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Diffstat (limited to 'arch/ppc/boot/simple/relocate.S')
| -rw-r--r-- | arch/ppc/boot/simple/relocate.S | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/arch/ppc/boot/simple/relocate.S b/arch/ppc/boot/simple/relocate.S new file mode 100644 index 00000000000..555a216ccc4 --- /dev/null +++ b/arch/ppc/boot/simple/relocate.S @@ -0,0 +1,216 @@ +/* + * arch/ppc/boot/simple/relocate.S + * + * This is the common part of the loader relocation and initialization + * process. All of the board/processor specific initialization is + * done before we get here. + * + * Author: Tom Rini + * trini@mvista.com + * Derived from arch/ppc/boot/prep/head.S (Cort Dougan, many others). + * + * 2001-2004 (c) MontaVista, Software, Inc. This file is licensed under + * the terms of the GNU General Public License version 2. This program + * is licensed "as is" without any warranty of any kind, whether express + * or implied. + */ + +#include <linux/config.h> +#include <asm/cache.h> +#include <asm/ppc_asm.h> + +#define GETSYM(reg, sym) \ + lis reg, sym@h; ori reg, reg, sym@l + + .text + /* We get called from the early initialization code. + * Register 3 has the address where we were loaded, + * Register 4 contains any residual data passed from the + * boot rom. + */ + .globl relocate +relocate: + /* Save r3, r4 for later. + * The r8/r11 are legacy registers so I don't have to + * rewrite the code below :-). + */ + mr r8, r3 + mr r11, r4 + + /* compute the size of the whole image in words. */ + GETSYM(r4,start) + GETSYM(r5,end) + + addi r5,r5,3 /* round up */ + sub r5,r5,r4 /* end - start */ + srwi r5,r5,2 + mr r7,r5 /* Save for later use. */ + + /* + * Check if we need to relocate ourselves to the link addr or were + * we loaded there to begin with. + */ + cmpw cr0,r3,r4 + beq start_ldr /* If 0, we don't need to relocate */ + + /* Move this code somewhere safe. This is max(load + size, end) + * r8 == load address + */ + GETSYM(r4, start) + GETSYM(r5, end) + + sub r6,r5,r4 + add r6,r8,r6 /* r6 == phys(load + size) */ + + cmpw r5,r6 + bgt 1f + b 2f +1: + mr r6, r5 +2: + /* dest is in r6 */ + /* Ensure alignment --- this code is precautionary */ + addi r6,r6,4 + li r5,0x0003 + andc r6,r6,r5 + + /* Find physical address and size of do_relocate */ + GETSYM(r5, __relocate_start) + GETSYM(r4, __relocate_end) + GETSYM(r3, start) + + /* Size to copy */ + sub r4,r4,r5 + srwi r4,r4,2 + + /* Src addr to copy (= __relocate_start - start + where_loaded) */ + sub r3,r5,r3 + add r5,r8,r3 + + /* Save dest */ + mr r3, r6 + + /* Do the copy */ + mtctr r4 +3: lwz r4,0(r5) + stw r4,0(r3) + addi r3,r3,4 + addi r5,r5,4 + bdnz 3b + + GETSYM(r4, __relocate_start) + GETSYM(r5, do_relocate) + + sub r4,r5,r4 /* Get entry point for do_relocate in */ + add r6,r6,r4 /* relocated section */ + + /* This will return to the relocated do_relocate */ + mtlr r6 + b flush_instruction_cache + + .section ".relocate_code","xa" + +do_relocate: + /* We have 2 cases --- start < load, or start > load + * This determines whether we copy from the end, or the start. + * Its easier to have 2 loops than to have paramaterised + * loops. Sigh. + */ + li r6,0 /* Clear checksum */ + mtctr r7 /* Setup for a loop */ + + GETSYM(r4, start) + mr r3,r8 /* Get the load addr */ + + cmpw cr0,r4,r3 /* If we need to copy from the end, do so */ + bgt do_relocate_from_end + +do_relocate_from_start: +1: lwz r5,0(r3) /* Load and decrement */ + stw r5,0(r4) /* Store and decrement */ + addi r3,r3,4 + addi r4,r4,4 + xor r6,r6,r5 /* Update checksum */ + bdnz 1b /* Are we done? */ + b do_relocate_out /* Finished */ + +do_relocate_from_end: + GETSYM(r3, end) + slwi r4,r7,2 + add r4,r8,r4 /* Get the physical end */ +1: lwzu r5,-4(r4) + stwu r5, -4(r3) + xor r6,r6,r5 + bdnz 1b + +do_relocate_out: + GETSYM(r3,start_ldr) + mtlr r3 /* Easiest way to do an absolute jump */ +/* Some boards don't boot up with the I-cache enabled. Do that + * now because the decompress runs much faster that way. + * As a side effect, we have to ensure the data cache is not enabled + * so we can access the serial I/O without trouble. + */ + b flush_instruction_cache + + .previous + +start_ldr: +/* Clear all of BSS and set up stack for C calls */ + lis r3,edata@h + ori r3,r3,edata@l + lis r4,end@h + ori r4,r4,end@l + subi r3,r3,4 + subi r4,r4,4 + li r0,0 +50: stwu r0,4(r3) + cmpw cr0,r3,r4 + bne 50b +90: mr r9,r1 /* Save old stack pointer (in case it matters) */ + lis r1,.stack@h + ori r1,r1,.stack@l + addi r1,r1,4096*2 + subi r1,r1,256 + li r2,0x000F /* Mask pointer to 16-byte boundary */ + andc r1,r1,r2 + + /* + * Exec kernel loader + */ + mr r3,r8 /* Load point */ + mr r4,r7 /* Program length */ + mr r5,r6 /* Checksum */ + mr r6,r11 /* Residual data */ + mr r7,r25 /* Validated OFW interface */ + bl load_kernel + + /* + * Make sure the kernel knows we don't have things set in + * registers. -- Tom + */ + li r4,0 + li r5,0 + li r6,0 + + /* + * Start at the begining. + */ +#ifdef CONFIG_PPC_MULTIPLATFORM + li r9,0xc + mtlr r9 + /* tell kernel we're prep, by putting 0xdeadc0de at KERNELLOAD, + * and tell the kernel to start on the 4th instruction since we + * overwrite the first 3 sometimes (which are 'nop'). + */ + lis r10,0xdeadc0de@h + ori r10,r10,0xdeadc0de@l + li r9,0 + stw r10,0(r9) +#else + li r9,0 + mtlr r9 +#endif + blr + + .comm .stack,4096*2,4 |