1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_EXECMEM_ALLOC_H
3 #define _LINUX_EXECMEM_ALLOC_H
4
5 #include <linux/types.h>
6 #include <linux/moduleloader.h>
7
8 #if (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) && \
9 !defined(CONFIG_KASAN_VMALLOC)
10 #include <linux/kasan.h>
11 #define MODULE_ALIGN (PAGE_SIZE << KASAN_SHADOW_SCALE_SHIFT)
12 #else
13 #define MODULE_ALIGN PAGE_SIZE
14 #endif
15
16 /**
17 * enum execmem_type - types of executable memory ranges
18 *
19 * There are several subsystems that allocate executable memory.
20 * Architectures define different restrictions on placement,
21 * permissions, alignment and other parameters for memory that can be used
22 * by these subsystems.
23 * Types in this enum identify subsystems that allocate executable memory
24 * and let architectures define parameters for ranges suitable for
25 * allocations by each subsystem.
26 *
27 * @EXECMEM_DEFAULT: default parameters that would be used for types that
28 * are not explicitly defined.
29 * @EXECMEM_MODULE_TEXT: parameters for module text sections
30 * @EXECMEM_KPROBES: parameters for kprobes
31 * @EXECMEM_FTRACE: parameters for ftrace
32 * @EXECMEM_BPF: parameters for BPF
33 * @EXECMEM_MODULE_DATA: parameters for module data sections
34 * @EXECMEM_TYPE_MAX:
35 */
36 enum execmem_type {
37 EXECMEM_DEFAULT,
38 EXECMEM_MODULE_TEXT = EXECMEM_DEFAULT,
39 EXECMEM_KPROBES,
40 EXECMEM_FTRACE,
41 EXECMEM_BPF,
42 EXECMEM_MODULE_DATA,
43 EXECMEM_TYPE_MAX,
44 };
45
46 /**
47 * enum execmem_range_flags - options for executable memory allocations
48 * @EXECMEM_KASAN_SHADOW: allocate kasan shadow
49 * @EXECMEM_ROX_CACHE: allocations should use ROX cache of huge pages
50 */
51 enum execmem_range_flags {
52 EXECMEM_KASAN_SHADOW = (1 << 0),
53 EXECMEM_ROX_CACHE = (1 << 1),
54 };
55
56 #ifdef CONFIG_ARCH_HAS_EXECMEM_ROX
57 /**
58 * execmem_fill_trapping_insns - set memory to contain instructions that
59 * will trap
60 * @ptr: pointer to memory to fill
61 * @size: size of the range to fill
62 * @writable: is the memory poited by @ptr is writable or ROX
63 *
64 * A hook for architecures to fill execmem ranges with invalid instructions.
65 * Architectures that use EXECMEM_ROX_CACHE must implement this.
66 */
67 void execmem_fill_trapping_insns(void *ptr, size_t size, bool writable);
68 #endif
69
70 /**
71 * struct execmem_range - definition of an address space suitable for code and
72 * related data allocations
73 * @start: address space start
74 * @end: address space end (inclusive)
75 * @fallback_start: start of the secondary address space range for fallback
76 * allocations on architectures that require it
77 * @fallback_end: start of the secondary address space (inclusive)
78 * @pgprot: permissions for memory in this address space
79 * @alignment: alignment required for text allocations
80 * @flags: options for memory allocations for this range
81 */
82 struct execmem_range {
83 unsigned long start;
84 unsigned long end;
85 unsigned long fallback_start;
86 unsigned long fallback_end;
87 pgprot_t pgprot;
88 unsigned int alignment;
89 enum execmem_range_flags flags;
90 };
91
92 /**
93 * struct execmem_info - architecture parameters for code allocations
94 * @ranges: array of parameter sets defining architecture specific
95 * parameters for executable memory allocations. The ranges that are not
96 * explicitly initialized by an architecture use parameters defined for
97 * @EXECMEM_DEFAULT.
98 */
99 struct execmem_info {
100 struct execmem_range ranges[EXECMEM_TYPE_MAX];
101 };
102
103 /**
104 * execmem_arch_setup - define parameters for allocations of executable memory
105 *
106 * A hook for architectures to define parameters for allocations of
107 * executable memory. These parameters should be filled into the
108 * @execmem_info structure.
109 *
110 * For architectures that do not implement this method a default set of
111 * parameters will be used
112 *
113 * Return: a structure defining architecture parameters and restrictions
114 * for allocations of executable memory
115 */
116 struct execmem_info *execmem_arch_setup(void);
117
118 /**
119 * execmem_alloc - allocate executable memory
120 * @type: type of the allocation
121 * @size: how many bytes of memory are required
122 *
123 * Allocates memory that will contain executable code, either generated or
124 * loaded from kernel modules.
125 *
126 * Allocates memory that will contain data coupled with executable code,
127 * like data sections in kernel modules.
128 *
129 * The memory will have protections defined by architecture for executable
130 * region of the @type.
131 *
132 * Return: a pointer to the allocated memory or %NULL
133 */
134 void *execmem_alloc(enum execmem_type type, size_t size);
135
136 /**
137 * execmem_free - free executable memory
138 * @ptr: pointer to the memory that should be freed
139 */
140 void execmem_free(void *ptr);
141
142 #ifdef CONFIG_MMU
143 /**
144 * execmem_vmap - create virtual mapping for EXECMEM_MODULE_DATA memory
145 * @size: size of the virtual mapping in bytes
146 *
147 * Maps virtually contiguous area in the range suitable for EXECMEM_MODULE_DATA.
148 *
149 * Return: the area descriptor on success or %NULL on failure.
150 */
151 struct vm_struct *execmem_vmap(size_t size);
152 #endif
153
154 /**
155 * execmem_update_copy - copy an update to executable memory
156 * @dst: destination address to update
157 * @src: source address containing the data
158 * @size: how many bytes of memory shold be copied
159 *
160 * Copy @size bytes from @src to @dst using text poking if the memory at
161 * @dst is read-only.
162 *
163 * Return: a pointer to @dst or NULL on error
164 */
165 void *execmem_update_copy(void *dst, const void *src, size_t size);
166
167 /**
168 * execmem_is_rox - check if execmem is read-only
169 * @type - the execmem type to check
170 *
171 * Return: %true if the @type is read-only, %false if it's writable
172 */
173 bool execmem_is_rox(enum execmem_type type);
174
175 #if defined(CONFIG_EXECMEM) && !defined(CONFIG_ARCH_WANTS_EXECMEM_LATE)
176 void execmem_init(void);
177 #else
execmem_init(void)178 static inline void execmem_init(void) {}
179 #endif
180
181 #endif /* _LINUX_EXECMEM_ALLOC_H */
182