| Andrew Walbran | 15068b0 | 2022-03-22 15:57:34 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2022 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * https://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | .macro adr_l, reg:req, sym:req |
| 18 | adrp \reg, \sym |
| 19 | add \reg, \reg, :lo12:\sym |
| 20 | .endm |
| 21 | |
| 22 | /** |
| 23 | * This is a generic entry point for an image. It carries out the operations |
| 24 | * required to prepare the loaded image to be run. Specifically, it zeroes the |
| 25 | * bss section using registers x25 and above, prepares the stack, enables |
| 26 | * floating point, and sets up the exception vector. |
| 27 | */ |
| 28 | .section .init.entry, "ax" |
| 29 | .global entry |
| 30 | entry: |
| 31 | /* Disable trapping floating point access in EL1. */ |
| 32 | mrs x30, cpacr_el1 |
| 33 | orr x30, x30, #(0x3 << 20) |
| 34 | msr cpacr_el1, x30 |
| 35 | isb |
| 36 | |
| 37 | /* Zero out the bss section. */ |
| 38 | adr_l x29, bss_begin |
| 39 | adr_l x30, bss_end |
| 40 | 0: cmp x29, x30 |
| 41 | b.hs 1f |
| 42 | stp xzr, xzr, [x29], #16 |
| 43 | b 0b |
| 44 | |
| 45 | 1: /* Prepare the stack. */ |
| 46 | adr x30, boot_stack_end |
| 47 | mov sp, x30 |
| 48 | |
| 49 | /* Call into Rust code. */ |
| 50 | bl main |
| 51 | |
| 52 | /* Loop forever waiting for interrupts. */ |
| 53 | 2: wfi |
| 54 | b 2b |