Skip to content

Commit

Permalink
Merge pull request #87 from paulfantom/code-format
Browse files Browse the repository at this point in the history 
parca-agent: format C code according to GNU formatting guidelines
  • Loading branch information
@brancz
brancz committed Oct 11, 2021
2 parents 6f51b2a + fd93c0c commit 3ed0de7
Show file tree
Hide file tree
Showing 2 changed files with 78 additions and 66 deletions.
4 changes: 4 additions & 0 deletions Makefile
View file
Expand Up @@ -229,6 +229,10 @@ README.md: $(CMD_EMBEDMD) $(OUT_DIR)/help.txt deploy/manifests
.PHONY: format
format: go-fmt check-license

.PHONY: c-fmt
c-fmt:
clang-format -i --style=GNU $(BPF_SRC)

.PHONY: go-fmt
go-fmt:
go fmt $(shell go list ./... | grep -E -v "pkg/internal/pprof|pkg/internal/go")
Expand Down
140 changes: 74 additions & 66 deletions parca-agent.bpf.c
View file
@@ -1,9 +1,12 @@
// +build ignore
// ^^ this is a golang build tag meant to exclude this C file from compilation by the CGO compiler
// ^^ this is a golang build tag meant to exclude this C file from compilation
// by the CGO compiler

/* In Linux 5.4 asm_inline was introduced, but it's not supported by clang.
* Redefine it to just asm to enable successful compilation.
* see https://github.com/iovisor/bcc/commit/2d1497cde1cc9835f759a707b42dea83bee378b8 for more details
* see
* https://github.com/iovisor/bcc/commit/2d1497cde1cc9835f759a707b42dea83bee378b8
* for more details
*/
#include "vmlinux.h"
#ifdef asm_inline
Expand All @@ -15,101 +18,106 @@

#undef container_of
//#include "bpf_core_read.h"
#include <bpf_helpers.h>
#include <bpf_tracing.h>
#include <bpf_core_read.h>
#include <bpf_endian.h>
#include <bpf_helpers.h>
#include <bpf_tracing.h>

#if defined(bpf_target_x86)
#define PT_REGS_PARM6(ctx) ((ctx)->r9)
#define PT_REGS_PARM6(ctx) ((ctx)->r9)
#elif defined(bpf_target_arm64)
#define PT_REGS_PARM6(x) (((PT_REGS_ARM64 *)(x))->regs[5])
#endif

#define MAX_STACK_ADDRESSES 1024 // Max amount of different stack trace addresses to buffer in the Map
#define MAX_STACK_DEPTH 127 // Max depth of each stack trace to track
// Max amount of different stack trace addresses to buffer in the Map
#define MAX_STACK_ADDRESSES 1024
// Max depth of each stack trace to track
#define MAX_STACK_DEPTH 127

#define BPF_MAP(_name, _type, _key_type, _value_type, _max_entries) \
struct bpf_map_def SEC("maps") _name = { \
.type = _type, \
.key_size = sizeof(_key_type), \
.value_size = sizeof(_value_type), \
.max_entries = _max_entries, \
};
#define BPF_MAP(_name, _type, _key_type, _value_type, _max_entries) \
struct bpf_map_def SEC ("maps") _name = { \
.type = _type, \
.key_size = sizeof (_key_type), \
.value_size = sizeof (_value_type), \
.max_entries = _max_entries, \
};

// Stack Traces are slightly different
// in that the value is 1 big byte array
// of the stack addresses
#define BPF_STACK_TRACE(_name, _max_entries) \
struct bpf_map_def SEC("maps") _name = { \
.type = BPF_MAP_TYPE_STACK_TRACE, \
.key_size = sizeof(u32), \
.value_size = sizeof(size_t) * MAX_STACK_DEPTH, \
.max_entries = _max_entries, \
};

#define BPF_HASH(_name, _key_type, _value_type) \
BPF_MAP(_name, BPF_MAP_TYPE_HASH, _key_type, _value_type, 10240);

/*=============================== INTERNAL STRUCTS ===========================*/

typedef struct stack_count_key {
u32 pid;
int user_stack_id;
int kernel_stack_id;
#define BPF_STACK_TRACE(_name, _max_entries) \
struct bpf_map_def SEC ("maps") _name = { \
.type = BPF_MAP_TYPE_STACK_TRACE, \
.key_size = sizeof (u32), \
.value_size = sizeof (size_t) * MAX_STACK_DEPTH, \
.max_entries = _max_entries, \
};

#define BPF_HASH(_name, _key_type, _value_type) \
BPF_MAP (_name, BPF_MAP_TYPE_HASH, _key_type, _value_type, 10240);

/*============================= INTERNAL STRUCTS ============================*/

typedef struct stack_count_key
{
u32 pid;
int user_stack_id;
int kernel_stack_id;
} stack_count_key_t;

/*=================================== MAPS =====================================*/
/*================================ MAPS =====================================*/

BPF_HASH(counts, stack_count_key_t, u64);
BPF_STACK_TRACE(stack_traces, MAX_STACK_ADDRESSES);
BPF_HASH (counts, stack_count_key_t, u64);
BPF_STACK_TRACE (stack_traces, MAX_STACK_ADDRESSES);

/*============================== HELPER FUNCTIONS ==============================*/
/*=========================== HELPER FUNCTIONS ==============================*/

static __always_inline void *
bpf_map_lookup_or_try_init(void *map, const void *key, const void *init)
bpf_map_lookup_or_try_init (void *map, const void *key, const void *init)
{
void *val;
long err;
void *val;
long err;

val = bpf_map_lookup_elem(map, key);
if (val)
return val;
val = bpf_map_lookup_elem (map, key);
if (val)
return val;

err = bpf_map_update_elem(map, key, init, BPF_NOEXIST);
// 17 == EEXIST
if (err && err != -17)
return 0;
err = bpf_map_update_elem (map, key, init, BPF_NOEXIST);
// 17 == EEXIST
if (err && err != -17)
return 0;

return bpf_map_lookup_elem(map, key);
return bpf_map_lookup_elem (map, key);
}

// This code gets a bit complex. Probably not suitable for casual hacking.
SEC("perf_event")
int do_sample(struct bpf_perf_event_data *ctx) {
u64 id = bpf_get_current_pid_tgid();
u32 tgid = id >> 32;
u32 pid = id;
SEC ("perf_event")
int
do_sample (struct bpf_perf_event_data *ctx)
{
u64 id = bpf_get_current_pid_tgid ();
u32 tgid = id >> 32;
u32 pid = id;

if (pid == 0)
return 0;
if (pid == 0)
return 0;

// create map key
stack_count_key_t key = {.pid = tgid};
// create map key
stack_count_key_t key = { .pid = tgid };

// get stacks
key.user_stack_id = bpf_get_stackid(ctx, &stack_traces, BPF_F_USER_STACK);
key.kernel_stack_id = bpf_get_stackid(ctx, &stack_traces, 0);
// get stacks
key.user_stack_id = bpf_get_stackid (ctx, &stack_traces, BPF_F_USER_STACK);
key.kernel_stack_id = bpf_get_stackid (ctx, &stack_traces, 0);

u64 zero = 0;
u64 *count;
count = bpf_map_lookup_or_try_init(&counts, &key, &zero);
if (!count)
return 0;
u64 zero = 0;
u64 *count;
count = bpf_map_lookup_or_try_init (&counts, &key, &zero);
if (!count)
return 0;

__sync_fetch_and_add(count, 1);
__sync_fetch_and_add (count, 1);

return 0;
return 0;
}

char LICENSE[] SEC("license") = "GPL";
char LICENSE[] SEC ("license") = "GPL";

0 comments on commit 3ed0de7

Please sign in to comment.