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 /*-------------------------------------------------------------- 37 * Switch to Kernel Mode stack if SP points to User Mode stack 38 * 39 * Entry : r9 contains pre-IRQ/exception/trap status32 40 * Exit : SP set to K mode stack 41 * SP at the time of entry (K/U) saved @ pt_regs->sp 42 * Clobbers: r9 43 *-------------------------------------------------------------*/ 44 45 .macro SWITCH_TO_KERNEL_STK 46 47 /* User Mode when this happened ? Yes: Proceed to switch stack */ 48 bbit1 r9, STATUS_U_BIT, 88f 49 50 /* OK we were already in kernel mode when this event happened, thus can 51 * assume SP is kernel mode SP. _NO_ need to do any stack switching 52 */ 53 54 #ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS 55 /* However.... 56 * If Level 2 Interrupts enabled, we may end up with a corner case: 57 * 1. User Task executing 58 * 2. L1 IRQ taken, ISR starts (CPU auto-switched to KERNEL mode) 59 * 3. But before it could switch SP from USER to KERNEL stack 60 * a L2 IRQ "Interrupts" L1 61 * Thay way although L2 IRQ happened in Kernel mode, stack is still 62 * not switched. 63 * To handle this, we may need to switch stack even if in kernel mode 64 * provided SP has values in range of USER mode stack ( < 0x7000_0000 ) 65 */ 66 brlo sp, VMALLOC_START, 88f 67 68 /* TODO: vineetg: 69 * We need to be a bit more cautious here. What if a kernel bug in 70 * L1 ISR, caused SP to go whaco (some small value which looks like 71 * USER stk) and then we take L2 ISR. 72 * Above brlo alone would treat it as a valid L1-L2 scenario 73 * instead of shouting around 74 * The only feasible way is to make sure this L2 happened in 75 * L1 prelogue ONLY i.e. ilink2 is less than a pre-set marker in 76 * L1 ISR before it switches stack 77 */ 78 79 #endif 80 81 /*------Intr/Ecxp happened in kernel mode, SP already setup ------ */ 82 /* save it nevertheless @ pt_regs->sp for uniformity */ 83 84 b.d 66f 85 st sp, [sp, PT_sp - SZ_PT_REGS] 86 87 88: /*------Intr/Ecxp happened in user mode, "switch" stack ------ */ 88 89 GET_CURR_TASK_ON_CPU r9 90 91 /* With current tsk in r9, get it's kernel mode stack base */ 92 GET_TSK_STACK_BASE r9, r9 93 94 /* save U mode SP @ pt_regs->sp */ 95 st sp, [r9, PT_sp - SZ_PT_REGS] 96 97 /* final SP switch */ 98 mov sp, r9 99 66: 100 .endm 101 102 /*------------------------------------------------------------ 103 * "FAKE" a rtie to return from CPU Exception context 104 * This is to re-enable Exceptions within exception 105 * Look at EV_ProtV to see how this is actually used 106 *-------------------------------------------------------------*/ 107 108 .macro FAKE_RET_FROM_EXCPN 109 110 lr r9, [status32] 111 bclr r9, r9, STATUS_AE_BIT 112 or r9, r9, (STATUS_E1_MASK|STATUS_E2_MASK) 113 sr r9, [erstatus] 114 mov r9, 55f 115 sr r9, [eret] 116 rtie 117 55: 118 .endm 119 120 /*-------------------------------------------------------------- 121 * For early Exception/ISR Prologue, a core reg is temporarily needed to 122 * code the rest of prolog (stack switching). This is done by stashing 123 * it to memory (non-SMP case) or SCRATCH0 Aux Reg (SMP). 124 * 125 * Before saving the full regfile - this reg is restored back, only 126 * to be saved again on kernel mode stack, as part of pt_regs. 127 *-------------------------------------------------------------*/ 128 .macro PROLOG_FREEUP_REG reg, mem 129 st \reg, [\mem] 130 .endm 131 132 .macro PROLOG_RESTORE_REG reg, mem 133 ld \reg, [\mem] 134 .endm 135 136 /*-------------------------------------------------------------- 137 * Exception Entry prologue 138 * -Switches stack to K mode (if not already) 139 * -Saves the register file 140 * 141 * After this it is safe to call the "C" handlers 142 *-------------------------------------------------------------*/ 143 .macro EXCEPTION_PROLOGUE 144 145 /* Need at least 1 reg to code the early exception prologue */ 146 PROLOG_FREEUP_REG r9, @ex_saved_reg1 147 148 /* U/K mode at time of exception (stack not switched if already K) */ 149 lr r9, [erstatus] 150 151 /* ARC700 doesn't provide auto-stack switching */ 152 SWITCH_TO_KERNEL_STK 153 154 #ifdef CONFIG_ARC_CURR_IN_REG 155 /* Treat r25 as scratch reg (save on stack) and load with "current" */ 156 PUSH r25 157 GET_CURR_TASK_ON_CPU r25 158 #else 159 sub sp, sp, 4 160 #endif 161 162 st.a r0, [sp, -8] /* orig_r0 needed for syscall (skip ECR slot) */ 163 sub sp, sp, 4 /* skip pt_regs->sp, already saved above */ 164 165 /* Restore r9 used to code the early prologue */ 166 PROLOG_RESTORE_REG r9, @ex_saved_reg1 167 168 /* now we are ready to save the regfile */ 169 SAVE_R0_TO_R12 170 PUSH gp 171 PUSH fp 172 PUSH blink 173 PUSHAX eret 174 PUSHAX erstatus 175 PUSH lp_count 176 PUSHAX lp_end 177 PUSHAX lp_start 178 PUSHAX erbta 179 180 lr r10, [ecr] 181 st r10, [sp, PT_event] /* EV_Trap expects r10 to have ECR */ 182 .endm 183 184 /*-------------------------------------------------------------- 185 * Restore all registers used by system call or Exceptions 186 * SP should always be pointing to the next free stack element 187 * when entering this macro. 188 * 189 * NOTE: 190 * 191 * It is recommended that lp_count/ilink1/ilink2 not be used as a dest reg 192 * for memory load operations. If used in that way interrupts are deffered 193 * by hardware and that is not good. 194 *-------------------------------------------------------------*/ 195 .macro EXCEPTION_EPILOGUE 196 197 POPAX erbta 198 POPAX lp_start 199 POPAX lp_end 200 201 POP r9 202 mov lp_count, r9 ;LD to lp_count is not allowed 203 204 POPAX erstatus 205 POPAX eret 206 POP blink 207 POP fp 208 POP gp 209 RESTORE_R12_TO_R0 210 211 #ifdef CONFIG_ARC_CURR_IN_REG 212 ld r25, [sp, 12] 213 #endif 214 ld sp, [sp] /* restore original sp */ 215 /* orig_r0, ECR, user_r25 skipped automatically */ 216 .endm 217 218 /* Dummy ECR values for Interrupts */ 219 #define event_IRQ1 0x0031abcd 220 #define event_IRQ2 0x0032abcd 221 222 .macro INTERRUPT_PROLOGUE LVL 223 224 /* free up r9 as scratchpad */ 225 PROLOG_FREEUP_REG r9, @int\LVL\()_saved_reg 226 227 /* Which mode (user/kernel) was the system in when intr occurred */ 228 lr r9, [status32_l\LVL\()] 229 230 SWITCH_TO_KERNEL_STK 231 232 #ifdef CONFIG_ARC_CURR_IN_REG 233 /* Treat r25 as scratch reg (save on stack) and load with "current" */ 234 PUSH r25 235 GET_CURR_TASK_ON_CPU r25 236 #else 237 sub sp, sp, 4 238 #endif 239 240 PUSH 0x003\LVL\()abcd /* Dummy ECR */ 241 sub sp, sp, 8 /* skip orig_r0 (not needed) 242 skip pt_regs->sp, already saved above */ 243 244 /* Restore r9 used to code the early prologue */ 245 PROLOG_RESTORE_REG r9, @int\LVL\()_saved_reg 246 247 SAVE_R0_TO_R12 248 PUSH gp 249 PUSH fp 250 PUSH blink 251 PUSH ilink\LVL\() 252 PUSHAX status32_l\LVL\() 253 PUSH lp_count 254 PUSHAX lp_end 255 PUSHAX lp_start 256 PUSHAX bta_l\LVL\() 257 258 .endm 259 260 /*-------------------------------------------------------------- 261 * Restore all registers used by interrupt handlers. 262 * 263 * NOTE: 264 * 265 * It is recommended that lp_count/ilink1/ilink2 not be used as a dest reg 266 * for memory load operations. If used in that way interrupts are deffered 267 * by hardware and that is not good. 268 *-------------------------------------------------------------*/ 269 .macro INTERRUPT_EPILOGUE LVL 270 271 POPAX bta_l\LVL\() 272 POPAX lp_start 273 POPAX lp_end 274 275 POP r9 276 mov lp_count, r9 ;LD to lp_count is not allowed 277 278 POPAX status32_l\LVL\() 279 POP ilink\LVL\() 280 POP blink 281 POP fp 282 POP gp 283 RESTORE_R12_TO_R0 284 285 #ifdef CONFIG_ARC_CURR_IN_REG 286 ld r25, [sp, 12] 287 #endif 288 ld sp, [sp] /* restore original sp */ 289 /* orig_r0, ECR, user_r25 skipped automatically */ 290 .endm 291 292 /* Get thread_info of "current" tsk */ 293 .macro GET_CURR_THR_INFO_FROM_SP reg 294 bic \reg, sp, (THREAD_SIZE - 1) 295 .endm 296 297 /* Get CPU-ID of this core */ 298 .macro GET_CPU_ID reg 299 lr \reg, [identity] 300 lsr \reg, \reg, 8 301 bmsk \reg, \reg, 7 302 .endm 303 304 #endif /* __ASM_ARC_ENTRY_COMPACT_H */ 305