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 separate 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_KEEP_AE 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 st.a r0, [sp, -8] /* orig_r0 needed for syscall (skip ECR slot) */ 155 sub sp, sp, 4 /* skip pt_regs->sp, already saved above */ 156 157 /* Restore r9 used to code the early prologue */ 158 PROLOG_RESTORE_REG r9, @ex_saved_reg1 159 160 /* now we are ready to save the regfile */ 161 SAVE_R0_TO_R12 162 PUSH gp 163 PUSH fp 164 PUSH blink 165 PUSHAX eret 166 PUSHAX erstatus 167 PUSH lp_count 168 PUSHAX lp_end 169 PUSHAX lp_start 170 PUSHAX erbta 171 172 lr r10, [ecr] 173 st r10, [sp, PT_event] 174 175 #ifdef CONFIG_ARC_CURR_IN_REG 176 /* gp already saved on stack: now load with "current" */ 177 GET_CURR_TASK_ON_CPU gp 178 #endif 179 ; OUTPUT: r10 has ECR expected by EV_Trap 180 .endm 181 182 .macro EXCEPTION_PROLOGUE 183 184 EXCEPTION_PROLOGUE_KEEP_AE ; return ECR in r10 185 186 lr r0, [efa] 187 mov r1, sp 188 189 FAKE_RET_FROM_EXCPN ; clobbers r9 190 .endm 191 192 /*-------------------------------------------------------------- 193 * Restore all registers used by system call or Exceptions 194 * SP should always be pointing to the next free stack element 195 * when entering this macro. 196 * 197 * NOTE: 198 * 199 * It is recommended that lp_count/ilink1/ilink2 not be used as a dest reg 200 * for memory load operations. If used in that way interrupts are deffered 201 * by hardware and that is not good. 202 *-------------------------------------------------------------*/ 203 .macro EXCEPTION_EPILOGUE 204 205 POPAX erbta 206 POPAX lp_start 207 POPAX lp_end 208 209 POP r9 210 mov lp_count, r9 ;LD to lp_count is not allowed 211 212 POPAX erstatus 213 POPAX eret 214 POP blink 215 POP fp 216 POP gp 217 RESTORE_R12_TO_R0 218 219 ld sp, [sp] /* restore original sp */ 220 /* orig_r0, ECR skipped automatically */ 221 .endm 222 223 /* Dummy ECR values for Interrupts */ 224 #define event_IRQ1 0x0031abcd 225 #define event_IRQ2 0x0032abcd 226 227 .macro INTERRUPT_PROLOGUE LVL 228 229 /* free up r9 as scratchpad */ 230 PROLOG_FREEUP_REG r9, @int\LVL\()_saved_reg 231 232 /* Which mode (user/kernel) was the system in when intr occurred */ 233 lr r9, [status32_l\LVL\()] 234 235 SWITCH_TO_KERNEL_STK 236 237 238 PUSH 0x003\LVL\()abcd /* Dummy ECR */ 239 sub sp, sp, 8 /* skip orig_r0 (not needed) 240 skip pt_regs->sp, already saved above */ 241 242 /* Restore r9 used to code the early prologue */ 243 PROLOG_RESTORE_REG r9, @int\LVL\()_saved_reg 244 245 SAVE_R0_TO_R12 246 PUSH gp 247 PUSH fp 248 PUSH blink 249 PUSH ilink\LVL\() 250 PUSHAX status32_l\LVL\() 251 PUSH lp_count 252 PUSHAX lp_end 253 PUSHAX lp_start 254 PUSHAX bta_l\LVL\() 255 256 #ifdef CONFIG_ARC_CURR_IN_REG 257 /* gp already saved on stack: now load with "current" */ 258 GET_CURR_TASK_ON_CPU gp 259 #endif 260 .endm 261 262 /*-------------------------------------------------------------- 263 * Restore all registers used by interrupt handlers. 264 * 265 * NOTE: 266 * 267 * It is recommended that lp_count/ilink1/ilink2 not be used as a dest reg 268 * for memory load operations. If used in that way interrupts are deffered 269 * by hardware and that is not good. 270 *-------------------------------------------------------------*/ 271 .macro INTERRUPT_EPILOGUE LVL 272 273 POPAX bta_l\LVL\() 274 POPAX lp_start 275 POPAX lp_end 276 277 POP r9 278 mov lp_count, r9 ;LD to lp_count is not allowed 279 280 POPAX status32_l\LVL\() 281 POP ilink\LVL\() 282 POP blink 283 POP fp 284 POP gp 285 RESTORE_R12_TO_R0 286 287 ld sp, [sp] /* restore original sp; orig_r0, ECR skipped implicitly */ 288 .endm 289 290 /* Get thread_info of "current" tsk */ 291 .macro GET_CURR_THR_INFO_FROM_SP reg 292 bic \reg, sp, (THREAD_SIZE - 1) 293 .endm 294 295 /* Get CPU-ID of this core */ 296 .macro GET_CPU_ID reg 297 lr \reg, [identity] 298 lsr \reg, \reg, 8 299 bmsk \reg, \reg, 7 300 .endm 301 302 #endif /* __ASM_ARC_ENTRY_COMPACT_H */ 303