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4260eff804
passed in from u-boot across the call to self_reloc and any other early-init code, and restore them before calling main(). The self_reloc() routine uses r0 and r1 (and calling it uses lr), and depending on what values get left in them, main() would intermittantly lock up trying to interpret them as argc and argv values. This problem affected the self-relocatable ubldr.bin but not ubldr (the elf version).
139 lines
3.9 KiB
ArmAsm
139 lines
3.9 KiB
ArmAsm
/*-
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* Copyright (c) 2008 Semihalf, Rafal Czubak
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <machine/asm.h>
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#include <machine/armreg.h>
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.text
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.extern _C_LABEL(self_reloc), _C_LABEL(main)
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.weak _DYNAMIC
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/*
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* Entry point to the loader that U-Boot passes control to.
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*/
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.globl _start
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_start:
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#ifdef _ARM_ARCH_6
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mrc p15, 0, ip, c1, c0, 0
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orr ip, ip, #(CPU_CONTROL_UNAL_ENABLE)
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orr ip, ip, #(CPU_CONTROL_AFLT_ENABLE)
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mcr p15, 0, ip, c1, c0, 0
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#endif
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/*
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* Save r0 and r1 (argc and argv passed from u-boot), and lr (trashed
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* by the call to self_reloc below) until we're ready to call main().
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*/
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push {r0, r1, lr}
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/*
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* Do self-relocation when the weak external symbol _DYNAMIC is non-NULL.
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* When linked as a dynamic relocatable file, the linker automatically
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* defines _DYNAMIC with a value that is the offset of the dynamic
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* relocation info section.
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* Note that we're still on u-boot's stack here, but the self_reloc
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* code uses only a couple dozen bytes of stack space.
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*/
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adr ip, .here_off /* .here_off is a symbol whose value */
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ldr r0, [ip] /* is its own offset in the text seg. */
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sub r0, ip, r0 /* Get its pc-relative address and */
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ldr r1, .dynamic_off /* subtract its value and we get */
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teq r1, #0 /* r0 = physaddr we were loaded at. */
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addne r1, r1, r0 /* r1 = dynamic section physaddr. */
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blne _C_LABEL(self_reloc) /* Do reloc if _DYNAMIC is non-NULL. */
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/* Hint where to look for the API signature */
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ldr ip, =uboot_address
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str sp, [ip]
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/* Save U-Boot's r8 and r9 */
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ldr ip, =saved_regs
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str r8, [ip, #0]
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str r9, [ip, #4]
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/*
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* First restore argc, argv, and the u-boot return address, then
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* Start loader. This is basically a tail-recursion call; if main()
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* returns, it returns to u-boot (which reports the value returned r0).
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*/
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pop {r0, r1, lr}
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b main
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/*
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* Data for self-relocation, in the text segment for pc-rel access.
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*/
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.here_off:
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.word .
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.dynamic_off:
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.word _DYNAMIC
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/*
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* syscall()
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*/
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ENTRY(syscall)
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/* Save caller's lr, r8 and r9 */
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ldr ip, =saved_regs
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str r8, [ip, #8]
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str r9, [ip, #12]
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str lr, [ip, #16]
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/* Restore U-Boot's r8 and r9 */
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ldr r8, [ip, #0]
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ldr r9, [ip, #4]
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/* Call into U-Boot */
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ldr lr, =return_from_syscall
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ldr ip, =syscall_ptr
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ldr pc, [ip]
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return_from_syscall:
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/* Restore loader's r8, r9 and lr */
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ldr ip, =saved_regs
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ldr lr, [ip, #16]
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ldr r9, [ip, #12]
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ldr r8, [ip, #8]
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/* Return to caller */
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mov pc, lr
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/*
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* Data section
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*/
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.data
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.align 4
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.globl syscall_ptr
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syscall_ptr:
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.long 0
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.globl uboot_address
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uboot_address:
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.long 0
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saved_regs:
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.long 0 /* U-Boot's r8 */
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.long 0 /* U-Boot's r9 */
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.long 0 /* Loader's r8 */
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.long 0 /* Loader's r9 */
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.long 0 /* Loader's lr */
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