patch-2.1.16 linux/arch/ppc/boot/head.S

• Lines: 238
• Date: Wed Dec 18 10:49:52 1996
• Orig file: v2.1.15/linux/arch/ppc/boot/head.S
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v2.1.15/linux/arch/ppc/boot/head.S linux/arch/ppc/boot/head.S
@@ -0,0 +1,237 @@
+#include "../kernel/ppc_defs.h"
+#include "../kernel/ppc_asm.tmpl"
+
+	.text
+
+/*
+ * This code is loaded by the ROM loader at some arbitrary location.
+ * Move it to high memory so that it can load the kernel at 0x0000.
+ */
+
+	.globl	start
+start:
+	bl	start_
+start_:
+/* TEMP - No residual data on BeBox (yet) */
+#if 0	
+#define IS_BE_BOX	0x42654278	/* 'BeBx' */
+	lis	r2,IS_BE_BOX>>16
+	ori	r2,r2,IS_BE_BOX&0xFFFF
+	cmp	0,r30,r2
+	bne	notBeBox
+	li	r3,0
+#endif	
+notBeBox:
+/* TEMP */
+	mr	r11,r3		/* Save pointer to residual data */
+	mfmsr	r3		/* Turn off interrupts */
+	li	r4,0
+	ori	r4,r4,MSR_EE
+	andc	r3,r3,r4
+	mtmsr	r3
+/* Copy relocation code down to location 0x0100 (where we hope it's safe!) */
+	mflr	r3
+	addi	r5,r3,start_ldr-start_
+	addi	r3,r3,relocate-start_
+	li	r4,0x0100
+	mtctr	r4
+	subi	r3,r3,4
+	subi	r4,r4,4
+00:	lwzu	r6,4(r3)
+	stwu	r6,4(r4)
+	cmp	0,r3,r5
+	bne	00b
+	mflr	r21
+	mfctr	r22
+	bl	flush_instruction_cache
+	mtlr	r21
+	mtctr	r22
+	bctr			/* Jump to code */
+/* Relocate code to final resting spot */
+relocate:
+	mflr	r3		/* Compute code bias */
+	subi	r3,r3,4
+	mr	r8,r3
+	lis	r4,start@h
+	ori	r4,r4,start@l
+	lis	r5,edata@h
+	ori	r5,r5,edata@l
+	addi	r5,r5,3			/* Round up - just in case */
+	sub	r5,r5,r4		/* Compute # longwords to move */
+	srwi	r5,r5,2
+	mtctr	r5
+	mr	r7,r5
+	li	r6,0
+	subi	r3,r3,4			/* Set up for loop */
+	subi	r4,r4,4
+00:	lwzu	r5,4(r3)
+	stwu	r5,4(r4)
+	xor	r6,r6,r5
+	bdnz	00b
+	lis	r3,start_ldr@h
+	ori	r3,r3,start_ldr@l
+	mtlr	r3			/* Easiest way to do an absolute jump */
+	blr
+start_ldr:	
+/* Clear all of BSS */
+	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)
+	cmp	0,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
+/* Run loader */
+	mr	r3,r8			/* Load point */
+	mr	r4,r7			/* Program length */
+	mr	r5,r6			/* Checksum */
+	mr	r6,r11			/* Residual data */
+	bl	decompress_kernel
+	/*mr	r29,r3*/			/* R3 = TotalMemory */
+	/*lis	r28,hold_residual@h
+	ori	r28,r28,hold_residual@l*/
+	/* changed to use r3 (as firmware does) for kernel
+	   as ptr to residual -- Cort*/
+	li	r5,0x100		/* Kernel code starts here */
+	mtlr	r5
+	blr	
+hang:
+	b	hang	
+
+	.globl	_get_SP
+_get_SP:
+	mr	r3,r1
+	blr
+
+	.globl	_get_PVR
+_get_PVR:
+	mfspr	r3,PVR
+	blr
+
+	.globl	_get_MSR
+_get_MSR:
+	mfmsr	r3
+	blr
+
+	.globl	_put_MSR
+_put_MSR:
+	sync
+	mtmsr	r3
+	blr
+
+	.globl	_get_HID0
+_get_HID0:
+	mfspr	r3,HID0
+	blr
+	
+	.globl	_put_HID0
+_put_HID0:
+	sync
+	mtspr	HID0,r3
+	blr
+
+/*
+ * This space [buffer] is used to forceably flush the data cache when
+ * running in copyback mode.  This is necessary IFF the data cache could
+ * contain instructions for which the instruction cache has stale data.
+ * Since the instruction cache NEVER snoops the data cache, memory must
+ * be made coherent with the data cache to insure that the instruction
+ * cache gets a valid instruction stream.  Note that this flushing is
+ * only performed when switching from system to user mode since this is
+ * the only juncture [as far as the OS goes] where the data cache may
+ * contain instructions, e.g. after a disk read.
+ */
+#define NUM_CACHE_LINES 128*8
+#define CACHE_LINE_SIZE 32 
+#if 0
+cache_flush_buffer:
+	.space	NUM_CACHE_LINES*CACHE_LINE_SIZE	/* CAUTION! these need to match hardware */
+#else
+#define cache_flush_buffer 0x1000
+#endif
+
+
+/*
+ * Flush instruction cache
+ * *** I'm really paranoid here!
+ */
+_GLOBAL(flush_instruction_cache)
+	mflr	r5
+	bl	flush_data_cache
+	mfspr	r3,HID0	/* Caches are controlled by this register */
+	li	r4,0
+	ori	r4,r4,(HID0_ICE|HID0_ICFI)
+	or	r3,r3,r4	/* Need to enable+invalidate to clear */
+	mtspr	HID0,r3
+	andc	r3,r3,r4
+	ori	r3,r3,HID0_ICE	/* Enable cache */
+	mtspr	HID0,r3
+	mtlr	r5
+	blr
+
+/*
+ * Flush data cache
+ * *** I'm really paranoid here!
+ */
+_GLOBAL(flush_data_cache)
+	lis	r3,cache_flush_buffer@h
+	ori	r3,r3,cache_flush_buffer@l
+	li	r4,NUM_CACHE_LINES
+	mtctr	r4
+#if 0
+00:	dcbz	0,r3			/* Flush cache line with minimal BUS traffic */
+#else
+00:	lwz	r4,0(r3)
+#endif
+	addi	r3,r3,CACHE_LINE_SIZE	/* Next line, please */
+	bdnz	00b	
+10:	blr
+
+/*
+ * Flush a particular page from the DATA cache
+ * Note: this is necessary because the instruction cache does *not*
+ * snoop from the data cache.
+ *	void flush_page(void *page)
+ */
+_GLOBAL(flush_page)
+	li	r4,0x0FFF
+	andc	r3,r3,r4		/* Get page base address */
+	li	r4,4096/CACHE_LINE_SIZE	/* Number of lines in a page */
+	mtctr	r4
+00:	dcbf	0,r3			/* Clear line */
+	icbi	0,r3
+	addi	r3,r3,CACHE_LINE_SIZE
+	bdnz	00b
+	blr
+
+/*
+ * Execute a [foreign] function
+ *
+ * run(p1, p2, cp, ep, entry)
+ *
+ */
+ 	.globl	run
+run:
+	mtctr	r7			/* Entry point */
+#define IS_PreP 0x50726550		/* 'PreP' */	
+	lis	r30,IS_PreP>>16
+	ori	r30,r30,IS_PreP&0xFFFF
+	mr	11,r5
+	mr	12,r6
+	mr	r28,r5
+	mr	r29,r6
+	mr	11,r5
+	mr	12,r6
+	bctr
+
+	.comm	.stack,4096*2,4