aboutsummaryrefslogtreecommitdiff
path: root/arch/mips/kernel/head.S
blob: e712dcf18b2de22bbc6c14d9fbf84f37e9542215 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 1994, 1995 Waldorf Electronics
 * Written by Ralf Baechle and Andreas Busse
 * Copyright (C) 1994 - 99, 2003, 06 Ralf Baechle
 * Copyright (C) 1996 Paul M. Antoine
 * Modified for DECStation and hence R3000 support by Paul M. Antoine
 * Further modifications by David S. Miller and Harald Koerfgen
 * Copyright (C) 1999 Silicon Graphics, Inc.
 * Kevin Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
 * Copyright (C) 2000 MIPS Technologies, Inc.  All rights reserved.
 */
#include <linux/init.h>
#include <linux/threads.h>

#include <asm/addrspace.h>
#include <asm/asm.h>
#include <asm/asmmacro.h>
#include <asm/irqflags.h>
#include <asm/regdef.h>
#include <asm/pgtable-bits.h>
#include <asm/mipsregs.h>
#include <asm/stackframe.h>

#include <kernel-entry-init.h>

	/*
	 * For the moment disable interrupts, mark the kernel mode and
	 * set ST0_KX so that the CPU does not spit fire when using
	 * 64-bit addresses.  A full initialization of the CPU's status
	 * register is done later in per_cpu_trap_init().
	 */
	.macro	setup_c0_status set clr
	.set	push
#ifdef CONFIG_MIPS_MT_SMTC
	/*
	 * For SMTC, we need to set privilege and disable interrupts only for
	 * the current TC, using the TCStatus register.
	 */
	mfc0	t0, CP0_TCSTATUS
	/* Fortunately CU 0 is in the same place in both registers */
	/* Set TCU0, TMX, TKSU (for later inversion) and IXMT */
	li	t1, ST0_CU0 | 0x08001c00
	or	t0, t1
	/* Clear TKSU, leave IXMT */
	xori	t0, 0x00001800
	mtc0	t0, CP0_TCSTATUS
	_ehb
	/* We need to leave the global IE bit set, but clear EXL...*/
	mfc0	t0, CP0_STATUS
	or	t0, ST0_CU0 | ST0_EXL | ST0_ERL | \set | \clr
	xor	t0, ST0_EXL | ST0_ERL | \clr
	mtc0	t0, CP0_STATUS
#else
	mfc0	t0, CP0_STATUS
	or	t0, ST0_CU0|\set|0x1f|\clr
	xor	t0, 0x1f|\clr
	mtc0	t0, CP0_STATUS
	.set	noreorder
	sll	zero,3				# ehb
#endif
	.set	pop
	.endm

	.macro	setup_c0_status_pri
#ifdef CONFIG_64BIT
	setup_c0_status ST0_KX 0
#else
	setup_c0_status 0 0
#endif
	.endm

	.macro	setup_c0_status_sec
#ifdef CONFIG_64BIT
	setup_c0_status ST0_KX ST0_BEV
#else
	setup_c0_status 0 ST0_BEV
#endif
	.endm

#ifndef CONFIG_NO_EXCEPT_FILL
	/*
	 * Reserved space for exception handlers.
	 * Necessary for machines which link their kernels at KSEG0.
	 */
	.fill	0x400
#endif

EXPORT(_stext)

#ifdef CONFIG_BOOT_RAW
	/*
	 * Give us a fighting chance of running if execution beings at the
	 * kernel load address.	 This is needed because this platform does
	 * not have a ELF loader yet.
	 */
FEXPORT(__kernel_entry)
	j	kernel_entry
#endif

	__REF

NESTED(kernel_entry, 16, sp)			# kernel entry point

	kernel_entry_setup			# cpu specific setup

	setup_c0_status_pri

	/* We might not get launched at the address the kernel is linked to,
	   so we jump there.  */
	PTR_LA	t0, 0f
	jr	t0
0:

#ifdef CONFIG_MIPS_MT_SMTC
	/*
	 * In SMTC kernel, "CLI" is thread-specific, in TCStatus.
	 * We still need to enable interrupts globally in Status,
	 * and clear EXL/ERL.
	 *
	 * TCContext is used to track interrupt levels under
	 * service in SMTC kernel. Clear for boot TC before
	 * allowing any interrupts.
	 */
	mtc0	zero, CP0_TCCONTEXT

	mfc0	t0, CP0_STATUS
	ori	t0, t0, 0xff1f
	xori	t0, t0, 0x001e
	mtc0	t0, CP0_STATUS
#endif /* CONFIG_MIPS_MT_SMTC */

	PTR_LA		t0, __bss_start		# clear .bss
	LONG_S		zero, (t0)
	PTR_LA		t1, __bss_stop - LONGSIZE
1:
	PTR_ADDIU	t0, LONGSIZE
	LONG_S		zero, (t0)
	bne		t0, t1, 1b

	LONG_S		a0, fw_arg0		# firmware arguments
	LONG_S		a1, fw_arg1
	LONG_S		a2, fw_arg2
	LONG_S		a3, fw_arg3

	MTC0		zero, CP0_CONTEXT	# clear context register
	PTR_LA		$28, init_thread_union
	/* Set the SP after an empty pt_regs.  */
	PTR_LI		sp, _THREAD_SIZE - 32 - PT_SIZE
	PTR_ADDU	sp, $28
	back_to_back_c0_hazard
	set_saved_sp	sp, t0, t1
	PTR_SUBU	sp, 4 * SZREG		# init stack pointer

	j		start_kernel
	END(kernel_entry)

#ifdef CONFIG_SMP
/*
 * SMP slave cpus entry point.	Board specific code for bootstrap calls this
 * function after setting up the stack and gp registers.
 */
NESTED(smp_bootstrap, 16, sp)
#ifdef CONFIG_MIPS_MT_SMTC
	/*
	 * Read-modify-writes of Status must be atomic, and this
	 * is one case where CLI is invoked without EXL being
	 * necessarily set. The CLI and setup_c0_status will
	 * in fact be redundant for all but the first TC of
	 * each VPE being booted.
	 */
	DMT	10	# dmt t2 /* t0, t1 are used by CLI and setup_c0_status() */
	jal	mips_ihb
#endif /* CONFIG_MIPS_MT_SMTC */
	smp_slave_setup
	setup_c0_status_sec
#ifdef CONFIG_MIPS_MT_SMTC
	andi	t2, t2, VPECONTROL_TE
	beqz	t2, 2f
	EMT		# emt
2:
#endif /* CONFIG_MIPS_MT_SMTC */
	j	start_secondary
	END(smp_bootstrap)
#endif /* CONFIG_SMP */