powerpc/kernel/head_64.S

1 /* SPDX-License-Identifier: GPL-2.0-or-later */
4  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
9  *  Low-level exception handlers and MMU support
16  *  This file contains the entry point for the 64-bit kernel along
17  *  with some early initialization code common to all 64-bit powerpc
23 #include <asm/reg.h>
27 #include <asm/head-64.h>
28 #include <asm/asm-offsets.h>
41 #include <asm/ppc-opcode.h>
43 #include <asm/feature-fixups.h>
45 /* The physical memory is laid out such that the secondary processor
47  * using the layout described in exceptions-64s.S
56  *   3. If the RTAS supports "query-cpu-stopped-state", then secondary
57  *      CPUs will enter as directed by "start-cpu" RTAS call, which is
59  *   4. Else the secondary CPUs will enter at secondary_hold (0x60) as
60  *      directed by the "start-cpu" RTS call, with PIR in r3.
61  * -or- For OPAL entry:
63  *   2. The primary CPU enters at 0 with device-tree in r3, OPAL base
65  *   3. Secondary CPUs enter as directed by OPAL_START_CPU call, which
91 	/* Secondary processors spin on this value until it becomes non-zero.
92 	 * When non-zero, it contains the real address of the function the cpu
100 	/* Secondary processors write this value with their cpu # */
109 	 * is used by kexec-tools to keep the the kdump kernel in the
117 #define RUN_AT_LOAD_DEFAULT 0x72756e30  /* "run0" -- relocate to 0 by default */
120 	/* Do not move this variable as kexec-tools knows about it. */
130  * The following code is used to hold secondary processors
161 	/* All secondary cpus wait here until told to start. */
202 #include "exceptions-64s.S"
211  * The booting_thread_hwid holds the thread id we want to boot in cpu
286 	 * If the old value of BUCSR is non-zero, this thread has run
305 	/* turn on 64-bit mode */
320  * On pSeries and most other platforms, secondary processors spin
333 	/* turn on 64-bit mode */
348  * one we wanted to boot. If not, start the specified thread and stop the
478  *   r5 != NULL -> OF entry, we go to prom_init, "legacy" parameter content
481  *   r5 == NULL -> kexec style entry. r3 is a physical pointer to the
495 	addis	r26,r26,(_stext - 0b)@ha
496 	addi	r26,r26,(_stext - 0b)@l	/* current runtime base addr */
499 	 * Are we booted from a PROM Of-type client-interface ?
503 	b	__boot_from_prom		/* yes -> prom */
548 	 * Align the stack to 16-byte boundary
550 	 * boot binary, the stack pointer may be unaligned on PowerMac
572 	/* We never return. We also hit that trap if trying to boot
657 p_end: .8byte _end - copy_to_here
662 	 * _end - copy_to_here to the copy limit and run again.
680 	addi	r5,r5,-8
681 	addi	r6,r6,-8
713  * On PowerMac, secondary processors starts from the reset vector, which
732 	/* turn on 64-bit mode */
781  * secondary processors.  The execution environment is relocation off.
837  * zero the stack back-chain pointer and get the TOC virtual address
879  * are running at the moment, using position-independent code.
882  * TOC in -mcmodel=medium mode. After we relocate to 0 but before
892 	ld	r2,(p_toc - 0b)(r11)
898 p_toc:	.8byte	__toc_start + 0x8000 - 0b
912 	 * to clear it now for kexec-style entry.
920 	addi	r8,r8,-8
952 	stdu	r0,-STACK_FRAME_OVERHEAD(r1)
998  * We put a few things here that have to be page-aligned.
999  * This stuff goes at the beginning of the bss, which is page-aligned.