1/* SPDX-License-Identifier: GPL-2.0-only */ 2/* 3 * EFI entry point. 4 * 5 * Copyright (C) 2013, 2014 Red Hat, Inc. 6 * Author: Mark Salter <msalter@redhat.com> 7 */ 8#include <linux/linkage.h> 9#include <linux/init.h> 10 11#include <asm/assembler.h> 12 13#define EFI_LOAD_ERROR 0x8000000000000001 14 15 __INIT 16 17 /* 18 * We arrive here from the EFI boot manager with: 19 * 20 * * CPU in little-endian mode 21 * * MMU on with identity-mapped RAM 22 * * Icache and Dcache on 23 * 24 * We will most likely be running from some place other than where 25 * we want to be. The kernel image wants to be placed at TEXT_OFFSET 26 * from start of RAM. 27 */ 28ENTRY(entry) 29 /* 30 * Create a stack frame to save FP/LR with extra space 31 * for image_addr variable passed to efi_entry(). 32 */ 33 stp x29, x30, [sp, #-32]! 34 mov x29, sp 35 36 /* 37 * Call efi_entry to do the real work. 38 * x0 and x1 are already set up by firmware. Current runtime 39 * address of image is calculated and passed via *image_addr. 40 * 41 * unsigned long efi_entry(void *handle, 42 * efi_system_table_t *sys_table, 43 * unsigned long *image_addr) ; 44 */ 45 adr_l x8, _text 46 add x2, sp, 16 47 str x8, [x2] 48 bl efi_entry 49 cmn x0, #1 50 b.eq efi_load_fail 51 52 /* 53 * efi_entry() will have copied the kernel image if necessary and we 54 * return here with device tree address in x0 and the kernel entry 55 * point stored at *image_addr. Save those values in registers which 56 * are callee preserved. 57 */ 58 mov x20, x0 // DTB address 59 ldr x0, [sp, #16] // relocated _text address 60 ldr w21, =stext_offset 61 add x21, x0, x21 62 63 /* 64 * Calculate size of the kernel Image (same for original and copy). 65 */ 66 adr_l x1, _text 67 adr_l x2, _edata 68 sub x1, x2, x1 69 70 /* 71 * Flush the copied Image to the PoC, and ensure it is not shadowed by 72 * stale icache entries from before relocation. 73 */ 74 bl __flush_dcache_area 75 ic ialluis 76 77 /* 78 * Ensure that the rest of this function (in the original Image) is 79 * visible when the caches are disabled. The I-cache can't have stale 80 * entries for the VA range of the current image, so no maintenance is 81 * necessary. 82 */ 83 adr x0, entry 84 adr x1, entry_end 85 sub x1, x1, x0 86 bl __flush_dcache_area 87 88 /* Turn off Dcache and MMU */ 89 mrs x0, CurrentEL 90 cmp x0, #CurrentEL_EL2 91 b.ne 1f 92 mrs x0, sctlr_el2 93 bic x0, x0, #1 << 0 // clear SCTLR.M 94 bic x0, x0, #1 << 2 // clear SCTLR.C 95 pre_disable_mmu_workaround 96 msr sctlr_el2, x0 97 isb 98 b 2f 991: 100 mrs x0, sctlr_el1 101 bic x0, x0, #1 << 0 // clear SCTLR.M 102 bic x0, x0, #1 << 2 // clear SCTLR.C 103 pre_disable_mmu_workaround 104 msr sctlr_el1, x0 105 isb 1062: 107 /* Jump to kernel entry point */ 108 mov x0, x20 109 mov x1, xzr 110 mov x2, xzr 111 mov x3, xzr 112 br x21 113 114efi_load_fail: 115 mov x0, #EFI_LOAD_ERROR 116 ldp x29, x30, [sp], #32 117 ret 118 119entry_end: 120ENDPROC(entry) 121