1/* 2 * EFI entry point. 3 * 4 * Copyright (C) 2013, 2014 Red Hat, Inc. 5 * Author: Mark Salter <msalter@redhat.com> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 * 11 */ 12#include <linux/linkage.h> 13#include <linux/init.h> 14 15#include <asm/assembler.h> 16 17#define EFI_LOAD_ERROR 0x8000000000000001 18 19 __INIT 20 21 /* 22 * We arrive here from the EFI boot manager with: 23 * 24 * * CPU in little-endian mode 25 * * MMU on with identity-mapped RAM 26 * * Icache and Dcache on 27 * 28 * We will most likely be running from some place other than where 29 * we want to be. The kernel image wants to be placed at TEXT_OFFSET 30 * from start of RAM. 31 */ 32ENTRY(entry) 33 /* 34 * Create a stack frame to save FP/LR with extra space 35 * for image_addr variable passed to efi_entry(). 36 */ 37 stp x29, x30, [sp, #-32]! 38 39 /* 40 * Call efi_entry to do the real work. 41 * x0 and x1 are already set up by firmware. Current runtime 42 * address of image is calculated and passed via *image_addr. 43 * 44 * unsigned long efi_entry(void *handle, 45 * efi_system_table_t *sys_table, 46 * unsigned long *image_addr) ; 47 */ 48 adrp x8, _text 49 add x8, x8, #:lo12:_text 50 add x2, sp, 16 51 str x8, [x2] 52 bl efi_entry 53 cmn x0, #1 54 b.eq efi_load_fail 55 56 /* 57 * efi_entry() will have copied the kernel image if necessary and we 58 * return here with device tree address in x0 and the kernel entry 59 * point stored at *image_addr. Save those values in registers which 60 * are callee preserved. 61 */ 62 mov x20, x0 // DTB address 63 ldr x0, [sp, #16] // relocated _text address 64 movz x21, #:abs_g0:stext_offset 65 add x21, x0, x21 66 67 /* 68 * Calculate size of the kernel Image (same for original and copy). 69 */ 70 adrp x1, _text 71 add x1, x1, #:lo12:_text 72 adrp x2, _edata 73 add x2, x2, #:lo12:_edata 74 sub x1, x2, x1 75 76 /* 77 * Flush the copied Image to the PoC, and ensure it is not shadowed by 78 * stale icache entries from before relocation. 79 */ 80 bl __flush_dcache_area 81 ic ialluis 82 83 /* 84 * Ensure that the rest of this function (in the original Image) is 85 * visible when the caches are disabled. The I-cache can't have stale 86 * entries for the VA range of the current image, so no maintenance is 87 * necessary. 88 */ 89 adr x0, entry 90 adr x1, entry_end 91 sub x1, x1, x0 92 bl __flush_dcache_area 93 94 /* Turn off Dcache and MMU */ 95 mrs x0, CurrentEL 96 cmp x0, #CurrentEL_EL2 97 b.ne 1f 98 mrs x0, sctlr_el2 99 bic x0, x0, #1 << 0 // clear SCTLR.M 100 bic x0, x0, #1 << 2 // clear SCTLR.C 101 msr sctlr_el2, x0 102 isb 103 b 2f 1041: 105 mrs x0, sctlr_el1 106 bic x0, x0, #1 << 0 // clear SCTLR.M 107 bic x0, x0, #1 << 2 // clear SCTLR.C 108 msr sctlr_el1, x0 109 isb 1102: 111 /* Jump to kernel entry point */ 112 mov x0, x20 113 mov x1, xzr 114 mov x2, xzr 115 mov x3, xzr 116 br x21 117 118efi_load_fail: 119 mov x0, #EFI_LOAD_ERROR 120 ldp x29, x30, [sp], #32 121 ret 122 123entry_end: 124ENDPROC(entry) 125