1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
217 lines
4.7 KiB
ArmAsm
217 lines
4.7 KiB
ArmAsm
/*
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* arch/ppc/boot/simple/relocate.S
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*
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* This is the common part of the loader relocation and initialization
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* process. All of the board/processor specific initialization is
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* done before we get here.
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*
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* Author: Tom Rini
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* trini@mvista.com
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* Derived from arch/ppc/boot/prep/head.S (Cort Dougan, many others).
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*
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* 2001-2004 (c) MontaVista, Software, Inc. This file is licensed under
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* the terms of the GNU General Public License version 2. This program
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* is licensed "as is" without any warranty of any kind, whether express
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* or implied.
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*/
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#include <linux/config.h>
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#include <asm/cache.h>
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#include <asm/ppc_asm.h>
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#define GETSYM(reg, sym) \
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lis reg, sym@h; ori reg, reg, sym@l
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.text
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/* We get called from the early initialization code.
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* Register 3 has the address where we were loaded,
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* Register 4 contains any residual data passed from the
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* boot rom.
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*/
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.globl relocate
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relocate:
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/* Save r3, r4 for later.
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* The r8/r11 are legacy registers so I don't have to
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* rewrite the code below :-).
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*/
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mr r8, r3
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mr r11, r4
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/* compute the size of the whole image in words. */
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GETSYM(r4,start)
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GETSYM(r5,end)
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addi r5,r5,3 /* round up */
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sub r5,r5,r4 /* end - start */
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srwi r5,r5,2
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mr r7,r5 /* Save for later use. */
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/*
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* Check if we need to relocate ourselves to the link addr or were
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* we loaded there to begin with.
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*/
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cmpw cr0,r3,r4
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beq start_ldr /* If 0, we don't need to relocate */
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/* Move this code somewhere safe. This is max(load + size, end)
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* r8 == load address
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*/
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GETSYM(r4, start)
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GETSYM(r5, end)
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sub r6,r5,r4
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add r6,r8,r6 /* r6 == phys(load + size) */
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cmpw r5,r6
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bgt 1f
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b 2f
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1:
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mr r6, r5
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2:
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/* dest is in r6 */
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/* Ensure alignment --- this code is precautionary */
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addi r6,r6,4
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li r5,0x0003
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andc r6,r6,r5
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/* Find physical address and size of do_relocate */
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GETSYM(r5, __relocate_start)
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GETSYM(r4, __relocate_end)
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GETSYM(r3, start)
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/* Size to copy */
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sub r4,r4,r5
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srwi r4,r4,2
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/* Src addr to copy (= __relocate_start - start + where_loaded) */
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sub r3,r5,r3
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add r5,r8,r3
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/* Save dest */
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mr r3, r6
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/* Do the copy */
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mtctr r4
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3: lwz r4,0(r5)
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stw r4,0(r3)
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addi r3,r3,4
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addi r5,r5,4
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bdnz 3b
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GETSYM(r4, __relocate_start)
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GETSYM(r5, do_relocate)
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sub r4,r5,r4 /* Get entry point for do_relocate in */
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add r6,r6,r4 /* relocated section */
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/* This will return to the relocated do_relocate */
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mtlr r6
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b flush_instruction_cache
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.section ".relocate_code","xa"
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do_relocate:
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/* We have 2 cases --- start < load, or start > load
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* This determines whether we copy from the end, or the start.
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* Its easier to have 2 loops than to have paramaterised
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* loops. Sigh.
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*/
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li r6,0 /* Clear checksum */
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mtctr r7 /* Setup for a loop */
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GETSYM(r4, start)
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mr r3,r8 /* Get the load addr */
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cmpw cr0,r4,r3 /* If we need to copy from the end, do so */
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bgt do_relocate_from_end
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do_relocate_from_start:
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1: lwz r5,0(r3) /* Load and decrement */
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stw r5,0(r4) /* Store and decrement */
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addi r3,r3,4
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addi r4,r4,4
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xor r6,r6,r5 /* Update checksum */
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bdnz 1b /* Are we done? */
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b do_relocate_out /* Finished */
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do_relocate_from_end:
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GETSYM(r3, end)
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slwi r4,r7,2
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add r4,r8,r4 /* Get the physical end */
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1: lwzu r5,-4(r4)
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stwu r5, -4(r3)
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xor r6,r6,r5
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bdnz 1b
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do_relocate_out:
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GETSYM(r3,start_ldr)
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mtlr r3 /* Easiest way to do an absolute jump */
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/* Some boards don't boot up with the I-cache enabled. Do that
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* now because the decompress runs much faster that way.
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* As a side effect, we have to ensure the data cache is not enabled
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* so we can access the serial I/O without trouble.
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*/
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b flush_instruction_cache
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.previous
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start_ldr:
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/* Clear all of BSS and set up stack for C calls */
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lis r3,edata@h
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ori r3,r3,edata@l
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lis r4,end@h
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ori r4,r4,end@l
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subi r3,r3,4
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subi r4,r4,4
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li r0,0
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50: stwu r0,4(r3)
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cmpw cr0,r3,r4
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bne 50b
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90: mr r9,r1 /* Save old stack pointer (in case it matters) */
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lis r1,.stack@h
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ori r1,r1,.stack@l
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addi r1,r1,4096*2
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subi r1,r1,256
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li r2,0x000F /* Mask pointer to 16-byte boundary */
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andc r1,r1,r2
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/*
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* Exec kernel loader
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*/
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mr r3,r8 /* Load point */
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mr r4,r7 /* Program length */
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mr r5,r6 /* Checksum */
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mr r6,r11 /* Residual data */
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mr r7,r25 /* Validated OFW interface */
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bl load_kernel
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/*
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* Make sure the kernel knows we don't have things set in
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* registers. -- Tom
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*/
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li r4,0
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li r5,0
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li r6,0
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/*
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* Start at the begining.
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*/
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#ifdef CONFIG_PPC_MULTIPLATFORM
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li r9,0xc
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mtlr r9
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/* tell kernel we're prep, by putting 0xdeadc0de at KERNELLOAD,
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* and tell the kernel to start on the 4th instruction since we
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* overwrite the first 3 sometimes (which are 'nop').
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*/
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lis r10,0xdeadc0de@h
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ori r10,r10,0xdeadc0de@l
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li r9,0
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stw r10,0(r9)
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#else
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li r9,0
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mtlr r9
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#endif
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blr
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.comm .stack,4096*2,4
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