relocate_32.S

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * This file contains kexec low-level functions.
 *
 * Copyright (C) 2002-2003 Eric Biederman  <[email protected]>
 * GameCube/ppc32 port Copyright (C) 2004 Albert Herranz
 * PPC44x port. Copyright (C) 2011,  IBM Corporation
 * 		Author: Suzuki Poulose <[email protected]>
 */

#include <linux/objtool.h>
#include <asm/reg.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/ppc_asm.h>
#include <asm/kexec.h>

	.text

	/*
	 * Must be relocatable PIC code callable as a C function.
	 */
	.globl relocate_new_kernel
relocate_new_kernel:
	/* r3 = page_list   */
	/* r4 = reboot_code_buffer */
	/* r5 = start_address      */

#ifdef CONFIG_PPC_85xx

	mr	r29, r3
	mr	r30, r4
	mr	r31, r5

#define ENTRY_MAPPING_KEXEC_SETUP
#include <kernel/85xx_entry_mapping.S>
#undef ENTRY_MAPPING_KEXEC_SETUP

	mr      r3, r29
	mr      r4, r30
	mr      r5, r31

	li	r0, 0
#elif defined(CONFIG_44x)

	/* Save our parameters */
	mr	r29, r3
	mr	r30, r4
	mr	r31, r5

#ifdef CONFIG_PPC_47x
	/* Check for 47x cores */
	mfspr	r3,SPRN_PVR
	srwi	r3,r3,16
	cmplwi	cr0,r3,PVR_476FPE@h
	beq	setup_map_47x
	cmplwi	cr0,r3,PVR_476@h
	beq	setup_map_47x
	cmplwi	cr0,r3,PVR_476_ISS@h
	beq	setup_map_47x
#endif /* CONFIG_PPC_47x */

/*
 * Code for setting up 1:1 mapping for PPC440x for KEXEC
 *
 * We cannot switch off the MMU on PPC44x.
 * So we:
 * 1) Invalidate all the mappings except the one we are running from.
 * 2) Create a tmp mapping for our code in the other address space(TS) and
 *    jump to it. Invalidate the entry we started in.
 * 3) Create a 1:1 mapping for 0-2GiB in chunks of 256M in original TS.
 * 4) Jump to the 1:1 mapping in original TS.
 * 5) Invalidate the tmp mapping.
 *
 * - Based on the kexec support code for FSL BookE
 *
 */

	/*
	 * Load the PID with kernel PID (0).
	 * Also load our MSR_IS and TID to MMUCR for TLB search.
	 */
	li	r3, 0
	mtspr	SPRN_PID, r3
	mfmsr	r4
	andi.	r4,r4,MSR_IS@l
	beq	wmmucr
	oris	r3,r3,PPC44x_MMUCR_STS@h
wmmucr:
	mtspr	SPRN_MMUCR,r3
	sync

	/*
	 * Invalidate all the TLB entries except the current entry
	 * where we are running from
	 */
	bcl	20,31,$+4			/* Find our address */
0:	mflr	r5				/* Make it accessible */
	tlbsx	r23,0,r5			/* Find entry we are in */
	li	r4,0				/* Start at TLB entry 0 */
	li	r3,0				/* Set PAGEID inval value */
1:	cmpw	r23,r4				/* Is this our entry? */
	beq	skip				/* If so, skip the inval */
	tlbwe	r3,r4,PPC44x_TLB_PAGEID		/* If not, inval the entry */
skip:
	addi	r4,r4,1				/* Increment */
	cmpwi	r4,64				/* Are we done?	*/
	bne	1b				/* If not, repeat */
	isync

	/* Create a temp mapping and jump to it */
	andi.	r6, r23, 1		/* Find the index to use */
	addi	r24, r6, 1		/* r24 will contain 1 or 2 */

	mfmsr	r9			/* get the MSR */
	rlwinm	r5, r9, 27, 31, 31	/* Extract the MSR[IS] */
	xori	r7, r5, 1		/* Use the other address space */

	/* Read the current mapping entries */
	tlbre	r3, r23, PPC44x_TLB_PAGEID
	tlbre	r4, r23, PPC44x_TLB_XLAT
	tlbre	r5, r23, PPC44x_TLB_ATTRIB

	/* Save our current XLAT entry */
	mr	r25, r4

	/* Extract the TLB PageSize */
	li	r10, 1 			/* r10 will hold PageSize */
	rlwinm	r11, r3, 0, 24, 27	/* bits 24-27 */

	/* XXX: As of now we use 256M, 4K pages */
	cmpwi	r11, PPC44x_TLB_256M
	bne	tlb_4k
	rotlwi	r10, r10, 28		/* r10 = 256M */
	b	write_out
tlb_4k:
	cmpwi	r11, PPC44x_TLB_4K
	bne	default
	rotlwi	r10, r10, 12		/* r10 = 4K */
	b	write_out
default:
	rotlwi	r10, r10, 10		/* r10 = 1K */

write_out:
	/*
	 * Write out the tmp 1:1 mapping for this code in other address space
	 * Fixup  EPN = RPN , TS=other address space
	 */
	insrwi	r3, r7, 1, 23		/* Bit 23 is TS for PAGEID field */

	/* Write out the tmp mapping entries */
	tlbwe	r3, r24, PPC44x_TLB_PAGEID
	tlbwe	r4, r24, PPC44x_TLB_XLAT
	tlbwe	r5, r24, PPC44x_TLB_ATTRIB

	subi	r11, r10, 1		/* PageOffset Mask = PageSize - 1 */
	not	r10, r11		/* Mask for PageNum */

	/* Switch to other address space in MSR */
	insrwi	r9, r7, 1, 26		/* Set MSR[IS] = r7 */

	bcl	20,31,$+4
1:	mflr	r8
	addi	r8, r8, (2f-1b)		/* Find the target offset */

	/* Jump to the tmp mapping */
	mtspr	SPRN_SRR0, r8
	mtspr	SPRN_SRR1, r9
	rfi

2:
	/* Invalidate the entry we were executing from */
	li	r3, 0
	tlbwe	r3, r23, PPC44x_TLB_PAGEID

	/* attribute fields. rwx for SUPERVISOR mode */
	li	r5, 0
	ori	r5, r5, (PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | PPC44x_TLB_G)

	/* Create 1:1 mapping in 256M pages */
	xori	r7, r7, 1			/* Revert back to Original TS */

	li	r8, 0				/* PageNumber */
	li	r6, 3				/* TLB Index, start at 3  */

next_tlb:
	rotlwi	r3, r8, 28			/* Create EPN (bits 0-3) */
	mr	r4, r3				/* RPN = EPN  */
	ori	r3, r3, (PPC44x_TLB_VALID | PPC44x_TLB_256M) /* SIZE = 256M, Valid */
	insrwi	r3, r7, 1, 23			/* Set TS from r7 */

	tlbwe	r3, r6, PPC44x_TLB_PAGEID	/* PageID field : EPN, V, SIZE */
	tlbwe	r4, r6, PPC44x_TLB_XLAT		/* Address translation : RPN   */
	tlbwe	r5, r6, PPC44x_TLB_ATTRIB	/* Attributes */

	addi	r8, r8, 1			/* Increment PN */
	addi	r6, r6, 1			/* Increment TLB Index */
	cmpwi	r8, 8				/* Are we done ? */
	bne	next_tlb
	isync

	/* Jump to the new mapping 1:1 */
	li	r9,0
	insrwi	r9, r7, 1, 26			/* Set MSR[IS] = r7 */

	bcl	20,31,$+4
1:	mflr	r8
	and	r8, r8, r11			/* Get our offset within page */
	addi	r8, r8, (2f-1b)

	and	r5, r25, r10			/* Get our target PageNum */
	or	r8, r8, r5			/* Target jump address */

	mtspr	SPRN_SRR0, r8
	mtspr	SPRN_SRR1, r9
	rfi
2:
	/* Invalidate the tmp entry we used */
	li	r3, 0
	tlbwe	r3, r24, PPC44x_TLB_PAGEID
	sync
	b	ppc44x_map_done

#ifdef CONFIG_PPC_47x

	/* 1:1 mapping for 47x */

setup_map_47x:

	/*
	 * Load the kernel pid (0) to PID and also to MMUCR[TID].
	 * Also set the MSR IS->MMUCR STS
	 */
	li	r3, 0
	mtspr	SPRN_PID, r3			/* Set PID */
	mfmsr	r4				/* Get MSR */
	andi.	r4, r4, MSR_IS@l		/* TS=1? */
	beq	1f				/* If not, leave STS=0 */
	oris	r3, r3, PPC47x_MMUCR_STS@h	/* Set STS=1 */
1:	mtspr	SPRN_MMUCR, r3			/* Put MMUCR */
	sync

	/* Find the entry we are running from */
	bcl	20,31,$+4
2:	mflr	r23
	tlbsx	r23, 0, r23
	tlbre	r24, r23, 0			/* TLB Word 0 */
	tlbre	r25, r23, 1			/* TLB Word 1 */
	tlbre	r26, r23, 2			/* TLB Word 2 */


	/*
	 * Invalidates all the tlb entries by writing to 256 RPNs(r4)
	 * of 4k page size in all  4 ways (0-3 in r3).
	 * This would invalidate the entire UTLB including the one we are
	 * running from. However the shadow TLB entries would help us
	 * to continue the execution, until we flush them (rfi/isync).
	 */
	addis	r3, 0, 0x8000			/* specify the way */
	addi	r4, 0, 0			/* TLB Word0 = (EPN=0, VALID = 0) */
	addi	r5, 0, 0
	b	clear_utlb_entry

	/* Align the loop to speed things up. from head_44x.S */
	.align	6

clear_utlb_entry:

	tlbwe	r4, r3, 0
	tlbwe	r5, r3, 1
	tlbwe	r5, r3, 2
	addis	r3, r3, 0x2000			/* Increment the way */
	cmpwi	r3, 0
	bne	clear_utlb_entry
	addis	r3, 0, 0x8000
	addis	r4, r4, 0x100			/* Increment the EPN */
	cmpwi	r4, 0
	bne	clear_utlb_entry

	/* Create the entries in the other address space */
	mfmsr	r5
	rlwinm	r7, r5, 27, 31, 31		/* Get the TS (Bit 26) from MSR */
	xori	r7, r7, 1			/* r7 = !TS */

	insrwi	r24, r7, 1, 21			/* Change the TS in the saved TLB word 0 */

	/*
	 * write out the TLB entries for the tmp mapping
	 * Use way '0' so that we could easily invalidate it later.
	 */
	lis	r3, 0x8000			/* Way '0' */

	tlbwe	r24, r3, 0
	tlbwe	r25, r3, 1
	tlbwe	r26, r3, 2

	/* Update the msr to the new TS */
	insrwi	r5, r7, 1, 26

	bcl	20,31,$+4
1:	mflr	r6
	addi	r6, r6, (2f-1b)

	mtspr	SPRN_SRR0, r6
	mtspr	SPRN_SRR1, r5
	rfi

	/*
	 * Now we are in the tmp address space.
	 * Create a 1:1 mapping for 0-2GiB in the original TS.
	 */
2:
	li	r3, 0
	li	r4, 0				/* TLB Word 0 */
	li	r5, 0				/* TLB Word 1 */
	li	r6, 0
	ori	r6, r6, PPC47x_TLB2_S_RWX	/* TLB word 2 */

	li	r8, 0				/* PageIndex */

	xori	r7, r7, 1			/* revert back to original TS */

write_utlb:
	rotlwi	r5, r8, 28			/* RPN = PageIndex * 256M */
						/* ERPN = 0 as we don't use memory above 2G */

	mr	r4, r5				/* EPN = RPN */
	ori	r4, r4, (PPC47x_TLB0_VALID | PPC47x_TLB0_256M)
	insrwi	r4, r7, 1, 21			/* Insert the TS to Word 0 */

	tlbwe	r4, r3, 0			/* Write out the entries */
	tlbwe	r5, r3, 1
	tlbwe	r6, r3, 2
	addi	r8, r8, 1
	cmpwi	r8, 8				/* Have we completed ? */
	bne	write_utlb

	/* make sure we complete the TLB write up */
	isync

	/*
	 * Prepare to jump to the 1:1 mapping.
	 * 1) Extract page size of the tmp mapping
	 *    DSIZ = TLB_Word0[22:27]
	 * 2) Calculate the physical address of the address
	 *    to jump to.
	 */
	rlwinm	r10, r24, 0, 22, 27

	cmpwi	r10, PPC47x_TLB0_4K
	li	r10, 0x1000			/* r10 = 4k */
	beq	0f

	/* Defaults to 256M */
	lis	r10, 0x1000

0:	bcl	20,31,$+4
1:	mflr	r4
	addi	r4, r4, (2f-1b)			/* virtual address  of 2f */

	subi	r11, r10, 1			/* offsetmask = Pagesize - 1 */
	not	r10, r11			/* Pagemask = ~(offsetmask) */

	and	r5, r25, r10			/* Physical page */
	and	r6, r4, r11			/* offset within the current page */

	or	r5, r5, r6			/* Physical address for 2f */

	/* Switch the TS in MSR to the original one */
	mfmsr	r8
	insrwi	r8, r7, 1, 26

	mtspr	SPRN_SRR1, r8
	mtspr	SPRN_SRR0, r5
	rfi

2:
	/* Invalidate the tmp mapping */
	lis	r3, 0x8000			/* Way '0' */

	clrrwi	r24, r24, 12			/* Clear the valid bit */
	tlbwe	r24, r3, 0
	tlbwe	r25, r3, 1
	tlbwe	r26, r3, 2

	/* Make sure we complete the TLB write and flush the shadow TLB */
	isync

#endif

ppc44x_map_done:


	/* Restore the parameters */
	mr	r3, r29
	mr	r4, r30
	mr	r5, r31

	li	r0, 0
#else
	li	r0, 0

	/*
	 * Set Machine Status Register to a known status,
	 * switch the MMU off and jump to 1: in a single step.
	 */

	mr	r8, r0
	ori     r8, r8, MSR_RI|MSR_ME
	mtspr	SPRN_SRR1, r8
	addi	r8, r4, 1f - relocate_new_kernel
	mtspr	SPRN_SRR0, r8
	sync
	rfi

1:
#endif
	/* from this point address translation is turned off */
	/* and interrupts are disabled */

	/* set a new stack at the bottom of our page... */
	/* (not really needed now) */
	addi	r1, r4, KEXEC_CONTROL_PAGE_SIZE - 8 /* for LR Save+Back Chain */
	stw	r0, 0(r1)

	/* Do the copies */
	li	r6, 0 /* checksum */
	mr	r0, r3
	b	1f

0:	/* top, read another word for the indirection page */
	lwzu	r0, 4(r3)

1:
	/* is it a destination page? (r8) */
	rlwinm.	r7, r0, 0, 31, 31 /* IND_DESTINATION (1<<0) */
	beq	2f

	rlwinm	r8, r0, 0, 0, 19 /* clear kexec flags, page align */
	b	0b

2:	/* is it an indirection page? (r3) */
	rlwinm.	r7, r0, 0, 30, 30 /* IND_INDIRECTION (1<<1) */
	beq	2f

	rlwinm	r3, r0, 0, 0, 19 /* clear kexec flags, page align */
	subi	r3, r3, 4
	b	0b

2:	/* are we done? */
	rlwinm.	r7, r0, 0, 29, 29 /* IND_DONE (1<<2) */
	beq	2f
	b	3f

2:	/* is it a source page? (r9) */
	rlwinm.	r7, r0, 0, 28, 28 /* IND_SOURCE (1<<3) */
	beq	0b

	rlwinm	r9, r0, 0, 0, 19 /* clear kexec flags, page align */

	li	r7, PAGE_SIZE / 4
	mtctr   r7
	subi    r9, r9, 4
	subi    r8, r8, 4
9:
	lwzu    r0, 4(r9)  /* do the copy */
	xor	r6, r6, r0
	stwu    r0, 4(r8)
	dcbst	0, r8
	sync
	icbi	0, r8
	bdnz    9b

	addi    r9, r9, 4
	addi    r8, r8, 4
	b	0b

3:

	/* To be certain of avoiding problems with self-modifying code
	 * execute a serializing instruction here.
	 */
	isync
	sync

	mfspr	r3, SPRN_PIR /* current core we are running on */
	mr	r4, r5 /* load physical address of chunk called */

	/* jump to the entry point, usually the setup routine */
	mtlr	r5
	blrl

1:	b	1b

relocate_new_kernel_end:

	.globl relocate_new_kernel_size
relocate_new_kernel_size:
	.long relocate_new_kernel_end - relocate_new_kernel