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/*
* June 27, 2001 Manuel Novoa III
*
* This is a heavily modified version of gcc's output for the _syscall5 macro.
* The idea (originally from dietlibc) is that all syscall functions simply set
* the syscall number as the first argument, then set the syscall arguments as
* the next up-to-five arguments, and then jump here. All the common work is
* done by syscall(), saving a fair amount of generated code when a number of
* syscalls are used. The (potential) cost is some unnecessary pushes, pops,
* and movs but the execution time penalty should be relatively small compared
* to the cost of the syscall itself.
*
* July 24, 2002
*
* Modified by Erik Andersen to take all function parameters from off the stack
* like a proper function and eliminates the old 255 syscall number limit. So
* now we can just call this as a function as syscall() per the function
* prototype in unistd.h, so to call _exit(42) you can just call.
* syscall(__NR_exit, 42);
* and things will just work.
*/
#include <features.h>
.text
.global syscall
.type syscall,%function
.align 4
syscall:
pushl %edi
pushl %esi
pushl %ebx
movl 36(%esp),%edi; /* Load the 5 syscall argument registers */
movl 32(%esp),%esi;
movl 28(%esp),%edx;
movl 24(%esp),%ecx;
movl 20(%esp),%ebx;
movl 16(%esp),%eax /* Load syscall number into %eax. */
#APP
int $0x80
#NO_APP
cmpl $-4095,%eax
jbe .Ldone
#ifdef __PIC__
call Lhere
Lhere:
popl %ebx
addl $_GLOBAL_OFFSET_TABLE_+[.-Lhere],%ebx
negl %eax
movl %eax,%ecx
#ifdef __UCLIBC_HAS_THREADS__
call __errno_location@PLT
#else
movl errno@GOT(%ebx),%eax
#endif /* __UCLIBC_HAS_THREADS__ */
movl %ecx,(%eax)
#else
negl %eax
#ifdef __UCLIBC_HAS_THREADS__
movl %eax,%ecx
call __errno_location
movl %ecx,(%eax)
#else
movl %eax,errno
#endif /* __UCLIBC_HAS_THREADS__ */
#endif /* __PIC__ */
movl $-1,%eax
.p2align 4,,7
.Ldone:
popl %ebx
popl %esi
popl %edi
ret
.Lsize:
.size syscall,.Lsize-syscall
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