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Text File | 1993-01-07 | 54.0 KB | 1,689 lines

/* * machTrap.s -- * * Traps for sun4. * * Copyright 1989 Regents of the University of California * Permission to use, copy, modify, and distribute this * software and its documentation for any purpose and without * fee is hereby granted, provided that the above copyright * notice appear in all copies. The University of California * makes no representations about the suitability of this * software for any purpose. It is provided "as is" without * express or implied warranty. */ .seg "data" .asciz "$Header: /cdrom/src/kernel/Cvsroot/kernel/mach/sun4.md/machTrap.s,v 9.15 93/01/06 20:09:19 mgbaker Exp $ SPRITE (Berkeley)" .align 8 .seg "text" #include "user/proc.h" #include "machConst.h" #include "machAsmDefs.h" .align 8 .seg "text" /* * ---------------------------------------------------------------------- * * MachTrap -- * * All traps except window overflow and window underflow go through * this trap handler. This handler is used to save the appropriate * state, set up the kernel stack, and then jump to the correct * handler depending on the type of trap. The handler assumes that * we have saved the trap %psr into %CUR_PSR_REG before we get here (as * an instruction in the vector table that made us branch here). * * Window overflow and underflow jump directly from the vector table * to their handlers, since in the most common cases they do not need * to save state and they should be as fast as possible. * * The scheme of things: * * 1) Check to see if we're in an invalid window. If so, deal first with * window overflow. * 2) Now that it's safe to overwrite our out registers, update the stack * pointer. If coming from user mode, this means pulling the kernel * stack pointer out of the state structure and adding the appropriate * amount. Otherwise, it means just means adding the appropriate amount to * our %fp. * 3) Save the rest of the trap state (globals) to the stack. Note that * although locals and ins contain trap state (ins are our caller's outs * which we shouldn't mess up, and the psr and other state registers are * in our locals) we need not save them explicitly, since they will be * saved as a part of the normal window overflow and underflow. There * are exceptions to this, such as context switching or debugger traps, * where we must explicitly save the window to the stack, but the * exceptions must take care of this for themselves. * 4) Re-enable traps and disable interrupts. Traps must be disabled * so that if we get another window overflow or underflow, * we'll be able to deal with it. * 5) Figure out what handler to call and call it. * * The handler must call our return-from-trap post-amble, rather than * return here. * * If a window underflow or overflow trap discovers that it must do * something tricky, such as call Vm_PageIn, that requires turning * on traps and interrupts, then it will call MachTrap to save state * for it. This is why there are entries in MachTrap for window * overflow and underflow. These are the entries to take care of the * "slow trap" overflows and underflows. * * Results: * None. * * Side effects: * We make space on our kernel stack to save this trap window. * If it is a user process entering the kernel, then we make its trapRegs * field point to this save-window area on the kernel stack. * * ---------------------------------------------------------------------- */ .global _MachTrap _MachTrap: /* * Save the state registers. This is safe, since we're saving them * to local registers and we can do this even if we've entered * into an invalid window. * In the vector table that jumps here, we have already saved * the %psr into %CUR_PSR_REG. The trap instruction itself saved * the trap pc and next pc into local registers %CUR_PC_REG and * %NEXT_PC_REG. This means we must save only the %tbr and the %y * registers. */ mov %tbr, %CUR_TBR_REG mov %y, %CUR_Y_REG /* * Are we in an invalid window? */ MACH_INVALID_WINDOW_TEST() be WindowOkay nop /* * Deal with window overflow - put return addr in SAFE_TEMP since * the overflow handler will look for the return address there.. * It is okay to do this, even if we got here after due to a slow * overflow trap due to special action needed, because if we did that, * then we've already taken care of the overflow problem and so we * won't get it here and so we won't be overwriting the return address * in SAFE_TEMP. */ set MachWindowOverflow, %VOL_TEMP1 jmpl %VOL_TEMP1, %SAFE_TEMP nop WindowOkay: /* * Now that we know our out registers are safe to use, since we're * in a valid window, update our stack pointer. * If coming from user mode, I need to get kernel sp from * state structure. If we came from kernel * mode, just subtract a stack frame from the current frame pointer and * continue. To see if we came from user mode, we look at the * previous state bit (PS) in the processor state register. * I set up the stack pointer in the delay slot of the branch if I came * from kernel mode, so it's as fast as possible. I annul the * instruction if it turns out to be a user stack. * We must give the stack a full state frame so that C routines * we call will have space to store their arguments. (System calls, * for example!) * * NOTE: The amount we bump up the stack by here must * agree with the debugger stack test in the window underflow routine, * so that we don't trash our stack when returning from the * debugger!!!!! */ andcc %CUR_PSR_REG, MACH_PS_BIT, %g0 /* previous state? */ bne,a DoneWithUserStuff /* was kernel mode */ add %fp, -MACH_SAVED_STATE_FRAME, %sp /* set kernel sp */ MACH_GET_CUR_STATE_PTR(%VOL_TEMP2, %VOL_TEMP1) /* into %VOL_TEMP2 */ add %VOL_TEMP2, MACH_KSP_OFFSET, %VOL_TEMP1 /* &(machPtr->ksp) */ ld [%VOL_TEMP1], %sp /* machPtr->ksp */ set (MACH_KERN_STACK_SIZE - MACH_SAVED_STATE_FRAME), %VOL_TEMP1 add %sp, %VOL_TEMP1, %sp /* * Since we came from user mode, set the trapRegs field of the * current state structure to the value of our new kernel sp, * since the trap regs are saved on top of the stack. */ add %VOL_TEMP2, MACH_TRAP_REGS_OFFSET, %VOL_TEMP2 st %sp, [%VOL_TEMP2] DoneWithUserStuff: /* Test stack alignment here?? */ /* * This only saves the globals to the stack. The locals * and ins make it there through normal overflow and underflow. * * NOTE that we cannot trash %g1 even after saving the global * registers, since that is the register that contains the system * call number for system call traps! */ MACH_SAVE_GLOBAL_STATE() /* traps on, maskable interrupts off */ MACH_SR_HIGHPRIO() /* * It is tedious to do all these serial comparisons against the * trap type, so this should be changed to a jump table. It's this * way right now because I'm working on other things and this is * easy for debugging. */ and %CUR_TBR_REG, MACH_TRAP_TYPE_MASK, %VOL_TEMP1 /* get trap */ cmp %VOL_TEMP1, MACH_LEVEL0_INT bl NotAnInterrupt nop cmp %VOL_TEMP1, MACH_LEVEL15_INT bgu NotAnInterrupt nop /* * It's an interrupt. */ b MachHandleInterrupt nop NotAnInterrupt: cmp %VOL_TEMP1, MACH_TRAP_SYSCALL /* system call */ be MachSyscallTrap nop cmp %VOL_TEMP1, MACH_INSTR_ACCESS /* instruction fault */ be MachHandlePageFault nop cmp %VOL_TEMP1, MACH_DATA_ACCESS /* data fault */ be MachHandlePageFault nop cmp %VOL_TEMP1, MACH_TRAP_SIG_RETURN /* ret from handler */ be _MachReturnFromSignal nop cmp %VOL_TEMP1, MACH_TRAP_FLUSH_WINDOWS /* flush window trap */ be MachFlushWindowsToStackTrap nop cmp %VOL_TEMP1, MACH_TRAP_UNIX_SYSCALL /* unix syscall */ be MachUnixSyscallTrap nop cmp %VOL_TEMP1, MACH_TRAP_INSTR_2 /* Dynamic linking */ be MachLinkTrap nop /* * These next few are handled by C routines, and we want them to * return to MachReturnFromTrap, so set that address as the return pc. */ cmp %VOL_TEMP1, MACH_ILLEGAL_INSTR /* illegal instr */ set _MachReturnFromTrap, %RETURN_ADDR_REG /* set return pc */ mov %VOL_TEMP1, %o0 mov %CUR_PC_REG, %o1 mov %CUR_PSR_REG, %o2 be _MachHandleTrap /* C routine */ nop cmp %VOL_TEMP1, MACH_PRIV_INSTR /* privileged instr */ set _MachReturnFromTrap, %RETURN_ADDR_REG /* set return pc */ mov %VOL_TEMP1, %o0 mov %CUR_PC_REG, %o1 mov %CUR_PSR_REG, %o2 be _MachHandleTrap /* C routine */ nop cmp %VOL_TEMP1, MACH_MEM_ADDR_ALIGN /* addr not aligned */ set _MachReturnFromTrap, %RETURN_ADDR_REG /* set return pc */ mov %VOL_TEMP1, %o0 mov %CUR_PC_REG, %o1 mov %CUR_PSR_REG, %o2 be _MachHandleTrap /* C routine */ nop cmp %VOL_TEMP1, MACH_TAG_OVERFLOW /* tagged instr ovfl */ set _MachReturnFromTrap, %RETURN_ADDR_REG /* set return pc */ mov %VOL_TEMP1, %o0 mov %CUR_PC_REG, %o1 mov %CUR_PSR_REG, %o2 be _MachHandleTrap /* C routine */ nop cmp %VOL_TEMP1, MACH_FP_EXCEP /* fp unit badness */ set _MachReturnFromTrap, %RETURN_ADDR_REG /* set return pc */ mov %VOL_TEMP1, %o0 mov %CUR_PC_REG, %o1 mov %CUR_PSR_REG, %o2 be _MachHandleTrap /* C routine */ nop cmp %VOL_TEMP1, MACH_FP_DISABLED /* fp unit disabled */ set _MachReturnFromTrap, %RETURN_ADDR_REG /* set return pc */ mov %VOL_TEMP1, %o0 mov %CUR_PC_REG, %o1 mov %CUR_PSR_REG, %o2 be _MachHandleTrap /* C routine */ nop /* * We never get here directly from the window overflow trap. * Instead, what this means is that after handling a window * overflow trap, on the way out we had to deal with a special * user action. Because we don't save state, etc, on a regular * window overflow, we've executed the above code to save the * state for us. Now we just want to go back and deal with the * special overflow. */ cmp %VOL_TEMP1, MACH_WINDOW_OVERFLOW /* weird overflow */ be MachReturnToOverflowWithSavedState nop cmp %VOL_TEMP1, MACH_WINDOW_UNDERFLOW /* weird underflow */ be MachReturnToUnderflowWithSavedState nop cmp %VOL_TEMP1, MACH_TRAP_DEBUGGER /* enter debugger */ be _MachHandleDebugTrap nop b _MachHandleDebugTrap /* all others to debugger */ nop /* * ---------------------------------------------------------------------- * * MachReturnFromTrap -- * * Go through the inverse of MachTrap. The trap handlers that MachTrap * called return to here rather than MachTrap. * * The scheme of things: * * 1) Determine if we are returning to user mode. If so, then we must * check the specialHandling flag. If it is set, then we must call * MachUserAction. * 2) If we called MachUserAction, then we must check its return value * to see if we need to deal with any signals. If we do, then * we call MachHandleSignal(). It returns to user mode itself via * a rett instruction, so we don't come back here until the * return-from-signal trap that the user ends up executing to return to * the kernel from a signal. * 3) For both returns to user mode and returns to kernel mode, we * must next check if we would return to an invalid window. If so, * we must make it valid or we will get a watchdog reset. We may * call the window underflow routine to do this. But, if we are * returning to user mode, we must check to make sure the user stack * is resident, since the underflow routine can't get any page faults. * If the user stack isn't resident, we page it in. * 4) Finally, we disable traps again (or the rett instruction will * give us a watchdog reset), restore the global registers, restore * the %tbr, %y registers, restore the %psr to the trap psr, and rett * (return from trap) to the saved trap pc and next pc. * * Results: * None. * * Side effects: * We jump back to where we came from. If we came from a system call * or certain other traps, we'll actually return to where we came from * plus 8, or else we would re-execute the system call instruction. * The addition of 8 was done by the individual handlers that know * whether or not they would need to do this. * * If a user process has a bad stack pointer, we will kill it here and * print out a message. * * ---------------------------------------------------------------------- */ .global _MachReturnFromTrap _MachReturnFromTrap: /* Are we a user or kernel process? */ andcc %CUR_PSR_REG, MACH_PS_BIT, %g0 bne NormalReturn nop /* Do we need to take a special action? Check special handling flag. */ MACH_GET_CUR_PROC_PTR(%VOL_TEMP1) sethi %hi(_machSpecialHandlingOffset), %VOL_TEMP2 ld [%VOL_TEMP2 + %lo(_machSpecialHandlingOffset)], %VOL_TEMP2 add %VOL_TEMP1, %VOL_TEMP2, %VOL_TEMP1 ld [%VOL_TEMP1], %VOL_TEMP1 tst %VOL_TEMP1 be NormalReturn nop call _MachUserAction nop /* Check if we must handle a signal */ tst %RETURN_VAL_REG be NormalReturn nop cmp %RETURN_VAL_REG, 2 be DoUnixSignal nop /* * We must handle a signal. Call the leaf routine MachSetupSignal. * It does its own return from trap, so we don't come back here when * it's done! */ call _MachHandleSignal nop DoUnixSignal: MACH_RESTORE_WINDOW_FROM_STACK() nop sub %fp, 0x8f0, %fp nop NormalReturn: MACH_UNDERFLOW_TEST() be UnderflowOkay nop /* * Make sure stack is resident. We don't want to get a page * fault in the underflow routine, because it moves into the window * to restore and so its calls to Vm code would move into this * window and overwrite it! First check if it's a user process, since * that should be the only case where the stack isn't resident. */ andcc %CUR_PSR_REG, MACH_PS_BIT, %g0 bne CallUnderflow nop /* * It's a user process, so check residence and protection fields of pte. * Before anything we check stack alignment. */ andcc %fp, 0x7, %g0 bne KillUserProc nop MACH_CHECK_FOR_FAULT(%fp, %VOL_TEMP1) be CheckNextFault nop /* * Call VM Stuff with the %fp which will be stack pointer in * the window we restore. */ QUICK_ENABLE_INTR(%VOL_TEMP1) mov %fp, %o0 clr %o1 /* also check for protection????? */ call _Vm_PageIn, 2 nop QUICK_DISABLE_INTR(%VOL_TEMP1) tst %RETURN_VAL_REG bne KillUserProc nop CheckNextFault: /* Check other extreme of area we'd touch */ add %fp, (MACH_SAVED_WINDOW_SIZE - 4), %o0 MACH_CHECK_FOR_FAULT(%o0, %VOL_TEMP1) be CallUnderflow nop QUICK_ENABLE_INTR(%VOL_TEMP1) clr %o1 call _Vm_PageIn, 2 nop QUICK_DISABLE_INTR(%VOL_TEMP1) tst %RETURN_VAL_REG be CallUnderflow nop KillUserProc: /* * Kill user process! Its stack is bad. */ MACH_SR_HIGHPRIO() /* traps back on for overflow from printf */ set _MachReturnFromTrapDeathString, %o0 call _printf, 1 nop MACH_GET_CUR_PROC_PTR(%o0) /* procPtr in %o0 */ sethi %hi(_machGenFlagsOffset), %o1 ld [%o1 + %lo(_machGenFlagsOffset)], %o1 add %o0, %o1, %o1 ld [%o1], %o1 sethi %hi(_machForeignFlag), %o2 ld [%o2 + %lo(_machForeignFlag)], %o2 andcc %o1, %o2, %o1 /* Is this a migrated proc? */ be DebugIt nop set PROC_TERM_DESTROYED, %o0 /* If so, kill it. */ set PROC_BAD_STACK, %o1 clr %o2 call _Proc_ExitInt, 3 nop DebugIt: /* Else, make it debuggable. */ MACH_GET_CUR_PROC_PTR(%o0) /* procPtr in %o0 */ call _Sig_CheckForKill, 1 /* kill proc if KILL signal */ nop MACH_GET_CUR_PROC_PTR(%o0) /* procPtr in %o0 */ set TRUE, %o1 /* debug TRUE */ set PROC_TERM_DESTROYED, %o2 set PROC_BAD_STACK, %o3 clr %o4 call _Proc_SuspendProcess, 5 nop ba DebugIt /* proc should loop if continued */ nop CallUnderflow: set MachWindowUnderflow, %VOL_TEMP1 jmpl %VOL_TEMP1, %RETURN_ADDR_REG nop UnderflowOkay: MACH_DISABLE_TRAPS(%VOL_TEMP1, %VOL_TEMP2) MACH_RESTORE_GLOBAL_STATE() /* restore y reg */ mov %CUR_Y_REG, %y /* restore tbr reg */ mov %CUR_TBR_REG, %tbr /* restore psr */ MACH_RESTORE_PSR() jmp %CUR_PC_REG rett %NEXT_PC_REG nop /* * ---------------------------------------------------------------------- * * MachHandleWindowOverflowTrap -- * * Trap entrance to the window overflow handler. We try to get in and * out of here as quickly as possible in the normal case. Unlike * most traps, we jump here directly from the trap table, and do not * go through the usual MachTrap preamble. This means no * state has been saved and we have no stack pointer. This in turn means * that we cannot turn traps on, since we have no saved state and no place * to save the trap registers. This routine sets up a return * address, calls the overflow handler, restores the psr, and * returns from the trap. It assumes that the trap psr was stored in * %CUR_PSR_REG before jumping here (in the trap vector table). * * When we return to this routine from the actual overflow handling * routine, we check to see if we're returning to user mode. If we aren't * we can just leave this routine normally. If we're returning to user * mode, however, we must check for some special cases. It may be that * the user stack wasn't resident and that we had to save the overflow * window to a special internal buffer rather than the user stack. If this * is so, we require extra processing. So we call MachTrap to save state * for us and then call MachReturnFromTrap, which will handle the fact * that the window was saved to an internal buffer. The effect of all of * this is to turn the overflow trap into a "slow overflow trap" that goes * through the usual trap preamble and postamble. * * Results: * None. * * Side effects: * The mach state structure may be modified if this is a user window * and its stack isn't resident, causing us to save the window to * the buffers in the mach state structure. * * ---------------------------------------------------------------------- */ .global MachHandleWindowOverflowTrap MachHandleWindowOverflowTrap: /* * Call actual overflow handler. */ set MachWindowOverflow, %VOL_TEMP1 jmpl %VOL_TEMP1, %SAFE_TEMP nop /* * If returning to user mode, check special handling flags here to * see if we need to do any fancy processing (due to the user's * stack not being resident so we had to save the window to an internal * buffer instead). */ andcc %CUR_PSR_REG, MACH_PS_BIT, %g0 /* user or kernel? */ bne NormalOverflowReturn nop /* Do we need to take a special action? Check special handling flag. */ MACH_GET_CUR_PROC_PTR(%VOL_TEMP1) sethi %hi(_machSpecialHandlingOffset), %VOL_TEMP2 ld [%VOL_TEMP2 + %lo(_machSpecialHandlingOffset)], %VOL_TEMP2 add %VOL_TEMP1, %VOL_TEMP2, %VOL_TEMP1 ld [%VOL_TEMP1], %VOL_TEMP1 tst %VOL_TEMP1 be NormalOverflowReturn nop /* * We need to save state and allocate space on the stack, etc. * Run through regular trap preamble to do this. The trap preamble * will then return us to here. This is all in preparation for * calling MachReturnFromTrap, since that will call MachUserAction * to deal with the window saved to the internal buffer. */ call _MachTrap nop MachReturnToOverflowWithSavedState: /* * Now call trap postamble to restore state and push saved window to * the user stack. MachReturnFromTrap will return to user mode, so * we will not come back here after this call! */ call _MachReturnFromTrap nop /* * This was a normal fast window overflow trap, so just return. */ NormalOverflowReturn: MACH_RESTORE_PSR() jmp %CUR_PC_REG rett %NEXT_PC_REG nop /* * ---------------------------------------------------------------------- * * MachWindowOverflow -- * * Window overflow handler. It's set up so that it can be called from the * fast window overflow trap handler, or it can be called directly from * MachTrap for any trap that causes us to land inside an invalid window. * * The window we've trapped into is currently invalid. We want to * make it valid. We do this by moving one window further, saving that * window to the stack, marking it as the new invalid window, and then * moving back to the window that we trapped into. It is then valid * and usable. Note that we move first to the window to save and then * mark it invalid. In the other order we would get another overflow * trap, but with traps turned off, which causes a watchdog reset... * Note that %sp should point to the lowest address usable * word in the current stack frame. %fp is the %sp of the * caller's stack frame, so the first (highest in memory) usable word * of a current stack frame is (%fp - 4). * * This code will be called with traps DISABLED, so nothing in this * code is allowed to cause a trap. This means no procedure calls are * allowed. * * Results: * Returns to the address %SAFE_TEMP + 8. * * Side effects: * The window invalid mask changes and a register window is saved. * The mach state structure may change if we need to save this window * into its internal buffers (if it's a user window and the stack isn't * resident). * * ---------------------------------------------------------------------- */ .global MachWindowOverflow MachWindowOverflow: /* * We enter inside of an invalid window, so we can't use in registers, * out registers or global registers to begin with. * We temporarily clear out some globals since we won't be able to * use locals in window we move to before saving it. Using them would * mess them up for window's owner. */ mov %g3, %VOL_TEMP1 mov %g4, %VOL_TEMP2 save /* move to the window to save */ MACH_ADVANCE_WIM(%g3, %g4) /* reset %wim to current window */ /* * If this is a user window, then see if stack space is resident. * If it is, go ahead, but if not, then set special handling and * save to buffers. It's fairly dreadful that we must do all this * checking here, since this will slow down all the overflow traps. */ set MACH_MAX_USER_STACK_ADDR, %g3 /* %sp in user space? */ subcc %g3, %sp, %g0 /* need sp < highest addr */ bleu NotUserStack nop set MACH_FIRST_USER_ADDR, %g3 /* need sp >= lowest addr */ subcc %sp, %g3, %g0 bgeu UserStack nop NotUserStack: set MACH_STACK_BOTTOM, %g3 subcc %sp, %g3, %g0 /* need sp >= lowest addr */ blu BadStack nop set VMMACH_DEV_START_ADDR, %g3 /* need sp < highest addr */ subcc %g3, %sp, %g0 bgu NormalOverflow nop BadStack: /* * Assume it was a user process's bad stack pointer. We can't kill * the process here, so just take over the window and the user process * will die a terrible death later. To take over the window, we just * return, since we've already advanced the %wim. */ ba ReturnFromOverflow nop UserStack: /* * If the stack alignment is bad, we just take over the window and * assume the user process will die a horrible death later on. */ andcc %sp, 0x7, %g0 bne ReturnFromOverflow nop /* Would saving window cause a page fault? */ MACH_CHECK_FOR_FAULT(%sp, %g3) bne SaveToInternalBuffer nop /* check other address extreme */ add %sp, (MACH_SAVED_WINDOW_SIZE - 4), %g4 MACH_CHECK_FOR_FAULT(%g4, %g3) be NormalOverflow nop SaveToInternalBuffer: /* * The stack wasn't resident, so we must save to an internal buffer * and set the special handling flag. * We update the saved mask to show that this window had to be saved * to the internal buffers. We do this by or'ing in the value of * the current window invalid mask, since it's been set to point to * this window we must save. */ MACH_GET_CUR_STATE_PTR(%g3, %g4) /* puts machStatePtr in %g3 */ sethi %hi(_machCurStatePtr), %g4 /* update it */ st %g3, [%g4 + %lo(_machCurStatePtr)] add %g3, MACH_SAVED_MASK_OFFSET, %g3 ld [%g3], %g3 mov %wim, %g4 or %g3, %g4, %g4 sethi %hi(_machCurStatePtr), %g3 ld [%g3 + %lo(_machCurStatePtr)], %g3 add %g3, MACH_SAVED_MASK_OFFSET, %g3 st %g4, [%g3] /* * Get and set the special handling flag in the current process state. */ MACH_GET_CUR_PROC_PTR(%g3) sethi %hi(_machSpecialHandlingOffset), %g4 ld [%g4 + %lo(_machSpecialHandlingOffset)], %g4 add %g3, %g4, %g3 mov 0x1, %g4 st %g4, [%g3] /* * Save the current user stack pointer for this window. */ sethi %hi(_machCurStatePtr), %g3 ld [%g3 + %lo(_machCurStatePtr)], %g3 add %g3, MACH_SAVED_SPS_OFFSET, %g3 mov %psr, %g4 and %g4, MACH_CWP_BITS, %g4 /* Multiply by 4 bytes per int */ sll %g4, 2, %g4 add %g3, %g4, %g3 st %sp, [%g3] /* * Now save to internal buffer. */ sethi %hi(_machCurStatePtr), %g3 ld [%g3 + %lo(_machCurStatePtr)], %g3 add %g3, MACH_SAVED_REGS_OFFSET, %g3 /* * Current window * 4 bytes per reg is still in %g4. Now we just * need to multiply it by the number of registers per window. */ sll %g4, MACH_NUM_REG_SHIFT, %g4 add %g3, %g4, %g3 /* offset to start saving at */ MACH_SAVE_WINDOW_TO_BUFFER(%g3) set ReturnFromOverflow, %g3 jmp %g3 nop NormalOverflow: /* * Save this window to stack - save locals and ins to top 16 words * on the stack. (Since our stack grows down, the top word is %sp * and the bottom will be (%sp + offset). */ MACH_SAVE_WINDOW_TO_STACK() ReturnFromOverflow: restore /* move back to trap window */ mov %VOL_TEMP1, %g3 /* restore global registers */ mov %VOL_TEMP2, %g4 /* * jump to calling routine - this may be a trap-handler or not. */ jmp %SAFE_TEMP + 8 nop /* * ---------------------------------------------------------------------- * * MachHandleWindowUnderflowTrap -- * * Trap entrance to the window underflow handler. This sets up a * return address, retreats a window, calls the underflow handler, * advances back to window in which we entered the routine, restores * the psr, and returns from the trap. We must retreat a window since * on a trap we are 2 windows away from the window to restore, but * on returning from a trap and checking if we need to restore a window, * we are only one window away. See the comments in MachWindowUnderflow() * for more details. * Because we must do some work in the window we were executing in when * we took a trap, we must make sure to save and restore the registers * we use there. This means clearing two globals out for this purpose. * We save and restore the globals in the actual trap window, since we * know we can use the local registers there freely. The underflow * routine expects its return address in %RETURN_ADDR_REG, so this is the * register we must save and restore in the inbetween window. * * In the case where the window we're restoring is for a user process, * we must also check for whether the stack is resident and writable. * If it isn't, we must page it in. To do this is gross. Since the * trap window we've entered into is 2 windows away from the window to * restore, we must move back one window and check the %fp there. (This * will be the %sp in the actual window to restore.) If it isn't * resident, then we must move forward again to the trap window and call * MachTrap to save state for us. Then we can call the Vm_PageIn code * from the trap window to page in the nasty stuff. If it fails, we * must kill the user process. All of this is complicated a bit further * by the fact that we have 2 addresses to test: the %fp and the * %fp + the size of the saved window stuff. So we check both for * residence. If both are okay, we just do normal underflow. If one or * the other fails, we save state. We then test the first address, * if it fails, we page it in. Then if the second one fails, we also * page it in. It most likely will have been paged in by the first one, * though. Then, after all this, we call the normal underflow which * should then be protected from page faults. It has to be, since * it operates in one window back from the trap window where we saved * state, and we can't have any calls to Vm code there overwriting our * saved state. Then we return. If we marked that we had to save * state, then we must restore state by calling MachReturnFromTrap and * leaving as if this had all been a slow trap instead. Unfortunately, * we must test some stuff twice, since there are no registers to save * anything into (%VOL_TEMP registers are blasted by the MachTrap code, * and the SAFE_TEMP register is already used to mark whether we saved * state). * * NOTE: In the case where we must save state by calling MachTrap, * a lot of the underflow code is duplicated in MachReturnFromTrap, * which we also end up calling. The reason I cannot simply call * MachReturnFrom trap then to do all that work, is that I must do the * work in one window away in the case of a real underflow trap. There * may be a way to deal with this, but I haven't done it yet. * * Results: * None. * * Side effects: * The window in question is restored. * * ---------------------------------------------------------------------- */ .global MachHandleWindowUnderflowTrap MachHandleWindowUnderflowTrap: /* * We need a global to mark further actions, and a global to save * the fp in if we find it needs to be page faulted. We can save one * global in SAFE_TEMP since it's only whacked by MachTrap, which is * the only thing that might whack it, in case MachTrap gets an * overflow. But we won't get one since this is an underflow trap. * %o5 also appears to be safe here since it is not overwritten * by parameters to Vm_PageIn, etc. We also need 2 more globals for * checking whether the stack will cause a fault. We use a few more * out registers that we hope Vm_PageIn won't trash. NOTE: WE ARE * MAKING AN ASSUMPTION that Vm_PageIn isn't compiled to mess with its * in registers. If we switch compilers, this may break!!! */ mov %g3, %SAFE_TEMP mov %g4, %o5 mov %g2, %o3 mov %g5, %o4 /* Test if we came from user mode. */ andcc %CUR_PSR_REG, MACH_PS_BIT, %g0 bne NormalUnderflow nop /* * Test if stack is resident for window we need to restore. * This means move back a window and test its frame pointer since * we've trapped into a window 2 away from the one whose stack is * in question. */ restore /* * If the alignment of the user stack pointer is bad, kill the process! * We must be back in the trap window to do that. */ andcc %fp, 0x7, %g0 be,a CheckForFaults clr %g3 /* g3 clear for no problem yet */ mov 0x1, %g3 /* Mark why we will save state */ bne,a MustSaveState save /* back to trap window, in annulled delay slot */ CheckForFaults: /* * %g3 will have have a record of what faults would occur. */ MACH_CHECK_STACK_FAULT(%fp, %g2, %g3, %g5, UndflFault1, UndflFault2) mov %fp, %g4 /* in case we need to fault it */ be NormalUnderflow save /* back to trap window */ MustSaveState: /* * We need to save state. We must do this in actual trap window. * This state-saving enables traps. We will return to * MachReturnToUnderflowWithSavedState */ call _MachTrap nop MachReturnToUnderflowWithSavedState: /* * We had to save state for some reason. %g3 contains the reason * why. */ cmp %g3, 0x1 be KillTheProc nop andcc %g3, 0x2, %g0 be CheckNextUnderflow /* It wasn't first possible fault */ nop QUICK_ENABLE_INTR(%VOL_TEMP1) /* Address that would fault is in %g4. */ mov %g4, %o0 clr %o1 /* also check protection???? */ call _Vm_PageIn, 2 nop QUICK_DISABLE_INTR(%VOL_TEMP1) tst %RETURN_VAL_REG be CheckNextUnderflow /* succeeded, try next */ nop /* Otherwise, bad return, fall through to kill process. */ KillTheProc: /* Need I restore all the global registers here since it's dying? */ mov %SAFE_TEMP, %g3 /* restore g3 */ mov %o5, %g4 /* restore g4 */ mov %o3, %g2 /* etc */ mov %o4, %g5 /* KILL IT - must be in trap window */ MACH_SR_HIGHPRIO() /* traps back on for overflow from printf */ set _MachHandleWindowUnderflowDeathString, %o0 call _printf, 1 nop MACH_GET_CUR_PROC_PTR(%o0) /* procPtr in %o0 */ sethi %hi(_machGenFlagsOffset), %o1 ld [%o1 + %lo(_machGenFlagsOffset)], %o1 add %o0, %o1, %o1 ld [%o1], %o1 sethi %hi(_machForeignFlag), %o2 ld [%o2 + %lo(_machForeignFlag)], %o2 andcc %o1, %o2, %o1 /* Is this a migrated proc? */ be SuspendIt nop set PROC_TERM_DESTROYED, %o0 /* If so, kill it. */ set PROC_BAD_STACK, %o1 clr %o2 call _Proc_ExitInt, 3 nop SuspendIt: /* Else, make it debuggable. */ MACH_GET_CUR_PROC_PTR(%o0) /* procPtr in %o0 */ call _Sig_CheckForKill, 1 /* kill proc if KILL signal */ nop MACH_GET_CUR_PROC_PTR(%o0) /* procPtr in %o0 */ set TRUE, %o1 /* debug TRUE */ set PROC_TERM_DESTROYED, %o2 set PROC_BAD_STACK, %o3 clr %o4 call _Proc_SuspendProcess, 5 nop ba SuspendIt /* proc should loop if continued */ nop CheckNextUnderflow: andcc %g3, 0x4, %g0 /* See if second address would fault */ be BackAgain nop QUICK_ENABLE_INTR(%VOL_TEMP1) /* old %fp is in %g4 */ add %g4, (MACH_SAVED_WINDOW_SIZE - 4), %o0 clr %o1 /* also check protection???? */ call _Vm_PageIn, 2 nop QUICK_DISABLE_INTR(%VOL_TEMP1) tst %RETURN_VAL_REG bne KillTheProc nop BackAgain: /* * Don't deal with underflow itself. Just pretend this was only * a stack page fault. User's restore instruction will get * re-executed and will cause a further underflow trap. This time, * the page should be there. */ /* Restore globals */ mov %SAFE_TEMP, %g3 /* restore g3 and g4 */ mov %o5, %g4 mov %o3, %g2 mov %o4, %g5 call _MachReturnFromTrap nop NormalUnderflow: restore /* retreat a window */ /* * We need to preserve l6 and l7 in this window */ mov %l6, %g2 mov %l7, %g5 mov %RETURN_ADDR_REG, %g3 /* save reg in global */ set MachWindowUnderflow, %g4 /* put address in global */ jmpl %g4, %RETURN_ADDR_REG /* our return addr to reg */ nop mov %g3, %RETURN_ADDR_REG /* restore ret_addr */ mov %g2, %l6 mov %g5, %l7 save /* back to trap window */ /* Restore globals */ mov %SAFE_TEMP, %g3 /* restore g3, g4, g2 & g5 */ mov %o5, %g4 mov %o3, %g2 mov %o4, %g5 MACH_RESTORE_PSR() /* restore psr */ jmp %CUR_PC_REG /* return from trap */ rett %NEXT_PC_REG nop /* * ---------------------------------------------------------------------- * * MachWindowUnderflow -- * * Window underflow handler. It's set up so that it can be called as a * result of a window underflow trap or as a result of needing to restore * an invalid window before returning from a trap or interrupt. * The address of the calling instruction is stored in %RETURN_ADDR_REG, * which is the normal place. * * The window we are in when we enter is one beyond the invalid window we * need to restore. On an underflow trap we enter the kernel 2 windows * away from the window that is invalid. (This is because we tried to * retreat to an invalid window and couldn't, so we trapped. Trapping * advances the current window, so we are 2 windows away from the invalid * window.) From the trap handler, then, we must retreat one window * before calling this routine so that we're only one window away from * the invalid window. Then after returning from here, we must do a * save to get back to our old trap window. * * First we mark the window behind the invalid window as the * new invalid window, and then we move to the invalid window. Then we * restore data from the stack into the invalid window. Then we return * to our previous window. Note that we first mark * the new invalid window and then move to the old invalid window. If * we did this in the other order, we'd get another window underflow trap. * (This is the opposite order from window overflow.) * * For the window to restore, the %sp should be good since it doesn't * get changed by these routines, even if it was a user window and this * is a kernel window. * * The %sp should point to highest (on stack, lowest in memory) * usable word in the current stack frame. %fp is the %sp of the * caller's stack frame, so the first (highest in memory) usable word * of a current stack frame is (%fp - 4). * * Results: * None. * * Side effects: * The window invalid mask changes and a register window is restored. * * ---------------------------------------------------------------------- */ .global MachWindowUnderflow MachWindowUnderflow: /* * Check to see if we're about to return to the trap window from * the debugger. If so, then the frame pointer should be equal * to the base of the debugger stack. If it is, change it to be * the top of the regular stack, so that when we return to the previous * window, our sp is at the top of the regular stack. * NOTE: The test below must agree with the amount we bump up the stack * by in MachTrap. */ sethi %hi(_machDebugStackStart), %VOL_TEMP1 /* base of stack */ ld [%VOL_TEMP1 + %lo(_machDebugStackStart)], %VOL_TEMP1 set MACH_FULL_STACK_FRAME, %VOL_TEMP2 sub %VOL_TEMP1, %VOL_TEMP2, %VOL_TEMP1 /* offset from base */ cmp %VOL_TEMP1, %fp bne RegularStack nop DealWithDebugStack: /* Set stack pointer of next window to regular frame pointer */ sethi %hi(_machSavedRegisterState), %VOL_TEMP1 ld [%VOL_TEMP1 + %lo(_machSavedRegisterState)], %fp RegularStack: /* * We assume that by the time we've gotten here, the stack has been * made resident, if it was a user stack, and we can just go blasting * ahead. * * It should be ok to use locals here - it's a dead window. * Note that this means one cannot do a restore and then a save * and expect that the old locals in the dead window are still the * same. That would be a really dumb thing to think anyway. */ /* mark new invalid window */ MACH_RETREAT_WIM(%VOL_TEMP1, %VOL_TEMP2) /* move to window to restore */ restore /* restore data from stack to window - stack had better be resident! */ MACH_RESTORE_WINDOW_FROM_STACK() /* Move back to previous window. Clear registers too??? */ save /* * jump to calling routine - this may be a trap-handler or not. */ jmp %RETURN_ADDR_REG + 8 nop /* * ---------------------------------------------------------------------- * * MachHandleDebugTrap -- * * Enter the debugger. This means make sure all the windows are * saved to the stack, save my stack pointer, switch the stack pointer * to the debugger stack, and go. * * When we return, we change stack pointers and go to the usual * return from trap routine. * * Results: * None. * * Side effects: * None. * * ---------------------------------------------------------------------- */ .global _MachHandleDebugTrap _MachHandleDebugTrap: /* * If we came from user mode, we do different stuff. */ andcc %CUR_PSR_REG, MACH_PS_BIT, %g0 /* previous state? */ bne KernelDebug /* was kernel mode */ nop call _MachUserDebug nop set _MachReturnFromTrap, %VOL_TEMP1 jmp %VOL_TEMP1 nop KernelDebug: /* * This points to the top stack frame, which consists of a * Mach_RegState structure. This is handed to the debugger. We * also use this to restore our stack pointer upon returning from the * debugger. */ sethi %hi(_machSavedRegisterState), %VOL_TEMP1 st %sp, [%VOL_TEMP1 + %lo(_machSavedRegisterState)] /* * Now make sure all windows are flushed to the stack. We do this * with MACH_NUM_WINDOWS - 1 saves and restores. The window overflow * and underflow traps will then handle this for us. We put the counter * in a global, since they have all been saved already and are free * for our use and we need the value across windows. */ sethi %hi(_machNumWindows), %g2 ld [%g2 + %lo(_machNumWindows)], %g2 sub %g2, 1, %g1 SaveSomeMore: save subcc %g1, 1, %g1 bne SaveSomeMore nop sub %g2, 1, %g1 RestoreSomeMore: restore subcc %g1, 1, %g1 bne RestoreSomeMore nop /* Set stack base for debugger */ sethi %hi(_machDebugStackStart), %VOL_TEMP1 /* stack base */ ld [%VOL_TEMP1 + %lo(_machDebugStackStart)], %VOL_TEMP1 set MACH_FULL_STACK_FRAME, %VOL_TEMP2 sub %VOL_TEMP1, %VOL_TEMP2, %sp /* offset from base */ /* get trap type into o0 from local saved value */ and %CUR_TBR_REG, MACH_TRAP_TYPE_MASK, %o0 srl %o0, 4, %o0 /* put saved reg ptr into o1 */ sethi %hi(_machSavedRegisterState), %VOL_TEMP1 ld [%VOL_TEMP1 + %lo(_machSavedRegisterState)], %o1 /* * Set wim to this window, so that when we return from debugger, * we'll restore the registers for this window from the stack state * handled by the debugger. This is safe to do before calling the * debugger, since we just saved all the windows to the stack. */ MACH_SET_WIM_TO_CWP() /* * Is there a window of vulnerability here when the sp doesn't match * what's saved on the stack and I might restore incorrectly from * stack if I took another trap? But interrupts should be off and * I shouldn't get a trap. */ /* call debugger */ call _Dbg_Main,2 nop /* put saved stack pointer into %sp. */ sethi %hi(_machSavedRegisterState), %VOL_TEMP1 ld [%VOL_TEMP1 + %lo(_machSavedRegisterState)], %sp /* finish as for regular trap */ set _MachReturnFromTrap, %VOL_TEMP1 jmp %VOL_TEMP1 nop /* * ---------------------------------------------------------------------- * * MachSyscallTrap -- * * This is the code to handle system call traps. The number of the * system call is in %g1. * * Results: * Returns a status to the caller in the caller's %o0 (or %i0). * * Side effects: * Depends on the kernel call. * * ---------------------------------------------------------------------- */ .global MachSyscallTrap MachSyscallTrap: /* * So that we don't re-execute the trap instruction when we * return from the system call trap via the return trap procedure, * we increment the return pc and npc here. */ mov %NEXT_PC_REG, %CUR_PC_REG add %NEXT_PC_REG, 0x4, %NEXT_PC_REG /* * Make sure user stack pointer is written into state structure so that * it can be used while processing the system call. (Who uses it??) * This means saving the frame pointer (previous user stack pointer). */ MACH_GET_CUR_STATE_PTR(%VOL_TEMP1, %VOL_TEMP2) /* into %VOL_TEMP1 */ add %VOL_TEMP1, MACH_TRAP_REGS_OFFSET, %VOL_TEMP1 ld [%VOL_TEMP1], %VOL_TEMP1 add %VOL_TEMP1, MACH_FP_OFFSET, %VOL_TEMP1 st %fp, [%VOL_TEMP1] /* If fork call, save registers and invalidate trapRegs stuff????? */ /* * Check number of kernel call for validity. This was stored in %g1. * We must be careful not to have trashed it. But if we end up * trashing it, we could instead pull it out of the saved globals state * in the mach state structure since it got saved there. */ set _machMaxSysCall, %VOL_TEMP1 ld [%VOL_TEMP1], %VOL_TEMP1 cmp %VOL_TEMP1, %g1 bgeu GoodSysCall nop /* * If bad, (take user error? - on spur) then do normal return from trap. * Is this magic number a return value? It's in the sun3 code. */ set SYS_INVALID_SYSTEM_CALL, %RETURN_VAL_REG set ReturnFromSyscall, %VOL_TEMP1 jmp %VOL_TEMP1 nop GoodSysCall: /* * Save sys call number into lastSysCall field in process state so * that migration can figure out what it was supposed to be. * %g1 must still contain syscall number. */ MACH_GET_CUR_STATE_PTR(%VOL_TEMP1, %VOL_TEMP2) /* into %VOL_TEMP1 */ set _machLastSysCallOffset, %VOL_TEMP2 ld [%VOL_TEMP2], %VOL_TEMP2 add %VOL_TEMP1, %VOL_TEMP2, %VOL_TEMP1 st %g1, [%VOL_TEMP1] /* * Fetch args. Copy them from user space if they aren't all in * the input registers. For now I copy all the input registers, * since there isn't a table giving the actual number of args? * For args beyond the number of words that can fit in the input * registers, I get the offset to copy to and the pc to jump to inside * the copying from tables set up in Mach_SyscallInit. If there * are no args to copy, then the pc gets set to jump to * MachFetchArgsEnd. */ mov %i5, %o5 mov %i4, %o4 mov %i3, %o3 mov %i2, %o2 mov %i1, %o1 mov %i0, %o0 /* * Fetch offsets to copy from and to out of table. */ sll %g1, 2, %g1 /* system call index */ set _machArgOffsets, %VOL_TEMP2 /* offset in table */ add %g1, %VOL_TEMP2, %VOL_TEMP2 /* addr in table */ ld [%VOL_TEMP2], %VOL_TEMP2 /* offset value */ add %fp, %VOL_TEMP2, %VOL_TEMP1 /* need global here? */ add %sp, %VOL_TEMP2, %VOL_TEMP2 /* need global here? */ /* * Fetch pc branch address out of table and put it into %SAFE_TEMP */ set _machArgDispatch, %SAFE_TEMP add %g1, %SAFE_TEMP, %SAFE_TEMP ld [%SAFE_TEMP], %SAFE_TEMP jmp %SAFE_TEMP nop .global _MachFetchArgs _MachFetchArgs: ld [%VOL_TEMP1], %SAFE_TEMP /* first word - pc offset 0 */ st %SAFE_TEMP, [%VOL_TEMP2] add %VOL_TEMP1, 4, %VOL_TEMP1 add %VOL_TEMP2, 4, %VOL_TEMP2 ld [%VOL_TEMP1], %SAFE_TEMP /* second word - pc offset 16 */ st %SAFE_TEMP, [%VOL_TEMP2] add %VOL_TEMP1, 4, %VOL_TEMP1 add %VOL_TEMP2, 4, %VOL_TEMP2 ld [%VOL_TEMP1], %SAFE_TEMP /* third word - pc offset 32 */ st %SAFE_TEMP, [%VOL_TEMP2] add %VOL_TEMP1, 4, %VOL_TEMP1 add %VOL_TEMP2, 4, %VOL_TEMP2 ld [%VOL_TEMP1], %SAFE_TEMP /* fourth word */ st %SAFE_TEMP, [%VOL_TEMP2] add %VOL_TEMP1, 4, %VOL_TEMP1 add %VOL_TEMP2, 4, %VOL_TEMP2 ld [%VOL_TEMP1], %SAFE_TEMP /* fifth word */ st %SAFE_TEMP, [%VOL_TEMP2] add %VOL_TEMP1, 4, %VOL_TEMP1 add %VOL_TEMP2, 4, %VOL_TEMP2 ld [%VOL_TEMP1], %SAFE_TEMP /* sixth word */ st %SAFE_TEMP, [%VOL_TEMP2] add %VOL_TEMP1, 4, %VOL_TEMP1 add %VOL_TEMP2, 4, %VOL_TEMP2 ld [%VOL_TEMP1], %SAFE_TEMP /* seventh word */ st %SAFE_TEMP, [%VOL_TEMP2] add %VOL_TEMP1, 4, %VOL_TEMP1 add %VOL_TEMP2, 4, %VOL_TEMP2 ld [%VOL_TEMP1], %SAFE_TEMP /* eighth word */ st %SAFE_TEMP, [%VOL_TEMP2] add %VOL_TEMP1, 4, %VOL_TEMP1 add %VOL_TEMP2, 4, %VOL_TEMP2 ld [%VOL_TEMP1], %SAFE_TEMP /* ninth word */ st %SAFE_TEMP, [%VOL_TEMP2] add %VOL_TEMP1, 4, %VOL_TEMP1 add %VOL_TEMP2, 4, %VOL_TEMP2 ld [%VOL_TEMP1], %SAFE_TEMP /* tenth word */ st %SAFE_TEMP, [%VOL_TEMP2] add %VOL_TEMP1, 4, %VOL_TEMP1 add %VOL_TEMP2, 4, %VOL_TEMP2 /* * Marks last place where PC could be when a page fault occurs while * fetching arguments. Needed to distinguish between a page fault * during arg fetch (which is okay) from other page faults in the * kernel, which are fatal errors. */ .global _MachFetchArgsEnd _MachFetchArgsEnd: /* get address from table */ MACH_GET_CUR_PROC_PTR(%VOL_TEMP1) /* into %VOL_TEMP1 */ set _machKcallTableOffset, %VOL_TEMP2 ld [%VOL_TEMP2], %VOL_TEMP2 /* offset to kcalls */ add %VOL_TEMP1, %VOL_TEMP2, %VOL_TEMP1 ld [%VOL_TEMP1], %VOL_TEMP1 /* addr of array */ add %g1, %VOL_TEMP1, %VOL_TEMP1 /* index to kcall */ ld [%VOL_TEMP1], %VOL_TEMP1 /* got addr */ /* enable interrupts */ QUICK_ENABLE_INTR(%VOL_TEMP2) /* go do it */ call %VOL_TEMP1 nop ReturnFromSyscall: /* Disable interrupts. */ QUICK_DISABLE_INTR(%VOL_TEMP1) /* * Move return value to caller's return val register. */ mov %RETURN_VAL_REG, %RETURN_VAL_REG_CHILD /* * Sun3 checks special handling flag here. I do it in return from * trap, if we came from a user process. */ /* restore the stack pointers? */ /* do normal return from trap */ set _MachReturnFromTrap, %VOL_TEMP1 jmp %VOL_TEMP1 nop /* * ---------------------------------------------------------------------- * * MachLinkTrap -- * * This is the code to handle a dynamic linking trap #2. * Apparently we don't have to do anything. * * Results: * None. * * Side effects: * None. * * ---------------------------------------------------------------------- */ .global MachLinkTrap MachLinkTrap: /* * So that we don't re-execute the trap instruction when we * return from the system call trap via the return trap procedure, * we increment the return pc and npc here. */ mov %NEXT_PC_REG, %CUR_PC_REG add %NEXT_PC_REG, 0x4, %NEXT_PC_REG /* do normal return from trap */ set _MachReturnFromTrap, %VOL_TEMP1 jmp %VOL_TEMP1 nop /* * ---------------------------------------------------------------------- * * MachUnixSyscallTrap -- * * This is the code to handle unix system call traps. The number of the * system call is in %g1. * * Results: * Returns a status to the caller in the caller's %o0 (or %i0). * * Side effects: * Depends on the kernel call. * * ---------------------------------------------------------------------- */ .global MachUnixSyscallTrap MachUnixSyscallTrap: /* * So that we don't re-execute the trap instruction when we * return from the system call trap via the return trap procedure, * we increment the return pc and npc here. */ mov %NEXT_PC_REG, %CUR_PC_REG add %NEXT_PC_REG, 0x4, %NEXT_PC_REG /* * Make sure user stack pointer is written into state structure so that * it can be used while processing the system call. (Who uses it??) * This means saving the frame pointer (previous user stack pointer). */ MACH_GET_CUR_STATE_PTR(%VOL_TEMP1, %VOL_TEMP2) /* into %VOL_TEMP1 */ add %VOL_TEMP1, MACH_TRAP_REGS_OFFSET, %VOL_TEMP1 ld [%VOL_TEMP1], %VOL_TEMP1 add %VOL_TEMP1, MACH_FP_OFFSET, %VOL_TEMP1 st %fp, [%VOL_TEMP1] nop /* If fork call, save registers and invalidate trapRegs stuff????? */ /* * Check number of kernel call for validity. This was stored in %g1. * We must be careful not to have trashed it. But if we end up * trashing it, we could instead pull it out of the saved globals state * in the mach state structure since it got saved there. */ set _sysUnixNumSyscalls, %VOL_TEMP1 ld [%VOL_TEMP1], %VOL_TEMP1 cmp %VOL_TEMP1, %g1 bgeu GoodUnixSysCall nop /* * If bad, (take user error? - on spur) then do normal return from trap. * Is this magic number a return value? It's in the sun3 code. */ set -1, %RETURN_VAL_REG set ReturnFromUnixSyscall, %VOL_TEMP1 jmp %VOL_TEMP1 nop GoodUnixSysCall: /* * Save sys call number into lastSysCall field in process state so * that migration can figure out what it was supposed to be. * %g1 must still contain syscall number. */ MACH_GET_CUR_STATE_PTR(%VOL_TEMP1, %VOL_TEMP2) /* into %VOL_TEMP1 */ set _machLastSysCallOffset, %VOL_TEMP2 ld [%VOL_TEMP2], %VOL_TEMP2 add %VOL_TEMP1, %VOL_TEMP2, %VOL_TEMP1 st %g1, [%VOL_TEMP1] /* * Save i0 for call restart. */ st %i0, [%VOL_TEMP1+4] /* * Fetch args. Copy them from user space if they aren't all in * the input registers. For now I copy all the input registers, * since there isn't a table giving the actual number of args? * For args beyond the number of words that can fit in the input * registers, I get the offset to copy to and the pc to jump to inside * the copying from tables set up in Mach_SyscallInit. If there * are no args to copy, then the pc gets set to jump to * MachFetchArgsEnd. */ mov %i5, %o5 mov %i4, %o4 mov %i3, %o3 mov %i2, %o2 mov %i1, %o1 mov %i0, %o0 cmp %g1, 0x8b /* Sigreturn */ be DoSigreturn sll %g1, 3, %g1 set _sysUnixSysCallTable, %VOL_TEMP2 add %g1, %VOL_TEMP2, %VOL_TEMP2 /* index to kcall */ ld [%VOL_TEMP2], %VOL_TEMP2 /* got addr */ /* enable interrupts */ QUICK_ENABLE_INTR(%VOL_TEMP1) /* go do it */ call %VOL_TEMP2 nop ReturnFromUnixSyscall: /* Disable interrupts. */ QUICK_DISABLE_INTR(%VOL_TEMP1) /* * Move return value to caller's return val register. */ /* * Check if error. */ cmp %RETURN_VAL_REG, -1 bne UnixOk nop /* * Get the errno from the pcb and use it as the return value. */ MACH_GET_CUR_PROC_PTR(%VOL_TEMP1) /* into %VOL_TEMP1 */ set MACH_UNIX_ERRNO_OFFSET, %VOL_TEMP2 add %VOL_TEMP1, %VOL_TEMP2, %VOL_TEMP1 ld [%VOL_TEMP1], %VOL_TEMP1 mov %VOL_TEMP1, %RETURN_VAL_REG_CHILD /* * Set the carry to indicate an error. */ mov %CUR_PSR_REG, %VOL_TEMP2 set MACH_CARRY_BIT, %VOL_TEMP1 or %VOL_TEMP2, %VOL_TEMP1, %VOL_TEMP2 mov %VOL_TEMP2, %CUR_PSR_REG set _MachReturnFromTrap, %VOL_TEMP1 jmp %VOL_TEMP1 nop UnixOk: mov %RETURN_VAL_REG, %RETURN_VAL_REG_CHILD mov %o1, %i1 mov %CUR_PSR_REG, %VOL_TEMP2 set MACH_CARRY_BITMASK, %VOL_TEMP1 and %VOL_TEMP2, %VOL_TEMP1, %VOL_TEMP2 mov %VOL_TEMP2, %CUR_PSR_REG set _MachReturnFromTrap, %VOL_TEMP1 jmp %VOL_TEMP1 nop DoSigreturn: /* We have to skip the errno checking */ QUICK_ENABLE_INTR(%VOL_TEMP1) /* go do it */ call _Mach_SigreturnStub nop MACH_RESTORE_WINDOW_FROM_STACK() /* Disable interrupts. */ QUICK_DISABLE_INTR(%VOL_TEMP1) set _MachReturnFromTrap, %VOL_TEMP1 jmp %VOL_TEMP1 nop /* * ---------------------------------------------------------------------- * * MachHandlePageFault -- * * An instruction or data fault has occurred. This routine will retrieve * the fault error from the bus error register and the faulting address * from the address error register and will call * Vm routines to handle faulting in the page. * * Results: * Returns to MachReturnFromTrap rather than its caller. * * Side effects: * The page that caused the fault will become valid. * * ---------------------------------------------------------------------- */ .global MachHandlePageFault MachHandlePageFault: #ifdef sun4c /* synchronous error register value as first arg - clears it too. */ set VMMACH_SYNC_ERROR_REG, %o0 lda [%o0] VMMACH_CONTROL_SPACE, %o0 /* synch error address register value as second arg - clears it. */ set VMMACH_SYNC_ERROR_ADDR_REG, %o1 lda [%o1] VMMACH_CONTROL_SPACE, %o1 /* clear async regs as well since they latch on sync errors as well. */ set VMMACH_ASYNC_ERROR_REG, %VOL_TEMP1 lda [%VOL_TEMP1] VMMACH_CONTROL_SPACE, %g0 /* async error addr reg as well, so clear it. Very silly. */ set VMMACH_ASYNC_ERROR_ADDR_REG, %VOL_TEMP1 lda [%VOL_TEMP1] VMMACH_CONTROL_SPACE, %g0 #else /* bus error register value as first arg. */ set VMMACH_BUS_ERROR_REG, %o0 lduba [%o0] VMMACH_CONTROL_SPACE, %o0 /* memory address causing the error as second arg */ set VMMACH_ADDR_ERROR_REG, %o1 ld [%o1], %o1 /* Write the address register to clear it */ set VMMACH_ADDR_ERROR_REG, %VOL_TEMP1 st %o1, [%VOL_TEMP1] #endif /* trap value of the psr as third arg */ mov %CUR_PSR_REG, %o2 /* trap value of pc as fourth argument */ mov %CUR_PC_REG, %o3 #ifndef sun4c /* * If the trap was on a pc access rather than a data access, the * memoory address register won't have frozen the correct address. * Just move the pc into the second argument. */ and %CUR_TBR_REG, MACH_TRAP_TYPE_MASK, %VOL_TEMP1 cmp %VOL_TEMP1, MACH_INSTR_ACCESS bne AddressValueOkay nop mov %CUR_PC_REG, %o1 #endif AddressValueOkay: /* enable interrupts */ /* QUICK_ENABLE_INTR(%VOL_TEMP1) */ call _MachPageFault, 4 nop /* Disable interrupts. */ QUICK_DISABLE_INTR(%VOL_TEMP1) set _MachReturnFromTrap, %VOL_TEMP1 jmp %VOL_TEMP1 nop /* * ---------------------------------------------------------------------- * * MachFlushWindowsToStackTrap -- * * A trap requesting that all our windows be flushed to the stack has * occured. Bump up our return pc, since we don't want to re-execute * the trap, and then call the appropriate routine. * * Results: * Returns to MachReturnFromTrap, rather than our caller. * * Side effects: * Register windows will be flushed to the stack and the invalid * window mask will be set to point to the window before us. * * ---------------------------------------------------------------------- */ .global MachFlushWindowsToStackTrap MachFlushWindowsToStackTrap: mov %NEXT_PC_REG, %CUR_PC_REG add %NEXT_PC_REG, 4, %NEXT_PC_REG call _Mach_FlushWindowsToStack nop set _MachReturnFromTrap, %VOL_TEMP1 jmp %VOL_TEMP1 nop