xref: /openbmc/linux/arch/arm/include/asm/uaccess-asm.h (revision a9ff6961)
1 /* SPDX-License-Identifier: GPL-2.0-only */
2 
3 #ifndef __ASM_UACCESS_ASM_H__
4 #define __ASM_UACCESS_ASM_H__
5 
6 #include <asm/asm-offsets.h>
7 #include <asm/domain.h>
8 #include <asm/page.h>
9 #include <asm/thread_info.h>
10 
11 	.macro	csdb
12 #ifdef CONFIG_THUMB2_KERNEL
13 	.inst.w	0xf3af8014
14 #else
15 	.inst	0xe320f014
16 #endif
17 	.endm
18 
19 	.macro check_uaccess, addr:req, size:req, limit:req, tmp:req, bad:req
20 #ifndef CONFIG_CPU_USE_DOMAINS
21 	adds	\tmp, \addr, #\size - 1
22 	sbcscc	\tmp, \tmp, \limit
23 	bcs	\bad
24 #ifdef CONFIG_CPU_SPECTRE
25 	movcs	\addr, #0
26 	csdb
27 #endif
28 #endif
29 	.endm
30 
31 	.macro uaccess_mask_range_ptr, addr:req, size:req, limit:req, tmp:req
32 #ifdef CONFIG_CPU_SPECTRE
33 	sub	\tmp, \limit, #1
34 	subs	\tmp, \tmp, \addr	@ tmp = limit - 1 - addr
35 	addhs	\tmp, \tmp, #1		@ if (tmp >= 0) {
36 	subshs	\tmp, \tmp, \size	@ tmp = limit - (addr + size) }
37 	movlo	\addr, #0		@ if (tmp < 0) addr = NULL
38 	csdb
39 #endif
40 	.endm
41 
42 	.macro	uaccess_disable, tmp, isb=1
43 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
44 	/*
45 	 * Whenever we re-enter userspace, the domains should always be
46 	 * set appropriately.
47 	 */
48 	mov	\tmp, #DACR_UACCESS_DISABLE
49 	mcr	p15, 0, \tmp, c3, c0, 0		@ Set domain register
50 	.if	\isb
51 	instr_sync
52 	.endif
53 #endif
54 	.endm
55 
56 	.macro	uaccess_enable, tmp, isb=1
57 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
58 	/*
59 	 * Whenever we re-enter userspace, the domains should always be
60 	 * set appropriately.
61 	 */
62 	mov	\tmp, #DACR_UACCESS_ENABLE
63 	mcr	p15, 0, \tmp, c3, c0, 0
64 	.if	\isb
65 	instr_sync
66 	.endif
67 #endif
68 	.endm
69 
70 #if defined(CONFIG_CPU_SW_DOMAIN_PAN) || defined(CONFIG_CPU_USE_DOMAINS)
71 #define DACR(x...)	x
72 #else
73 #define DACR(x...)
74 #endif
75 
76 	/*
77 	 * Save the address limit on entry to a privileged exception.
78 	 *
79 	 * If we are using the DACR for kernel access by the user accessors
80 	 * (CONFIG_CPU_USE_DOMAINS=y), always reset the DACR kernel domain
81 	 * back to client mode, whether or not \disable is set.
82 	 *
83 	 * If we are using SW PAN, set the DACR user domain to no access
84 	 * if \disable is set.
85 	 */
86 	.macro	uaccess_entry, tsk, tmp0, tmp1, tmp2, disable
87  DACR(	mrc	p15, 0, \tmp0, c3, c0, 0)
88  DACR(	str	\tmp0, [sp, #SVC_DACR])
89 	.if \disable && IS_ENABLED(CONFIG_CPU_SW_DOMAIN_PAN)
90 	/* kernel=client, user=no access */
91 	mov	\tmp2, #DACR_UACCESS_DISABLE
92 	mcr	p15, 0, \tmp2, c3, c0, 0
93 	instr_sync
94 	.elseif IS_ENABLED(CONFIG_CPU_USE_DOMAINS)
95 	/* kernel=client */
96 	bic	\tmp2, \tmp0, #domain_mask(DOMAIN_KERNEL)
97 	orr	\tmp2, \tmp2, #domain_val(DOMAIN_KERNEL, DOMAIN_CLIENT)
98 	mcr	p15, 0, \tmp2, c3, c0, 0
99 	instr_sync
100 	.endif
101 	.endm
102 
103 	/* Restore the user access state previously saved by uaccess_entry */
104 	.macro	uaccess_exit, tsk, tmp0, tmp1
105  DACR(	ldr	\tmp0, [sp, #SVC_DACR])
106  DACR(	mcr	p15, 0, \tmp0, c3, c0, 0)
107 	.endm
108 
109 #undef DACR
110 
111 #endif /* __ASM_UACCESS_ASM_H__ */
112