Thread (42 messages) 42 messages, 4 authors, 2020-09-02

Re: [PATCH bpf-next v1 7/8] bpf: Propagate bpf_per_cpu_ptr() to /tools

From: Yonghong Song <hidden>
Date: 2020-08-20 17:31:29
Also in: bpf, linux-kselftest, lkml


On 8/19/20 3:40 PM, Hao Luo wrote:
Sync tools/include/linux/uapi/bpf.h with include/linux/uapi/bpf.h
This can be folded into the previous patch.
quoted hunk ↗ jump to hunk
Signed-off-by: Hao Luo <redacted>
---
  tools/include/uapi/linux/bpf.h | 15 +++++++++++++++
  1 file changed, 15 insertions(+)
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 468376f2910b..7e3dfb2bbb86 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3415,6 +3415,20 @@ union bpf_attr {
   *		A non-negative value equal to or less than *size* on success,
   *		or a negative error in case of failure.
   *
+ * void *bpf_per_cpu_ptr(const void *ptr, u32 cpu)
+ *	Description
+ *		Take the address of a percpu ksym and return a pointer pointing
+ *		to the variable on *cpu*. A ksym is an extern variable decorated
+ *		with '__ksym'. A ksym is percpu if there is a global percpu var
+ *		(either static or global) defined of the same name in the kernel.
+ *
+ *		bpf_per_cpu_ptr() has the same semantic as per_cpu_ptr() in the
+ *		kernel, except that bpf_per_cpu_ptr() may return NULL. This
+ *		happens if *cpu* is larger than nr_cpu_ids. The caller of
+ *		bpf_per_cpu_ptr() must check the returned value.
+ *	Return
+ *		A generic pointer pointing to the variable on *cpu*.
+ *
   */
  #define __BPF_FUNC_MAPPER(FN)		\
  	FN(unspec),			\
@@ -3559,6 +3573,7 @@ union bpf_attr {
  	FN(skc_to_tcp_request_sock),	\
  	FN(skc_to_udp6_sock),		\
  	FN(get_task_stack),		\
+	FN(bpf_per_cpu_ptr),		\
  	/* */
  
  /* integer value in 'imm' field of BPF_CALL instruction selects which helper
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