samples/bpf: Use BPF_KSYSCALL macro in syscall tracing programs

This commit enhances the syscall tracing programs by using the
BPF_SYSCALL macro to reduce the inconvenience of parsing arguments from
pt_regs. By simplifying argument extraction, bpf program will become
clear to understand.
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221224071527.2292-6-danieltimlee@gmail.com

samples/bpf/map_perf_test.bpf.c

@@ -101,7 +101,7 @@ struct {
 } lru_hash_lookup_map SEC(".maps");
 
 SEC("ksyscall/getuid")
-int stress_hmap(struct pt_regs *ctx)
+int BPF_KSYSCALL(stress_hmap)
 {
 	u32 key = bpf_get_current_pid_tgid();
 	long init_val = 1;
@@ -119,7 +119,7 @@ int stress_hmap(struct pt_regs *ctx)
 }
 
 SEC("ksyscall/geteuid")
-int stress_percpu_hmap(struct pt_regs *ctx)
+int BPF_KSYSCALL(stress_percpu_hmap)
 {
 	u32 key = bpf_get_current_pid_tgid();
 	long init_val = 1;
@@ -136,7 +136,7 @@ int stress_percpu_hmap(struct pt_regs *ctx)
 }
 
 SEC("ksyscall/getgid")
-int stress_hmap_alloc(struct pt_regs *ctx)
+int BPF_KSYSCALL(stress_hmap_alloc)
 {
 	u32 key = bpf_get_current_pid_tgid();
 	long init_val = 1;
@@ -153,7 +153,7 @@ int stress_hmap_alloc(struct pt_regs *ctx)
 }
 
 SEC("ksyscall/getegid")
-int stress_percpu_hmap_alloc(struct pt_regs *ctx)
+int BPF_KSYSCALL(stress_percpu_hmap_alloc)
 {
 	u32 key = bpf_get_current_pid_tgid();
 	long init_val = 1;
@@ -168,11 +168,10 @@ int stress_percpu_hmap_alloc(struct pt_regs *ctx)
 	}
 	return 0;
 }
-
 SEC("ksyscall/connect")
-int stress_lru_hmap_alloc(struct pt_regs *ctx)
+int BPF_KSYSCALL(stress_lru_hmap_alloc, int fd, struct sockaddr_in *uservaddr,
+		 int addrlen)
 {
-	struct pt_regs *real_regs = (struct pt_regs *)PT_REGS_PARM1_CORE(ctx);
 	char fmt[] = "Failed at stress_lru_hmap_alloc. ret:%dn";
 	union {
 		u16 dst6[8];
@@ -185,14 +184,11 @@ int stress_lru_hmap_alloc(struct pt_regs *ctx)
 			u32 key;
 		};
 	} test_params;
-	struct sockaddr_in6 *in6;
+	struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)uservaddr;
 	u16 test_case;
-	int addrlen, ret;
 	long val = 1;
 	u32 key = 0;
-
-	in6 = (struct sockaddr_in6 *)PT_REGS_PARM2_CORE(real_regs);
-	addrlen = (int)PT_REGS_PARM3_CORE(real_regs);
+	int ret;
 
 	if (addrlen != sizeof(*in6))
 		return 0;
@@ -250,7 +246,7 @@ int stress_lru_hmap_alloc(struct pt_regs *ctx)
 }
 
 SEC("ksyscall/gettid")
-int stress_lpm_trie_map_alloc(struct pt_regs *ctx)
+int BPF_KSYSCALL(stress_lpm_trie_map_alloc)
 {
 	union {
 		u32 b32[2];
@@ -272,7 +268,7 @@ int stress_lpm_trie_map_alloc(struct pt_regs *ctx)
 }
 
 SEC("ksyscall/getpgid")
-int stress_hash_map_lookup(struct pt_regs *ctx)
+int BPF_KSYSCALL(stress_hash_map_lookup)
 {
 	u32 key = 1, i;
 	long *value;
@@ -285,7 +281,7 @@ int stress_hash_map_lookup(struct pt_regs *ctx)
 }
 
 SEC("ksyscall/getppid")
-int stress_array_map_lookup(struct pt_regs *ctx)
+int BPF_KSYSCALL(stress_array_map_lookup)
 {
 	u32 key = 1, i;
 	long *value;

samples/bpf/test_current_task_under_cgroup.bpf.c

@@ -8,6 +8,8 @@
 #include "vmlinux.h"
 #include <linux/version.h>
 #include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
 
 struct {
 	__uint(type, BPF_MAP_TYPE_CGROUP_ARRAY);
@@ -25,7 +27,7 @@ struct {
 
 /* Writes the last PID that called sync to a map at index 0 */
 SEC("ksyscall/sync")
-int bpf_prog1(struct pt_regs *ctx)
+int BPF_KSYSCALL(bpf_prog1)
 {
 	u64 pid = bpf_get_current_pid_tgid();
 	int idx = 0;

samples/bpf/test_probe_write_user.bpf.c

@@ -27,24 +27,22 @@ struct {
  * of course, across platforms, and over time, the ABI may change.
  */
 SEC("ksyscall/connect")
-int bpf_prog1(struct pt_regs *ctx)
+int BPF_KSYSCALL(bpf_prog1, int fd, struct sockaddr_in *uservaddr,
+		 int addrlen)
 {
-	struct pt_regs *real_regs = (struct pt_regs *)PT_REGS_PARM1_CORE(ctx);
-	void *sockaddr_arg = (void *)PT_REGS_PARM2_CORE(real_regs);
-	int sockaddr_len = (int)PT_REGS_PARM3_CORE(real_regs);
 	struct sockaddr_in new_addr, orig_addr = {};
 	struct sockaddr_in *mapped_addr;
 
-	if (sockaddr_len > sizeof(orig_addr))
+	if (addrlen > sizeof(orig_addr))
 		return 0;
 
-	if (bpf_probe_read_user(&orig_addr, sizeof(orig_addr), sockaddr_arg) != 0)
+	if (bpf_probe_read_user(&orig_addr, sizeof(orig_addr), uservaddr) != 0)
 		return 0;
 
 	mapped_addr = bpf_map_lookup_elem(&dnat_map, &orig_addr);
 	if (mapped_addr != NULL) {
 		memcpy(&new_addr, mapped_addr, sizeof(new_addr));
-		bpf_probe_write_user(sockaddr_arg, &new_addr,
+		bpf_probe_write_user(uservaddr, &new_addr,
 				     sizeof(new_addr));
 	}
 	return 0;