[Bug 1884719] Re: Function not implemented when using libaio

[Martin Grigorov <1884719@bugs.launchpad.net>]

Executing `QEMU_STRACE= ./out` here gives:


259 brk(NULL) = 0x0000000000421000
259 uname(0x40008003d8) = 0
259 faccessat(AT_FDCWD,"/etc/ld.so.preload",R_OK,AT_SYMLINK_NOFOLLOW|0x50) = -1 errno=2 (No such file or directory)
259 openat(AT_FDCWD,"/etc/ld.so.cache",O_RDONLY|O_CLOEXEC) = 3
259 fstat(3,0x00000040007ff960) = 0
259 mmap(NULL,13646,PROT_READ,MAP_PRIVATE,3,0) = 0x0000004000843000
259 close(3) = 0
259 openat(AT_FDCWD,"/lib64/libaio.so.1",O_RDONLY|O_CLOEXEC) = 3
259 read(3,0x7ffb20,832) = 832
259 fstat(3,0x00000040007ff9b0) = 0
259 mmap(NULL,131096,PROT_EXEC|PROT_READ,MAP_PRIVATE|MAP_DENYWRITE,3,0) = 0x0000004000847000
259 mprotect(0x0000004000849000,118784,PROT_NONE) = 0
259 mmap(0x0000004000866000,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_DENYWRITE|MAP_FIXED,3,0xf000) = 0x0000004000866000
259 mmap(0x0000004000867000,24,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,-1,0) = 0x0000004000867000
259 close(3) = 0
259 openat(AT_FDCWD,"/lib64/libc.so.6",O_RDONLY|O_CLOEXEC) = 3
259 read(3,0x7ffb00,832) = 832
259 fstat(3,0x00000040007ff990) = 0
259 mmap(NULL,8192,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS,-1,0) = 0x0000004000868000
259 mmap(NULL,1527680,PROT_EXEC|PROT_READ,MAP_PRIVATE|MAP_DENYWRITE,3,0) = 0x000000400086a000
259 mprotect(0x00000040009c3000,77824,PROT_NONE) = 0
259 mmap(0x00000040009d6000,24576,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_DENYWRITE|MAP_FIXED,3,0x15c000) = 0x00000040009d6000
259 mmap(0x00000040009dc000,12160,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,-1,0) = 0x00000040009dc000
259 close(3) = 0
259 mprotect(0x00000040009d6000,16384,PROT_READ) = 0
259 mprotect(0x0000004000866000,4096,PROT_READ) = 0
259 mprotect(0x000000000041f000,4096,PROT_READ) = 0
259 mprotect(0x0000004000840000,4096,PROT_READ) = 0
259 munmap(0x0000004000843000,13646) = 0
259 brk(NULL) = 0x0000000000421000
259 brk(0x0000000000442000) = 0x0000000000442000
259 brk(NULL) = 0x0000000000442000
259 io_setup(10,4330144,4330160,4330144,274886726560,511) = -1 errno=38 (Function not implemented)
259 io_destroy(0,274886726560,38,274886726560,511,512) = -1 errno=38 (Function not implemented)
259 fstat(1,0x0000004000800388) = 0
259 write(1,0x4212c0,11)res is: -38 = 11
259 exit_group(0)


Thanks for looking into this issue, Laurent Vivier!

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https://bugs.launchpad.net/bugs/1884719

Title:
  Function not implemented when using libaio

Status in QEMU:
  New

Bug description:
  Hello

  I experience "Function not implemented" errors when trying to use
  Linux libaio library in foreign architecture, e.g. aarch64.

  I've faced this problem while using https://github.com/multiarch/qemu-user-static, i.e. Docker+QEMU. 
  I understand that I do not use plain QEMU and you may count this report as a "distribution of QEMU"! Just let me know what are the steps to test it with plain QEMU and I will test and update this ticket!

  
  Here are the steps to reproduce the issue:

  1) On x86_64 machine register QEMU:

      `docker run -it --rm --privileged multiarch/qemu-user-static
  --reset --credential yes --persistent yes`

  2) Start a Docker image with foreign CPU architecture, e.g. aarch64

      `docker run -it arm64v8/centos:8 bash`

  3) Inside the Docker container install GCC and libaio

      `yum install gcc libaio libaio-devel`

  4) Compile the following C program

  ```
  #include <stdio.h>
  #include <errno.h>
  #include <libaio.h>
  #include <stdlib.h>

  struct io_control {
      io_context_t ioContext;
  };

  int main() {
      int queueSize = 10;

      struct io_control * theControl = (struct io_control *) malloc(sizeof(struct io_control));
      if (theControl == NULL) {
          printf("theControl is NULL");
          return 123;
      }

      int res = io_queue_init(queueSize, &theControl->ioContext);
      io_queue_release(theControl->ioContext);
      free(theControl);
      printf("res is: %d", res);
  }
  ```

      ```
      cat > test.c
          [PASTE THE CODE ABOVE HERE]
      ^D
      ```

      `gcc test.c -o out -laio && ./out`

  
  When executed directly on aarch64 machine (i.e. without emulation) or on x86_64 Docker image (e.g. centos:8) it prints `res is: 0`, i.e. it successfully initialized a LibAIO queue.

  But when executed on Docker image with foreign/emulated CPU
  architecture it prints `res is: -38` (ENOSYS). `man io_queue_init`
  says that error ENOSYS is returned when "Not implemented."

  Environment:

  QEMU version: 5.0.0.2  (https://github.com/multiarch/qemu-user-static/blob/master/.travis.yml#L24-L28)
  Container application: Docker
  Output of `docker --version`:

  ```
  Client:
   Version:           19.03.8
   API version:       1.40
   Go version:        go1.13.8
   Git commit:        afacb8b7f0
   Built:             Wed Mar 11 23:42:35 2020
   OS/Arch:           linux/amd64
   Experimental:      false

  Server:
   Engine:
    Version:          19.03.8
    API version:      1.40 (minimum version 1.12)
    Go version:       go1.13.8
    Git commit:       afacb8b7f0
    Built:            Wed Mar 11 22:48:33 2020
    OS/Arch:          linux/amd64
    Experimental:     false
   containerd:
    Version:          1.3.3-0ubuntu2
    GitCommit:        
   runc:
    Version:          spec: 1.0.1-dev
    GitCommit:        
   docker-init:
    Version:          0.18.0
    GitCommit:        
  ```

  Same happens with Ubuntu (arm64v8/ubuntu:focal).

  I've tried to `strace` it but :

  ```
  /usr/bin/strace: ptrace(PTRACE_TRACEME, ...): Function not implemented
  /usr/bin/strace: PTRACE_SETOPTIONS: Function not implemented
  /usr/bin/strace: detach: waitpid(112): No child processes
  /usr/bin/strace: Process 112 detached
  ```

  Here are the steps to reproduce the problem with strace:

       ```
       docker run --rm -it --security-opt seccomp:unconfined --security-opt apparmor:unconfined --privileged --cap-add ALL arm64v8/centos:8 bash

       yum install -y strace`

       strace echo Test
       ```

  Note: I used --privileged, disabled seccomp and apparmor, and added
  all capabilities

  Disabling security solves the "Permission denied" problem but then
  comes the "Not implemented" one.

  
  Any idea what could be the problem and how to work it around ?
  I've googled a lot but I wasn't able to find any problems related to libaio on QEMU.

  Thank you!
  Martin

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