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#include <asm/dwarf.h> 47 48#if defined(CONFIG_PREEMPT) 49# define preempt_stop() cli ; TRACE_IRQS_OFF 50#else 51# define preempt_stop() 52# define resume_kernel __restore_all 53#endif 54 55 56 .align 2 57ENTRY(exception_error) 58 ! 59 TRACE_IRQS_ON 60 sti 61 mov.l 1f, r0 62 jmp @r0 63 nop 64 65 .align 2 661: .long do_exception_error 67 68 .align 2 69ret_from_exception: 70 CFI_STARTPROC simple 71 CFI_DEF_CFA r14, 0 72 CFI_REL_OFFSET 17, 64 73 CFI_REL_OFFSET 15, 0 74 CFI_REL_OFFSET 14, 56 75 preempt_stop() 76ENTRY(ret_from_irq) 77 ! 78 mov #OFF_SR, r0 79 mov.l @(r0,r15), r0 ! get status register 80 shll r0 81 shll r0 ! kernel space? 82 get_current_thread_info r8, r0 83 bt resume_kernel ! Yes, it's from kernel, go back soon 84 85#ifdef CONFIG_PREEMPT 86 bra resume_userspace 87 nop 88ENTRY(resume_kernel) 89 cli 90 TRACE_IRQS_OFF 91 mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count 92 tst r0, r0 93 bf noresched 94need_resched: 95 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 96 tst #_TIF_NEED_RESCHED, r0 ! need_resched set? 97 bt noresched 98 99 mov #OFF_SR, r0 100 mov.l @(r0,r15), r0 ! get status register 101 shlr r0 102 and #(0xf0>>1), r0 ! interrupts off (exception path)? 103 cmp/eq #(0xf0>>1), r0 104 bt noresched 105 mov.l 3f, r0 106 jsr @r0 ! call preempt_schedule_irq 107 nop 108 bra need_resched 109 nop 110 111noresched: 112 bra __restore_all 113 nop 114 115 .align 2 1161: .long PREEMPT_ACTIVE 1172: .long schedule 1183: .long preempt_schedule_irq 119#endif 120 121ENTRY(resume_userspace) 122 ! r8: current_thread_info 123 cli 124 TRACE_IRQS_OfF 125 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 126 tst #(_TIF_WORK_MASK & 0xff), r0 127 bt/s __restore_all 128 tst #_TIF_NEED_RESCHED, r0 129 130 .align 2 131work_pending: 132 ! r0: current_thread_info->flags 133 ! r8: current_thread_info 134 ! t: result of "tst #_TIF_NEED_RESCHED, r0" 135 bf/s work_resched 136 tst #(_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK), r0 137work_notifysig: 138 bt/s __restore_all 139 mov r15, r4 140 mov r12, r5 ! set arg1(save_r0) 141 mov r0, r6 142 mov.l 2f, r1 143 mov.l 3f, r0 144 jmp @r1 145 lds r0, pr 146work_resched: 147 mov.l 1f, r1 148 jsr @r1 ! schedule 149 nop 150 cli 151 TRACE_IRQS_OFF 152 ! 153 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 154 tst #(_TIF_WORK_MASK & 0xff), r0 155 bt __restore_all 156 bra work_pending 157 tst #_TIF_NEED_RESCHED, r0 158 159 .align 2 1601: .long schedule 1612: .long do_notify_resume 1623: .long resume_userspace 163 164 .align 2 165syscall_exit_work: 166 ! r0: current_thread_info->flags 167 ! r8: current_thread_info 168 tst #(_TIF_WORK_SYSCALL_MASK & 0xff), r0 169 bt/s work_pending 170 tst #_TIF_NEED_RESCHED, r0 171 TRACE_IRQS_ON 172 sti 173 mov r15, r4 174 mov.l 8f, r0 ! do_syscall_trace_leave 175 jsr @r0 176 nop 177 bra resume_userspace 178 nop 179 180 .align 2 181syscall_trace_entry: 182 ! Yes it is traced. 183 mov r15, r4 184 mov.l 7f, r11 ! Call do_syscall_trace_enter which notifies 185 jsr @r11 ! superior (will chomp R[0-7]) 186 nop 187 mov.l r0, @(OFF_R0,r15) ! Save return value 188 ! Reload R0-R4 from kernel stack, where the 189 ! parent may have modified them using 190 ! ptrace(POKEUSR). (Note that R0-R2 are 191 ! used by the system call handler directly 192 ! from the kernel stack anyway, so don't need 193 ! to be reloaded here.) This allows the parent 194 ! to rewrite system calls and args on the fly. 195 mov.l @(OFF_R4,r15), r4 ! arg0 196 mov.l @(OFF_R5,r15), r5 197 mov.l @(OFF_R6,r15), r6 198 mov.l @(OFF_R7,r15), r7 ! arg3 199 mov.l @(OFF_R3,r15), r3 ! syscall_nr 200 ! 201 mov.l 2f, r10 ! Number of syscalls 202 cmp/hs r10, r3 203 bf syscall_call 204 mov #-ENOSYS, r0 205 bra syscall_exit 206 mov.l r0, @(OFF_R0,r15) ! Return value 207 208__restore_all: 209 mov #OFF_SR, r0 210 mov.l @(r0,r15), r0 ! get status register 211 212 shlr2 r0 213 and #0x3c, r0 214 cmp/eq #0x3c, r0 215 bt 1f 216 TRACE_IRQS_ON 217 bra 2f 218 nop 2191: 220 TRACE_IRQS_OFF 2212: 222 mov.l 3f, r0 223 jmp @r0 224 nop 225 226 .align 2 2273: .long restore_all 228 229 .align 2 230syscall_badsys: ! Bad syscall number 231 get_current_thread_info r8, r0 232 mov #-ENOSYS, r0 233 bra resume_userspace 234 mov.l r0, @(OFF_R0,r15) ! Return value 235 236/* 237 * The main debug trap handler. 238 * 239 * r8=TRA (not the trap number!) 240 * 241 * Note: This assumes that the trapa value is left in its original 242 * form (without the shlr2 shift) so the calculation for the jump 243 * call table offset remains a simple in place mask. 244 */ 245debug_trap: 246 mov r8, r0 247 and #(0xf << 2), r0 248 mov.l 1f, r8 249 add r0, r8 250 mov.l @r8, r8 251 jsr @r8 252 nop 253 bra __restore_all 254 nop 255 CFI_ENDPROC 256 257 .align 2 2581: .long debug_trap_table 259 260/* 261 * Syscall interface: 262 * 263 * Syscall #: R3 264 * Arguments #0 to #3: R4--R7 265 * Arguments #4 to #6: R0, R1, R2 266 * TRA: (number of arguments + ABI revision) x 4 267 * 268 * This code also handles delegating other traps to the BIOS/gdb stub 269 * according to: 270 * 271 * Trap number 272 * (TRA>>2) Purpose 273 * -------- ------- 274 * 0x00-0x0f original SH-3/4 syscall ABI (not in general use). 275 * 0x10-0x1f general SH-3/4 syscall ABI. 276 * 0x20-0x2f syscall ABI for SH-2 parts. 277 * 0x30-0x3f debug traps used by the kernel. 278 * 0x40-0xff Not supported by all parts, so left unhandled. 279 * 280 * Note: When we're first called, the TRA value must be shifted 281 * right 2 bits in order to get the value that was used as the "trapa" 282 * argument. 283 */ 284 285 .align 2 286 .globl ret_from_fork 287ret_from_fork: 288 mov.l 1f, r8 289 jsr @r8 290 mov r0, r4 291 bra syscall_exit 292 nop 293 .align 2 2941: .long schedule_tail 295 296/* 297 * The poorly named main trapa decode and dispatch routine, for 298 * system calls and debug traps through their respective jump tables. 299 */ 300ENTRY(system_call) 301 setup_frame_reg 302#if !defined(CONFIG_CPU_SH2) 303 mov.l 1f, r9 304 mov.l @r9, r8 ! Read from TRA (Trap Address) Register 305#endif 306 307 mov #OFF_TRA, r10 308 add r15, r10 309 mov.l r8, @r10 ! set TRA value to tra 310 311 /* 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 nop 318 319 TRACE_IRQS_ON 320 sti 321 322 ! 323 get_current_thread_info r8, r10 324 mov.l @(TI_FLAGS,r8), r8 325 mov #(_TIF_WORK_SYSCALL_MASK & 0xff), r10 326 mov #(_TIF_WORK_SYSCALL_MASK >> 8), r9 327 tst r10, r8 328 shll8 r9 329 bf syscall_trace_entry 330 tst r9, r8 331 bf syscall_trace_entry 332 ! 333 mov.l 2f, r8 ! Number of syscalls 334 cmp/hs r8, r3 335 bt syscall_badsys 336 ! 337syscall_call: 338 shll2 r3 ! x4 339 mov.l 3f, r8 ! Load the address of sys_call_table 340 add r8, r3 341 mov.l @r3, r8 342 jsr @r8 ! jump to specific syscall handler 343 nop 344 mov.l @(OFF_R0,r15), r12 ! save r0 345 mov.l r0, @(OFF_R0,r15) ! save the return value 346 ! 347syscall_exit: 348 cli 349 TRACE_IRQS_OFF 350 ! 351 get_current_thread_info r8, r0 352 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 353 tst #(_TIF_ALLWORK_MASK & 0xff), r0 354 mov #(_TIF_ALLWORK_MASK >> 8), r1 355 bf syscall_exit_work 356 shlr8 r0 357 tst r0, r1 358 bf syscall_exit_work 359 bra __restore_all 360 nop 361 .align 2 362#if !defined(CONFIG_CPU_SH2) 3631: .long TRA 364#endif 3652: .long NR_syscalls 3663: .long sys_call_table 3677: .long do_syscall_trace_enter 3688: .long do_syscall_trace_leave 369