_STACK                (1ULL << 8)
+#define BPF_F_FAST_STACK_CMP            (1ULL << 9)
+#define BPF_F_REUSE_STACKID             (1ULL << 10)
+
 /* user accessible mirror of in-kernel sk_buff.
  * new fields can only be added to the end of this structure
  */