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 3f, 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_ACTIVE 1232: .long schedule 1243: .long preempt_schedule_irq 125#endif 126 127ENTRY(resume_userspace) 128 ! r8: current_thread_info 129 cli 130 TRACE_IRQS_OFF 131 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 132 tst #(_TIF_WORK_MASK & 0xff), r0 133 bt/s __restore_all 134 tst #_TIF_NEED_RESCHED, r0 135 136 .align 2 137work_pending: 138 ! r0: current_thread_info->flags 139 ! r8: current_thread_info 140 ! t: result of "tst #_TIF_NEED_RESCHED, r0" 141 bf/s work_resched 142 tst #_TIF_SIGPENDING, r0 143work_notifysig: 144 bt/s __restore_all 145 mov r15, r4 146 mov r12, r5 ! set arg1(save_r0) 147 mov r0, r6 148 sti 149 mov.l 2f, r1 150 mov.l 3f, r0 151 jmp @r1 152 lds r0, pr 153work_resched: 154 mov.l 1f, r1 155 jsr @r1 ! schedule 156 nop 157 cli 158 TRACE_IRQS_OFF 159 ! 160 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 161 tst #(_TIF_WORK_MASK & 0xff), r0 162 bt __restore_all 163 bra work_pending 164 tst #_TIF_NEED_RESCHED, r0 165 166 .align 2 1671: .long schedule 1682: .long do_notify_resume 1693: .long resume_userspace 170 171 .align 2 172syscall_exit_work: 173 ! r0: current_thread_info->flags 174 ! r8: current_thread_info 175 tst #(_TIF_WORK_SYSCALL_MASK & 0xff), r0 176 bt/s work_pending 177 tst #_TIF_NEED_RESCHED, r0 178 TRACE_IRQS_ON 179 sti 180 mov r15, r4 181 mov.l 8f, r0 ! do_syscall_trace_leave 182 jsr @r0 183 nop 184 bra resume_userspace 185 nop 186 187 .align 2 188syscall_trace_entry: 189 ! Yes it is traced. 190 mov r15, r4 191 mov.l 7f, r11 ! Call do_syscall_trace_enter which notifies 192 jsr @r11 ! superior (will chomp R[0-7]) 193 nop 194 mov.l r0, @(OFF_R0,r15) ! Save return value 195 ! Reload R0-R4 from kernel stack, where the 196 ! parent may have modified them using 197 ! ptrace(POKEUSR). (Note that R0-R2 are 198 ! used by the system call handler directly 199 ! from the kernel stack anyway, so don't need 200 ! to be reloaded here.) This allows the parent 201 ! to rewrite system calls and args on the fly. 202 mov.l @(OFF_R4,r15), r4 ! arg0 203 mov.l @(OFF_R5,r15), r5 204 mov.l @(OFF_R6,r15), r6 205 mov.l @(OFF_R7,r15), r7 ! arg3 206 mov.l @(OFF_R3,r15), r3 ! syscall_nr 207 ! 208 mov.l 2f, r10 ! Number of syscalls 209 cmp/hs r10, r3 210 bf syscall_call 211 mov #-ENOSYS, r0 212 bra syscall_exit 213 mov.l r0, @(OFF_R0,r15) ! Return value 214 215__restore_all: 216 mov #OFF_SR, r0 217 mov.l @(r0,r15), r0 ! get status register 218 219 shlr2 r0 220 and #0x3c, r0 221 cmp/eq #0x3c, r0 222 bt 1f 223 TRACE_IRQS_ON 224 bra 2f 225 nop 2261: 227 TRACE_IRQS_OFF 2282: 229 mov.l 3f, r0 230 jmp @r0 231 nop 232 233 .align 2 2343: .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 CFI_ENDPROC 263 264 .align 2 2651: .long debug_trap_table 266 267/* 268 * Syscall interface: 269 * 270 * Syscall #: R3 271 * Arguments #0 to #3: R4--R7 272 * Arguments #4 to #6: R0, R1, R2 273 * TRA: (number of arguments + ABI revision) x 4 274 * 275 * This code also handles delegating other traps to the BIOS/gdb stub 276 * according to: 277 * 278 * Trap number 279 * (TRA>>2) Purpose 280 * -------- ------- 281 * 0x00-0x0f original SH-3/4 syscall ABI (not in general use). 282 * 0x10-0x1f general SH-3/4 syscall ABI. 283 * 0x20-0x2f syscall ABI for SH-2 parts. 284 * 0x30-0x3f debug traps used by the kernel. 285 * 0x40-0xff Not supported by all parts, so left unhandled. 286 * 287 * Note: When we're first called, the TRA value must be shifted 288 * right 2 bits in order to get the value that was used as the "trapa" 289 * argument. 290 */ 291 292 .align 2 293 .globl ret_from_fork 294ret_from_fork: 295 mov.l 1f, r8 296 jsr @r8 297 mov r0, r4 298 bra syscall_exit 299 nop 300 .align 2 3011: .long schedule_tail 302 303/* 304 * The poorly named main trapa decode and dispatch routine, for 305 * system calls and debug traps through their respective jump tables. 306 */ 307ENTRY(system_call) 308 setup_frame_reg 309#if !defined(CONFIG_CPU_SH2) 310 mov.l 1f, r9 311 mov.l @r9, r8 ! Read from TRA (Trap Address) Register 312#endif 313 314 mov #OFF_TRA, r10 315 add r15, r10 316 mov.l r8, @r10 ! set TRA value to tra 317 318 /* 319 * Check the trap type 320 */ 321 mov #((0x20 << 2) - 1), r9 322 cmp/hi r9, r8 323 bt/s debug_trap ! it's a debug trap.. 324 nop 325 326 TRACE_IRQS_ON 327 sti 328 329 ! 330 get_current_thread_info r8, r10 331 mov.l @(TI_FLAGS,r8), r8 332 mov #(_TIF_WORK_SYSCALL_MASK & 0xff), r10 333 mov #(_TIF_WORK_SYSCALL_MASK >> 8), r9 334 tst r10, r8 335 shll8 r9 336 bf syscall_trace_entry 337 tst r9, r8 338 bf syscall_trace_entry 339 ! 340 mov.l 2f, r8 ! Number of syscalls 341 cmp/hs r8, r3 342 bt syscall_badsys 343 ! 344syscall_call: 345 shll2 r3 ! x4 346 mov.l 3f, r8 ! Load the address of sys_call_table 347 add r8, r3 348 mov.l @r3, r8 349 jsr @r8 ! jump to specific syscall handler 350 nop 351 mov.l @(OFF_R0,r15), r12 ! save r0 352 mov.l r0, @(OFF_R0,r15) ! save the return value 353 ! 354syscall_exit: 355 cli 356 TRACE_IRQS_OFF 357 ! 358 get_current_thread_info r8, r0 359 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 360 tst #(_TIF_ALLWORK_MASK & 0xff), r0 361 mov #(_TIF_ALLWORK_MASK >> 8), r1 362 bf syscall_exit_work 363 shlr8 r0 364 tst r0, r1 365 bf syscall_exit_work 366 bra __restore_all 367 nop 368 .align 2 369#if !defined(CONFIG_CPU_SH2) 3701: .long TRA 371#endif 3722: .long NR_syscalls 3733: .long sys_call_table 3747: .long do_syscall_trace_enter 3758: .long do_syscall_trace_leave 376