/* * .seg "data" * .asciz "@(#)trap.s 1.1 92/07/30 SMI" * Copyright (c) 1986 by Sun Microsystems, Inc. */ #include #include #include /* * Make sure the vector for 'trap #0' is installed. Kadb in particular * depends on this. * * set_vec(vbr) * int vbr; */ ENTRY(set_vec) bclr 0xfff, %o0 ! set tt field to 0x80 for trap #0 or %o0, 0x800, %o0 set trap_0, %o1 ldd [%o1], %o2 ! copy prototype to trap table std %o2, [%o0] ldd [%o1 + 8], %o2 std %o2, [%o0 + 8] mov %psr, %o0 ! enable traps or %o0, PSR_ET, %o0 mov %o0, %psr nop retl mov %g0, %o0 .align 8 trap_0: sethi %hi(systrap), %l7 or %l7, %lo(systrap), %l7 jmp %l7 mov %psr, %l0 .align 4 /* * System call handler. We get here after a 't 0' instruction, so we're * trapped somewhere in a syscall stub. We won't rett directly back to the * caller; instead we'll make it look like we simply called syscall(). * Syscall()'s return will pass control back to the stub right after * the trap instruction. */ systrap: ! ! When we enter: ! %i0 : syscall code ! %i1 : arg 0 ! %i2 : arg 1 ! %i3 : arg 2 ! %l1 : trapped %pc ! %l2 : trapped %npc ! ! Decrement the return address so the system call returns to the right place. ! sub %l1, 4, %i7 ! ! Push the args, then leave room for a window overflow. This must be ! based on CALLER'S current stack pointer (our frame pointer), not our ! current sp, since we want out of this window. ! st %i1, [%fp + 0] st %i2, [%fp + 4] st %i3, [%fp + 8] mov %fp, %i1 add %fp, -SA(MINFRAME), %fp ! ! Set up addresses so that when we leave the trap control passes to syscall(). ! set _syscall, %l1 add %l1, 4, %l2 jmp %l1 rett %l2
