trampoline_64.S

  1/* SPDX-License-Identifier: GPL-2.0-only */
  2/*
  3 * kexec trampoline
  4 *
  5 * Based on code taken from kexec-tools and kexec-lite.
  6 *
  7 * Copyright (C) 2004 - 2005, Milton D Miller II, IBM Corporation
  8 * Copyright (C) 2006, Mohan Kumar M, IBM Corporation
  9 * Copyright (C) 2013, Anton Blanchard, IBM Corporation
 10 */
 11
 12#include <asm/asm-compat.h>
 13#include <asm/crashdump-ppc64.h>
 14
 15	.balign 256
 16	.globl purgatory_start
 17purgatory_start:
 18	b	master
 19
 20	/* ABI: possible run_at_load flag at 0x5c */
 21	.org purgatory_start + 0x5c
 22	.globl run_at_load
 23run_at_load:
 24	.long 0
 25	.size run_at_load, . - run_at_load
 26
 27	/* ABI: slaves start at 60 with r3=phys */
 28	.org purgatory_start + 0x60
 29slave:
 30	b .
 31	/* ABI: end of copied region */
 32	.org purgatory_start + 0x100
 33	.size purgatory_start, . - purgatory_start
 34
 35/*
 36 * The above 0x100 bytes at purgatory_start are replaced with the
 37 * code from the kernel (or next stage) by setup_purgatory().
 38 */
 39
 40master:
 41	or	%r1,%r1,%r1	/* low priority to let other threads catchup */
 42	isync
 43	mr	%r17,%r3	/* save cpu id to r17 */
 44	mr	%r15,%r4	/* save physical address in reg15 */
 45
 46	/* Work out where we're running */
 47	bcl	20, 31, 0f
 480:	mflr	%r18
 49
 50	/*
 51	 * Copy BACKUP_SRC_SIZE bytes from BACKUP_SRC_START to
 52	 * backup_start 8 bytes at a time.
 53	 *
 54	 * Use r3 = dest, r4 = src, r5 = size, r6 = count
 55	 */
 56	ld	%r3, (backup_start - 0b)(%r18)
 57	cmpdi	%cr0, %r3, 0
 58	beq	.Lskip_copy	/* skip if there is no backup region */
 59	lis	%r5, BACKUP_SRC_SIZE@h
 60	ori	%r5, %r5, BACKUP_SRC_SIZE@l
 61	cmpdi	%cr0, %r5, 0
 62	beq	.Lskip_copy	/* skip if copy size is zero */
 63	lis	%r4, BACKUP_SRC_START@h
 64	ori	%r4, %r4, BACKUP_SRC_START@l
 65	li	%r6, 0
 66.Lcopy_loop:
 67	ldx	%r0, %r6, %r4
 68	stdx	%r0, %r6, %r3
 69	addi	%r6, %r6, 8
 70	cmpld	%cr0, %r6, %r5
 71	blt	.Lcopy_loop
 72
 73.Lskip_copy:
 74	or	%r3,%r3,%r3	/* ok now to high priority, lets boot */
 75	lis	%r6,0x1
 76	mtctr	%r6		/* delay a bit for slaves to catch up */
 77	bdnz	.		/* before we overwrite 0-100 again */
 78
 79	/* load device-tree address */
 80	ld	%r3, (dt_offset - 0b)(%r18)
 81	mr	%r16,%r3	/* save dt address in reg16 */
 82	li	%r4,20
 83	LWZX_BE	%r6,%r3,%r4	/* fetch __be32 version number at byte 20 */
 84	cmpwi	%cr0,%r6,2	/* v2 or later? */
 85	blt	1f
 86	li	%r4,28
 87	STWX_BE	%r17,%r3,%r4	/* Store my cpu as __be32 at byte 28 */
 881:
 89	/* Load opal base and entry values in r8 & r9 respectively */
 90	ld	%r8,(opal_base - 0b)(%r18)
 91	ld	%r9,(opal_entry - 0b)(%r18)
 92
 93	/* load the kernel address */
 94	ld	%r4,(kernel - 0b)(%r18)
 95
 96	/* load the run_at_load flag */
 97	/* possibly patched by kexec */
 98	ld	%r6,(run_at_load - 0b)(%r18)
 99	/* and patch it into the kernel */
100	stw	%r6,(0x5c)(%r4)
101
102	mr	%r3,%r16	/* restore dt address */
103
104	li	%r5,0		/* r5 will be 0 for kernel */
105
106	mfmsr	%r11
107	andi.	%r10,%r11,1	/* test MSR_LE */
108	bne	.Little_endian
109
110	mtctr	%r4		/* prepare branch to */
111	bctr			/* start kernel */
112
113.Little_endian:
114	mtsrr0	%r4		/* prepare branch to */
115
116	clrrdi	%r11,%r11,1	/* clear MSR_LE */
117	mtsrr1	%r11
118
119	rfid			/* update MSR and start kernel */
120
121	.balign 8
122	.globl kernel
123kernel:
124	.8byte  0x0
125	.size kernel, . - kernel
126
127	.balign 8
128	.globl dt_offset
129dt_offset:
130	.8byte  0x0
131	.size dt_offset, . - dt_offset
132
133	.balign 8
134	.globl backup_start
135backup_start:
136	.8byte  0x0
137	.size backup_start, . - backup_start
138
139	.balign 8
140	.globl opal_base
141opal_base:
142	.8byte  0x0
143	.size opal_base, . - opal_base
144
145	.balign 8
146	.globl opal_entry
147opal_entry:
148	.8byte  0x0
149	.size opal_entry, . - opal_entry
150
151	.data
152	.balign 8
153.globl purgatory_sha256_digest
154purgatory_sha256_digest:
155	.skip	32
156	.size purgatory_sha256_digest, . - purgatory_sha256_digest
157
158	.balign 8
159.globl purgatory_sha_regions
160purgatory_sha_regions:
161	.skip	8 * 2 * 16
162	.size purgatory_sha_regions, . - purgatory_sha_regions