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#if 0 147 /* If we're sure every task_struct is THREAD_SIZE aligned, 148 we can speed this up. */ 149 sethi %hi(STACK_OFFSET), %curptr 150 or %curptr, %lo(STACK_OFFSET), %curptr 151 sub %t_kstack, %curptr, %curptr 152#else 153 sethi %hi(~(THREAD_SIZE - 1)), %curptr 154 and %t_kstack, %curptr, %curptr 155#endif 156 157 /* Clear current_thread_info->w_saved */ 158 st %g0, [%curptr + TI_W_SAVED] 159 160 /* See if we are in the trap window. */ 161 andcc %t_twinmask, %t_wim, %g0 162 bne trap_setup_user_spill ! yep we are 163 orn %g0, %t_twinmask, %g1 ! negate trap win mask into %g1 164 165 /* Trap from user, but not into the invalid window. 166 * Calculate new umask. The way this works is, 167 * any window from the %wim at trap time until 168 * the window right before the one we are in now, 169 * is a user window. A diagram: 170 * 171 * 7 6 5 4 3 2 1 0 window number 172 * --------------- 173 * I L T mnemonic 174 * 175 * Window 'I' is the invalid window in our example, 176 * window 'L' is the window the user was in when 177 * the trap occurred, window T is the trap window 178 * we are in now. So therefore, windows 5, 4 and 179 * 3 are user windows. The following sequence 180 * computes the user winmask to represent this. 181 */ 182 subcc %t_wim, %t_twinmask, %g2 183 bneg,a 1f 184 sub %g2, 0x1, %g2 1851: 186 andn %g2, %t_twinmask, %g2 187tsetup_patch3: 188 and %g2, 0xff, %g2 ! patched on 7win Sparcs 189 st %g2, [%curptr + TI_UWINMASK] ! store new umask 190 191 jmpl %t_retpc + 0x8, %g0 ! return to caller 192 mov %t_kstack, %sp ! and onto kernel stack 193 194trap_setup_user_spill: 195 /* A spill occurred from either kernel or user mode 196 * and there exist some user windows to deal with. 197 * A mask of the currently valid user windows 198 * is in %g1 upon entry to here. 199 */ 200 201tsetup_patch4: 202 and %g1, 0xff, %g1 ! patched on 7win Sparcs, mask 203 srl %t_wim, 0x1, %g2 ! compute new %wim 204tsetup_patch5: 205 sll %t_wim, 0x7, %t_wim ! patched on 7win Sparcs 206 or %t_wim, %g2, %g2 ! %g2 is new %wim 207tsetup_patch6: 208 and %g2, 0xff, %g2 ! patched on 7win Sparcs 209 andn %g1, %g2, %g1 ! clear this bit in %g1 210 st %g1, [%curptr + TI_UWINMASK] 211 212 save %g0, %g0, %g0 213 214 wr %g2, 0x0, %wim 215 216 /* Call MMU-architecture dependent stack checking 217 * routine. 218 */ 219 .globl tsetup_mmu_patchme 220tsetup_mmu_patchme: 221 b tsetup_sun4c_stackchk 222 andcc %sp, 0x7, %g0 223 224 /* Architecture specific stack checking routines. When either 225 * of these routines are called, the globals are free to use 226 * as they have been safely stashed on the new kernel stack 227 * pointer. Thus the definition below for simplicity. 228 */ 229#define glob_tmp g1 230 231tsetup_sun4c_stackchk: 232 /* Done by caller: andcc %sp, 0x7, %g0 */ 233 bne trap_setup_user_stack_is_bolixed 234 sra %sp, 29, %glob_tmp 235 236 add %glob_tmp, 0x1, %glob_tmp 237 andncc %glob_tmp, 0x1, %g0 238 bne trap_setup_user_stack_is_bolixed 239 and %sp, 0xfff, %glob_tmp ! delay slot 240 241 /* See if our dump area will be on more than one 242 * page. 243 */ 244 add %glob_tmp, 0x38, %glob_tmp 245 andncc %glob_tmp, 0xff8, %g0 246 be tsetup_sun4c_onepage ! only one page to check 247 lda [%sp] ASI_PTE, %glob_tmp ! have to check first page anyways 248 249tsetup_sun4c_twopages: 250 /* Is first page ok permission wise? */ 251 srl %glob_tmp, 29, %glob_tmp 252 cmp %glob_tmp, 0x6 253 bne trap_setup_user_stack_is_bolixed 254 add %sp, 0x38, %glob_tmp /* Is second page in vma hole? */ 255 256 sra %glob_tmp, 29, %glob_tmp 257 add %glob_tmp, 0x1, %glob_tmp 258 andncc %glob_tmp, 0x1, %g0 259 bne trap_setup_user_stack_is_bolixed 260 add %sp, 0x38, %glob_tmp 261 262 lda [%glob_tmp] ASI_PTE, %glob_tmp 263 264tsetup_sun4c_onepage: 265 srl %glob_tmp, 29, %glob_tmp 266 cmp %glob_tmp, 0x6 ! can user write to it? 267 bne trap_setup_user_stack_is_bolixed ! failure 268 nop 269 270 STORE_WINDOW(sp) 271 272 restore %g0, %g0, %g0 273 274 jmpl %t_retpc + 0x8, %g0 275 mov %t_kstack, %sp 276 277 .globl tsetup_srmmu_stackchk 278tsetup_srmmu_stackchk: 279 /* Check results of callers andcc %sp, 0x7, %g0 */ 280 bne trap_setup_user_stack_is_bolixed 281 sethi %hi(PAGE_OFFSET), %glob_tmp 282 283 cmp %glob_tmp, %sp 284 bleu,a 1f 285 lda [%g0] ASI_M_MMUREGS, %glob_tmp ! read MMU control 286 287trap_setup_user_stack_is_bolixed: 288 /* From user/kernel into invalid window w/bad user 289 * stack. Save bad user stack, and return to caller. 290 */ 291 SAVE_BOLIXED_USER_STACK(curptr, g3) 292 restore %g0, %g0, %g0 293 294 jmpl %t_retpc + 0x8, %g0 295 mov %t_kstack, %sp 296 2971: 298 /* Clear the fault status and turn on the no_fault bit. */ 299 or %glob_tmp, 0x2, %glob_tmp ! or in no_fault bit 300 sta %glob_tmp, [%g0] ASI_M_MMUREGS ! set it 301 302 /* Dump the registers and cross fingers. */ 303 STORE_WINDOW(sp) 304 305 /* Clear the no_fault bit and check the status. */ 306 andn %glob_tmp, 0x2, %glob_tmp 307 sta %glob_tmp, [%g0] ASI_M_MMUREGS 308 mov AC_M_SFAR, %glob_tmp 309 lda [%glob_tmp] ASI_M_MMUREGS, %g0 310 mov AC_M_SFSR, %glob_tmp 311 lda [%glob_tmp] ASI_M_MMUREGS, %glob_tmp ! save away status of winstore 312 andcc %glob_tmp, 0x2, %g0 ! did we fault? 313 bne trap_setup_user_stack_is_bolixed ! failure 314 nop 315 316 restore %g0, %g0, %g0 317 318 jmpl %t_retpc + 0x8, %g0 319 mov %t_kstack, %sp 320 321