kernel-hacking-2024-linux-s.../samples/bpf/tracex4.bpf.c
Rong Tao d205d4af3a samples/bpf: tracex4: Fix failed to create kretprobe 'kmem_cache_alloc_node+0x0'
commit 7bd230a266 ("mm/slab: enable slab allocation tagging for kmalloc
and friends") [1] swap kmem_cache_alloc_node() to
kmem_cache_alloc_node_noprof().

    linux/samples/bpf$ sudo ./tracex4
    libbpf: prog 'bpf_prog2': failed to create kretprobe
    'kmem_cache_alloc_node+0x0' perf event: No such file or directory
    ERROR: bpf_program__attach failed

Signed-off-by: Rong Tao <rongtao@cestc.cn>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: 7bd230a266
Link: https://lore.kernel.org/bpf/tencent_34E5BCCAC5ABF3E81222AD81B1D05F16DE06@qq.com
2024-08-27 16:17:44 -07:00

54 lines
1.2 KiB
C

/* Copyright (c) 2015 PLUMgrid, http://plumgrid.com
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*/
#include "vmlinux.h"
#include <linux/version.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
struct pair {
u64 val;
u64 ip;
};
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__type(key, long);
__type(value, struct pair);
__uint(max_entries, 1000000);
} my_map SEC(".maps");
/* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe
* example will no longer be meaningful
*/
SEC("kprobe/kmem_cache_free")
int bpf_prog1(struct pt_regs *ctx)
{
long ptr = PT_REGS_PARM2(ctx);
bpf_map_delete_elem(&my_map, &ptr);
return 0;
}
SEC("kretprobe/kmem_cache_alloc_node_noprof")
int bpf_prog2(struct pt_regs *ctx)
{
long ptr = PT_REGS_RC(ctx);
long ip = 0;
/* get ip address of kmem_cache_alloc_node_noprof() caller */
BPF_KRETPROBE_READ_RET_IP(ip, ctx);
struct pair v = {
.val = bpf_ktime_get_ns(),
.ip = ip,
};
bpf_map_update_elem(&my_map, &ptr, &v, BPF_ANY);
return 0;
}
char _license[] SEC("license") = "GPL";
u32 _version SEC("version") = LINUX_VERSION_CODE;