[RFC PATCH 1/4] bpf tools: Add bpf_update_elem() and perf_event_open() for common bpf operations

[Kaixu Xia]

This patch introduces bpf_update_elem() and perf_event_open()
in bpf.c/h for common bpf operations.

Signed-off-by: Kaixu Xia <xiakaixu@xxxxxxxxxx>
---
 tools/lib/bpf/bpf.c | 34 ++++++++++++++++++++++++++++++++++
 tools/lib/bpf/bpf.h |  4 ++++
 2 files changed, 38 insertions(+)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index a633105..5ff7f09 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -10,6 +10,7 @@
 #include <memory.h>
 #include <unistd.h>
 #include <asm/unistd.h>
+#include <sys/syscall.h>
 #include <linux/bpf.h>
 #include "bpf.h"
 
@@ -29,6 +30,18 @@
 # endif
 #endif
 
+#if defined(__i386__)
+#ifndef __NR_perf_event_open
+# define __NR_perf_event_open 336
+#endif
+#endif
+
+#if defined(__x86_64__)
+#ifndef __NR_perf_event_open
+# define __NR_perf_event_open 298
+#endif
+#endif
+
 static __u64 ptr_to_u64(void *ptr)
 {
 	return (__u64) (unsigned long) ptr;
@@ -55,6 +68,20 @@ int bpf_create_map(enum bpf_map_type map_type, int key_size,
 	return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
 }
 
+int bpf_update_elem(int fd, void *key, void *value, unsigned long long flags)
+{
+	union bpf_attr attr;
+
+	memset(&attr, '\0', sizeof(attr));
+
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+	attr.value = ptr_to_u64(value);
+	attr.flags = flags;
+
+	return sys_bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
+}
+
 int bpf_load_program(enum bpf_prog_type type, struct bpf_insn *insns,
 		     size_t insns_cnt, char *license,
 		     u32 kern_version, char *log_buf, size_t log_buf_sz)
@@ -83,3 +110,10 @@ int bpf_load_program(enum bpf_prog_type type, struct bpf_insn *insns,
 	log_buf[0] = 0;
 	return sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
 }
+
+int perf_event_open(struct perf_event_attr *attr, int pid, int cpu,
+		    int group_fd, unsigned long flags)
+{
+	return syscall(__NR_perf_event_open, attr, pid, cpu,
+		       group_fd, flags);
+}
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 854b736..7f1283c 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -12,6 +12,10 @@
 
 int bpf_create_map(enum bpf_map_type map_type, int key_size, int value_size,
 		   int max_entries);
+int bpf_update_elem(int fd, void *key, void *value, unsigned long long flags);
+struct perf_event_attr;
+int perf_event_open(struct perf_event_attr *attr, int pid, int cpu,
+		    int group_fd, unsigned long flags);
 
 /* Recommend log buffer size */
 #define BPF_LOG_BUF_SIZE 65536
-- 
1.8.3.4

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