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/* * BK Id: %F% %I% %G% %U% %#% */ /* Copyright (c) 1997 Paul Mackerras <paulus@cs.anu.edu.au> * Initial Power Macintosh COFF version. * Copyright (c) 1999 Grant Erickson <grant@lcse.umn.edu> * Modifications for IBM PowerPC 400-class processor evaluation * boards. * * Module name: crt0.S * * Description: * Boot loader execution entry point. Clears out .bss section as per * ANSI C requirements. Invalidates and flushes the caches over the * range covered by the boot loader's .text section. Sets up a stack * below the .text section entry point. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <linux/config.h> #include <asm/ppc_asm.h> .text .globl _start _start: #ifdef XCOFF .long __start,0,0 .globl __start __start: #endif ## Flush and invalidate the caches for the range in memory covering ## the .text section of the boot loader lis r9,_start@h # r9 = &_start lis r8,_etext@ha # addi r8,r8,_etext@l # r8 = &_etext 3: dcbf r0,r9 # Flush the data cache icbi r0,r9 # Invalidate the instruction cache addi r9,r9,0x10 # Increment by one cache line cmplw cr0,r9,r8 # Are we at the end yet? blt 3b # No, keep flushing and invalidating sync # sync ; isync after flushing the icache isync ## Clear out the BSS as per ANSI C requirements lis r7,_end@ha addi r7,r7,_end@l # r7 = &_end lis r8,__bss_start@ha # addi r8,r8,__bss_start@l # r8 = &_bss_start ## Determine how large an area, in number of words, to clear subf r7,r8,r7 # r7 = &_end - &_bss_start + 1 addi r7,r7,3 # r7 += 3 srwi. r7,r7,2 # r7 = size in words. beq 2f # If the size is zero, do not bother addi r8,r8,-4 # r8 -= 4 mtctr r7 # SPRN_CTR = number of words to clear li r0,0 # r0 = 0 1: stwu r0,4(r8) # Clear out a word bdnz 1b # If we are not done yet, keep clearing 2: #ifdef CONFIG_4xx ## Set up the stack lis r9,_start@h # r9 = &_start (text section entry) addi r9,r9,_start@l subi r1,r9,64 # Start the stack 64 bytes below _start clrrwi r1,r1,4 # Make sure it is aligned on 16 bytes. li r0,0 stwu r0,-16(r1) mtlr r9 #endif b start # All done, start the real work. |