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 81 shlr2 r0 82 and #0x3c, r0 83 cmp/eq #0x3c, r0 84 bt 9f 85 TRACE_IRQS_ON 869: 87 mov #OFF_SR, r0 88 mov.l @(r0,r15), r0 ! get status register 89 shll r0 90 shll r0 ! kernel space? 91 get_current_thread_info r8, r0 92 bt resume_kernel ! Yes, it's from kernel, go back soon 93 94#ifdef CONFIG_PREEMPT 95 bra resume_userspace 96 nop 97ENTRY(resume_kernel) 98 cli 99 mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count 100 tst r0, r0 101 bf noresched 102need_resched: 103 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 104 tst #_TIF_NEED_RESCHED, r0 ! need_resched set? 105 bt noresched 106 107 mov #OFF_SR, r0 108 mov.l @(r0,r15), r0 ! get status register 109 and #0xf0, r0 ! interrupts off (exception path)? 110 cmp/eq #0xf0, r0 111 bt noresched 112 mov.l 3f, r0 113 jsr @r0 ! call preempt_schedule_irq 114 nop 115 bra need_resched 116 nop 117 118noresched: 119 bra __restore_all 120 nop 121 122 .align 2 1231: .long PREEMPT_ACTIVE 1242: .long schedule 1253: .long preempt_schedule_irq 126#endif 127 128ENTRY(resume_userspace) 129 ! r8: current_thread_info 130 cli 131 TRACE_IRQS_OfF 132 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 133 tst #(_TIF_WORK_MASK & 0xff), r0 134 bt/s __restore_all 135 tst #_TIF_NEED_RESCHED, r0 136 137 .align 2 138work_pending: 139 ! r0: current_thread_info->flags 140 ! r8: current_thread_info 141 ! t: result of "tst #_TIF_NEED_RESCHED, r0" 142 bf/s work_resched 143 tst #(_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK), r0 144work_notifysig: 145 bt/s __restore_all 146 mov r15, r4 147 mov r12, r5 ! set arg1(save_r0) 148 mov r0, r6 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.l 1f, r0 217 jmp @r0 218 nop 219 220 .align 2 2211: .long restore_all 222 223 .align 2 224syscall_badsys: ! Bad syscall number 225 get_current_thread_info r8, r0 226 mov #-ENOSYS, r0 227 bra resume_userspace 228 mov.l r0, @(OFF_R0,r15) ! Return value 229 230/* 231 * The main debug trap handler. 232 * 233 * r8=TRA (not the trap number!) 234 * 235 * Note: This assumes that the trapa value is left in its original 236 * form (without the shlr2 shift) so the calculation for the jump 237 * call table offset remains a simple in place mask. 238 */ 239debug_trap: 240 mov r8, r0 241 and #(0xf << 2), r0 242 mov.l 1f, r8 243 add r0, r8 244 mov.l @r8, r8 245 jsr @r8 246 nop 247 bra __restore_all 248 nop 249 CFI_ENDPROC 250 251 .align 2 2521: .long debug_trap_table 253 254/* 255 * Syscall interface: 256 * 257 * Syscall #: R3 258 * Arguments #0 to #3: R4--R7 259 * Arguments #4 to #6: R0, R1, R2 260 * TRA: (number of arguments + ABI revision) x 4 261 * 262 * This code also handles delegating other traps to the BIOS/gdb stub 263 * according to: 264 * 265 * Trap number 266 * (TRA>>2) Purpose 267 * -------- ------- 268 * 0x00-0x0f original SH-3/4 syscall ABI (not in general use). 269 * 0x10-0x1f general SH-3/4 syscall ABI. 270 * 0x20-0x2f syscall ABI for SH-2 parts. 271 * 0x30-0x3f debug traps used by the kernel. 272 * 0x40-0xff Not supported by all parts, so left unhandled. 273 * 274 * Note: When we're first called, the TRA value must be shifted 275 * right 2 bits in order to get the value that was used as the "trapa" 276 * argument. 277 */ 278 279 .align 2 280 .globl ret_from_fork 281ret_from_fork: 282 mov.l 1f, r8 283 jsr @r8 284 mov r0, r4 285 bra syscall_exit 286 nop 287 .align 2 2881: .long schedule_tail 289 290/* 291 * The poorly named main trapa decode and dispatch routine, for 292 * system calls and debug traps through their respective jump tables. 293 */ 294ENTRY(system_call) 295 setup_frame_reg 296#if !defined(CONFIG_CPU_SH2) 297 mov.l 1f, r9 298 mov.l @r9, r8 ! Read from TRA (Trap Address) Register 299#endif 300 301 mov #OFF_TRA, r10 302 add r15, r10 303 mov.l r8, @r10 ! set TRA value to tra 304 305 /* 306 * Check the trap type 307 */ 308 mov #((0x20 << 2) - 1), r9 309 cmp/hi r9, r8 310 bt/s debug_trap ! it's a debug trap.. 311 nop 312 313 TRACE_IRQS_ON 314 sti 315 316 ! 317 get_current_thread_info r8, r10 318 mov.l @(TI_FLAGS,r8), r8 319 mov #(_TIF_WORK_SYSCALL_MASK & 0xff), r10 320 mov #(_TIF_WORK_SYSCALL_MASK >> 8), r9 321 tst r10, r8 322 shll8 r9 323 bf syscall_trace_entry 324 tst r9, r8 325 bf syscall_trace_entry 326 ! 327 mov.l 2f, r8 ! Number of syscalls 328 cmp/hs r8, r3 329 bt syscall_badsys 330 ! 331syscall_call: 332 shll2 r3 ! x4 333 mov.l 3f, r8 ! Load the address of sys_call_table 334 add r8, r3 335 mov.l @r3, r8 336 jsr @r8 ! jump to specific syscall handler 337 nop 338 mov.l @(OFF_R0,r15), r12 ! save r0 339 mov.l r0, @(OFF_R0,r15) ! save the return value 340 ! 341syscall_exit: 342 cli 343 TRACE_IRQS_OFF 344 ! 345 get_current_thread_info r8, r0 346 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 347 tst #(_TIF_ALLWORK_MASK & 0xff), r0 348 mov #(_TIF_ALLWORK_MASK >> 8), r1 349 bf syscall_exit_work 350 shlr8 r0 351 tst r0, r1 352 bf syscall_exit_work 353 bra __restore_all 354 nop 355 .align 2 356#if !defined(CONFIG_CPU_SH2) 3571: .long TRA 358#endif 3592: .long NR_syscalls 3603: .long sys_call_table 3617: .long do_syscall_trace_enter 3628: .long do_syscall_trace_leave 363