/* * 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 .global syscall .type syscall,%function syscall: pushl %ebp pushl %edi pushl %esi pushl %ebx movl 44(%esp),%ebp /* Load the 6 syscall argument registers */ movl 40(%esp),%edi movl 36(%esp),%esi movl 32(%esp),%edx movl 28(%esp),%ecx movl 24(%esp),%ebx movl 20(%esp),%eax /* Load syscall number into %eax. */ int $0x80 popl %ebx popl %esi popl %edi popl %ebp cmpl $-4095,%eax jae __syscall_error ret /* Return to caller. */ .size syscall,.-syscall