| /* |
| * 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 |
