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Subject[PATCHv1 007/211] unicore32: new file arch/unicore32/boot/compressed/head.S
Date
From: Guan Xuetao <guanxuetao@mprc.pku.edu.cn>

entry point before uncompressed in UniCore32 linux-kernel

Signed-off-by: Guan Xuetao <guanxuetao@mprc.pku.edu.cn>
---
arch/unicore32/boot/compressed/head.S | 203
+++++++++++++++++++++++++++++++++
1 files changed, 203 insertions(+), 0 deletions(-)

diff --git a/arch/unicore32/boot/compressed/head.S
b/arch/unicore32/boot/compressed/head.S
new file mode 100644
index 0000000..ced47bd
--- /dev/null
+++ b/arch/unicore32/boot/compressed/head.S
@@ -0,0 +1,203 @@
+/*
+ * linux/arch/unicore32/boot/compressed/head.S
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ * Copyright (C) 2001-2010 GUAN Xue-tao
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/linkage.h>
+
+#define csub cmpsub
+#define cand cmpand
+#define nop8 nop; nop; nop; nop; nop; nop; nop; nop
+
+ .section ".start", #alloc, #execinstr
+ .text
+start:
+ .type start,#function
+
+ /* Initialize ASR, PRIV mode and INTR off */
+ mov r0, #0xD3
+ mov.a asr, r0
+
+ adr r0, LC0
+ ldm (r1, r2, r3, r5, r6, r7, r8), [r0]+
+ ldw sp, [r0+], #28
+ sub.a r0, r0, r1 @ calculate the delta offset
+
+ /*
+ * if delta is zero, we are running at the address
+ * we were linked at.
+ */
+ beq not_relocated
+
+ /*
+ * We're running at a different address. We need to fix
+ * up various pointers:
+ * r5 - zImage base address (_start)
+ * r7 - GOT start
+ * r8 - GOT end
+ */
+ add r5, r5, r0
+ add r7, r7, r0
+ add r8, r8, r0
+
+ /*
+ * we need to fix up pointers into the BSS region.
+ * r2 - BSS start
+ * r3 - BSS end
+ * sp - stack pointer
+ */
+ add r2, r2, r0
+ add r3, r3, r0
+ add sp, sp, r0
+
+ /*
+ * Relocate all entries in the GOT table.
+ * This fixes up the C references.
+ * r7 - GOT start
+ * r8 - GOT end
+ */
+1001: ldw r1, [r7+], #0
+ add r1, r1, r0
+ stw.w r1, [r7]+, #4
+ csub.a r7, r8
+ bub 1001b
+
+not_relocated:
+ /*
+ * Clear BSS region.
+ * r2 - BSS start
+ * r3 - BSS end
+ */
+ mov r0, #0
+1002: stw.w r0, [r2]+, #4
+ csub.a r2, r3
+ bub 1002b
+
+ /*
+ * Turn on the cache.
+ */
+ mov r0, #0
+ movc p0.c5, r0, #28 @ cache invalidate all
+ nop8
+ movc p0.c6, r0, #6 @ tlb invalidate all
+ nop8
+
+ mov r0, #0x1c @ en icache and wb dcache
+ movc p0.c1, r0, #0
+ nop8
+
+ /*
+ * Set up some pointers, for starting decompressing.
+ */
+
+ mov r1, sp @ malloc space above stack
+ add r2, sp, #0x10000 @ 64k max
+
+ /*
+ * Check to see if we will overwrite ourselves.
+ * r4 = final kernel address
+ * r5 = start of this image
+ * r6 = size of decompressed image
+ * r2 = end of malloc space (and therefore this image)
+ * We basically want:
+ * r4 >= r2 -> OK
+ * r4 + image length <= r5 -> OK
+ */
+ ldw r4, =zreladdr
+ csub.a r4, r2
+ bea wont_overwrite
+ add r0, r4, r6
+ csub.a r0, r5
+ beb wont_overwrite
+
+ /*
+ * If overwrite, just print error message
+ */
+ b __error_overwrite
+
+ /*
+ * We're not in danger of overwriting ourselves.
+ * Do this the simple way.
+ */
+wont_overwrite:
+ /*
+ * decompress_kernel:
+ * r0: output_start
+ * r1: free_mem_ptr_p
+ * r2: free_mem_ptr_end_p
+ */
+ mov r0, r4
+ b.l decompress_kernel @ C functions
+
+ /*
+ * Clean and flush the cache to maintain consistency.
+ */
+ mov r0, #0
+ movc p0.c5, r0, #14 @ flush dcache
+ nop8
+ movc p0.c5, r0, #20 @ icache invalidate all
+ nop8
+
+ /*
+ * Turn off the Cache and MMU.
+ */
+ mov r0, #0 @ disable i/d cache and MMU
+ movc p0.c1, r0, #0
+ nop8
+
+ mov r0, #0 @ must be zero
+ ldw r4, =zreladdr
+ mov pc, r4 @ call kernel
+
+
+ .align 2
+ .type LC0, #object
+LC0: .word LC0 @ r1
+ .word __bss_start @ r2
+ .word _end @ r3
+ .word _start @ r5
+ .word _image_size @ r6
+ .word _got_start @ r7
+ .word _got_end @ r8
+ .word decompress_stack_end @ sp
+ .size LC0, . - LC0
+
+print_string:
+#ifdef CONFIG_DEBUG_OCD
+2001: ldb.w r1, [r0]+, #1
+ csub.a r1, #0
+ bne 2002f
+ mov pc, lr
+2002:
+ movc r2, p1.c0, #0
+ cand.a r2, #2
+ bne 2002b
+ movc p1.c1, r1, #1
+ csub.a r1, #'\n'
+ cmoveq r1, #'\r'
+ beq 2002b
+ b 2001b
+#else
+ mov pc, lr
+#endif
+
+__error_overwrite:
+ adr r0, str_error
+ b.l print_string
+2001: nop8
+ b 2001b
+str_error: .asciz "\nError: Kernel address OVERWRITE\n"
+ .align
+
+ .ltorg
+
+ .align 4
+ .section ".stack", "aw", %nobits
+decompress_stack: .space 4096
+decompress_stack_end:


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