Commit | Line | Data |
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3c7f2550 MS |
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 | */ | |
32 | ENTRY(efi_stub_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 relocated the kernel image if necessary | |
58 | * and we return here with device tree address in x0 and the kernel | |
59 | * entry point stored at *image_addr. Save those values in registers | |
60 | * which are callee preserved. | |
61 | */ | |
62 | mov x20, x0 // DTB address | |
63 | ldr x0, [sp, #16] // relocated _text address | |
64 | mov x21, x0 | |
65 | ||
66 | /* | |
67 | * Flush dcache covering current runtime addresses | |
68 | * of kernel text/data. Then flush all of icache. | |
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 | bl __flush_dcache_area | |
77 | ic ialluis | |
78 | ||
79 | /* Turn off Dcache and MMU */ | |
80 | mrs x0, CurrentEL | |
81 | cmp x0, #PSR_MODE_EL2t | |
82 | ccmp x0, #PSR_MODE_EL2h, #0x4, ne | |
83 | b.ne 1f | |
84 | mrs x0, sctlr_el2 | |
85 | bic x0, x0, #1 << 0 // clear SCTLR.M | |
86 | bic x0, x0, #1 << 2 // clear SCTLR.C | |
87 | msr sctlr_el2, x0 | |
88 | isb | |
89 | b 2f | |
90 | 1: | |
91 | mrs x0, sctlr_el1 | |
92 | bic x0, x0, #1 << 0 // clear SCTLR.M | |
93 | bic x0, x0, #1 << 2 // clear SCTLR.C | |
94 | msr sctlr_el1, x0 | |
95 | isb | |
96 | 2: | |
97 | /* Jump to kernel entry point */ | |
98 | mov x0, x20 | |
99 | mov x1, xzr | |
100 | mov x2, xzr | |
101 | mov x3, xzr | |
102 | br x21 | |
103 | ||
104 | efi_load_fail: | |
105 | mov x0, #EFI_LOAD_ERROR | |
106 | ldp x29, x30, [sp], #32 | |
107 | ret | |
108 | ||
109 | ENDPROC(efi_stub_entry) |