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, 60 74 CFI_REL_OFFSET 14, 56 75 CFI_REL_OFFSET 13, 52 76 CFI_REL_OFFSET 12, 48 77 CFI_REL_OFFSET 11, 44 78 CFI_REL_OFFSET 10, 40 79 CFI_REL_OFFSET 9, 36 80 CFI_REL_OFFSET 8, 32 81 preempt_stop() 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 TRACE_IRQS_OFF 97 mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count 98 tst r0, r0 99 bf noresched 100need_resched: 101 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 102 tst #_TIF_NEED_RESCHED, r0 ! need_resched set? 103 bt noresched 104 105 mov #OFF_SR, r0 106 mov.l @(r0,r15), r0 ! get status register 107 shlr r0 108 and #(0xf0>>1), r0 ! interrupts off (exception path)? 109 cmp/eq #(0xf0>>1), r0 110 bt noresched 111 mov.l 1f, r0 112 jsr @r0 ! call preempt_schedule_irq 113 nop 114 bra need_resched 115 nop 116 117noresched: 118 bra __restore_all 119 nop 120 121 .align 2 1221: .long preempt_schedule_irq 123#endif 124 125ENTRY(resume_userspace) 126 ! r8: current_thread_info 127 cli 128 TRACE_IRQS_OFF 129 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 130 tst #(_TIF_WORK_MASK & 0xff), r0 131 bt/s __restore_all 132 tst #_TIF_NEED_RESCHED, r0 133 134 .align 2 135work_pending: 136 ! r0: current_thread_info->flags 137 ! r8: current_thread_info 138 ! t: result of "tst #_TIF_NEED_RESCHED, r0" 139 bf/s work_resched 140 tst #(_TIF_SIGPENDING | _TIF_NOTIFY_RESUME), r0 141work_notifysig: 142 bt/s __restore_all 143 mov r15, r4 144 mov r12, r5 ! set arg1(save_r0) 145 mov r0, r6 146 sti 147 mov.l 2f, r1 148 mov.l 3f, r0 149 jmp @r1 150 lds r0, pr 151work_resched: 152 mov.l 1f, r1 153 jsr @r1 ! schedule 154 nop 155 cli 156 TRACE_IRQS_OFF 157 ! 158 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 159 tst #(_TIF_WORK_MASK & 0xff), r0 160 bt __restore_all 161 bra work_pending 162 tst #_TIF_NEED_RESCHED, r0 163 164 .align 2 1651: .long schedule 1662: .long do_notify_resume 1673: .long resume_userspace 168 169 .align 2 170syscall_exit_work: 171 ! r0: current_thread_info->flags 172 ! r8: current_thread_info 173 tst #(_TIF_WORK_SYSCALL_MASK & 0xff), r0 174 bt/s work_pending 175 tst #_TIF_NEED_RESCHED, r0 176 TRACE_IRQS_ON 177 sti 178 mov r15, r4 179 mov.l 8f, r0 ! do_syscall_trace_leave 180 jsr @r0 181 nop 182 bra resume_userspace 183 nop 184 185 .align 2 186syscall_trace_entry: 187 ! Yes it is traced. 188 mov r15, r4 189 mov.l 7f, r11 ! Call do_syscall_trace_enter which notifies 190 jsr @r11 ! superior (will chomp R[0-7]) 191 nop 192 mov.l r0, @(OFF_R0,r15) ! Save return value 193 ! Reload R0-R4 from kernel stack, where the 194 ! parent may have modified them using 195 ! ptrace(POKEUSR). (Note that R0-R2 are 196 ! used by the system call handler directly 197 ! from the kernel stack anyway, so don't need 198 ! to be reloaded here.) This allows the parent 199 ! to rewrite system calls and args on the fly. 200 mov.l @(OFF_R4,r15), r4 ! arg0 201 mov.l @(OFF_R5,r15), r5 202 mov.l @(OFF_R6,r15), r6 203 mov.l @(OFF_R7,r15), r7 ! arg3 204 mov.l @(OFF_R3,r15), r3 ! syscall_nr 205 ! 206 mov.l 2f, r10 ! Number of syscalls 207 cmp/hs r10, r3 208 bf syscall_call 209 mov #-ENOSYS, r0 210 bra syscall_exit 211 mov.l r0, @(OFF_R0,r15) ! Return value 212 213__restore_all: 214 mov #OFF_SR, r0 215 mov.l @(r0,r15), r0 ! get status register 216 217 shlr2 r0 218 and #0x3c, r0 219 cmp/eq #0x3c, r0 220 bt 1f 221 TRACE_IRQS_ON 222 bra 2f 223 nop 2241: 225 TRACE_IRQS_OFF 2262: 227 mov.l 3f, r0 228 jmp @r0 229 nop 230 231 .align 2 2323: .long restore_all 233 234 .align 2 235syscall_badsys: ! Bad syscall number 236 get_current_thread_info r8, r0 237 mov #-ENOSYS, r0 238 bra resume_userspace 239 mov.l r0, @(OFF_R0,r15) ! Return value 240 241/* 242 * The main debug trap handler. 243 * 244 * r8=TRA (not the trap number!) 245 * 246 * Note: This assumes that the trapa value is left in its original 247 * form (without the shlr2 shift) so the calculation for the jump 248 * call table offset remains a simple in place mask. 249 */ 250debug_trap: 251 mov r8, r0 252 and #(0xf << 2), r0 253 mov.l 1f, r8 254 add r0, r8 255 mov.l @r8, r8 256 jsr @r8 257 nop 258 bra __restore_all 259 nop 260 CFI_ENDPROC 261 262 .align 2 2631: .long debug_trap_table 264 265/* 266 * Syscall interface: 267 * 268 * Syscall #: R3 269 * Arguments #0 to #3: R4--R7 270 * Arguments #4 to #6: R0, R1, R2 271 * TRA: (number of arguments + ABI revision) x 4 272 * 273 * This code also handles delegating other traps to the BIOS/gdb stub 274 * according to: 275 * 276 * Trap number 277 * (TRA>>2) Purpose 278 * -------- ------- 279 * 0x00-0x0f original SH-3/4 syscall ABI (not in general use). 280 * 0x10-0x1f general SH-3/4 syscall ABI. 281 * 0x20-0x2f syscall ABI for SH-2 parts. 282 * 0x30-0x3f debug traps used by the kernel. 283 * 0x40-0xff Not supported by all parts, so left unhandled. 284 * 285 * Note: When we're first called, the TRA value must be shifted 286 * right 2 bits in order to get the value that was used as the "trapa" 287 * argument. 288 */ 289 290 .align 2 291 .globl ret_from_fork 292ret_from_fork: 293 mov.l 1f, r8 294 jsr @r8 295 mov r0, r4 296 bra syscall_exit 297 nop 298 299 .align 2 300 .globl ret_from_kernel_thread 301ret_from_kernel_thread: 302 mov.l 1f, r8 303 jsr @r8 304 mov r0, r4 305 mov.l @(OFF_R5,r15), r5 ! fn 306 jsr @r5 307 mov.l @(OFF_R4,r15), r4 ! arg 308 bra syscall_exit 309 nop 310 311 .align 2 3121: .long schedule_tail 313 314/* 315 * The poorly named main trapa decode and dispatch routine, for 316 * system calls and debug traps through their respective jump tables. 317 */ 318ENTRY(system_call) 319 setup_frame_reg 320#if !defined(CONFIG_CPU_SH2) 321 mov.l 1f, r9 322 mov.l @r9, r8 ! Read from TRA (Trap Address) Register 323#endif 324 325 mov #OFF_TRA, r10 326 add r15, r10 327 mov.l r8, @r10 ! set TRA value to tra 328 329 /* 330 * Check the trap type 331 */ 332 mov #((0x20 << 2) - 1), r9 333 cmp/hi r9, r8 334 bt/s debug_trap ! it's a debug trap.. 335 nop 336 337 TRACE_IRQS_ON 338 sti 339 340 ! 341 get_current_thread_info r8, r10 342 mov.l @(TI_FLAGS,r8), r8 343 mov #(_TIF_WORK_SYSCALL_MASK & 0xff), r10 344 mov #(_TIF_WORK_SYSCALL_MASK >> 8), r9 345 tst r10, r8 346 shll8 r9 347 bf syscall_trace_entry 348 tst r9, r8 349 bf syscall_trace_entry 350 ! 351 mov.l 2f, r8 ! Number of syscalls 352 cmp/hs r8, r3 353 bt syscall_badsys 354 ! 355syscall_call: 356 shll2 r3 ! x4 357 mov.l 3f, r8 ! Load the address of sys_call_table 358 add r8, r3 359 mov.l @r3, r8 360 jsr @r8 ! jump to specific syscall handler 361 nop 362 mov.l @(OFF_R0,r15), r12 ! save r0 363 mov.l r0, @(OFF_R0,r15) ! save the return value 364 ! 365syscall_exit: 366 cli 367 TRACE_IRQS_OFF 368 ! 369 get_current_thread_info r8, r0 370 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 371 tst #(_TIF_ALLWORK_MASK & 0xff), r0 372 mov #(_TIF_ALLWORK_MASK >> 8), r1 373 bf syscall_exit_work 374 shlr8 r0 375 tst r0, r1 376 bf syscall_exit_work 377 bra __restore_all 378 nop 379 .align 2 380#if !defined(CONFIG_CPU_SH2) 3811: .long TRA 382#endif 3832: .long NR_syscalls 3843: .long sys_call_table 3857: .long do_syscall_trace_enter 3868: .long do_syscall_trace_leave 387