asm.c

#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_core_read.h>

#define PATH_MAX 1024

struct path_key {
	char container_path[PATH_MAX];  // 1024 bytes
	char directory_path[PATH_MAX];  // 1024 bytes
};

struct {
	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
	__uint(max_entries, 1);
	__type(key, u32);
	__type(value, struct path_key);
} temp_map SEC(".maps");

SEC("kprobe/vfs_open_broken")
int broken_no_barrier(struct pt_regs *ctx)
{
	u32 idx = 0;
	struct path_key *out = bpf_map_lookup_elem(&temp_map, &idx);
	if (!out)
		return 0;

	__builtin_memset(out->container_path, 0, sizeof(out->container_path));
	// asm volatile("" ::: "memory");
	__builtin_memset(out->directory_path, 0, sizeof(out->directory_path));

	const char *path = "/some/path";
	bpf_probe_read_kernel_str(out->directory_path,
				  sizeof(out->directory_path), path);

	return 0;
}

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