xref: /openbmc/linux/arch/arm/kernel/hyp-stub.S (revision 48cc39c3) 
1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * Copyright (c) 2012 Linaro Limited.
4 */
5
6#include <linux/init.h>
7#include <linux/irqchip/arm-gic-v3.h>
8#include <linux/linkage.h>
9#include <asm/assembler.h>
10#include <asm/virt.h>
11
12#ifndef ZIMAGE
13/*
14 * For the kernel proper, we need to find out the CPU boot mode long after
15 * boot, so we need to store it in a writable variable.
16 *
17 * This is not in .bss, because we set it sufficiently early that the boot-time
18 * zeroing of .bss would clobber it.
19 */
20.data
21	.align	2
22ENTRY(__boot_cpu_mode)
23	.long	0
24.text
25
26	/*
27	 * Save the primary CPU boot mode. Requires 2 scratch registers.
28	 */
29	.macro	store_primary_cpu_mode	reg1, reg2
30	mrs	\reg1, cpsr
31	and	\reg1, \reg1, #MODE_MASK
32	str_l	\reg1, __boot_cpu_mode, \reg2
33	.endm
34
35	/*
36	 * Compare the current mode with the one saved on the primary CPU.
37	 * If they don't match, record that fact. The Z bit indicates
38	 * if there's a match or not.
39	 * Requires 2 additional scratch registers.
40	 */
41	.macro	compare_cpu_mode_with_primary mode, reg1, reg2
42	adr_l	\reg2, __boot_cpu_mode
43	ldr	\reg1, [\reg2]
44	cmp	\mode, \reg1		@ matches primary CPU boot mode?
45	orrne	\reg1, \reg1, #BOOT_CPU_MODE_MISMATCH
46	strne	\reg1, [\reg2]		@ record what happened and give up
47	.endm
48
49#else	/* ZIMAGE */
50
51	.macro	store_primary_cpu_mode	reg1:req, reg2:req
52	.endm
53
54/*
55 * The zImage loader only runs on one CPU, so we don't bother with mult-CPU
56 * consistency checking:
57 */
58	.macro	compare_cpu_mode_with_primary mode, reg1, reg2
59	cmp	\mode, \mode
60	.endm
61
62#endif /* ZIMAGE */
63
64/*
65 * Hypervisor stub installation functions.
66 *
67 * These must be called with the MMU and D-cache off.
68 * They are not ABI compliant and are only intended to be called from the kernel
69 * entry points in head.S.
70 */
71@ Call this from the primary CPU
72ENTRY(__hyp_stub_install)
73	store_primary_cpu_mode	r4, r5
74ENDPROC(__hyp_stub_install)
75
76	@ fall through...
77
78@ Secondary CPUs should call here
79ENTRY(__hyp_stub_install_secondary)
80	mrs	r4, cpsr
81	and	r4, r4, #MODE_MASK
82
83	/*
84	 * If the secondary has booted with a different mode, give up
85	 * immediately.
86	 */
87	compare_cpu_mode_with_primary	r4, r5, r6
88	retne	lr
89
90	/*
91	 * Once we have given up on one CPU, we do not try to install the
92	 * stub hypervisor on the remaining ones: because the saved boot mode
93	 * is modified, it can't compare equal to the CPSR mode field any
94	 * more.
95	 *
96	 * Otherwise...
97	 */
98
99	cmp	r4, #HYP_MODE
100	retne	lr			@ give up if the CPU is not in HYP mode
101
102/*
103 * Configure HSCTLR to set correct exception endianness/instruction set
104 * state etc.
105 * Turn off all traps
106 * Eventually, CPU-specific code might be needed -- assume not for now
107 *
108 * This code relies on the "eret" instruction to synchronize the
109 * various coprocessor accesses. This is done when we switch to SVC
110 * (see safe_svcmode_maskall).
111 */
112	@ Now install the hypervisor stub:
113	W(adr)	r7, __hyp_stub_vectors
114	mcr	p15, 4, r7, c12, c0, 0	@ set hypervisor vector base (HVBAR)
115
116	@ Disable all traps, so we don't get any nasty surprise
117	mov	r7, #0
118	mcr	p15, 4, r7, c1, c1, 0	@ HCR
119	mcr	p15, 4, r7, c1, c1, 2	@ HCPTR
120	mcr	p15, 4, r7, c1, c1, 3	@ HSTR
121
122THUMB(	orr	r7, #(1 << 30)	)	@ HSCTLR.TE
123ARM_BE8(orr	r7, r7, #(1 << 25))     @ HSCTLR.EE
124	mcr	p15, 4, r7, c1, c0, 0	@ HSCTLR
125
126	mrc	p15, 4, r7, c1, c1, 1	@ HDCR
127	and	r7, #0x1f		@ Preserve HPMN
128	mcr	p15, 4, r7, c1, c1, 1	@ HDCR
129
130	@ Make sure NS-SVC is initialised appropriately
131	mrc	p15, 0, r7, c1, c0, 0	@ SCTLR
132	orr	r7, #(1 << 5)		@ CP15 barriers enabled
133	bic	r7, #(3 << 7)		@ Clear SED/ITD for v8 (RES0 for v7)
134	bic	r7, #(3 << 19)		@ WXN and UWXN disabled
135	mcr	p15, 0, r7, c1, c0, 0	@ SCTLR
136
137	mrc	p15, 0, r7, c0, c0, 0	@ MIDR
138	mcr	p15, 4, r7, c0, c0, 0	@ VPIDR
139
140	mrc	p15, 0, r7, c0, c0, 5	@ MPIDR
141	mcr	p15, 4, r7, c0, c0, 5	@ VMPIDR
142
143#if !defined(ZIMAGE) && defined(CONFIG_ARM_ARCH_TIMER)
144	@ make CNTP_* and CNTPCT accessible from PL1
145	mrc	p15, 0, r7, c0, c1, 1	@ ID_PFR1
146	ubfx	r7, r7, #16, #4
147	teq	r7, #0
148	beq	1f
149	mrc	p15, 4, r7, c14, c1, 0	@ CNTHCTL
150	orr	r7, r7, #3		@ PL1PCEN | PL1PCTEN
151	mcr	p15, 4, r7, c14, c1, 0	@ CNTHCTL
152	mov	r7, #0
153	mcrr	p15, 4, r7, r7, c14	@ CNTVOFF
154
155	@ Disable virtual timer in case it was counting
156	mrc	p15, 0, r7, c14, c3, 1	@ CNTV_CTL
157	bic	r7, #1			@ Clear ENABLE
158	mcr	p15, 0, r7, c14, c3, 1	@ CNTV_CTL
1591:
160#endif
161
162#ifdef CONFIG_ARM_GIC_V3
163	@ Check whether GICv3 system registers are available
164	mrc	p15, 0, r7, c0, c1, 1	@ ID_PFR1
165	ubfx	r7, r7, #28, #4
166	teq	r7, #0
167	beq	2f
168
169	@ Enable system register accesses
170	mrc	p15, 4, r7, c12, c9, 5	@ ICC_HSRE
171	orr	r7, r7, #(ICC_SRE_EL2_ENABLE | ICC_SRE_EL2_SRE)
172	mcr	p15, 4, r7, c12, c9, 5	@ ICC_HSRE
173	isb
174
175	@ SRE bit could be forced to 0 by firmware.
176	@ Check whether it sticks before accessing any other sysreg
177	mrc	p15, 4, r7, c12, c9, 5	@ ICC_HSRE
178	tst	r7, #ICC_SRE_EL2_SRE
179	beq	2f
180	mov	r7, #0
181	mcr	p15, 4, r7, c12, c11, 0	@ ICH_HCR
1822:
183#endif
184
185	bx	lr			@ The boot CPU mode is left in r4.
186ENDPROC(__hyp_stub_install_secondary)
187
188__hyp_stub_do_trap:
189#ifdef ZIMAGE
190	teq	r0, #HVC_SET_VECTORS
191	bne	1f
192	/* Only the ZIMAGE stubs can change the HYP vectors */
193	mcr	p15, 4, r1, c12, c0, 0	@ set HVBAR
194	b	__hyp_stub_exit
195#endif
196
1971:	teq	r0, #HVC_SOFT_RESTART
198	bne	2f
199	bx	r1
200
2012:	ldr	r0, =HVC_STUB_ERR
202	__ERET
203
204__hyp_stub_exit:
205	mov	r0, #0
206	__ERET
207ENDPROC(__hyp_stub_do_trap)
208
209/*
210 * __hyp_set_vectors is only used when ZIMAGE must bounce between HYP
211 * and SVC. For the kernel itself, the vectors are set once and for
212 * all by the stubs.
213 */
214ENTRY(__hyp_set_vectors)
215	mov	r1, r0
216	mov	r0, #HVC_SET_VECTORS
217	__HVC(0)
218	ret	lr
219ENDPROC(__hyp_set_vectors)
220
221ENTRY(__hyp_soft_restart)
222	mov	r1, r0
223	mov	r0, #HVC_SOFT_RESTART
224	__HVC(0)
225	ret	lr
226ENDPROC(__hyp_soft_restart)
227
228.align 5
229ENTRY(__hyp_stub_vectors)
230__hyp_stub_reset:	W(b)	.
231__hyp_stub_und:		W(b)	.
232__hyp_stub_svc:		W(b)	.
233__hyp_stub_pabort:	W(b)	.
234__hyp_stub_dabort:	W(b)	.
235__hyp_stub_trap:	W(b)	__hyp_stub_do_trap
236__hyp_stub_irq:		W(b)	.
237__hyp_stub_fiq:		W(b)	.
238ENDPROC(__hyp_stub_vectors)
239
240