2 * Copyright (c) 2008 Semihalf, Rafal Czubak
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
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14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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29 #include <machine/asm.h>
30 #include <machine/armreg.h>
33 .extern _C_LABEL(self_reloc), _C_LABEL(main)
37 * Entry point to the loader that U-Boot passes control to.
43 mrc p15, 0, ip, c1, c0, 0
44 orr ip, ip, #(CPU_CONTROL_UNAL_ENABLE)
45 orr ip, ip, #(CPU_CONTROL_AFLT_ENABLE)
46 mcr p15, 0, ip, c1, c0, 0
50 * Save r0 and r1 (argc and argv passed from u-boot), and lr (trashed
51 * by the call to self_reloc below) until we're ready to call main().
56 * Do self-relocation when the weak external symbol _DYNAMIC is non-NULL.
57 * When linked as a dynamic relocatable file, the linker automatically
58 * defines _DYNAMIC with a value that is the offset of the dynamic
59 * relocation info section.
60 * Note that we're still on u-boot's stack here, but the self_reloc
61 * code uses only a couple dozen bytes of stack space.
63 adr ip, .here_off /* .here_off is a symbol whose value */
64 ldr r0, [ip] /* is its own offset in the text seg. */
65 sub r0, ip, r0 /* Get its pc-relative address and */
66 ldr r1, .dynamic_off /* subtract its value and we get */
67 teq r1, #0 /* r0 = physaddr we were loaded at. */
68 addne r1, r1, r0 /* r1 = dynamic section physaddr. */
69 blne _C_LABEL(self_reloc) /* Do reloc if _DYNAMIC is non-NULL. */
71 /* Hint where to look for the API signature */
72 ldr ip, =uboot_address
75 /* Save U-Boot's r8 and r9 */
81 * First restore argc, argv, and the u-boot return address, then
82 * Start loader. This is basically a tail-recursion call; if main()
83 * returns, it returns to u-boot (which reports the value returned r0).
89 * Data for self-relocation, in the text segment for pc-rel access.
100 /* Save caller's lr, r8 and r9 */
105 /* Restore U-Boot's r8 and r9 */
108 /* Call into U-Boot */
109 ldr lr, =return_from_syscall
113 /* Restore loader's r8, r9 and lr */
118 /* Return to caller */
135 .long 0 /* U-Boot's r8 */
136 .long 0 /* U-Boot's r9 */
137 .long 0 /* Loader's r8 */
138 .long 0 /* Loader's r9 */
139 .long 0 /* Loader's lr */