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 63debug_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 72debug_enter: 73#if defined(CONFIG_SH_KGDB) 74 /* Jump to kgdb, pass stacked regs as arg */ 75debug_kernel_sw: 76 mov.l 3f, r0 77 jmp @r0 78 mov r15, r4 79 .align 2 803: .long kgdb_handle_exception 81#endif /* CONFIG_SH_KGDB */ 82 83#endif /* CONFIG_SH_STANDARD_BIOS || CONFIG_SH_KGDB */ 84 85 86 .align 2 87debug_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 101ENTRY(exception_error) 102 ! 103#ifdef CONFIG_TRACE_IRQFLAGS 104 mov.l 3f, r0 105 jsr @r0 106 nop 107#endif 108 sti 109 mov.l 2f, r0 110 jmp @r0 111 nop 112 113! 114 .align 2 1151: .long break_point_trap_software 1162: .long do_exception_error 117#ifdef CONFIG_TRACE_IRQFLAGS 1183: .long trace_hardirqs_on 119#endif 120 121 .align 2 122ret_from_exception: 123 preempt_stop() 124#ifdef CONFIG_TRACE_IRQFLAGS 125 mov.l 4f, r0 126 jsr @r0 127 nop 128#endif 129ENTRY(ret_from_irq) 130 ! 131 mov #OFF_SR, r0 132 mov.l @(r0,r15), r0 ! get status register 133 shll r0 134 shll r0 ! kernel space? 135 get_current_thread_info r8, r0 136 bt resume_kernel ! Yes, it's from kernel, go back soon 137 138#ifdef CONFIG_PREEMPT 139 bra resume_userspace 140 nop 141ENTRY(resume_kernel) 142 mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count 143 tst r0, r0 144 bf noresched 145need_resched: 146 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 147 tst #_TIF_NEED_RESCHED, r0 ! need_resched set? 148 bt noresched 149 150 mov #OFF_SR, r0 151 mov.l @(r0,r15), r0 ! get status register 152 and #0xf0, r0 ! interrupts off (exception path)? 153 cmp/eq #0xf0, r0 154 bt noresched 155 156 mov.l 1f, r0 157 mov.l r0, @(TI_PRE_COUNT,r8) 158 159#ifdef CONFIG_TRACE_IRQFLAGS 160 mov.l 3f, r0 161 jsr @r0 162 nop 163#endif 164 sti 165 mov.l 2f, r0 166 jsr @r0 167 nop 168 mov #0, r0 169 mov.l r0, @(TI_PRE_COUNT,r8) 170 cli 171#ifdef CONFIG_TRACE_IRQFLAGS 172 mov.l 4f, r0 173 jsr @r0 174 nop 175#endif 176 177 bra need_resched 178 nop 179 180noresched: 181 bra __restore_all 182 nop 183 184 .align 2 1851: .long PREEMPT_ACTIVE 1862: .long schedule 187#ifdef CONFIG_TRACE_IRQFLAGS 1883: .long trace_hardirqs_on 1894: .long trace_hardirqs_off 190#endif 191#endif 192 193ENTRY(resume_userspace) 194 ! r8: current_thread_info 195 cli 196#ifdef CONFIG_TRACE_IRQFLAGS 197 mov.l 5f, r0 198 jsr @r0 199 nop 200#endif 201 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 202 tst #_TIF_WORK_MASK, r0 203 bt/s __restore_all 204 tst #_TIF_NEED_RESCHED, r0 205 206 .align 2 207work_pending: 208 ! r0: current_thread_info->flags 209 ! r8: current_thread_info 210 ! t: result of "tst #_TIF_NEED_RESCHED, r0" 211 bf/s work_resched 212 tst #(_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK), r0 213work_notifysig: 214 bt/s __restore_all 215 mov r15, r4 216 mov r12, r5 ! set arg1(save_r0) 217 mov r0, r6 218 mov.l 2f, r1 219 mov.l 3f, r0 220 jmp @r1 221 lds r0, pr 222work_resched: 223#ifndef CONFIG_PREEMPT 224 ! gUSA handling 225 mov.l @(OFF_SP,r15), r0 ! get user space stack pointer 226 mov r0, r1 227 shll r0 228 bf/s 1f 229 shll r0 230 bf/s 1f 231 mov #OFF_PC, r0 232 ! SP >= 0xc0000000 : gUSA mark 233 mov.l @(r0,r15), r2 ! get user space PC (program counter) 234 mov.l @(OFF_R0,r15), r3 ! end point 235 cmp/hs r3, r2 ! r2 >= r3? 236 bt 1f 237 add r3, r1 ! rewind point #2 238 mov.l r1, @(r0,r15) ! reset PC to rewind point #2 239 ! 2401: 241#endif 242 mov.l 1f, r1 243 jsr @r1 ! schedule 244 nop 245 cli 246#ifdef CONFIG_TRACE_IRQFLAGS 247 mov.l 5f, r0 248 jsr @r0 249 nop 250#endif 251 ! 252 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 253 tst #_TIF_WORK_MASK, r0 254 bt __restore_all 255 bra work_pending 256 tst #_TIF_NEED_RESCHED, r0 257 258 .align 2 2591: .long schedule 2602: .long do_notify_resume 2613: .long restore_all 262#ifdef CONFIG_TRACE_IRQFLAGS 2634: .long trace_hardirqs_on 2645: .long trace_hardirqs_off 265#endif 266 267 .align 2 268syscall_exit_work: 269 ! r0: current_thread_info->flags 270 ! r8: current_thread_info 271 tst #_TIF_SYSCALL_TRACE, r0 272 bt/s work_pending 273 tst #_TIF_NEED_RESCHED, r0 274#ifdef CONFIG_TRACE_IRQFLAGS 275 mov.l 5f, r0 276 jsr @r0 277 nop 278#endif 279 sti 280 ! XXX setup arguments... 281 mov.l 4f, r0 ! do_syscall_trace 282 jsr @r0 283 nop 284 bra resume_userspace 285 nop 286 287 .align 2 288syscall_trace_entry: 289 ! Yes it is traced. 290 ! XXX setup arguments... 291 mov.l 4f, r11 ! Call do_syscall_trace which notifies 292 jsr @r11 ! superior (will chomp R[0-7]) 293 nop 294 ! Reload R0-R4 from kernel stack, where the 295 ! parent may have modified them using 296 ! ptrace(POKEUSR). (Note that R0-R2 are 297 ! used by the system call handler directly 298 ! from the kernel stack anyway, so don't need 299 ! to be reloaded here.) This allows the parent 300 ! to rewrite system calls and args on the fly. 301 mov.l @(OFF_R4,r15), r4 ! arg0 302 mov.l @(OFF_R5,r15), r5 303 mov.l @(OFF_R6,r15), r6 304 mov.l @(OFF_R7,r15), r7 ! arg3 305 mov.l @(OFF_R3,r15), r3 ! syscall_nr 306 ! 307 mov.l 2f, r10 ! Number of syscalls 308 cmp/hs r10, r3 309 bf syscall_call 310 mov #-ENOSYS, r0 311 bra syscall_exit 312 mov.l r0, @(OFF_R0,r15) ! Return value 313 314__restore_all: 315 mov.l 1f, r0 316 jmp @r0 317 nop 318 319 .align 2 3201: .long restore_all 321 322 .align 2 323not_syscall_tra: 324 bra debug_trap 325 nop 326 327 .align 2 328syscall_badsys: ! Bad syscall number 329 mov #-ENOSYS, r0 330 bra resume_userspace 331 mov.l r0, @(OFF_R0,r15) ! Return value 332 333 334/* 335 * Syscall interface: 336 * 337 * Syscall #: R3 338 * Arguments #0 to #3: R4--R7 339 * Arguments #4 to #6: R0, R1, R2 340 * TRA: (number of arguments + 0x10) x 4 341 * 342 * This code also handles delegating other traps to the BIOS/gdb stub 343 * according to: 344 * 345 * Trap number 346 * (TRA>>2) Purpose 347 * -------- ------- 348 * 0x0-0xf old syscall ABI 349 * 0x10-0x1f new syscall ABI 350 * 0x20-0xff delegated through debug_trap to BIOS/gdb stub. 351 * 352 * Note: When we're first called, the TRA value must be shifted 353 * right 2 bits in order to get the value that was used as the "trapa" 354 * argument. 355 */ 356 357 .align 2 358 .globl ret_from_fork 359ret_from_fork: 360 mov.l 1f, r8 361 jsr @r8 362 mov r0, r4 363 bra syscall_exit 364 nop 365 .align 2 3661: .long schedule_tail 367 ! 368ENTRY(system_call) 369#if !defined(CONFIG_CPU_SH2) 370 mov.l 1f, r9 371 mov.l @r9, r8 ! Read from TRA (Trap Address) Register 372#endif 373 ! 374 ! Is the trap argument >= 0x20? (TRA will be >= 0x80) 375 mov #0x7f, r9 376 cmp/hi r9, r8 377 bt/s not_syscall_tra 378 mov #OFF_TRA, r9 379 add r15, r9 380 mov.l r8, @r9 ! set TRA value to tra 381#ifdef CONFIG_TRACE_IRQFLAGS 382 mov.l 5f, r10 383 jsr @r10 384 nop 385#endif 386 sti 387 388 ! 389 get_current_thread_info r8, r10 390 mov.l @(TI_FLAGS,r8), r8 391 mov #_TIF_SYSCALL_TRACE, r10 392 tst r10, r8 393 bf syscall_trace_entry 394 ! 395 mov.l 2f, r8 ! Number of syscalls 396 cmp/hs r8, r3 397 bt syscall_badsys 398 ! 399syscall_call: 400 shll2 r3 ! x4 401 mov.l 3f, r8 ! Load the address of sys_call_table 402 add r8, r3 403 mov.l @r3, r8 404 jsr @r8 ! jump to specific syscall handler 405 nop 406 mov.l @(OFF_R0,r15), r12 ! save r0 407 mov.l r0, @(OFF_R0,r15) ! save the return value 408 ! 409syscall_exit: 410 cli 411#ifdef CONFIG_TRACE_IRQFLAGS 412 mov.l 6f, r0 413 jsr @r0 414 nop 415#endif 416 ! 417 get_current_thread_info r8, r0 418 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 419 tst #_TIF_ALLWORK_MASK, r0 420 bf syscall_exit_work 421 bra __restore_all 422 nop 423 .align 2 424#if !defined(CONFIG_CPU_SH2) 4251: .long TRA 426#endif 4272: .long NR_syscalls 4283: .long sys_call_table 4294: .long do_syscall_trace 430#ifdef CONFIG_TRACE_IRQFLAGS 4315: .long trace_hardirqs_on 4326: .long trace_hardirqs_off 433#endif 434