/* * 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. */ .text .align 4 .globl syscall .type syscall,@function 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