Attachment 302012 Details for Bug 427707 – io_getevents_bug.c

[patch] io_getevents_bug.c

io_getevents_bug.c (text/plain), 2.55 KB, created by Jakub Jelinek on 2008-04-10 15:47:08 UTC

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Creator: Jakub Jelinek

Created: 2008-04-10 15:47:08 UTC

Size: 2.55 KB

patch

obsolete

>/* Compile with:
>   gcc -m32 -O2 -o io_getevents_bug{,.c}
>   It should print Correct - ... message, but on F8/F9 i686 kernels
>   prints
>   Bug - %esi modified by io_getevents syscall, N * sizeof (struct kio_event) has been added
>   */
>#define _GNU_SOURCE
>#include <sys/syscall.h>
>#include <error.h>
>#include <errno.h>
>#include <fcntl.h>
>#include <unistd.h>
>#include <stdio.h>
>#include <stdint.h>
>#include <stdlib.h>
>#include <string.h>
>
>typedef unsigned long kctx_t;
>
>enum
>{   
>  IO_CMD_PREAD,
>  IO_CMD_PWRITE,
>  IO_CMD_FSYNC, 
>  IO_CMD_FDSYNC,
>  IO_CMD_PREADX,
>  IO_CMD_POLL   
>};
>  
>struct kiocb
>{
>  uint64_t kiocb_data;
>  uint64_t kiocb_key; 
>  uint16_t kiocb_lio_opcode;
>  int16_t  kiocb_req_prio;  
>  uint32_t kiocb_fildes;    
>  uint64_t kiocb_buf;       
>  uint64_t kiocb_nbytes;    
>  int64_t  kiocb_offset;    
>  int64_t  __pad3, __pad4;  
>};
>  
>struct kio_event
>{
>  uint64_t kioe_data;
>  uint64_t kioe_obj; 
>  int64_t  kioe_res; 
>  int64_t  kioe_res2;
>};
>
>char buf[20 * 4096] __attribute__((aligned (4096)));
>
>static void __attribute__((noinline))
>do_getevents (kctx_t ctx)
>{
>  struct kio_event ev[10];
>#ifndef __i386__
>  int ret = syscall (SYS_io_getevents, ctx, 1, 10, ev);
>#else
>  int ret, ebx;
>  struct kio_event *esi;
>  asm volatile ("movl %%ebx, %4\n\tmovl %3, %%ebx\n\tmovl %2, %%eax\n\tint $0x80\n\tmovl %4, %%ebx"
>		: "=a" (ret), "=S" (esi)
>		: "i" (SYS_io_getevents), "0" (ctx), "m" (ebx), "c" (1), "d" (10), "1" (ev), "D" (0)
>		: "memory");
>  if (esi == ev)
>    puts ("Correct, %esi hasn't been changed by io_getevents syscall");
>  else if (esi == &ev[ret])
>    printf ("Bug - %%esi modified by io_getevents syscall, %d * sizeof (struct kio_event) has been added\n", ret);
>  else
>    printf ("Bug - %esi modified by io_getevents syscall");
>#endif
>}
>
>int
>main (void)
>{
>  kctx_t ctx = 0;
>  int i;
>  struct kiocb iocbs[20];
>  struct kiocb *iocbp[20];
>  int fd = open ("/etc/services", O_RDONLY | O_DIRECT);
>
>  if (syscall (SYS_io_setup, 1024, &ctx))
>    error (EXIT_FAILURE, errno, "io_setup failed");
>  memset (iocbs, 0, sizeof (iocbs));
>  for (i = 0; i < 20; i++)
>    {
>      iocbs[i].kiocb_data = 0xdeadbeef + i;
>      iocbs[i].kiocb_lio_opcode = IO_CMD_PREAD;
>      iocbs[i].kiocb_fildes = fd;
>      iocbs[i].kiocb_buf = (uintptr_t) &buf[i * 4096];
>      iocbs[i].kiocb_nbytes = 4096;
>      iocbs[i].kiocb_offset = i * 4096;
>      iocbp[i] = &iocbs[i];
>    }
>  if (syscall (SYS_io_submit, ctx, 20, iocbp) < 0)
>    error (EXIT_FAILURE, errno, "io_submit failed");
>  do_getevents (ctx);
>  if (syscall (SYS_io_destroy, ctx))
>    error (EXIT_FAILURE, errno, "io_destroy failed");
>  return 0;
>}

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Attachments on bug 427707: 290923 | 297377 | 302012