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 cli 96 mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count 97 tst r0, r0 98 bf noresched 99need_resched: 100 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 101 tst #_TIF_NEED_RESCHED, r0 ! need_resched set? 102 bt noresched 103 104 mov #OFF_SR, r0 105 mov.l @(r0,r15), r0 ! get status register 106 and #0xf0, r0 ! interrupts off (exception path)? 107 cmp/eq #0xf0, r0 108 bt noresched 109 mov.l 3f, r0 110 jsr @r0 ! call preempt_schedule_irq 111 nop 112 bra need_resched 113 nop 114 115noresched: 116 bra __restore_all 117 nop 118 119 .align 2 1201: .long PREEMPT_ACTIVE 1212: .long schedule 1223: .long preempt_schedule_irq 123#endif 124 125ENTRY(resume_userspace) 126 ! r8: current_thread_info 127 cli 128#ifdef CONFIG_TRACE_IRQFLAGS 129 mov.l 5f, r0 130 jsr @r0 131 nop 132#endif 133 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 134 tst #_TIF_WORK_MASK, r0 135 bt/s __restore_all 136 tst #_TIF_NEED_RESCHED, r0 137 138 .align 2 139work_pending: 140 ! r0: current_thread_info->flags 141 ! r8: current_thread_info 142 ! t: result of "tst #_TIF_NEED_RESCHED, r0" 143 bf/s work_resched 144 tst #(_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK), r0 145work_notifysig: 146 bt/s __restore_all 147 mov r15, r4 148 mov r12, r5 ! set arg1(save_r0) 149 mov r0, r6 150 mov.l 2f, r1 151 mov.l 3f, r0 152 jmp @r1 153 lds r0, pr 154work_resched: 155 mov.l 1f, r1 156 jsr @r1 ! schedule 157 nop 158 cli 159#ifdef CONFIG_TRACE_IRQFLAGS 160 mov.l 5f, r0 161 jsr @r0 162 nop 163#endif 164 ! 165 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 166 tst #_TIF_WORK_MASK, r0 167 bt __restore_all 168 bra work_pending 169 tst #_TIF_NEED_RESCHED, r0 170 171 .align 2 1721: .long schedule 1732: .long do_notify_resume 1743: .long resume_userspace 175#ifdef CONFIG_TRACE_IRQFLAGS 1764: .long trace_hardirqs_on 1775: .long trace_hardirqs_off 178#endif 179 180 .align 2 181syscall_exit_work: 182 ! r0: current_thread_info->flags 183 ! r8: current_thread_info 184 tst #_TIF_WORK_SYSCALL_MASK, r0 185 bt/s work_pending 186 tst #_TIF_NEED_RESCHED, r0 187#ifdef CONFIG_TRACE_IRQFLAGS 188 mov.l 5f, r0 189 jsr @r0 190 nop 191#endif 192 sti 193 mov r15, r4 194 mov.l 8f, r0 ! do_syscall_trace_leave 195 jsr @r0 196 nop 197 bra resume_userspace 198 nop 199 200 .align 2 201syscall_trace_entry: 202 ! Yes it is traced. 203 mov r15, r4 204 mov.l 7f, r11 ! Call do_syscall_trace_enter which notifies 205 jsr @r11 ! superior (will chomp R[0-7]) 206 nop 207 mov.l r0, @(OFF_R0,r15) ! Save return value 208 ! Reload R0-R4 from kernel stack, where the 209 ! parent may have modified them using 210 ! ptrace(POKEUSR). (Note that R0-R2 are 211 ! used by the system call handler directly 212 ! from the kernel stack anyway, so don't need 213 ! to be reloaded here.) This allows the parent 214 ! to rewrite system calls and args on the fly. 215 mov.l @(OFF_R4,r15), r4 ! arg0 216 mov.l @(OFF_R5,r15), r5 217 mov.l @(OFF_R6,r15), r6 218 mov.l @(OFF_R7,r15), r7 ! arg3 219 mov.l @(OFF_R3,r15), r3 ! syscall_nr 220 ! 221 mov.l 2f, r10 ! Number of syscalls 222 cmp/hs r10, r3 223 bf syscall_call 224 mov #-ENOSYS, r0 225 bra syscall_exit 226 mov.l r0, @(OFF_R0,r15) ! Return value 227 228__restore_all: 229 mov.l 1f, r0 230 jmp @r0 231 nop 232 233 .align 2 2341: .long restore_all 235 236 .align 2 237syscall_badsys: ! Bad syscall number 238 get_current_thread_info r8, r0 239 mov #-ENOSYS, r0 240 bra resume_userspace 241 mov.l r0, @(OFF_R0,r15) ! Return value 242 243/* 244 * The main debug trap handler. 245 * 246 * r8=TRA (not the trap number!) 247 * 248 * Note: This assumes that the trapa value is left in its original 249 * form (without the shlr2 shift) so the calculation for the jump 250 * call table offset remains a simple in place mask. 251 */ 252debug_trap: 253 mov r8, r0 254 and #(0xf << 2), r0 255 mov.l 1f, r8 256 add r0, r8 257 mov.l @r8, r8 258 jsr @r8 259 nop 260 bra __restore_all 261 nop 262 263 .align 2 2641: .long debug_trap_table 265 266/* 267 * Syscall interface: 268 * 269 * Syscall #: R3 270 * Arguments #0 to #3: R4--R7 271 * Arguments #4 to #6: R0, R1, R2 272 * TRA: (number of arguments + ABI revision) x 4 273 * 274 * This code also handles delegating other traps to the BIOS/gdb stub 275 * according to: 276 * 277 * Trap number 278 * (TRA>>2) Purpose 279 * -------- ------- 280 * 0x00-0x0f original SH-3/4 syscall ABI (not in general use). 281 * 0x10-0x1f general SH-3/4 syscall ABI. 282 * 0x20-0x2f syscall ABI for SH-2 parts. 283 * 0x30-0x3f debug traps used by the kernel. 284 * 0x40-0xff Not supported by all parts, so left unhandled. 285 * 286 * Note: When we're first called, the TRA value must be shifted 287 * right 2 bits in order to get the value that was used as the "trapa" 288 * argument. 289 */ 290 291 .align 2 292 .globl ret_from_fork 293ret_from_fork: 294 mov.l 1f, r8 295 jsr @r8 296 mov r0, r4 297 bra syscall_exit 298 nop 299 .align 2 3001: .long schedule_tail 301 302/* 303 * The poorly named main trapa decode and dispatch routine, for 304 * system calls and debug traps through their respective jump tables. 305 */ 306ENTRY(system_call) 307#if !defined(CONFIG_CPU_SH2) 308 mov.l 1f, r9 309 mov.l @r9, r8 ! Read from TRA (Trap Address) Register 310#endif 311 /* 312 * Check the trap type 313 */ 314 mov #((0x20 << 2) - 1), r9 315 cmp/hi r9, r8 316 bt/s debug_trap ! it's a debug trap.. 317 mov #OFF_TRA, r9 318 add r15, r9 319 mov.l r8, @r9 ! set TRA value to tra 320#ifdef CONFIG_TRACE_IRQFLAGS 321 mov.l 5f, r10 322 jsr @r10 323 nop 324#endif 325 sti 326 327 ! 328 get_current_thread_info r8, r10 329 mov.l @(TI_FLAGS,r8), r8 330 mov #_TIF_WORK_SYSCALL_MASK, r10 331 tst r10, r8 332 bf syscall_trace_entry 333 ! 334 mov.l 2f, r8 ! Number of syscalls 335 cmp/hs r8, r3 336 bt syscall_badsys 337 ! 338syscall_call: 339 shll2 r3 ! x4 340 mov.l 3f, r8 ! Load the address of sys_call_table 341 add r8, r3 342 mov.l @r3, r8 343 jsr @r8 ! jump to specific syscall handler 344 nop 345 mov.l @(OFF_R0,r15), r12 ! save r0 346 mov.l r0, @(OFF_R0,r15) ! save the return value 347 ! 348syscall_exit: 349 cli 350#ifdef CONFIG_TRACE_IRQFLAGS 351 mov.l 6f, r0 352 jsr @r0 353 nop 354#endif 355 ! 356 get_current_thread_info r8, r0 357 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 358 tst #_TIF_ALLWORK_MASK, r0 359 bf syscall_exit_work 360 bra __restore_all 361 nop 362 .align 2 363#if !defined(CONFIG_CPU_SH2) 3641: .long TRA 365#endif 3662: .long NR_syscalls 3673: .long sys_call_table 368#ifdef CONFIG_TRACE_IRQFLAGS 3695: .long trace_hardirqs_on 3706: .long trace_hardirqs_off 371#endif 3727: .long do_syscall_trace_enter 3738: .long do_syscall_trace_leave 374