netdev - [PATCH bpf-next v4 06/10] tools/bpf: add bpf_get

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Date:   Sun, 22 Apr 2018 23:03:59 -0700
From:   Yonghong Song <yhs@...com>
To:     <ast@...com>, <daniel@...earbox.net>, <netdev@...r.kernel.org>
CC:     <kernel-team@...com>
Subject: [PATCH bpf-next v4 06/10] tools/bpf: add bpf_get_stack helper to tools headers

Signed-off-by: Yonghong Song <yhs@...com>
---
 tools/include/uapi/linux/bpf.h            | 19 +++++++++++++++++--
 tools/testing/selftests/bpf/bpf_helpers.h |  3 ++-
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 7f7fbb9..116eb5f 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -529,6 +529,17 @@ union bpf_attr {
  *             other bits - reserved
  *     Return: >= 0 stackid on success or negative error
  *
+ * int bpf_get_stack(ctx, buf, size, flags)
+ *     walk user or kernel stack and store the ips in buf
+ *     @ctx: struct pt_regs*
+ *     @buf: user buffer to fill stack
+ *     @size: the buf size
+ *     @flags: bits 0-7 - numer of stack frames to skip
+ *             bit 8 - collect user stack instead of kernel
+ *             bit 11 - get build-id as well if user stack
+ *             other bits - reserved
+ *     Return: >= 0 size copied on success or negative error
+ *
  * s64 bpf_csum_diff(from, from_size, to, to_size, seed)
  *     calculate csum diff
  *     @from: raw from buffer
@@ -841,7 +852,8 @@ union bpf_attr {
 	FN(msg_cork_bytes),		\
 	FN(msg_pull_data),		\
 	FN(bind),			\
-	FN(xdp_adjust_tail),
+	FN(xdp_adjust_tail),		\
+	FN(get_stack),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call
@@ -875,11 +887,14 @@ 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. */
+/* flags for both BPF_FUNC_get_stackid and BPF_FUNC_get_stack. */
 #define BPF_F_SKIP_FIELD_MASK		0xffULL
 #define BPF_F_USER_STACK		(1ULL << 8)
+/* flags used by BPF_FUNC_get_stackid only. */
 #define BPF_F_FAST_STACK_CMP		(1ULL << 9)
 #define BPF_F_REUSE_STACKID		(1ULL << 10)
+/* flags used by BPF_FUNC_get_stack only. */
+#define BPF_F_USER_BUILD_ID		(1ULL << 11)
 
 /* BPF_FUNC_skb_set_tunnel_key flags. */
 #define BPF_F_ZERO_CSUM_TX		(1ULL << 1)
diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
index 9271576..2d9d650 100644
--- a/tools/testing/selftests/bpf/bpf_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_helpers.h
@@ -98,7 +98,8 @@ static int (*bpf_bind)(void *ctx, void *addr, int addr_len) =
 	(void *) BPF_FUNC_bind;
 static int (*bpf_xdp_adjust_tail)(void *ctx, int offset) =
 	(void *) BPF_FUNC_xdp_adjust_tail;
-
+static int (*bpf_get_stack)(void *ctx, void *buf, int size, int flags) =
+	(void *) BPF_FUNC_get_stack;
 
 /* llvm builtin functions that eBPF C program may use to
  * emit BPF_LD_ABS and BPF_LD_IND instructions
-- 
2.9.5