| Jeenu Viswambharan | e86a247 | 2018-07-05 15:24:45 +0100 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved. |
| 3 | * |
| 4 | * SPDX-License-Identifier: BSD-3-Clause |
| 5 | */ |
| 6 | |
| 7 | |
| 8 | #include <asm_macros.S> |
| 9 | #include <context.h> |
| 10 | #include <ea_handle.h> |
| 11 | |
| 12 | |
| 13 | .globl handle_lower_el_ea_esb |
| 14 | .globl enter_lower_el_sync_ea |
| 15 | .globl enter_lower_el_async_ea |
| 16 | |
| 17 | |
| 18 | /* |
| 19 | * Function to delegate External Aborts synchronized by ESB instruction at EL3 |
| 20 | * vector entry. This function assumes GP registers x0-x29 have been saved, and |
| 21 | * are available for use. It delegates the handling of the EA to platform |
| 22 | * handler, and returns only upon successfully handling the EA; otherwise |
| 23 | * panics. On return from this function, the original exception handler is |
| 24 | * expected to resume. |
| 25 | */ |
| 26 | func handle_lower_el_ea_esb |
| 27 | mov x0, #ERROR_EA_ESB |
| 28 | mrs x1, DISR_EL1 |
| 29 | b ea_proceed |
| 30 | endfunc handle_lower_el_ea_esb |
| 31 | |
| 32 | |
| 33 | /* |
| 34 | * This function forms the tail end of Synchronous Exception entry from lower |
| 35 | * EL, and expects to handle only Synchronous External Aborts from lower EL. If |
| 36 | * any other kind of exception is detected, then this function reports unhandled |
| 37 | * exception. |
| 38 | * |
| 39 | * Since it's part of exception vector, this function doesn't expect any GP |
| 40 | * registers to have been saved. It delegates the handling of the EA to platform |
| 41 | * handler, and upon successfully handling the EA, exits EL3; otherwise panics. |
| 42 | */ |
| 43 | func enter_lower_el_sync_ea |
| 44 | /* |
| 45 | * Explicitly save x30 so as to free up a register and to enable |
| 46 | * branching. |
| 47 | */ |
| 48 | str x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR] |
| 49 | |
| 50 | mrs x30, esr_el3 |
| 51 | ubfx x30, x30, #ESR_EC_SHIFT, #ESR_EC_LENGTH |
| 52 | |
| 53 | /* Check for I/D aborts from lower EL */ |
| 54 | cmp x30, #EC_IABORT_LOWER_EL |
| 55 | b.eq 1f |
| 56 | |
| 57 | cmp x30, #EC_DABORT_LOWER_EL |
| 58 | b.ne 2f |
| 59 | |
| 60 | 1: |
| 61 | /* Test for EA bit in the instruction syndrome */ |
| 62 | mrs x30, esr_el3 |
| 63 | tbz x30, #ESR_ISS_EABORT_EA_BIT, 2f |
| 64 | |
| 65 | /* Save GP registers */ |
| 66 | bl save_gp_registers |
| 67 | |
| 68 | /* Setup exception class and syndrome arguments for platform handler */ |
| 69 | mov x0, #ERROR_EA_SYNC |
| 70 | mrs x1, esr_el3 |
| 71 | adr x30, el3_exit |
| 72 | b ea_proceed |
| 73 | |
| 74 | 2: |
| 75 | /* Synchronous exceptions other than the above are assumed to be EA */ |
| 76 | ldr x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR] |
| 77 | no_ret report_unhandled_exception |
| 78 | endfunc enter_lower_el_sync_ea |
| 79 | |
| 80 | |
| 81 | /* |
| 82 | * This function handles SErrors from lower ELs. |
| 83 | * |
| 84 | * Since it's part of exception vector, this function doesn't expect any GP |
| 85 | * registers to have been saved. It delegates the handling of the EA to platform |
| 86 | * handler, and upon successfully handling the EA, exits EL3; otherwise panics. |
| 87 | */ |
| 88 | func enter_lower_el_async_ea |
| 89 | /* |
| 90 | * Explicitly save x30 so as to free up a register and to enable |
| 91 | * branching |
| 92 | */ |
| 93 | str x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR] |
| 94 | |
| 95 | /* Save GP registers */ |
| 96 | bl save_gp_registers |
| 97 | |
| 98 | /* Setup exception class and syndrome arguments for platform handler */ |
| 99 | mov x0, #ERROR_EA_ASYNC |
| 100 | mrs x1, esr_el3 |
| 101 | adr x30, el3_exit |
| 102 | b ea_proceed |
| 103 | endfunc enter_lower_el_async_ea |
| 104 | |
| 105 | |
| 106 | /* |
| 107 | * Delegate External Abort handling to platform's EA handler. This function |
| 108 | * assumes that all GP registers have been saved by the caller. |
| 109 | * |
| 110 | * x0: EA reason |
| 111 | * x1: EA syndrome |
| 112 | */ |
| 113 | func ea_proceed |
| 114 | /* Save EL3 state */ |
| 115 | mrs x2, spsr_el3 |
| 116 | mrs x3, elr_el3 |
| 117 | stp x2, x3, [sp, #CTX_EL3STATE_OFFSET + CTX_SPSR_EL3] |
| 118 | |
| 119 | /* |
| 120 | * Save ESR as handling might involve lower ELs, and returning back to |
| 121 | * EL3 from there would trample the original ESR. |
| 122 | */ |
| 123 | mrs x4, scr_el3 |
| 124 | mrs x5, esr_el3 |
| 125 | stp x4, x5, [sp, #CTX_EL3STATE_OFFSET + CTX_SCR_EL3] |
| 126 | |
| 127 | /* |
| 128 | * Setup rest of arguments, and call platform External Abort handler. |
| 129 | * |
| 130 | * x0: EA reason (already in place) |
| 131 | * x1: Exception syndrome (already in place). |
| 132 | * x2: Cookie (unused for now). |
| 133 | * x3: Context pointer. |
| 134 | * x4: Flags (security state from SCR for now). |
| 135 | */ |
| 136 | mov x2, xzr |
| 137 | mov x3, sp |
| 138 | ubfx x4, x4, #0, #1 |
| 139 | |
| 140 | /* Switch to runtime stack */ |
| 141 | ldr x5, [sp, #CTX_EL3STATE_OFFSET + CTX_RUNTIME_SP] |
| 142 | msr spsel, #0 |
| 143 | mov sp, x5 |
| 144 | |
| 145 | mov x29, x30 |
| 146 | bl plat_ea_handler |
| 147 | mov x30, x29 |
| 148 | |
| 149 | /* Make SP point to context */ |
| 150 | msr spsel, #1 |
| 151 | |
| 152 | /* Restore EL3 state */ |
| 153 | ldp x1, x2, [sp, #CTX_EL3STATE_OFFSET + CTX_SPSR_EL3] |
| 154 | msr spsr_el3, x1 |
| 155 | msr elr_el3, x2 |
| 156 | |
| 157 | /* Restore ESR_EL3 and SCR_EL3 */ |
| 158 | ldp x3, x4, [sp, #CTX_EL3STATE_OFFSET + CTX_SCR_EL3] |
| 159 | msr scr_el3, x3 |
| 160 | msr esr_el3, x4 |
| 161 | |
| 162 | ret |
| 163 | endfunc ea_proceed |