/* $Id: etrap.S,v 1.18 1996/04/25 06:08:35 davem Exp $ * etrap.S: Sparc trap window preparation for entry into the * Linux kernel. * * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu) */ #include <asm/cprefix.h> #include <asm/head.h> #include <asm/asi.h> #include <asm/contregs.h> #include <asm/page.h> #include <asm/psr.h> #include <asm/ptrace.h> #include <asm/winmacro.h> /* Registers to not touch at all. */ #define t_psr l0 /* Set by caller */ #define t_pc l1 /* Set by caller */ #define t_npc l2 /* Set by caller */ #define t_wim l3 /* Set by caller */ #define t_twinmask l4 /* Set at beginning of this entry routine. */ #define t_kstack l5 /* Set right before pt_regs frame is built */ #define t_retpc l6 /* If you change this, change winmacro.h header file */ #define t_systable l7 /* Never touch this, could be the syscall table ptr. */ #define curptr g4 /* Set after pt_regs frame is built */ .text .align 4 /* SEVEN WINDOW PATCH INSTRUCTIONS */ .globl tsetup_7win_patch1, tsetup_7win_patch2 .globl tsetup_7win_patch3, tsetup_7win_patch4 .globl tsetup_7win_patch5, tsetup_7win_patch6 tsetup_7win_patch1: sll %t_wim, 0x6, %t_wim tsetup_7win_patch2: and %g2, 0x7f, %g2 tsetup_7win_patch3: and %g2, 0x7f, %g2 tsetup_7win_patch4: and %g1, 0x7f, %g1 tsetup_7win_patch5: sll %t_wim, 0x6, %t_wim tsetup_7win_patch6: and %g2, 0x7f, %g2 /* END OF PATCH INSTRUCTIONS */ /* At trap time, interrupts and all generic traps do the * following: * * rd %psr, %l0 * b some_handler * rd %wim, %l3 * nop * * Then 'some_handler' if it needs a trap frame (ie. it has * to call c-code and the trap cannot be handled in-window) * then it does the SAVE_ALL macro in entry.S which does * * sethi %hi(trap_setup), %l4 * jmpl %l4 + %lo(trap_setup), %l6 * mov 1, %l4 */ /* 2 3 4 window number * ----- * O T S mnemonic * * O == Current window before trap * T == Window entered when trap occurred * S == Window we will need to save if (1<<T) == %wim * * Before execution gets here, it must be guaranteed that * %l0 contains trap time %psr, %l1 and %l2 contain the * trap pc and npc, and %l3 contains the trap time %wim. */ .globl trap_setup, tsetup_patch1, tsetup_patch2 .globl tsetup_patch3, tsetup_patch4 .globl tsetup_patch5, tsetup_patch6 trap_setup: /* Calculate mask of trap window. See if from user * or kernel and branch conditionally. */ mov 1, %t_twinmask sll %t_twinmask, %t_psr, %t_twinmask ! t_twinmask = (1 << psr) andcc %t_psr, PSR_PS, %g0 ! fromsupv_p = (psr & PSR_PS) be trap_setup_from_user ! nope, from user mode nop /* From kernel, allocate more kernel stack and * build a pt_regs trap frame. */ sub %fp, (REGWIN_SZ + TRACEREG_SZ), %t_kstack STORE_PT_ALL(t_kstack, t_psr, t_pc, t_npc, g2) /* See if we are in the trap window. */ andcc %t_twinmask, %t_wim, %g0 be 1f nop b trap_setup_kernel_spill ! in trap window, clean up nop /* Trap from kernel with a window available. * Just do it... */ 1: jmpl %t_retpc + 0x8, %g0 ! return to caller mov %t_kstack, %sp ! jump onto new stack trap_setup_kernel_spill: LOAD_CURRENT(curptr, g1) ld [%curptr + THREAD_UMASK], %g1 orcc %g0, %g1, %g0 bne trap_setup_user_spill ! there are some user windows, yuck nop /* Spill from kernel, but only kernel windows, adjust * %wim and go. */ srl %t_wim, 0x1, %g2 ! begin computation of new %wim tsetup_patch1: sll %t_wim, 0x7, %t_wim ! patched on 7 window Sparcs or %t_wim, %g2, %g2 tsetup_patch2: and %g2, 0xff, %g2 ! patched on 7 window Sparcs save %g0, %g0, %g0 /* Set new %wim value */ wr %g2, 0x0, %wim WRITE_PAUSE /* Save the kernel window onto the corresponding stack. */ STORE_WINDOW(sp) restore %g0, %g0, %g0 jmpl %t_retpc + 0x8, %g0 ! return to caller mov %t_kstack, %sp ! and onto new kernel stack trap_setup_from_user: /* We can't use %curptr yet. */ LOAD_CURRENT(t_kstack, t_twinmask) mov 1, %t_twinmask ld [%t_kstack + TASK_SAVED_KSTACK], %t_kstack sll %t_twinmask, %t_psr, %t_twinmask ! t_twinmask = (1 << psr) /* Build pt_regs frame. */ STORE_PT_ALL(t_kstack, t_psr, t_pc, t_npc, g2) /* Clear current->tss.w_saved */ LOAD_CURRENT(curptr, g1) st %g0, [%curptr + THREAD_W_SAVED] /* See if we are in the trap window. */ andcc %t_twinmask, %t_wim, %g0 bne trap_setup_user_spill ! yep we are orn %g0, %t_twinmask, %g1 ! negate trap win mask into %g1 /* Trap from user, but not into the invalid window. * Calculate new umask. The way this works is, * any window from the %wim at trap time until * the window right before the one we are in now, * is a user window. A diagram: * * 7 6 5 4 3 2 1 0 window number * --------------- * I L T mnemonic * * Window 'I' is the invalid window in our example, * window 'L' is the window the user was in when * the trap occurred, window T is the trap window * we are in now. So therefore, windows 5, 4 and * 3 are user windows. The following sequence * computes the user winmask to represent this. */ subcc %t_wim, %t_twinmask, %g2 bneg,a 1f sub %g2, 0x1, %g2 1: andn %g2, %t_twinmask, %g2 tsetup_patch3: and %g2, 0xff, %g2 ! patched on 7win Sparcs st %g2, [%curptr + THREAD_UMASK] ! store new umask jmpl %t_retpc + 0x8, %g0 ! return to caller mov %t_kstack, %sp ! and onto kernel stack trap_setup_user_spill: /* A spill occurred from either kernel or user mode * and there exist some user windows to deal with. * A mask of the currently valid user windows * is in %g1 upon entry to here. */ tsetup_patch4: and %g1, 0xff, %g1 ! patched on 7win Sparcs, mask srl %t_wim, 0x1, %g2 ! compute new %wim tsetup_patch5: sll %t_wim, 0x7, %t_wim ! patched on 7win Sparcs or %t_wim, %g2, %g2 ! %g2 is new %wim tsetup_patch6: and %g2, 0xff, %g2 ! patched on 7win Sparcs andn %g1, %g2, %g1 ! clear this bit in %g1 st %g1, [%curptr + THREAD_UMASK] save %g0, %g0, %g0 wr %g2, 0x0, %wim WRITE_PAUSE /* Call MMU-architecture dependent stack checking * routine. */ .globl C_LABEL(tsetup_mmu_patchme) C_LABEL(tsetup_mmu_patchme): b C_LABEL(tsetup_sun4c_stackchk) andcc %sp, 0x7, %g0 trap_setup_user_stack_is_bolixed: /* From user/kernel into invalid window w/bad user * stack. Save bad user stack, and return to caller. */ SAVE_BOLIXED_USER_STACK(curptr, g3) restore %g0, %g0, %g0 jmpl %t_retpc + 0x8, %g0 mov %t_kstack, %sp trap_setup_good_ustack: STORE_WINDOW(sp) trap_setup_finish_up: restore %g0, %g0, %g0 jmpl %t_retpc + 0x8, %g0 mov %t_kstack, %sp /* Architecture specific stack checking routines. When either * of these routines are called, the globals are free to use * as they have been safely stashed on the new kernel stack * pointer. Thus the definition below for simplicity. */ #define glob_tmp g1 .globl C_LABEL(tsetup_sun4c_stackchk) C_LABEL(tsetup_sun4c_stackchk): /* Done by caller: andcc %sp, 0x7, %g0 */ be 1f sra %sp, 29, %glob_tmp b trap_setup_user_stack_is_bolixed nop 1: add %glob_tmp, 0x1, %glob_tmp andncc %glob_tmp, 0x1, %g0 be 1f and %sp, 0xfff, %glob_tmp ! delay slot b trap_setup_user_stack_is_bolixed nop /* See if our dump area will be on more than one * page. */ 1: add %glob_tmp, 0x38, %glob_tmp andncc %glob_tmp, 0xff8, %g0 be tsetup_sun4c_onepage ! only one page to check lda [%sp] ASI_PTE, %glob_tmp ! have to check first page anyways tsetup_sun4c_twopages: /* Is first page ok permission wise? */ srl %glob_tmp, 29, %glob_tmp cmp %glob_tmp, 0x6 be 1f add %sp, 0x38, %glob_tmp /* Is second page in vma hole? */ b trap_setup_user_stack_is_bolixed nop 1: sra %glob_tmp, 29, %glob_tmp add %glob_tmp, 0x1, %glob_tmp andncc %glob_tmp, 0x1, %g0 be 1f add %sp, 0x38, %glob_tmp b trap_setup_user_stack_is_bolixed nop 1: lda [%glob_tmp] ASI_PTE, %glob_tmp tsetup_sun4c_onepage: srl %glob_tmp, 29, %glob_tmp cmp %glob_tmp, 0x6 ! can user write to it? be trap_setup_good_ustack ! success nop b trap_setup_user_stack_is_bolixed nop .globl C_LABEL(tsetup_srmmu_stackchk) C_LABEL(tsetup_srmmu_stackchk): /* Check results of callers andcc %sp, 0x7, %g0 */ bne trap_setup_user_stack_is_bolixed sethi %hi(KERNBASE), %glob_tmp cmp %glob_tmp, %sp bleu trap_setup_user_stack_is_bolixed nop /* Clear the fault status and turn on the no_fault bit. */ lda [%g0] ASI_M_MMUREGS, %glob_tmp ! read MMU control or %glob_tmp, 0x2, %glob_tmp ! or in no_fault bit sta %glob_tmp, [%g0] ASI_M_MMUREGS ! set it /* Dump the registers and cross fingers. */ STORE_WINDOW(sp) /* Clear the no_fault bit and check the status. */ andn %glob_tmp, 0x2, %glob_tmp sta %glob_tmp, [%g0] ASI_M_MMUREGS mov AC_M_SFAR, %glob_tmp lda [%glob_tmp] ASI_M_MMUREGS, %g0 mov AC_M_SFSR, %glob_tmp lda [%glob_tmp] ASI_M_MMUREGS, %glob_tmp ! save away status of winstore andcc %glob_tmp, 0x2, %g0 ! did we fault? be trap_setup_finish_up ! cool beans, success nop b trap_setup_user_stack_is_bolixed ! we faulted, ugh nop