1/* $Id: entry-common.S,v 1.1.1.1 2007/08/03 18:52:16 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 58 .align 2 59ENTRY(exception_error) 60 ! 61#ifdef CONFIG_TRACE_IRQFLAGS 62 mov.l 2f, r0 63 jsr @r0 64 nop 65#endif 66 sti 67 mov.l 1f, r0 68 jmp @r0 69 nop 70 71 .align 2 721: .long do_exception_error 73#ifdef CONFIG_TRACE_IRQFLAGS 742: .long trace_hardirqs_on 75#endif 76 77 .align 2 78ret_from_exception: 79 preempt_stop() 80#ifdef CONFIG_TRACE_IRQFLAGS 81 mov.l 4f, r0 82 jsr @r0 83 nop 84#endif 85ENTRY(ret_from_irq) 86 ! 87 mov #OFF_SR, r0 88 mov.l @(r0,r15), r0 ! get status register 89 shll r0 90 shll r0 ! kernel space? 91 get_current_thread_info r8, r0 92 bt resume_kernel ! Yes, it's from kernel, go back soon 93 94#ifdef CONFIG_PREEMPT 95 bra resume_userspace 96 nop 97ENTRY(resume_kernel) 98 mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count 99 tst r0, r0 100 bf noresched 101need_resched: 102 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 103 tst #_TIF_NEED_RESCHED, r0 ! need_resched set? 104 bt noresched 105 106 mov #OFF_SR, r0 107 mov.l @(r0,r15), r0 ! get status register 108 and #0xf0, r0 ! interrupts off (exception path)? 109 cmp/eq #0xf0, r0 110 bt noresched 111 112 mov.l 1f, r0 113 mov.l r0, @(TI_PRE_COUNT,r8) 114 115#ifdef CONFIG_TRACE_IRQFLAGS 116 mov.l 3f, r0 117 jsr @r0 118 nop 119#endif 120 sti 121 mov.l 2f, r0 122 jsr @r0 123 nop 124 mov #0, r0 125 mov.l r0, @(TI_PRE_COUNT,r8) 126 cli 127#ifdef CONFIG_TRACE_IRQFLAGS 128 mov.l 4f, r0 129 jsr @r0 130 nop 131#endif 132 133 bra need_resched 134 nop 135 136noresched: 137 bra __restore_all 138 nop 139 140 .align 2 1411: .long PREEMPT_ACTIVE 1422: .long schedule 143#ifdef CONFIG_TRACE_IRQFLAGS 1443: .long trace_hardirqs_on 1454: .long trace_hardirqs_off 146#endif 147#endif 148 149ENTRY(resume_userspace) 150 ! r8: current_thread_info 151 cli 152#ifdef CONFIG_TRACE_IRQFLAGS 153 mov.l 5f, r0 154 jsr @r0 155 nop 156#endif 157 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 158 tst #_TIF_WORK_MASK, r0 159 bt/s __restore_all 160 tst #_TIF_NEED_RESCHED, r0 161 162 .align 2 163work_pending: 164 ! r0: current_thread_info->flags 165 ! r8: current_thread_info 166 ! t: result of "tst #_TIF_NEED_RESCHED, r0" 167 bf/s work_resched 168 tst #(_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK), r0 169work_notifysig: 170 bt/s __restore_all 171 mov r15, r4 172 mov r12, r5 ! set arg1(save_r0) 173 mov r0, r6 174 mov.l 2f, r1 175 mov.l 3f, r0 176 jmp @r1 177 lds r0, pr 178work_resched: 179#ifndef CONFIG_PREEMPT 180 ! gUSA handling 181 mov.l @(OFF_SP,r15), r0 ! get user space stack pointer 182 mov r0, r1 183 shll r0 184 bf/s 1f 185 shll r0 186 bf/s 1f 187 mov #OFF_PC, r0 188 ! SP >= 0xc0000000 : gUSA mark 189 mov.l @(r0,r15), r2 ! get user space PC (program counter) 190 mov.l @(OFF_R0,r15), r3 ! end point 191 cmp/hs r3, r2 ! r2 >= r3? 192 bt 1f 193 add r3, r1 ! rewind point #2 194 mov.l r1, @(r0,r15) ! reset PC to rewind point #2 195 ! 1961: 197#endif 198 mov.l 1f, r1 199 jsr @r1 ! schedule 200 nop 201 cli 202#ifdef CONFIG_TRACE_IRQFLAGS 203 mov.l 5f, r0 204 jsr @r0 205 nop 206#endif 207 ! 208 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 209 tst #_TIF_WORK_MASK, r0 210 bt __restore_all 211 bra work_pending 212 tst #_TIF_NEED_RESCHED, r0 213 214 .align 2 2151: .long schedule 2162: .long do_notify_resume 2173: .long restore_all 218#ifdef CONFIG_TRACE_IRQFLAGS 2194: .long trace_hardirqs_on 2205: .long trace_hardirqs_off 221#endif 222 223 .align 2 224syscall_exit_work: 225 ! r0: current_thread_info->flags 226 ! r8: current_thread_info 227 tst #_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP, r0 228 bt/s work_pending 229 tst #_TIF_NEED_RESCHED, r0 230#ifdef CONFIG_TRACE_IRQFLAGS 231 mov.l 5f, r0 232 jsr @r0 233 nop 234#endif 235 sti 236 ! XXX setup arguments... 237 mov.l 4f, r0 ! do_syscall_trace 238 jsr @r0 239 nop 240 bra resume_userspace 241 nop 242 243 .align 2 244syscall_trace_entry: 245 ! Yes it is traced. 246 ! XXX setup arguments... 247 mov.l 4f, r11 ! Call do_syscall_trace which notifies 248 jsr @r11 ! superior (will chomp R[0-7]) 249 nop 250 ! Reload R0-R4 from kernel stack, where the 251 ! parent may have modified them using 252 ! ptrace(POKEUSR). (Note that R0-R2 are 253 ! used by the system call handler directly 254 ! from the kernel stack anyway, so don't need 255 ! to be reloaded here.) This allows the parent 256 ! to rewrite system calls and args on the fly. 257 mov.l @(OFF_R4,r15), r4 ! arg0 258 mov.l @(OFF_R5,r15), r5 259 mov.l @(OFF_R6,r15), r6 260 mov.l @(OFF_R7,r15), r7 ! arg3 261 mov.l @(OFF_R3,r15), r3 ! syscall_nr 262 ! 263 mov.l 2f, r10 ! Number of syscalls 264 cmp/hs r10, r3 265 bf syscall_call 266 mov #-ENOSYS, r0 267 bra syscall_exit 268 mov.l r0, @(OFF_R0,r15) ! Return value 269 270__restore_all: 271 mov.l 1f, r0 272 jmp @r0 273 nop 274 275 .align 2 2761: .long restore_all 277 278 .align 2 279syscall_badsys: ! Bad syscall number 280 mov #-ENOSYS, r0 281 bra resume_userspace 282 mov.l r0, @(OFF_R0,r15) ! Return value 283 284/* 285 * The main debug trap handler. 286 * 287 * r8=TRA (not the trap number!) 288 * 289 * Note: This assumes that the trapa value is left in its original 290 * form (without the shlr2 shift) so the calculation for the jump 291 * call table offset remains a simple in place mask. 292 */ 293debug_trap: 294 mov r8, r0 295 and #(0xf << 2), r0 296 mov.l 1f, r8 297 add r0, r8 298 mov.l @r8, r8 299 jmp @r8 300 nop 301 302 .align 2 3031: .long debug_trap_table 304 305/* 306 * Syscall interface: 307 * 308 * Syscall #: R3 309 * Arguments #0 to #3: R4--R7 310 * Arguments #4 to #6: R0, R1, R2 311 * TRA: (number of arguments + ABI revision) x 4 312 * 313 * This code also handles delegating other traps to the BIOS/gdb stub 314 * according to: 315 * 316 * Trap number 317 * (TRA>>2) Purpose 318 * -------- ------- 319 * 0x00-0x0f original SH-3/4 syscall ABI (not in general use). 320 * 0x10-0x1f general SH-3/4 syscall ABI. 321 * 0x20-0x2f syscall ABI for SH-2 parts. 322 * 0x30-0x3f debug traps used by the kernel. 323 * 0x40-0xff Not supported by all parts, so left unhandled. 324 * 325 * Note: When we're first called, the TRA value must be shifted 326 * right 2 bits in order to get the value that was used as the "trapa" 327 * argument. 328 */ 329 330 .align 2 331 .globl ret_from_fork 332ret_from_fork: 333 mov.l 1f, r8 334 jsr @r8 335 mov r0, r4 336 bra syscall_exit 337 nop 338 .align 2 3391: .long schedule_tail 340 341/* 342 * The poorly named main trapa decode and dispatch routine, for 343 * system calls and debug traps through their respective jump tables. 344 */ 345ENTRY(system_call) 346#if !defined(CONFIG_CPU_SH2) 347 mov.l 1f, r9 348 mov.l @r9, r8 ! Read from TRA (Trap Address) Register 349#endif 350 /* 351 * Check the trap type 352 */ 353 mov #((0x20 << 2) - 1), r9 354 cmp/hi r9, r8 355 bt/s debug_trap ! it's a debug trap.. 356 mov #OFF_TRA, r9 357 add r15, r9 358 mov.l r8, @r9 ! set TRA value to tra 359#ifdef CONFIG_TRACE_IRQFLAGS 360 mov.l 5f, r10 361 jsr @r10 362 nop 363#endif 364 sti 365 366 ! 367 get_current_thread_info r8, r10 368 mov.l @(TI_FLAGS,r8), r8 369 mov #_TIF_SYSCALL_TRACE, r10 370 tst r10, r8 371 bf syscall_trace_entry 372 ! 373 mov.l 2f, r8 ! Number of syscalls 374 cmp/hs r8, r3 375 bt syscall_badsys 376 ! 377syscall_call: 378 shll2 r3 ! x4 379 mov.l 3f, r8 ! Load the address of sys_call_table 380 add r8, r3 381 mov.l @r3, r8 382 jsr @r8 ! jump to specific syscall handler 383 nop 384 mov.l @(OFF_R0,r15), r12 ! save r0 385 mov.l r0, @(OFF_R0,r15) ! save the return value 386 ! 387syscall_exit: 388 cli 389#ifdef CONFIG_TRACE_IRQFLAGS 390 mov.l 6f, r0 391 jsr @r0 392 nop 393#endif 394 ! 395 get_current_thread_info r8, r0 396 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 397 tst #_TIF_ALLWORK_MASK, r0 398 bf syscall_exit_work 399 bra __restore_all 400 nop 401 .align 2 402#if !defined(CONFIG_CPU_SH2) 4031: .long TRA 404#endif 4052: .long NR_syscalls 4063: .long sys_call_table 4074: .long do_syscall_trace 408#ifdef CONFIG_TRACE_IRQFLAGS 4095: .long trace_hardirqs_on 4106: .long trace_hardirqs_off 411#endif 412