1/* 2 * etrap.S: Sparc trap window preparation for entry into the 3 * Linux kernel. 4 * 5 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu) 6 */ 7 8#include <asm/head.h> 9#include <asm/asi.h> 10#include <asm/contregs.h> 11#include <asm/page.h> 12#include <asm/psr.h> 13#include <asm/ptrace.h> 14#include <asm/winmacro.h> 15#include <asm/asmmacro.h> 16#include <asm/thread_info.h> 17 18/* Registers to not touch at all. */ 19#define t_psr l0 /* Set by caller */ 20#define t_pc l1 /* Set by caller */ 21#define t_npc l2 /* Set by caller */ 22#define t_wim l3 /* Set by caller */ 23#define t_twinmask l4 /* Set at beginning of this entry routine. */ 24#define t_kstack l5 /* Set right before pt_regs frame is built */ 25#define t_retpc l6 /* If you change this, change winmacro.h header file */ 26#define t_systable l7 /* Never touch this, could be the syscall table ptr. */ 27#define curptr g6 /* Set after pt_regs frame is built */ 28 29 .text 30 .align 4 31 32 /* SEVEN WINDOW PATCH INSTRUCTIONS */ 33 .globl tsetup_7win_patch1, tsetup_7win_patch2 34 .globl tsetup_7win_patch3, tsetup_7win_patch4 35 .globl tsetup_7win_patch5, tsetup_7win_patch6 36tsetup_7win_patch1: sll %t_wim, 0x6, %t_wim 37tsetup_7win_patch2: and %g2, 0x7f, %g2 38tsetup_7win_patch3: and %g2, 0x7f, %g2 39tsetup_7win_patch4: and %g1, 0x7f, %g1 40tsetup_7win_patch5: sll %t_wim, 0x6, %t_wim 41tsetup_7win_patch6: and %g2, 0x7f, %g2 42 /* END OF PATCH INSTRUCTIONS */ 43 44 /* At trap time, interrupts and all generic traps do the 45 * following: 46 * 47 * rd %psr, %l0 48 * b some_handler 49 * rd %wim, %l3 50 * nop 51 * 52 * Then 'some_handler' if it needs a trap frame (ie. it has 53 * to call c-code and the trap cannot be handled in-window) 54 * then it does the SAVE_ALL macro in entry.S which does 55 * 56 * sethi %hi(trap_setup), %l4 57 * jmpl %l4 + %lo(trap_setup), %l6 58 * nop 59 */ 60 61 /* 2 3 4 window number 62 * ----- 63 * O T S mnemonic 64 * 65 * O == Current window before trap 66 * T == Window entered when trap occurred 67 * S == Window we will need to save if (1<<T) == %wim 68 * 69 * Before execution gets here, it must be guaranteed that 70 * %l0 contains trap time %psr, %l1 and %l2 contain the 71 * trap pc and npc, and %l3 contains the trap time %wim. 72 */ 73 74 .globl trap_setup, tsetup_patch1, tsetup_patch2 75 .globl tsetup_patch3, tsetup_patch4 76 .globl tsetup_patch5, tsetup_patch6 77trap_setup: 78 /* Calculate mask of trap window. See if from user 79 * or kernel and branch conditionally. 80 */ 81 mov 1, %t_twinmask 82 andcc %t_psr, PSR_PS, %g0 ! fromsupv_p = (psr & PSR_PS) 83 be trap_setup_from_user ! nope, from user mode 84 sll %t_twinmask, %t_psr, %t_twinmask ! t_twinmask = (1 << psr) 85 86 /* From kernel, allocate more kernel stack and 87 * build a pt_regs trap frame. 88 */ 89 sub %fp, (STACKFRAME_SZ + TRACEREG_SZ), %t_kstack 90 STORE_PT_ALL(t_kstack, t_psr, t_pc, t_npc, g2) 91 92 /* See if we are in the trap window. */ 93 andcc %t_twinmask, %t_wim, %g0 94 bne trap_setup_kernel_spill ! in trap window, clean up 95 nop 96 97 /* Trap from kernel with a window available. 98 * Just do it... 99 */ 100 jmpl %t_retpc + 0x8, %g0 ! return to caller 101 mov %t_kstack, %sp ! jump onto new stack 102 103trap_setup_kernel_spill: 104 ld [%curptr + TI_UWINMASK], %g1 105 orcc %g0, %g1, %g0 106 bne trap_setup_user_spill ! there are some user windows, yuck 107 /* Spill from kernel, but only kernel windows, adjust 108 * %wim and go. 109 */ 110 srl %t_wim, 0x1, %g2 ! begin computation of new %wim 111tsetup_patch1: 112 sll %t_wim, 0x7, %t_wim ! patched on 7 window Sparcs 113 or %t_wim, %g2, %g2 114tsetup_patch2: 115 and %g2, 0xff, %g2 ! patched on 7 window Sparcs 116 117 save %g0, %g0, %g0 118 119 /* Set new %wim value */ 120 wr %g2, 0x0, %wim 121 122 /* Save the kernel window onto the corresponding stack. */ 123 STORE_WINDOW(sp) 124 125 restore %g0, %g0, %g0 126 127 jmpl %t_retpc + 0x8, %g0 ! return to caller 128 mov %t_kstack, %sp ! and onto new kernel stack 129 130#define STACK_OFFSET (THREAD_SIZE - TRACEREG_SZ - STACKFRAME_SZ) 131 132trap_setup_from_user: 133 /* We can't use %curptr yet. */ 134 LOAD_CURRENT(t_kstack, t_twinmask) 135 136 sethi %hi(STACK_OFFSET), %t_twinmask 137 or %t_twinmask, %lo(STACK_OFFSET), %t_twinmask 138 add %t_kstack, %t_twinmask, %t_kstack 139 140 mov 1, %t_twinmask 141 sll %t_twinmask, %t_psr, %t_twinmask ! t_twinmask = (1 << psr) 142 143 /* Build pt_regs frame. */ 144 STORE_PT_ALL(t_kstack, t_psr, t_pc, t_npc, g2) 145 146 sethi %hi(~(THREAD_SIZE - 1)), %curptr 147 and %t_kstack, %curptr, %curptr 148 149 /* Clear current_thread_info->w_saved */ 150 st %g0, [%curptr + TI_W_SAVED] 151 152 /* See if we are in the trap window. */ 153 andcc %t_twinmask, %t_wim, %g0 154 bne trap_setup_user_spill ! yep we are 155 orn %g0, %t_twinmask, %g1 ! negate trap win mask into %g1 156 157 /* Trap from user, but not into the invalid window. 158 * Calculate new umask. The way this works is, 159 * any window from the %wim at trap time until 160 * the window right before the one we are in now, 161 * is a user window. A diagram: 162 * 163 * 7 6 5 4 3 2 1 0 window number 164 * --------------- 165 * I L T mnemonic 166 * 167 * Window 'I' is the invalid window in our example, 168 * window 'L' is the window the user was in when 169 * the trap occurred, window T is the trap window 170 * we are in now. So therefore, windows 5, 4 and 171 * 3 are user windows. The following sequence 172 * computes the user winmask to represent this. 173 */ 174 subcc %t_wim, %t_twinmask, %g2 175 bneg,a 1f 176 sub %g2, 0x1, %g2 1771: 178 andn %g2, %t_twinmask, %g2 179tsetup_patch3: 180 and %g2, 0xff, %g2 ! patched on 7win Sparcs 181 st %g2, [%curptr + TI_UWINMASK] ! store new umask 182 183 jmpl %t_retpc + 0x8, %g0 ! return to caller 184 mov %t_kstack, %sp ! and onto kernel stack 185 186trap_setup_user_spill: 187 /* A spill occurred from either kernel or user mode 188 * and there exist some user windows to deal with. 189 * A mask of the currently valid user windows 190 * is in %g1 upon entry to here. 191 */ 192 193tsetup_patch4: 194 and %g1, 0xff, %g1 ! patched on 7win Sparcs, mask 195 srl %t_wim, 0x1, %g2 ! compute new %wim 196tsetup_patch5: 197 sll %t_wim, 0x7, %t_wim ! patched on 7win Sparcs 198 or %t_wim, %g2, %g2 ! %g2 is new %wim 199tsetup_patch6: 200 and %g2, 0xff, %g2 ! patched on 7win Sparcs 201 andn %g1, %g2, %g1 ! clear this bit in %g1 202 st %g1, [%curptr + TI_UWINMASK] 203 204 save %g0, %g0, %g0 205 206 wr %g2, 0x0, %wim 207 208 /* Call MMU-architecture dependent stack checking 209 * routine. 210 */ 211 .globl tsetup_mmu_patchme 212tsetup_mmu_patchme: 213 b tsetup_sun4c_stackchk 214 andcc %sp, 0x7, %g0 215 216 /* Architecture specific stack checking routines. When either 217 * of these routines are called, the globals are free to use 218 * as they have been safely stashed on the new kernel stack 219 * pointer. Thus the definition below for simplicity. 220 */ 221#define glob_tmp g1 222 223tsetup_sun4c_stackchk: 224 /* Done by caller: andcc %sp, 0x7, %g0 */ 225 bne trap_setup_user_stack_is_bolixed 226 sra %sp, 29, %glob_tmp 227 228 add %glob_tmp, 0x1, %glob_tmp 229 andncc %glob_tmp, 0x1, %g0 230 bne trap_setup_user_stack_is_bolixed 231 and %sp, 0xfff, %glob_tmp ! delay slot 232 233 /* See if our dump area will be on more than one 234 * page. 235 */ 236 add %glob_tmp, 0x38, %glob_tmp 237 andncc %glob_tmp, 0xff8, %g0 238 be tsetup_sun4c_onepage ! only one page to check 239 lda [%sp] ASI_PTE, %glob_tmp ! have to check first page anyways 240 241tsetup_sun4c_twopages: 242 /* Is first page ok permission wise? */ 243 srl %glob_tmp, 29, %glob_tmp 244 cmp %glob_tmp, 0x6 245 bne trap_setup_user_stack_is_bolixed 246 add %sp, 0x38, %glob_tmp /* Is second page in vma hole? */ 247 248 sra %glob_tmp, 29, %glob_tmp 249 add %glob_tmp, 0x1, %glob_tmp 250 andncc %glob_tmp, 0x1, %g0 251 bne trap_setup_user_stack_is_bolixed 252 add %sp, 0x38, %glob_tmp 253 254 lda [%glob_tmp] ASI_PTE, %glob_tmp 255 256tsetup_sun4c_onepage: 257 srl %glob_tmp, 29, %glob_tmp 258 cmp %glob_tmp, 0x6 ! can user write to it? 259 bne trap_setup_user_stack_is_bolixed ! failure 260 nop 261 262 STORE_WINDOW(sp) 263 264 restore %g0, %g0, %g0 265 266 jmpl %t_retpc + 0x8, %g0 267 mov %t_kstack, %sp 268 269 .globl tsetup_srmmu_stackchk 270tsetup_srmmu_stackchk: 271 /* Check results of callers andcc %sp, 0x7, %g0 */ 272 bne trap_setup_user_stack_is_bolixed 273 sethi %hi(PAGE_OFFSET), %glob_tmp 274 275 cmp %glob_tmp, %sp 276 bleu,a 1f 277 lda [%g0] ASI_M_MMUREGS, %glob_tmp ! read MMU control 278 279trap_setup_user_stack_is_bolixed: 280 /* From user/kernel into invalid window w/bad user 281 * stack. Save bad user stack, and return to caller. 282 */ 283 SAVE_BOLIXED_USER_STACK(curptr, g3) 284 restore %g0, %g0, %g0 285 286 jmpl %t_retpc + 0x8, %g0 287 mov %t_kstack, %sp 288 2891: 290 /* Clear the fault status and turn on the no_fault bit. */ 291 or %glob_tmp, 0x2, %glob_tmp ! or in no_fault bit 292 sta %glob_tmp, [%g0] ASI_M_MMUREGS ! set it 293 294 /* Dump the registers and cross fingers. */ 295 STORE_WINDOW(sp) 296 297 /* Clear the no_fault bit and check the status. */ 298 andn %glob_tmp, 0x2, %glob_tmp 299 sta %glob_tmp, [%g0] ASI_M_MMUREGS 300 mov AC_M_SFAR, %glob_tmp 301 lda [%glob_tmp] ASI_M_MMUREGS, %g0 302 mov AC_M_SFSR, %glob_tmp 303 lda [%glob_tmp] ASI_M_MMUREGS, %glob_tmp ! save away status of winstore 304 andcc %glob_tmp, 0x2, %g0 ! did we fault? 305 bne trap_setup_user_stack_is_bolixed ! failure 306 nop 307 308 restore %g0, %g0, %g0 309 310 jmpl %t_retpc + 0x8, %g0 311 mov %t_kstack, %sp 312