1/* 2 * Copyright (C) 1999, 2000, 2002 Niibe Yutaka 3 * Copyright (C) 2003 - 2008 Paul Mundt 4 * 5 * This file is subject to the terms and conditions of the GNU General Public 6 * License. See the file "COPYING" in the main directory of this archive 7 * for more details. 8 * 9 */ 10 11! NOTE: 12! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address 13! to be jumped is too far, but it causes illegal slot exception. 14 15/* 16 * entry.S contains the system-call and fault low-level handling routines. 17 * This also contains the timer-interrupt handler, as well as all interrupts 18 * and faults that can result in a task-switch. 19 * 20 * NOTE: This code handles signal-recognition, which happens every time 21 * after a timer-interrupt and after each system call. 22 * 23 * NOTE: This code uses a convention that instructions in the delay slot 24 * of a transfer-control instruction are indented by an extra space, thus: 25 * 26 * jmp @k0 ! control-transfer instruction 27 * ldc k1, ssr ! delay slot 28 * 29 * Stack layout in 'ret_from_syscall': 30 * ptrace needs to have all regs on the stack. 31 * if the order here is changed, it needs to be 32 * updated in ptrace.c and ptrace.h 33 * 34 * r0 35 * ... 36 * r15 = stack pointer 37 * spc 38 * pr 39 * ssr 40 * gbr 41 * mach 42 * macl 43 * syscall # 44 * 45 */ 46 47#if defined(CONFIG_PREEMPT) 48# define preempt_stop() cli 49#else 50# define preempt_stop() 51# define resume_kernel __restore_all 52#endif 53 54 55 .align 2 56ENTRY(exception_error) 57 ! 58#ifdef CONFIG_TRACE_IRQFLAGS 59 mov.l 2f, r0 60 jsr @r0 61 nop 62#endif 63 sti 64 mov.l 1f, r0 65 jmp @r0 66 nop 67 68 .align 2 691: .long do_exception_error 70#ifdef CONFIG_TRACE_IRQFLAGS 712: .long trace_hardirqs_on 72#endif 73 74 .align 2 75ret_from_exception: 76 preempt_stop() 77#ifdef CONFIG_TRACE_IRQFLAGS 78 mov.l 4f, r0 79 jsr @r0 80 nop 81#endif 82ENTRY(ret_from_irq) 83 ! 84 mov #OFF_SR, r0 85 mov.l @(r0,r15), r0 ! get status register 86 shll r0 87 shll r0 ! kernel space? 88 get_current_thread_info r8, r0 89 bt resume_kernel ! Yes, it's from kernel, go back soon 90 91#ifdef CONFIG_PREEMPT 92 bra resume_userspace 93 nop 94ENTRY(resume_kernel) 95 mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count 96 tst r0, r0 97 bf noresched 98need_resched: 99 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 100 tst #_TIF_NEED_RESCHED, r0 ! need_resched set? 101 bt noresched 102 103 mov #OFF_SR, r0 104 mov.l @(r0,r15), r0 ! get status register 105 and #0xf0, r0 ! interrupts off (exception path)? 106 cmp/eq #0xf0, r0 107 bt noresched 108 109 mov.l 1f, r0 110 mov.l r0, @(TI_PRE_COUNT,r8) 111 112#ifdef CONFIG_TRACE_IRQFLAGS 113 mov.l 3f, r0 114 jsr @r0 115 nop 116#endif 117 sti 118 mov.l 2f, r0 119 jsr @r0 120 nop 121 mov #0, r0 122 mov.l r0, @(TI_PRE_COUNT,r8) 123 cli 124#ifdef CONFIG_TRACE_IRQFLAGS 125 mov.l 4f, r0 126 jsr @r0 127 nop 128#endif 129 130 bra need_resched 131 nop 132 133noresched: 134 bra __restore_all 135 nop 136 137 .align 2 1381: .long PREEMPT_ACTIVE 1392: .long schedule 140#ifdef CONFIG_TRACE_IRQFLAGS 1413: .long trace_hardirqs_on 1424: .long trace_hardirqs_off 143#endif 144#endif 145 146ENTRY(resume_userspace) 147 ! r8: current_thread_info 148 cli 149#ifdef CONFIG_TRACE_IRQFLAGS 150 mov.l 5f, r0 151 jsr @r0 152 nop 153#endif 154 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 155 tst #_TIF_WORK_MASK, r0 156 bt/s __restore_all 157 tst #_TIF_NEED_RESCHED, r0 158 159 .align 2 160work_pending: 161 ! r0: current_thread_info->flags 162 ! r8: current_thread_info 163 ! t: result of "tst #_TIF_NEED_RESCHED, r0" 164 bf/s work_resched 165 tst #(_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK), r0 166work_notifysig: 167 bt/s __restore_all 168 mov r15, r4 169 mov r12, r5 ! set arg1(save_r0) 170 mov r0, r6 171 mov.l 2f, r1 172 mov.l 3f, r0 173 jmp @r1 174 lds r0, pr 175work_resched: 176 mov.l 1f, r1 177 jsr @r1 ! schedule 178 nop 179 cli 180#ifdef CONFIG_TRACE_IRQFLAGS 181 mov.l 5f, r0 182 jsr @r0 183 nop 184#endif 185 ! 186 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 187 tst #_TIF_WORK_MASK, r0 188 bt __restore_all 189 bra work_pending 190 tst #_TIF_NEED_RESCHED, r0 191 192 .align 2 1931: .long schedule 1942: .long do_notify_resume 1953: .long resume_userspace 196#ifdef CONFIG_TRACE_IRQFLAGS 1974: .long trace_hardirqs_on 1985: .long trace_hardirqs_off 199#endif 200 201 .align 2 202syscall_exit_work: 203 ! r0: current_thread_info->flags 204 ! r8: current_thread_info 205 tst #_TIF_WORK_SYSCALL_MASK, r0 206 bt/s work_pending 207 tst #_TIF_NEED_RESCHED, r0 208#ifdef CONFIG_TRACE_IRQFLAGS 209 mov.l 5f, r0 210 jsr @r0 211 nop 212#endif 213 sti 214 mov r15, r4 215 mov.l 8f, r0 ! do_syscall_trace_leave 216 jsr @r0 217 nop 218 bra resume_userspace 219 nop 220 221 .align 2 222syscall_trace_entry: 223 ! Yes it is traced. 224 mov r15, r4 225 mov.l 7f, r11 ! Call do_syscall_trace_enter which notifies 226 jsr @r11 ! superior (will chomp R[0-7]) 227 nop 228 mov.l r0, @(OFF_R0,r15) ! Save return value 229 ! Reload R0-R4 from kernel stack, where the 230 ! parent may have modified them using 231 ! ptrace(POKEUSR). (Note that R0-R2 are 232 ! used by the system call handler directly 233 ! from the kernel stack anyway, so don't need 234 ! to be reloaded here.) This allows the parent 235 ! to rewrite system calls and args on the fly. 236 mov.l @(OFF_R4,r15), r4 ! arg0 237 mov.l @(OFF_R5,r15), r5 238 mov.l @(OFF_R6,r15), r6 239 mov.l @(OFF_R7,r15), r7 ! arg3 240 mov.l @(OFF_R3,r15), r3 ! syscall_nr 241 ! 242 mov.l 2f, r10 ! Number of syscalls 243 cmp/hs r10, r3 244 bf syscall_call 245 mov #-ENOSYS, r0 246 bra syscall_exit 247 mov.l r0, @(OFF_R0,r15) ! Return value 248 249__restore_all: 250 mov.l 1f, r0 251 jmp @r0 252 nop 253 254 .align 2 2551: .long restore_all 256 257 .align 2 258syscall_badsys: ! Bad syscall number 259 get_current_thread_info r8, r0 260 mov #-ENOSYS, r0 261 bra resume_userspace 262 mov.l r0, @(OFF_R0,r15) ! Return value 263 264/* 265 * The main debug trap handler. 266 * 267 * r8=TRA (not the trap number!) 268 * 269 * Note: This assumes that the trapa value is left in its original 270 * form (without the shlr2 shift) so the calculation for the jump 271 * call table offset remains a simple in place mask. 272 */ 273debug_trap: 274 mov r8, r0 275 and #(0xf << 2), r0 276 mov.l 1f, r8 277 add r0, r8 278 mov.l @r8, r8 279 jsr @r8 280 nop 281 bra __restore_all 282 nop 283 284 .align 2 2851: .long debug_trap_table 286 287/* 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 + ABI revision) 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 * 0x00-0x0f original SH-3/4 syscall ABI (not in general use). 302 * 0x10-0x1f general SH-3/4 syscall ABI. 303 * 0x20-0x2f syscall ABI for SH-2 parts. 304 * 0x30-0x3f debug traps used by the kernel. 305 * 0x40-0xff Not supported by all parts, so left unhandled. 306 * 307 * Note: When we're first called, the TRA value must be shifted 308 * right 2 bits in order to get the value that was used as the "trapa" 309 * argument. 310 */ 311 312 .align 2 313 .globl ret_from_fork 314ret_from_fork: 315 mov.l 1f, r8 316 jsr @r8 317 mov r0, r4 318 bra syscall_exit 319 nop 320 .align 2 3211: .long schedule_tail 322 323/* 324 * The poorly named main trapa decode and dispatch routine, for 325 * system calls and debug traps through their respective jump tables. 326 */ 327ENTRY(system_call) 328#if !defined(CONFIG_CPU_SH2) 329 mov.l 1f, r9 330 mov.l @r9, r8 ! Read from TRA (Trap Address) Register 331#endif 332 /* 333 * Check the trap type 334 */ 335 mov #((0x20 << 2) - 1), r9 336 cmp/hi r9, r8 337 bt/s debug_trap ! it's a debug trap.. 338 mov #OFF_TRA, r9 339 add r15, r9 340 mov.l r8, @r9 ! set TRA value to tra 341#ifdef CONFIG_TRACE_IRQFLAGS 342 mov.l 5f, r10 343 jsr @r10 344 nop 345#endif 346 sti 347 348 ! 349 get_current_thread_info r8, r10 350 mov.l @(TI_FLAGS,r8), r8 351 mov #_TIF_WORK_SYSCALL_MASK, r10 352 tst r10, r8 353 bf syscall_trace_entry 354 ! 355 mov.l 2f, r8 ! Number of syscalls 356 cmp/hs r8, r3 357 bt syscall_badsys 358 ! 359syscall_call: 360 shll2 r3 ! x4 361 mov.l 3f, r8 ! Load the address of sys_call_table 362 add r8, r3 363 mov.l @r3, r8 364 jsr @r8 ! jump to specific syscall handler 365 nop 366 mov.l @(OFF_R0,r15), r12 ! save r0 367 mov.l r0, @(OFF_R0,r15) ! save the return value 368 ! 369syscall_exit: 370 cli 371#ifdef CONFIG_TRACE_IRQFLAGS 372 mov.l 6f, r0 373 jsr @r0 374 nop 375#endif 376 ! 377 get_current_thread_info r8, r0 378 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 379 tst #_TIF_ALLWORK_MASK, r0 380 bf syscall_exit_work 381 bra __restore_all 382 nop 383 .align 2 384#if !defined(CONFIG_CPU_SH2) 3851: .long TRA 386#endif 3872: .long NR_syscalls 3883: .long sys_call_table 389#ifdef CONFIG_TRACE_IRQFLAGS 3905: .long trace_hardirqs_on 3916: .long trace_hardirqs_off 392#endif 3937: .long do_syscall_trace_enter 3948: .long do_syscall_trace_leave 395