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I am trying to write some uprobes for tracing nginx and am struggling to build the bpf program. More specifically, when including nginx header files in order to parse data, the build does not register my 64-bit architecture and wants to include gnu/stubs-32.h. Building without ngx_http.h works fine. This may not be specifically a libbpf issue, however I do not have the same problems with bpftrace or BCC where inclusion works without problems.

Any suggestions as to how to fix this is greatly appreciated.

Code

nginx.bpf.c

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

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

SEC("uprobe//usr/sbin/nginx:ngx_http_finalize_request")
int handle_ngx_http_finalize_request(struct pt_regs* ctx)
{
    int pid = bpf_get_current_pid_tgid() >> 32;
    bpf_printk("Is this getting triggered? %d.\n", pid);
    return 0;
}

nginx.c

#include <stdio.h>
#include <unistd.h>
#include <sys/resource.h>
#include <bpf/libbpf.h>
#include "nginx.skel.h"

static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args)
{
    return vfprintf(stderr, format, args);
}

int main(int argc, char **argv)
{
    struct nginx_bpf *skel;
    int err;

    libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
    libbpf_set_print(libbpf_print_fn);

    skel = nginx_bpf__open_and_load();
    if (!skel) {
        fprintf(stderr, "Failed to open and load BPF skeleton\n");
        return 1;
    }

    err = nginx_bpf__attach(skel);
    if (err) {
        fprintf(stderr, "Failed to auto-attach BPF skeleton: %d\n", err);
        goto cleanup;
    }

    printf("Successfully started!\n");

    for (;;) {
        sleep(1);
    }

cleanup:
    nginx_bpf__destroy(skel);
    return -err;
}

error message

❯ make
  BPF      .output/nginx.bpf.o
In file included from nginx.bpf.c:4:
In file included from /home/nela/master/nginx-1.18.0/src/http/ngx_http.h:12:
In file included from /home/nela/master/nginx-1.18.0/src/core/ngx_config.h:26:
In file included from /home/nela/master/nginx-1.18.0/src/os/unix/ngx_linux_config.h:18:
In file included from /usr/include/x86_64-linux-gnu/sys/types.h:25:
In file included from /usr/include/features.h:510:
/usr/include/x86_64-linux-gnu/gnu/stubs.h:7:12: fatal error: 'gnu/stubs-32.h' file not found
 # include <gnu/stubs-32.h>
           ^~~~~~~~~~~~~~~~
1 error generated.
make: *** [Makefile:106: .output/nginx.bpf.o] Error 1

System Information

❯ echo $CPATH
/home/nela/master/nginx-1.18.0/src/http/modules:/home/nela/master/nginx-1.18.0/src/http/v2:/home/nela/master/nginx-1.18.0/src/http:/home/nela/master/nginx-1.18.0/src/event:/home/nela/master/nginx-1.18.0/src/core:/home/nela/master/nginx-1.18.0/src:/home/nela/master/nginx-1.18.0/src/os/unix:/home/nela/master/nginx-1.18.0/objs:/home/nela/master/nginx-1.18.0:/usr/src/linux-headers-5.15.0-56-generic/include:/usr/src/linux-headers-5.15.0-56/include:/usr/include

❯ uname -a 
Linux nelasus 5.15.0-53-generic #59-Ubuntu SMP Mon Oct 17 18:53:30 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

❯ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 22.04.1 LTS
Release:        22.04
Codename:       jammy
nela
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0 Answers0