| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) Paul Mackerras 1997. |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or |
| 5 | * modify it under the terms of the GNU General Public License |
| 6 | * as published by the Free Software Foundation; either version |
| 7 | * 2 of the License, or (at your option) any later version. |
| 8 | * |
| 9 | * NOTE: this code runs in 32 bit mode and is packaged as ELF32. |
| 10 | */ |
| 11 | |
| 12 | #include <asm/ppc_asm.h> |
| 13 | |
| 14 | .text |
| 15 | .globl _start |
| 16 | _start: |
| 17 | lis r9,_start@h |
| 18 | lis r8,_etext@ha |
| 19 | addi r8,r8,_etext@l |
| 20 | 1: dcbf r0,r9 |
| 21 | icbi r0,r9 |
| 22 | addi r9,r9,0x20 |
| 23 | cmplwi 0,r9,8 |
| 24 | blt 1b |
| 25 | sync |
| 26 | isync |
| 27 | |
| 28 | ## Clear out the BSS as per ANSI C requirements |
| 29 | |
| 30 | lis r7,_end@ha |
| 31 | addi r7,r7,_end@l # r7 = &_end |
| 32 | lis r8,__bss_start@ha # |
| 33 | addi r8,r8,__bss_start@l # r8 = &_bss_start |
| 34 | |
| 35 | ## Determine how large an area, in number of words, to clear |
| 36 | |
| 37 | subf r7,r8,r7 # r7 = &_end - &_bss_start + 1 |
| 38 | addi r7,r7,3 # r7 += 3 |
| 39 | srwi. r7,r7,2 # r7 = size in words. |
| 40 | beq 3f # If the size is zero, don't bother |
| 41 | addi r8,r8,-4 # r8 -= 4 |
| 42 | mtctr r7 # SPRN_CTR = number of words to clear |
| 43 | li r0,0 # r0 = 0 |
| 44 | 2: stwu r0,4(r8) # Clear out a word |
| 45 | bdnz 2b # Keep clearing until done |
| 46 | 3: |
| 47 | b start |
| 48 | |