1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * Copyright (C) 2014-15 Synopsys, Inc. (www.synopsys.com) 4 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) 5 * 6 * Vineetg: March 2009 (Supporting 2 levels of Interrupts) 7 * Stack switching code can no longer reliably rely on the fact that 8 * if we are NOT in user mode, stack is switched to kernel mode. 9 * e.g. L2 IRQ interrupted a L1 ISR which had not yet completed 10 * it's prologue including stack switching from user mode 11 * 12 * Vineetg: Aug 28th 2008: Bug #94984 13 * -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap 14 * Normally CPU does this automatically, however when doing FAKE rtie, 15 * we also need to explicitly do this. The problem in macros 16 * FAKE_RET_FROM_EXCPN and FAKE_RET_FROM_EXCPN_LOCK_IRQ was that this bit 17 * was being "CLEARED" rather then "SET". Actually "SET" clears ZOL context 18 * 19 * Vineetg: May 5th 2008 20 * -Modified CALLEE_REG save/restore macros to handle the fact that 21 * r25 contains the kernel current task ptr 22 * - Defined Stack Switching Macro to be reused in all intr/excp hdlrs 23 * - Shaved off 11 instructions from RESTORE_ALL_INT1 by using the 24 * address Write back load ld.ab instead of seperate ld/add instn 25 * 26 * Amit Bhor, Sameer Dhavale: Codito Technologies 2004 27 */ 28 29 #ifndef __ASM_ARC_ENTRY_COMPACT_H 30 #define __ASM_ARC_ENTRY_COMPACT_H 31 32 #include <asm/asm-offsets.h> 33 #include <asm/irqflags-compact.h> 34 #include <asm/thread_info.h> /* For THREAD_SIZE */ 35 36 #ifdef CONFIG_ARC_PLAT_EZNPS 37 #include <plat/ctop.h> 38 #endif 39 40 /*-------------------------------------------------------------- 41 * Switch to Kernel Mode stack if SP points to User Mode stack 42 * 43 * Entry : r9 contains pre-IRQ/exception/trap status32 44 * Exit : SP set to K mode stack 45 * SP at the time of entry (K/U) saved @ pt_regs->sp 46 * Clobbers: r9 47 *-------------------------------------------------------------*/ 48 49 .macro SWITCH_TO_KERNEL_STK 50 51 /* User Mode when this happened ? Yes: Proceed to switch stack */ 52 bbit1 r9, STATUS_U_BIT, 88f 53 54 /* OK we were already in kernel mode when this event happened, thus can 55 * assume SP is kernel mode SP. _NO_ need to do any stack switching 56 */ 57 58 #ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS 59 /* However.... 60 * If Level 2 Interrupts enabled, we may end up with a corner case: 61 * 1. User Task executing 62 * 2. L1 IRQ taken, ISR starts (CPU auto-switched to KERNEL mode) 63 * 3. But before it could switch SP from USER to KERNEL stack 64 * a L2 IRQ "Interrupts" L1 65 * Thay way although L2 IRQ happened in Kernel mode, stack is still 66 * not switched. 67 * To handle this, we may need to switch stack even if in kernel mode 68 * provided SP has values in range of USER mode stack ( < 0x7000_0000 ) 69 */ 70 brlo sp, VMALLOC_START, 88f 71 72 /* TODO: vineetg: 73 * We need to be a bit more cautious here. What if a kernel bug in 74 * L1 ISR, caused SP to go whaco (some small value which looks like 75 * USER stk) and then we take L2 ISR. 76 * Above brlo alone would treat it as a valid L1-L2 scenario 77 * instead of shouting around 78 * The only feasible way is to make sure this L2 happened in 79 * L1 prelogue ONLY i.e. ilink2 is less than a pre-set marker in 80 * L1 ISR before it switches stack 81 */ 82 83 #endif 84 85 /*------Intr/Ecxp happened in kernel mode, SP already setup ------ */ 86 /* save it nevertheless @ pt_regs->sp for uniformity */ 87 88 b.d 66f 89 st sp, [sp, PT_sp - SZ_PT_REGS] 90 91 88: /*------Intr/Ecxp happened in user mode, "switch" stack ------ */ 92 93 GET_CURR_TASK_ON_CPU r9 94 95 /* With current tsk in r9, get it's kernel mode stack base */ 96 GET_TSK_STACK_BASE r9, r9 97 98 /* save U mode SP @ pt_regs->sp */ 99 st sp, [r9, PT_sp - SZ_PT_REGS] 100 101 /* final SP switch */ 102 mov sp, r9 103 66: 104 .endm 105 106 /*------------------------------------------------------------ 107 * "FAKE" a rtie to return from CPU Exception context 108 * This is to re-enable Exceptions within exception 109 * Look at EV_ProtV to see how this is actually used 110 *-------------------------------------------------------------*/ 111 112 .macro FAKE_RET_FROM_EXCPN 113 114 lr r9, [status32] 115 bclr r9, r9, STATUS_AE_BIT 116 or r9, r9, (STATUS_E1_MASK|STATUS_E2_MASK) 117 sr r9, [erstatus] 118 mov r9, 55f 119 sr r9, [eret] 120 rtie 121 55: 122 .endm 123 124 /*-------------------------------------------------------------- 125 * For early Exception/ISR Prologue, a core reg is temporarily needed to 126 * code the rest of prolog (stack switching). This is done by stashing 127 * it to memory (non-SMP case) or SCRATCH0 Aux Reg (SMP). 128 * 129 * Before saving the full regfile - this reg is restored back, only 130 * to be saved again on kernel mode stack, as part of pt_regs. 131 *-------------------------------------------------------------*/ 132 .macro PROLOG_FREEUP_REG reg, mem 133 #ifndef ARC_USE_SCRATCH_REG 134 sr \reg, [ARC_REG_SCRATCH_DATA0] 135 #else 136 st \reg, [\mem] 137 #endif 138 .endm 139 140 .macro PROLOG_RESTORE_REG reg, mem 141 #ifndef ARC_USE_SCRATCH_REG 142 lr \reg, [ARC_REG_SCRATCH_DATA0] 143 #else 144 ld \reg, [\mem] 145 #endif 146 .endm 147 148 /*-------------------------------------------------------------- 149 * Exception Entry prologue 150 * -Switches stack to K mode (if not already) 151 * -Saves the register file 152 * 153 * After this it is safe to call the "C" handlers 154 *-------------------------------------------------------------*/ 155 .macro EXCEPTION_PROLOGUE 156 157 /* Need at least 1 reg to code the early exception prologue */ 158 PROLOG_FREEUP_REG r9, @ex_saved_reg1 159 160 /* U/K mode at time of exception (stack not switched if already K) */ 161 lr r9, [erstatus] 162 163 /* ARC700 doesn't provide auto-stack switching */ 164 SWITCH_TO_KERNEL_STK 165 166 #ifdef CONFIG_ARC_CURR_IN_REG 167 /* Treat r25 as scratch reg (save on stack) and load with "current" */ 168 PUSH r25 169 GET_CURR_TASK_ON_CPU r25 170 #else 171 sub sp, sp, 4 172 #endif 173 174 st.a r0, [sp, -8] /* orig_r0 needed for syscall (skip ECR slot) */ 175 sub sp, sp, 4 /* skip pt_regs->sp, already saved above */ 176 177 /* Restore r9 used to code the early prologue */ 178 PROLOG_RESTORE_REG r9, @ex_saved_reg1 179 180 /* now we are ready to save the regfile */ 181 SAVE_R0_TO_R12 182 PUSH gp 183 PUSH fp 184 PUSH blink 185 PUSHAX eret 186 PUSHAX erstatus 187 PUSH lp_count 188 PUSHAX lp_end 189 PUSHAX lp_start 190 PUSHAX erbta 191 192 #ifdef CONFIG_ARC_PLAT_EZNPS 193 .word CTOP_INST_SCHD_RW 194 PUSHAX CTOP_AUX_GPA1 195 PUSHAX CTOP_AUX_EFLAGS 196 #endif 197 198 lr r10, [ecr] 199 st r10, [sp, PT_event] /* EV_Trap expects r10 to have ECR */ 200 .endm 201 202 /*-------------------------------------------------------------- 203 * Restore all registers used by system call or Exceptions 204 * SP should always be pointing to the next free stack element 205 * when entering this macro. 206 * 207 * NOTE: 208 * 209 * It is recommended that lp_count/ilink1/ilink2 not be used as a dest reg 210 * for memory load operations. If used in that way interrupts are deffered 211 * by hardware and that is not good. 212 *-------------------------------------------------------------*/ 213 .macro EXCEPTION_EPILOGUE 214 #ifdef CONFIG_ARC_PLAT_EZNPS 215 .word CTOP_INST_SCHD_RW 216 POPAX CTOP_AUX_EFLAGS 217 POPAX CTOP_AUX_GPA1 218 #endif 219 220 POPAX erbta 221 POPAX lp_start 222 POPAX lp_end 223 224 POP r9 225 mov lp_count, r9 ;LD to lp_count is not allowed 226 227 POPAX erstatus 228 POPAX eret 229 POP blink 230 POP fp 231 POP gp 232 RESTORE_R12_TO_R0 233 234 #ifdef CONFIG_ARC_CURR_IN_REG 235 ld r25, [sp, 12] 236 #endif 237 ld sp, [sp] /* restore original sp */ 238 /* orig_r0, ECR, user_r25 skipped automatically */ 239 .endm 240 241 /* Dummy ECR values for Interrupts */ 242 #define event_IRQ1 0x0031abcd 243 #define event_IRQ2 0x0032abcd 244 245 .macro INTERRUPT_PROLOGUE LVL 246 247 /* free up r9 as scratchpad */ 248 PROLOG_FREEUP_REG r9, @int\LVL\()_saved_reg 249 250 /* Which mode (user/kernel) was the system in when intr occurred */ 251 lr r9, [status32_l\LVL\()] 252 253 SWITCH_TO_KERNEL_STK 254 255 #ifdef CONFIG_ARC_CURR_IN_REG 256 /* Treat r25 as scratch reg (save on stack) and load with "current" */ 257 PUSH r25 258 GET_CURR_TASK_ON_CPU r25 259 #else 260 sub sp, sp, 4 261 #endif 262 263 PUSH 0x003\LVL\()abcd /* Dummy ECR */ 264 sub sp, sp, 8 /* skip orig_r0 (not needed) 265 skip pt_regs->sp, already saved above */ 266 267 /* Restore r9 used to code the early prologue */ 268 PROLOG_RESTORE_REG r9, @int\LVL\()_saved_reg 269 270 SAVE_R0_TO_R12 271 PUSH gp 272 PUSH fp 273 PUSH blink 274 PUSH ilink\LVL\() 275 PUSHAX status32_l\LVL\() 276 PUSH lp_count 277 PUSHAX lp_end 278 PUSHAX lp_start 279 PUSHAX bta_l\LVL\() 280 281 #ifdef CONFIG_ARC_PLAT_EZNPS 282 .word CTOP_INST_SCHD_RW 283 PUSHAX CTOP_AUX_GPA1 284 PUSHAX CTOP_AUX_EFLAGS 285 #endif 286 .endm 287 288 /*-------------------------------------------------------------- 289 * Restore all registers used by interrupt handlers. 290 * 291 * NOTE: 292 * 293 * It is recommended that lp_count/ilink1/ilink2 not be used as a dest reg 294 * for memory load operations. If used in that way interrupts are deffered 295 * by hardware and that is not good. 296 *-------------------------------------------------------------*/ 297 .macro INTERRUPT_EPILOGUE LVL 298 #ifdef CONFIG_ARC_PLAT_EZNPS 299 .word CTOP_INST_SCHD_RW 300 POPAX CTOP_AUX_EFLAGS 301 POPAX CTOP_AUX_GPA1 302 #endif 303 304 POPAX bta_l\LVL\() 305 POPAX lp_start 306 POPAX lp_end 307 308 POP r9 309 mov lp_count, r9 ;LD to lp_count is not allowed 310 311 POPAX status32_l\LVL\() 312 POP ilink\LVL\() 313 POP blink 314 POP fp 315 POP gp 316 RESTORE_R12_TO_R0 317 318 #ifdef CONFIG_ARC_CURR_IN_REG 319 ld r25, [sp, 12] 320 #endif 321 ld sp, [sp] /* restore original sp */ 322 /* orig_r0, ECR, user_r25 skipped automatically */ 323 .endm 324 325 /* Get thread_info of "current" tsk */ 326 .macro GET_CURR_THR_INFO_FROM_SP reg 327 bic \reg, sp, (THREAD_SIZE - 1) 328 .endm 329 330 #ifndef CONFIG_ARC_PLAT_EZNPS 331 /* Get CPU-ID of this core */ 332 .macro GET_CPU_ID reg 333 lr \reg, [identity] 334 lsr \reg, \reg, 8 335 bmsk \reg, \reg, 7 336 .endm 337 #endif 338 339 #endif /* __ASM_ARC_ENTRY_COMPACT_H */ 340