1/* 2 * Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved. 3 * 4 * SPDX-License-Identifier: BSD-3-Clause 5 */ 6 7 8#include <assert_macros.S> 9#include <asm_macros.S> 10#include <assert_macros.S> 11#include <bl31/ea_handle.h> 12#include <context.h> 13#include <lib/extensions/ras_arch.h> 14 15 16 .globl handle_lower_el_ea_esb 17 .globl enter_lower_el_sync_ea 18 .globl enter_lower_el_async_ea 19 20 21/* 22 * Function to delegate External Aborts synchronized by ESB instruction at EL3 23 * vector entry. This function assumes GP registers x0-x29 have been saved, and 24 * are available for use. It delegates the handling of the EA to platform 25 * handler, and returns only upon successfully handling the EA; otherwise 26 * panics. On return from this function, the original exception handler is 27 * expected to resume. 28 */ 29func handle_lower_el_ea_esb 30 mov x0, #ERROR_EA_ESB 31 mrs x1, DISR_EL1 32 b ea_proceed 33endfunc handle_lower_el_ea_esb 34 35 36/* 37 * This function forms the tail end of Synchronous Exception entry from lower 38 * EL, and expects to handle only Synchronous External Aborts from lower EL. If 39 * any other kind of exception is detected, then this function reports unhandled 40 * exception. 41 * 42 * Since it's part of exception vector, this function doesn't expect any GP 43 * registers to have been saved. It delegates the handling of the EA to platform 44 * handler, and upon successfully handling the EA, exits EL3; otherwise panics. 45 */ 46func enter_lower_el_sync_ea 47 /* 48 * Explicitly save x30 so as to free up a register and to enable 49 * branching. 50 */ 51 str x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR] 52 53 mrs x30, esr_el3 54 ubfx x30, x30, #ESR_EC_SHIFT, #ESR_EC_LENGTH 55 56 /* Check for I/D aborts from lower EL */ 57 cmp x30, #EC_IABORT_LOWER_EL 58 b.eq 1f 59 60 cmp x30, #EC_DABORT_LOWER_EL 61 b.ne 2f 62 631: 64 /* Test for EA bit in the instruction syndrome */ 65 mrs x30, esr_el3 66 tbz x30, #ESR_ISS_EABORT_EA_BIT, 2f 67 68 /* Save GP registers */ 69 bl save_gp_registers 70 71#if CTX_INCLUDE_PAUTH_REGS 72 bl pauth_context_save 73#endif 74 75 /* Setup exception class and syndrome arguments for platform handler */ 76 mov x0, #ERROR_EA_SYNC 77 mrs x1, esr_el3 78 adr x30, el3_exit 79 b delegate_sync_ea 80 812: 82 /* Synchronous exceptions other than the above are assumed to be EA */ 83 ldr x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR] 84 no_ret report_unhandled_exception 85endfunc enter_lower_el_sync_ea 86 87 88/* 89 * This function handles SErrors from lower ELs. 90 * 91 * Since it's part of exception vector, this function doesn't expect any GP 92 * registers to have been saved. It delegates the handling of the EA to platform 93 * handler, and upon successfully handling the EA, exits EL3; otherwise panics. 94 */ 95func enter_lower_el_async_ea 96 /* 97 * Explicitly save x30 so as to free up a register and to enable 98 * branching 99 */ 100 str x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR] 101 102 /* Save GP registers */ 103 bl save_gp_registers 104 105#if CTX_INCLUDE_PAUTH_REGS 106 bl pauth_context_save 107#endif 108 109 /* Setup exception class and syndrome arguments for platform handler */ 110 mov x0, #ERROR_EA_ASYNC 111 mrs x1, esr_el3 112 adr x30, el3_exit 113 b delegate_async_ea 114endfunc enter_lower_el_async_ea 115 116 117/* 118 * Prelude for Synchronous External Abort handling. This function assumes that 119 * all GP registers have been saved by the caller. 120 * 121 * x0: EA reason 122 * x1: EA syndrome 123 */ 124func delegate_sync_ea 125#if RAS_EXTENSION 126 /* 127 * Check for Uncontainable error type. If so, route to the platform 128 * fatal error handler rather than the generic EA one. 129 */ 130 ubfx x2, x1, #EABORT_SET_SHIFT, #EABORT_SET_WIDTH 131 cmp x2, #ERROR_STATUS_SET_UC 132 b.ne 1f 133 134 /* Check fault status code */ 135 ubfx x3, x1, #EABORT_DFSC_SHIFT, #EABORT_DFSC_WIDTH 136 cmp x3, #SYNC_EA_FSC 137 b.ne 1f 138 139 no_ret plat_handle_uncontainable_ea 1401: 141#endif 142 143 b ea_proceed 144endfunc delegate_sync_ea 145 146 147/* 148 * Prelude for Asynchronous External Abort handling. This function assumes that 149 * all GP registers have been saved by the caller. 150 * 151 * x0: EA reason 152 * x1: EA syndrome 153 */ 154func delegate_async_ea 155#if RAS_EXTENSION 156 /* 157 * Check for Implementation Defined Syndrome. If so, skip checking 158 * Uncontainable error type from the syndrome as the format is unknown. 159 */ 160 tbnz x1, #SERROR_IDS_BIT, 1f 161 162 /* 163 * Check for Uncontainable error type. If so, route to the platform 164 * fatal error handler rather than the generic EA one. 165 */ 166 ubfx x2, x1, #EABORT_AET_SHIFT, #EABORT_AET_WIDTH 167 cmp x2, #ERROR_STATUS_UET_UC 168 b.ne 1f 169 170 /* Check DFSC for SError type */ 171 ubfx x3, x1, #EABORT_DFSC_SHIFT, #EABORT_DFSC_WIDTH 172 cmp x3, #DFSC_SERROR 173 b.ne 1f 174 175 no_ret plat_handle_uncontainable_ea 1761: 177#endif 178 179 b ea_proceed 180endfunc delegate_async_ea 181 182 183/* 184 * Delegate External Abort handling to platform's EA handler. This function 185 * assumes that all GP registers have been saved by the caller. 186 * 187 * x0: EA reason 188 * x1: EA syndrome 189 */ 190func ea_proceed 191 /* 192 * If the ESR loaded earlier is not zero, we were processing an EA 193 * already, and this is a double fault. 194 */ 195 ldr x5, [sp, #CTX_EL3STATE_OFFSET + CTX_ESR_EL3] 196 cbz x5, 1f 197 no_ret plat_handle_double_fault 198 1991: 200 /* Save EL3 state */ 201 mrs x2, spsr_el3 202 mrs x3, elr_el3 203 stp x2, x3, [sp, #CTX_EL3STATE_OFFSET + CTX_SPSR_EL3] 204 205 /* 206 * Save ESR as handling might involve lower ELs, and returning back to 207 * EL3 from there would trample the original ESR. 208 */ 209 mrs x4, scr_el3 210 mrs x5, esr_el3 211 stp x4, x5, [sp, #CTX_EL3STATE_OFFSET + CTX_SCR_EL3] 212 213 /* 214 * Setup rest of arguments, and call platform External Abort handler. 215 * 216 * x0: EA reason (already in place) 217 * x1: Exception syndrome (already in place). 218 * x2: Cookie (unused for now). 219 * x3: Context pointer. 220 * x4: Flags (security state from SCR for now). 221 */ 222 mov x2, xzr 223 mov x3, sp 224 ubfx x4, x4, #0, #1 225 226 /* Switch to runtime stack */ 227 ldr x5, [sp, #CTX_EL3STATE_OFFSET + CTX_RUNTIME_SP] 228 msr spsel, #0 229 mov sp, x5 230 231 mov x29, x30 232#if ENABLE_ASSERTIONS 233 /* Stash the stack pointer */ 234 mov x28, sp 235#endif 236 bl plat_ea_handler 237 238#if ENABLE_ASSERTIONS 239 /* 240 * Error handling flows might involve long jumps; so upon returning from 241 * the platform error handler, validate that the we've completely 242 * unwound the stack. 243 */ 244 mov x27, sp 245 cmp x28, x27 246 ASM_ASSERT(eq) 247#endif 248 249 /* Make SP point to context */ 250 msr spsel, #1 251 252 /* Restore EL3 state and ESR */ 253 ldp x1, x2, [sp, #CTX_EL3STATE_OFFSET + CTX_SPSR_EL3] 254 msr spsr_el3, x1 255 msr elr_el3, x2 256 257 /* Restore ESR_EL3 and SCR_EL3 */ 258 ldp x3, x4, [sp, #CTX_EL3STATE_OFFSET + CTX_SCR_EL3] 259 msr scr_el3, x3 260 msr esr_el3, x4 261 262#if ENABLE_ASSERTIONS 263 cmp x4, xzr 264 ASM_ASSERT(ne) 265#endif 266 267 /* Clear ESR storage */ 268 str xzr, [sp, #CTX_EL3STATE_OFFSET + CTX_ESR_EL3] 269 270 ret x29 271endfunc ea_proceed 272