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 ; TRACE_IRQS_OFF 49#else 50# define preempt_stop() 51# define resume_kernel __restore_all 52#endif 53 54 55 .align 2 56ENTRY(exception_error) 57 ! 58 TRACE_IRQS_ON 59 sti 60 mov.l 1f, r0 61 jmp @r0 62 nop 63 64 .align 2 651: .long do_exception_error 66 67 .align 2 68ret_from_exception: 69 preempt_stop() 70ENTRY(ret_from_irq) 71 ! 72 mov #OFF_SR, r0 73 mov.l @(r0,r15), r0 ! get status register 74 75 shlr2 r0 76 and #0x3c, r0 77 cmp/eq #0x3c, r0 78 bt 9f 79 TRACE_IRQS_ON 809: 81 mov #OFF_SR, r0 82 mov.l @(r0,r15), r0 ! get status register 83 shll r0 84 shll r0 ! kernel space? 85 get_current_thread_info r8, r0 86 bt resume_kernel ! Yes, it's from kernel, go back soon 87 88#ifdef CONFIG_PREEMPT 89 bra resume_userspace 90 nop 91ENTRY(resume_kernel) 92 cli 93 mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count 94 tst r0, r0 95 bf noresched 96need_resched: 97 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 98 tst #_TIF_NEED_RESCHED, r0 ! need_resched set? 99 bt noresched 100 101 mov #OFF_SR, r0 102 mov.l @(r0,r15), r0 ! get status register 103 and #0xf0, r0 ! interrupts off (exception path)? 104 cmp/eq #0xf0, r0 105 bt noresched 106 mov.l 3f, r0 107 jsr @r0 ! call preempt_schedule_irq 108 nop 109 bra need_resched 110 nop 111 112noresched: 113 bra __restore_all 114 nop 115 116 .align 2 1171: .long PREEMPT_ACTIVE 1182: .long schedule 1193: .long preempt_schedule_irq 120#endif 121 122ENTRY(resume_userspace) 123 ! r8: current_thread_info 124 cli 125 TRACE_IRQS_OfF 126 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 127 tst #(_TIF_WORK_MASK & 0xff), r0 128 bt/s __restore_all 129 tst #_TIF_NEED_RESCHED, r0 130 131 .align 2 132work_pending: 133 ! r0: current_thread_info->flags 134 ! r8: current_thread_info 135 ! t: result of "tst #_TIF_NEED_RESCHED, r0" 136 bf/s work_resched 137 tst #(_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK), r0 138work_notifysig: 139 bt/s __restore_all 140 mov r15, r4 141 mov r12, r5 ! set arg1(save_r0) 142 mov r0, r6 143 mov.l 2f, r1 144 mov.l 3f, r0 145 jmp @r1 146 lds r0, pr 147work_resched: 148 mov.l 1f, r1 149 jsr @r1 ! schedule 150 nop 151 cli 152 TRACE_IRQS_OFF 153 ! 154 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 155 tst #(_TIF_WORK_MASK & 0xff), r0 156 bt __restore_all 157 bra work_pending 158 tst #_TIF_NEED_RESCHED, r0 159 160 .align 2 1611: .long schedule 1622: .long do_notify_resume 1633: .long resume_userspace 164 165 .align 2 166syscall_exit_work: 167 ! r0: current_thread_info->flags 168 ! r8: current_thread_info 169 tst #(_TIF_WORK_SYSCALL_MASK & 0xff), r0 170 bt/s work_pending 171 tst #_TIF_NEED_RESCHED, r0 172 TRACE_IRQS_ON 173 sti 174 mov r15, r4 175 mov.l 8f, r0 ! do_syscall_trace_leave 176 jsr @r0 177 nop 178 bra resume_userspace 179 nop 180 181 .align 2 182syscall_trace_entry: 183 ! Yes it is traced. 184 mov r15, r4 185 mov.l 7f, r11 ! Call do_syscall_trace_enter which notifies 186 jsr @r11 ! superior (will chomp R[0-7]) 187 nop 188 mov.l r0, @(OFF_R0,r15) ! Save return value 189 ! Reload R0-R4 from kernel stack, where the 190 ! parent may have modified them using 191 ! ptrace(POKEUSR). (Note that R0-R2 are 192 ! used by the system call handler directly 193 ! from the kernel stack anyway, so don't need 194 ! to be reloaded here.) This allows the parent 195 ! to rewrite system calls and args on the fly. 196 mov.l @(OFF_R4,r15), r4 ! arg0 197 mov.l @(OFF_R5,r15), r5 198 mov.l @(OFF_R6,r15), r6 199 mov.l @(OFF_R7,r15), r7 ! arg3 200 mov.l @(OFF_R3,r15), r3 ! syscall_nr 201 ! 202 mov.l 2f, r10 ! Number of syscalls 203 cmp/hs r10, r3 204 bf syscall_call 205 mov #-ENOSYS, r0 206 bra syscall_exit 207 mov.l r0, @(OFF_R0,r15) ! Return value 208 209__restore_all: 210 mov.l 1f, r0 211 jmp @r0 212 nop 213 214 .align 2 2151: .long restore_all 216 217 .align 2 218syscall_badsys: ! Bad syscall number 219 get_current_thread_info r8, r0 220 mov #-ENOSYS, r0 221 bra resume_userspace 222 mov.l r0, @(OFF_R0,r15) ! Return value 223 224/* 225 * The main debug trap handler. 226 * 227 * r8=TRA (not the trap number!) 228 * 229 * Note: This assumes that the trapa value is left in its original 230 * form (without the shlr2 shift) so the calculation for the jump 231 * call table offset remains a simple in place mask. 232 */ 233debug_trap: 234 mov r8, r0 235 and #(0xf << 2), r0 236 mov.l 1f, r8 237 add r0, r8 238 mov.l @r8, r8 239 jsr @r8 240 nop 241 bra __restore_all 242 nop 243 244 .align 2 2451: .long debug_trap_table 246 247/* 248 * Syscall interface: 249 * 250 * Syscall #: R3 251 * Arguments #0 to #3: R4--R7 252 * Arguments #4 to #6: R0, R1, R2 253 * TRA: (number of arguments + ABI revision) x 4 254 * 255 * This code also handles delegating other traps to the BIOS/gdb stub 256 * according to: 257 * 258 * Trap number 259 * (TRA>>2) Purpose 260 * -------- ------- 261 * 0x00-0x0f original SH-3/4 syscall ABI (not in general use). 262 * 0x10-0x1f general SH-3/4 syscall ABI. 263 * 0x20-0x2f syscall ABI for SH-2 parts. 264 * 0x30-0x3f debug traps used by the kernel. 265 * 0x40-0xff Not supported by all parts, so left unhandled. 266 * 267 * Note: When we're first called, the TRA value must be shifted 268 * right 2 bits in order to get the value that was used as the "trapa" 269 * argument. 270 */ 271 272 .align 2 273 .globl ret_from_fork 274ret_from_fork: 275 mov.l 1f, r8 276 jsr @r8 277 mov r0, r4 278 bra syscall_exit 279 nop 280 .align 2 2811: .long schedule_tail 282 283/* 284 * The poorly named main trapa decode and dispatch routine, for 285 * system calls and debug traps through their respective jump tables. 286 */ 287ENTRY(system_call) 288#if !defined(CONFIG_CPU_SH2) 289 mov.l 1f, r9 290 mov.l @r9, r8 ! Read from TRA (Trap Address) Register 291#endif 292 293 mov #OFF_TRA, r10 294 add r15, r10 295 mov.l r8, @r10 ! set TRA value to tra 296 297 /* 298 * Check the trap type 299 */ 300 mov #((0x20 << 2) - 1), r9 301 cmp/hi r9, r8 302 bt/s debug_trap ! it's a debug trap.. 303 nop 304 305 TRACE_IRQS_ON 306 sti 307 308 ! 309 get_current_thread_info r8, r10 310 mov.l @(TI_FLAGS,r8), r8 311 mov #(_TIF_WORK_SYSCALL_MASK & 0xff), r10 312 mov #(_TIF_WORK_SYSCALL_MASK >> 8), r9 313 tst r10, r8 314 shll8 r9 315 bf syscall_trace_entry 316 tst r9, r8 317 bf syscall_trace_entry 318 ! 319 mov.l 2f, r8 ! Number of syscalls 320 cmp/hs r8, r3 321 bt syscall_badsys 322 ! 323syscall_call: 324 shll2 r3 ! x4 325 mov.l 3f, r8 ! Load the address of sys_call_table 326 add r8, r3 327 mov.l @r3, r8 328 jsr @r8 ! jump to specific syscall handler 329 nop 330 mov.l @(OFF_R0,r15), r12 ! save r0 331 mov.l r0, @(OFF_R0,r15) ! save the return value 332 ! 333syscall_exit: 334 cli 335 TRACE_IRQS_OFF 336 ! 337 get_current_thread_info r8, r0 338 mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags 339 tst #(_TIF_ALLWORK_MASK & 0xff), r0 340 mov #(_TIF_ALLWORK_MASK >> 8), r1 341 bf syscall_exit_work 342 shlr8 r0 343 tst r0, r1 344 bf syscall_exit_work 345 bra __restore_all 346 nop 347 .align 2 348#if !defined(CONFIG_CPU_SH2) 3491: .long TRA 350#endif 3512: .long NR_syscalls 3523: .long sys_call_table 3537: .long do_syscall_trace_enter 3548: .long do_syscall_trace_leave 355