Yoshinori Sato | de39840 | 2006-11-05 16:15:19 +0900 | [diff] [blame] | 1 | /* $Id: entry.S,v 1.37 2004/06/11 13:02:46 doyu Exp $ |
| 2 | * |
| 3 | * linux/arch/sh/entry.S |
| 4 | * |
| 5 | * Copyright (C) 1999, 2000, 2002 Niibe Yutaka |
| 6 | * Copyright (C) 2003 Paul Mundt |
| 7 | * |
| 8 | * This file is subject to the terms and conditions of the GNU General Public |
| 9 | * License. See the file "COPYING" in the main directory of this archive |
| 10 | * for more details. |
| 11 | * |
| 12 | */ |
| 13 | |
| 14 | ! NOTE: |
| 15 | ! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address |
| 16 | ! to be jumped is too far, but it causes illegal slot exception. |
| 17 | |
| 18 | /* |
| 19 | * entry.S contains the system-call and fault low-level handling routines. |
| 20 | * This also contains the timer-interrupt handler, as well as all interrupts |
| 21 | * and faults that can result in a task-switch. |
| 22 | * |
| 23 | * NOTE: This code handles signal-recognition, which happens every time |
| 24 | * after a timer-interrupt and after each system call. |
| 25 | * |
| 26 | * NOTE: This code uses a convention that instructions in the delay slot |
| 27 | * of a transfer-control instruction are indented by an extra space, thus: |
| 28 | * |
| 29 | * jmp @k0 ! control-transfer instruction |
| 30 | * ldc k1, ssr ! delay slot |
| 31 | * |
| 32 | * Stack layout in 'ret_from_syscall': |
| 33 | * ptrace needs to have all regs on the stack. |
| 34 | * if the order here is changed, it needs to be |
| 35 | * updated in ptrace.c and ptrace.h |
| 36 | * |
| 37 | * r0 |
| 38 | * ... |
| 39 | * r15 = stack pointer |
| 40 | * spc |
| 41 | * pr |
| 42 | * ssr |
| 43 | * gbr |
| 44 | * mach |
| 45 | * macl |
| 46 | * syscall # |
| 47 | * |
| 48 | */ |
| 49 | |
| 50 | #if defined(CONFIG_PREEMPT) |
| 51 | # define preempt_stop() cli |
| 52 | #else |
| 53 | # define preempt_stop() |
| 54 | # define resume_kernel __restore_all |
| 55 | #endif |
| 56 | |
| 57 | #if defined(CONFIG_SH_STANDARD_BIOS) || defined(CONFIG_SH_KGDB) |
| 58 | ! Handle kernel debug if either kgdb (SW) or gdb-stub (FW) is present. |
| 59 | ! If both are configured, handle the debug traps (breakpoints) in SW, |
| 60 | ! but still allow BIOS traps to FW. |
| 61 | |
| 62 | .align 2 |
| 63 | debug_kernel: |
| 64 | #if defined(CONFIG_SH_STANDARD_BIOS) && defined(CONFIG_SH_KGDB) |
| 65 | /* Force BIOS call to FW (debug_trap put TRA in r8) */ |
| 66 | mov r8,r0 |
| 67 | shlr2 r0 |
| 68 | cmp/eq #0x3f,r0 |
| 69 | bt debug_kernel_fw |
| 70 | #endif /* CONFIG_SH_STANDARD_BIOS && CONFIG_SH_KGDB */ |
| 71 | |
| 72 | debug_enter: |
| 73 | #if defined(CONFIG_SH_KGDB) |
| 74 | /* Jump to kgdb, pass stacked regs as arg */ |
| 75 | debug_kernel_sw: |
| 76 | mov.l 3f, r0 |
| 77 | jmp @r0 |
| 78 | mov r15, r4 |
| 79 | .align 2 |
| 80 | 3: .long kgdb_handle_exception |
| 81 | #endif /* CONFIG_SH_KGDB */ |
| 82 | |
| 83 | #endif /* CONFIG_SH_STANDARD_BIOS || CONFIG_SH_KGDB */ |
| 84 | |
| 85 | |
| 86 | .align 2 |
| 87 | debug_trap: |
| 88 | #if defined(CONFIG_SH_STANDARD_BIOS) || defined(CONFIG_SH_KGDB) |
| 89 | mov #OFF_SR, r0 |
| 90 | mov.l @(r0,r15), r0 ! get status register |
| 91 | shll r0 |
| 92 | shll r0 ! kernel space? |
| 93 | bt/s debug_kernel |
| 94 | #endif |
| 95 | mov.l @r15, r0 ! Restore R0 value |
| 96 | mov.l 1f, r8 |
| 97 | jmp @r8 |
| 98 | nop |
| 99 | |
| 100 | .align 2 |
| 101 | ENTRY(exception_error) |
| 102 | ! |
| 103 | sti |
| 104 | mov.l 2f, r0 |
| 105 | jmp @r0 |
| 106 | nop |
| 107 | |
| 108 | ! |
| 109 | .align 2 |
| 110 | 1: .long break_point_trap_software |
| 111 | 2: .long do_exception_error |
| 112 | |
| 113 | .align 2 |
| 114 | ret_from_exception: |
| 115 | preempt_stop() |
| 116 | ENTRY(ret_from_irq) |
| 117 | ! |
| 118 | mov #OFF_SR, r0 |
| 119 | mov.l @(r0,r15), r0 ! get status register |
| 120 | shll r0 |
| 121 | shll r0 ! kernel space? |
| 122 | get_current_thread_info r8, r0 |
| 123 | bt resume_kernel ! Yes, it's from kernel, go back soon |
| 124 | |
| 125 | #ifdef CONFIG_PREEMPT |
| 126 | bra resume_userspace |
| 127 | nop |
| 128 | ENTRY(resume_kernel) |
| 129 | mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count |
| 130 | tst r0, r0 |
| 131 | bf noresched |
| 132 | need_resched: |
| 133 | mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags |
| 134 | tst #_TIF_NEED_RESCHED, r0 ! need_resched set? |
| 135 | bt noresched |
| 136 | |
| 137 | mov #OFF_SR, r0 |
| 138 | mov.l @(r0,r15), r0 ! get status register |
| 139 | and #0xf0, r0 ! interrupts off (exception path)? |
| 140 | cmp/eq #0xf0, r0 |
| 141 | bt noresched |
| 142 | |
| 143 | mov.l 1f, r0 |
| 144 | mov.l r0, @(TI_PRE_COUNT,r8) |
| 145 | |
| 146 | sti |
| 147 | mov.l 2f, r0 |
| 148 | jsr @r0 |
| 149 | nop |
| 150 | mov #0, r0 |
| 151 | mov.l r0, @(TI_PRE_COUNT,r8) |
| 152 | cli |
| 153 | |
| 154 | bra need_resched |
| 155 | nop |
| 156 | noresched: |
| 157 | bra __restore_all |
| 158 | nop |
| 159 | |
| 160 | .align 2 |
| 161 | 1: .long PREEMPT_ACTIVE |
| 162 | 2: .long schedule |
| 163 | #endif |
| 164 | |
| 165 | ENTRY(resume_userspace) |
| 166 | ! r8: current_thread_info |
| 167 | cli |
| 168 | mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags |
| 169 | tst #_TIF_WORK_MASK, r0 |
| 170 | bt/s __restore_all |
| 171 | tst #_TIF_NEED_RESCHED, r0 |
| 172 | |
| 173 | .align 2 |
| 174 | work_pending: |
| 175 | ! r0: current_thread_info->flags |
| 176 | ! r8: current_thread_info |
| 177 | ! t: result of "tst #_TIF_NEED_RESCHED, r0" |
| 178 | bf/s work_resched |
| 179 | tst #(_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK), r0 |
| 180 | work_notifysig: |
| 181 | bt/s __restore_all |
| 182 | mov r15, r4 |
| 183 | mov r12, r5 ! set arg1(save_r0) |
| 184 | mov r0, r6 |
| 185 | mov.l 2f, r1 |
| 186 | mov.l 3f, r0 |
| 187 | jmp @r1 |
| 188 | lds r0, pr |
| 189 | work_resched: |
| 190 | #ifndef CONFIG_PREEMPT |
| 191 | ! gUSA handling |
| 192 | mov.l @(OFF_SP,r15), r0 ! get user space stack pointer |
| 193 | mov r0, r1 |
| 194 | shll r0 |
| 195 | bf/s 1f |
| 196 | shll r0 |
| 197 | bf/s 1f |
| 198 | mov #OFF_PC, r0 |
| 199 | ! SP >= 0xc0000000 : gUSA mark |
| 200 | mov.l @(r0,r15), r2 ! get user space PC (program counter) |
| 201 | mov.l @(OFF_R0,r15), r3 ! end point |
| 202 | cmp/hs r3, r2 ! r2 >= r3? |
| 203 | bt 1f |
| 204 | add r3, r1 ! rewind point #2 |
| 205 | mov.l r1, @(r0,r15) ! reset PC to rewind point #2 |
| 206 | ! |
| 207 | 1: |
| 208 | #endif |
| 209 | mov.l 1f, r1 |
| 210 | jsr @r1 ! schedule |
| 211 | nop |
| 212 | cli |
| 213 | ! |
| 214 | mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags |
| 215 | tst #_TIF_WORK_MASK, r0 |
| 216 | bt __restore_all |
| 217 | bra work_pending |
| 218 | tst #_TIF_NEED_RESCHED, r0 |
| 219 | |
| 220 | .align 2 |
| 221 | 1: .long schedule |
| 222 | 2: .long do_notify_resume |
| 223 | 3: .long restore_all |
| 224 | |
| 225 | .align 2 |
| 226 | syscall_exit_work: |
| 227 | ! r0: current_thread_info->flags |
| 228 | ! r8: current_thread_info |
| 229 | tst #_TIF_SYSCALL_TRACE, r0 |
| 230 | bt/s work_pending |
| 231 | tst #_TIF_NEED_RESCHED, r0 |
| 232 | sti |
| 233 | ! XXX setup arguments... |
| 234 | mov.l 4f, r0 ! do_syscall_trace |
| 235 | jsr @r0 |
| 236 | nop |
| 237 | bra resume_userspace |
| 238 | nop |
| 239 | |
| 240 | .align 2 |
| 241 | syscall_trace_entry: |
| 242 | ! Yes it is traced. |
| 243 | ! XXX setup arguments... |
| 244 | mov.l 4f, r11 ! Call do_syscall_trace which notifies |
| 245 | jsr @r11 ! superior (will chomp R[0-7]) |
| 246 | nop |
| 247 | ! Reload R0-R4 from kernel stack, where the |
| 248 | ! parent may have modified them using |
| 249 | ! ptrace(POKEUSR). (Note that R0-R2 are |
| 250 | ! used by the system call handler directly |
| 251 | ! from the kernel stack anyway, so don't need |
| 252 | ! to be reloaded here.) This allows the parent |
| 253 | ! to rewrite system calls and args on the fly. |
| 254 | mov.l @(OFF_R4,r15), r4 ! arg0 |
| 255 | mov.l @(OFF_R5,r15), r5 |
| 256 | mov.l @(OFF_R6,r15), r6 |
| 257 | mov.l @(OFF_R7,r15), r7 ! arg3 |
| 258 | mov.l @(OFF_R3,r15), r3 ! syscall_nr |
Stuart Menefy | e0969e0 | 2006-11-24 13:01:36 +0900 | [diff] [blame] | 259 | ! |
Yoshinori Sato | de39840 | 2006-11-05 16:15:19 +0900 | [diff] [blame] | 260 | mov.l 2f, r10 ! Number of syscalls |
| 261 | cmp/hs r10, r3 |
| 262 | bf syscall_call |
| 263 | mov #-ENOSYS, r0 |
| 264 | bra syscall_exit |
| 265 | mov.l r0, @(OFF_R0,r15) ! Return value |
| 266 | |
| 267 | __restore_all: |
| 268 | mov.l 1f,r0 |
| 269 | jmp @r0 |
| 270 | nop |
| 271 | |
| 272 | .align 2 |
| 273 | 1: .long restore_all |
| 274 | |
Stuart Menefy | e0969e0 | 2006-11-24 13:01:36 +0900 | [diff] [blame] | 275 | .align 2 |
| 276 | not_syscall_tra: |
| 277 | bra debug_trap |
| 278 | nop |
| 279 | |
| 280 | .align 2 |
| 281 | syscall_badsys: ! Bad syscall number |
| 282 | mov #-ENOSYS, r0 |
| 283 | bra resume_userspace |
| 284 | mov.l r0, @(OFF_R0,r15) ! Return value |
| 285 | |
| 286 | |
Yoshinori Sato | de39840 | 2006-11-05 16:15:19 +0900 | [diff] [blame] | 287 | /* |
| 288 | * Syscall interface: |
| 289 | * |
| 290 | * Syscall #: R3 |
| 291 | * Arguments #0 to #3: R4--R7 |
| 292 | * Arguments #4 to #6: R0, R1, R2 |
| 293 | * TRA: (number of arguments + 0x10) x 4 |
| 294 | * |
| 295 | * This code also handles delegating other traps to the BIOS/gdb stub |
| 296 | * according to: |
| 297 | * |
| 298 | * Trap number |
| 299 | * (TRA>>2) Purpose |
| 300 | * -------- ------- |
| 301 | * 0x0-0xf old syscall ABI |
| 302 | * 0x10-0x1f new syscall ABI |
| 303 | * 0x20-0xff delegated through debug_trap to BIOS/gdb stub. |
| 304 | * |
| 305 | * Note: When we're first called, the TRA value must be shifted |
| 306 | * right 2 bits in order to get the value that was used as the "trapa" |
| 307 | * argument. |
| 308 | */ |
| 309 | |
| 310 | .align 2 |
| 311 | .globl ret_from_fork |
| 312 | ret_from_fork: |
| 313 | mov.l 1f, r8 |
| 314 | jsr @r8 |
| 315 | mov r0, r4 |
| 316 | bra syscall_exit |
| 317 | nop |
| 318 | .align 2 |
| 319 | 1: .long schedule_tail |
| 320 | ! |
| 321 | ENTRY(system_call) |
| 322 | #if !defined(CONFIG_CPU_SH2) |
| 323 | mov.l 1f, r9 |
| 324 | mov.l @r9, r8 ! Read from TRA (Trap Address) Register |
| 325 | #endif |
| 326 | ! |
| 327 | ! Is the trap argument >= 0x20? (TRA will be >= 0x80) |
| 328 | mov #0x7f, r9 |
| 329 | cmp/hi r9, r8 |
Stuart Menefy | e0969e0 | 2006-11-24 13:01:36 +0900 | [diff] [blame] | 330 | bt/s not_syscall_tra |
Yoshinori Sato | de39840 | 2006-11-05 16:15:19 +0900 | [diff] [blame] | 331 | mov #OFF_TRA, r9 |
| 332 | add r15, r9 |
Yoshinori Sato | de39840 | 2006-11-05 16:15:19 +0900 | [diff] [blame] | 333 | mov.l r8, @r9 ! set TRA value to tra |
| 334 | sti |
Stuart Menefy | e0969e0 | 2006-11-24 13:01:36 +0900 | [diff] [blame] | 335 | ! |
Yoshinori Sato | de39840 | 2006-11-05 16:15:19 +0900 | [diff] [blame] | 336 | get_current_thread_info r8, r10 |
Yoshinori Sato | de39840 | 2006-11-05 16:15:19 +0900 | [diff] [blame] | 337 | mov.l @(TI_FLAGS,r8), r8 |
| 338 | mov #_TIF_SYSCALL_TRACE, r10 |
| 339 | tst r10, r8 |
| 340 | bf syscall_trace_entry |
| 341 | ! |
Stuart Menefy | e0969e0 | 2006-11-24 13:01:36 +0900 | [diff] [blame] | 342 | mov.l 2f, r8 ! Number of syscalls |
| 343 | cmp/hs r8, r3 |
| 344 | bt syscall_badsys |
| 345 | ! |
Yoshinori Sato | de39840 | 2006-11-05 16:15:19 +0900 | [diff] [blame] | 346 | syscall_call: |
Stuart Menefy | e0969e0 | 2006-11-24 13:01:36 +0900 | [diff] [blame] | 347 | shll2 r3 ! x4 |
Yoshinori Sato | de39840 | 2006-11-05 16:15:19 +0900 | [diff] [blame] | 348 | mov.l 3f, r8 ! Load the address of sys_call_table |
Stuart Menefy | e0969e0 | 2006-11-24 13:01:36 +0900 | [diff] [blame] | 349 | add r8, r3 |
| 350 | mov.l @r3, r8 |
Yoshinori Sato | de39840 | 2006-11-05 16:15:19 +0900 | [diff] [blame] | 351 | jsr @r8 ! jump to specific syscall handler |
| 352 | nop |
| 353 | mov.l @(OFF_R0,r15), r12 ! save r0 |
| 354 | mov.l r0, @(OFF_R0,r15) ! save the return value |
| 355 | ! |
| 356 | syscall_exit: |
| 357 | cli |
| 358 | ! |
| 359 | get_current_thread_info r8, r0 |
| 360 | mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags |
| 361 | tst #_TIF_ALLWORK_MASK, r0 |
| 362 | bf syscall_exit_work |
| 363 | bra __restore_all |
| 364 | nop |
| 365 | .align 2 |
| 366 | #if !defined(CONFIG_CPU_SH2) |
| 367 | 1: .long TRA |
| 368 | #endif |
| 369 | 2: .long NR_syscalls |
| 370 | 3: .long sys_call_table |
| 371 | 4: .long do_syscall_trace |