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Subject[PATCH 11/33] perf augmented_raw_syscalls: Introduce helper to get the scratch space
Date
From: Arnaldo Carvalho de Melo <acme@redhat.com>

We need more than the BPF stack can give us to format the
raw_syscalls:sys_enter augmented tracepoint, so we use a PERCPU_ARRAY
map for that, use a helper to shorten the sequence to access that area.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
.../examples/bpf/augmented_raw_syscalls.c | 32 +++++++++----------
1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/tools/perf/examples/bpf/augmented_raw_syscalls.c b/tools/perf/examples/bpf/augmented_raw_syscalls.c
index 0a8d217d65c7..8fd5ea059903 100644
--- a/tools/perf/examples/bpf/augmented_raw_syscalls.c
+++ b/tools/perf/examples/bpf/augmented_raw_syscalls.c
@@ -78,8 +78,15 @@ struct augmented_args_payload {
};
};

+// We need more tmp space than the BPF stack can give us
bpf_map(augmented_args_tmp, PERCPU_ARRAY, int, struct augmented_args_payload, 1);

+static inline struct augmented_args_payload *augmented_args_payload(void)
+{
+ int key = 0;
+ return bpf_map_lookup_elem(&augmented_args_tmp, &key);
+}
+
static inline
unsigned int augmented_arg__read_str(struct augmented_arg *augmented_arg, const void *arg, unsigned int arg_len)
{
@@ -122,8 +129,7 @@ int syscall_unaugmented(struct syscall_enter_args *args)
SEC("!syscalls:sys_enter_connect")
int sys_enter_connect(struct syscall_enter_args *args)
{
- int key = 0;
- struct augmented_args_payload *augmented_args = bpf_map_lookup_elem(&augmented_args_tmp, &key);
+ struct augmented_args_payload *augmented_args = augmented_args_payload();
const void *sockaddr_arg = (const void *)args->args[1];
unsigned int socklen = args->args[2];
unsigned int len = sizeof(augmented_args->args);
@@ -143,8 +149,7 @@ int sys_enter_connect(struct syscall_enter_args *args)
SEC("!syscalls:sys_enter_sendto")
int sys_enter_sendto(struct syscall_enter_args *args)
{
- int key = 0;
- struct augmented_args_payload *augmented_args = bpf_map_lookup_elem(&augmented_args_tmp, &key);
+ struct augmented_args_payload *augmented_args = augmented_args_payload();
const void *sockaddr_arg = (const void *)args->args[4];
unsigned int socklen = args->args[5];
unsigned int len = sizeof(augmented_args->args);
@@ -164,8 +169,7 @@ int sys_enter_sendto(struct syscall_enter_args *args)
SEC("!syscalls:sys_enter_open")
int sys_enter_open(struct syscall_enter_args *args)
{
- int key = 0;
- struct augmented_args_payload *augmented_args = bpf_map_lookup_elem(&augmented_args_tmp, &key);
+ struct augmented_args_payload *augmented_args = augmented_args_payload();
const void *filename_arg = (const void *)args->args[0];
unsigned int len = sizeof(augmented_args->args);

@@ -181,8 +185,7 @@ int sys_enter_open(struct syscall_enter_args *args)
SEC("!syscalls:sys_enter_openat")
int sys_enter_openat(struct syscall_enter_args *args)
{
- int key = 0;
- struct augmented_args_payload *augmented_args = bpf_map_lookup_elem(&augmented_args_tmp, &key);
+ struct augmented_args_payload *augmented_args = augmented_args_payload();
const void *filename_arg = (const void *)args->args[1];
unsigned int len = sizeof(augmented_args->args);

@@ -198,8 +201,7 @@ int sys_enter_openat(struct syscall_enter_args *args)
SEC("!syscalls:sys_enter_rename")
int sys_enter_rename(struct syscall_enter_args *args)
{
- int key = 0;
- struct augmented_args_payload *augmented_args = bpf_map_lookup_elem(&augmented_args_tmp, &key);
+ struct augmented_args_payload *augmented_args = augmented_args_payload();
const void *oldpath_arg = (const void *)args->args[0],
*newpath_arg = (const void *)args->args[1];
unsigned int len = sizeof(augmented_args->args), oldpath_len;
@@ -217,8 +219,7 @@ int sys_enter_rename(struct syscall_enter_args *args)
SEC("!syscalls:sys_enter_renameat")
int sys_enter_renameat(struct syscall_enter_args *args)
{
- int key = 0;
- struct augmented_args_payload *augmented_args = bpf_map_lookup_elem(&augmented_args_tmp, &key);
+ struct augmented_args_payload *augmented_args = augmented_args_payload();
const void *oldpath_arg = (const void *)args->args[1],
*newpath_arg = (const void *)args->args[3];
unsigned int len = sizeof(augmented_args->args), oldpath_len;
@@ -248,14 +249,13 @@ int sys_enter(struct syscall_enter_args *args)
*/
unsigned int len = sizeof(augmented_args->args);
struct syscall *syscall;
- int key = 0;

if (pid_filter__has(&pids_filtered, getpid()))
return 0;

- augmented_args = bpf_map_lookup_elem(&augmented_args_tmp, &key);
- if (augmented_args == NULL)
- return 1;
+ augmented_args = augmented_args_payload();
+ if (augmented_args == NULL)
+ return 1;

probe_read(&augmented_args->args, sizeof(augmented_args->args), args);

--
2.21.0
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