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-rw-r--r--arch/ppc64/boot/crt0.S48
1 files changed, 48 insertions, 0 deletions
diff --git a/arch/ppc64/boot/crt0.S b/arch/ppc64/boot/crt0.S
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+/*
+ * Copyright (C) Paul Mackerras 1997.
+ *
+ * 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.
+ *
+ * NOTE: this code runs in 32 bit mode and is packaged as ELF32.
+ */
+
+#include <asm/ppc_asm.h>
+
+ .text
+ .globl _start
+_start:
+ lis r9,_start@h
+ lis r8,_etext@ha
+ addi r8,r8,_etext@l
+1: dcbf r0,r9
+ icbi r0,r9
+ addi r9,r9,0x20
+ cmplwi 0,r9,8
+ blt 1b
+ sync
+ 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 3f # If the size is zero, don't bother
+ addi r8,r8,-4 # r8 -= 4
+ mtctr r7 # SPRN_CTR = number of words to clear
+ li r0,0 # r0 = 0
+2: stwu r0,4(r8) # Clear out a word
+ bdnz 2b # Keep clearing until done
+3:
+ b start
+