root/arch/x86/um/stub_64.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #include <as-layout.h>
   3 
   4 .section .__syscall_stub, "ax"
   5         .globl batch_syscall_stub
   6 batch_syscall_stub:
   7         mov     $(STUB_DATA), %rbx
   8         /* load pointer to first operation */
   9         mov     %rbx, %rsp
  10         add     $0x10, %rsp
  11 again:
  12         /* load length of additional data */
  13         mov     0x0(%rsp), %rax
  14 
  15         /* if(length == 0) : end of list */
  16         /* write possible 0 to header */
  17         mov     %rax, 8(%rbx)
  18         cmp     $0, %rax
  19         jz      done
  20 
  21         /* save current pointer */
  22         mov     %rsp, 8(%rbx)
  23 
  24         /* skip additional data */
  25         add     %rax, %rsp
  26 
  27         /* load syscall-# */
  28         pop     %rax
  29 
  30         /* load syscall params */
  31         pop     %rdi
  32         pop     %rsi
  33         pop     %rdx
  34         pop     %r10
  35         pop     %r8
  36         pop     %r9
  37 
  38         /* execute syscall */
  39         syscall
  40 
  41         /* check return value */
  42         pop     %rcx
  43         cmp     %rcx, %rax
  44         je      again
  45 
  46 done:
  47         /* save return value */
  48         mov     %rax, (%rbx)
  49 
  50         /* stop */
  51         int3