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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2020 SiFive
4 */
5
6#include <linux/spinlock.h>
7#include <linux/mm.h>
8#include <linux/memory.h>
9#include <linux/uaccess.h>
10#include <linux/stop_machine.h>
11#include <asm/kprobes.h>
12#include <asm/cacheflush.h>
13#include <asm/fixmap.h>
14#include <asm/patch.h>
15
16struct patch_insn {
17 void *addr;
18 u32 insn;
19 atomic_t cpu_count;
20};
21
22#ifdef CONFIG_MMU
23/*
24 * The fix_to_virt(, idx) needs a const value (not a dynamic variable of
25 * reg-a0) or BUILD_BUG_ON failed with "idx >= __end_of_fixed_addresses".
26 * So use '__always_inline' and 'const unsigned int fixmap' here.
27 */
28static __always_inline void *patch_map(void *addr, const unsigned int fixmap)
29{
30 uintptr_t uintaddr = (uintptr_t) addr;
31 struct page *page;
32
33 if (core_kernel_text(uintaddr))
34 page = phys_to_page(__pa_symbol(addr));
35 else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
36 page = vmalloc_to_page(addr);
37 else
38 return addr;
39
40 BUG_ON(!page);
41
42 return (void *)set_fixmap_offset(fixmap, page_to_phys(page) +
43 (uintaddr & ~PAGE_MASK));
44}
45
46static void patch_unmap(int fixmap)
47{
48 clear_fixmap(fixmap);
49}
50NOKPROBE_SYMBOL(patch_unmap);
51
52static int patch_insn_write(void *addr, const void *insn, size_t len)
53{
54 void *waddr = addr;
55 bool across_pages = (((uintptr_t) addr & ~PAGE_MASK) + len) > PAGE_SIZE;
56 int ret;
57
58 /*
59 * Before reaching here, it was expected to lock the text_mutex
60 * already, so we don't need to give another lock here and could
61 * ensure that it was safe between each cores.
62 */
63 lockdep_assert_held(&text_mutex);
64
65 if (across_pages)
66 patch_map(addr + len, FIX_TEXT_POKE1);
67
68 waddr = patch_map(addr, FIX_TEXT_POKE0);
69
70 ret = copy_to_kernel_nofault(waddr, insn, len);
71
72 patch_unmap(FIX_TEXT_POKE0);
73
74 if (across_pages)
75 patch_unmap(FIX_TEXT_POKE1);
76
77 return ret;
78}
79NOKPROBE_SYMBOL(patch_insn_write);
80#else
81static int patch_insn_write(void *addr, const void *insn, size_t len)
82{
83 return copy_to_kernel_nofault(addr, insn, len);
84}
85NOKPROBE_SYMBOL(patch_insn_write);
86#endif /* CONFIG_MMU */
87
88int patch_text_nosync(void *addr, const void *insns, size_t len)
89{
90 u32 *tp = addr;
91 int ret;
92
93 ret = patch_insn_write(tp, insns, len);
94
95 if (!ret)
96 flush_icache_range((uintptr_t) tp, (uintptr_t) tp + len);
97
98 return ret;
99}
100NOKPROBE_SYMBOL(patch_text_nosync);
101
102static int patch_text_cb(void *data)
103{
104 struct patch_insn *patch = data;
105 int ret = 0;
106
107 if (atomic_inc_return(&patch->cpu_count) == num_online_cpus()) {
108 ret =
109 patch_text_nosync(patch->addr, &patch->insn,
110 GET_INSN_LENGTH(patch->insn));
111 atomic_inc(&patch->cpu_count);
112 } else {
113 while (atomic_read(&patch->cpu_count) <= num_online_cpus())
114 cpu_relax();
115 smp_mb();
116 }
117
118 return ret;
119}
120NOKPROBE_SYMBOL(patch_text_cb);
121
122int patch_text(void *addr, u32 insn)
123{
124 struct patch_insn patch = {
125 .addr = addr,
126 .insn = insn,
127 .cpu_count = ATOMIC_INIT(0),
128 };
129
130 return stop_machine_cpuslocked(patch_text_cb,
131 &patch, cpu_online_mask);
132}
133NOKPROBE_SYMBOL(patch_text);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2020 SiFive
4 */
5
6#include <linux/spinlock.h>
7#include <linux/mm.h>
8#include <linux/memory.h>
9#include <linux/uaccess.h>
10#include <linux/stop_machine.h>
11#include <asm/kprobes.h>
12#include <asm/cacheflush.h>
13#include <asm/fixmap.h>
14#include <asm/patch.h>
15
16struct patch_insn {
17 void *addr;
18 u32 insn;
19 atomic_t cpu_count;
20};
21
22#ifdef CONFIG_MMU
23/*
24 * The fix_to_virt(, idx) needs a const value (not a dynamic variable of
25 * reg-a0) or BUILD_BUG_ON failed with "idx >= __end_of_fixed_addresses".
26 * So use '__always_inline' and 'const unsigned int fixmap' here.
27 */
28static __always_inline void *patch_map(void *addr, const unsigned int fixmap)
29{
30 uintptr_t uintaddr = (uintptr_t) addr;
31 struct page *page;
32
33 if (core_kernel_text(uintaddr))
34 page = phys_to_page(__pa_symbol(addr));
35 else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
36 page = vmalloc_to_page(addr);
37 else
38 return addr;
39
40 BUG_ON(!page);
41
42 return (void *)set_fixmap_offset(fixmap, page_to_phys(page) +
43 (uintaddr & ~PAGE_MASK));
44}
45
46static void patch_unmap(int fixmap)
47{
48 clear_fixmap(fixmap);
49}
50NOKPROBE_SYMBOL(patch_unmap);
51
52static int patch_insn_write(void *addr, const void *insn, size_t len)
53{
54 void *waddr = addr;
55 bool across_pages = (((uintptr_t) addr & ~PAGE_MASK) + len) > PAGE_SIZE;
56 int ret;
57
58 /*
59 * Before reaching here, it was expected to lock the text_mutex
60 * already, so we don't need to give another lock here and could
61 * ensure that it was safe between each cores.
62 */
63 lockdep_assert_held(&text_mutex);
64
65 if (across_pages)
66 patch_map(addr + len, FIX_TEXT_POKE1);
67
68 waddr = patch_map(addr, FIX_TEXT_POKE0);
69
70 ret = copy_to_kernel_nofault(waddr, insn, len);
71
72 patch_unmap(FIX_TEXT_POKE0);
73
74 if (across_pages)
75 patch_unmap(FIX_TEXT_POKE1);
76
77 return ret;
78}
79NOKPROBE_SYMBOL(patch_insn_write);
80#else
81static int patch_insn_write(void *addr, const void *insn, size_t len)
82{
83 return copy_to_kernel_nofault(addr, insn, len);
84}
85NOKPROBE_SYMBOL(patch_insn_write);
86#endif /* CONFIG_MMU */
87
88int patch_text_nosync(void *addr, const void *insns, size_t len)
89{
90 u32 *tp = addr;
91 int ret;
92
93 ret = patch_insn_write(tp, insns, len);
94
95 if (!ret)
96 flush_icache_range((uintptr_t) tp, (uintptr_t) tp + len);
97
98 return ret;
99}
100NOKPROBE_SYMBOL(patch_text_nosync);
101
102static int patch_text_cb(void *data)
103{
104 struct patch_insn *patch = data;
105 int ret = 0;
106
107 if (atomic_inc_return(&patch->cpu_count) == 1) {
108 ret =
109 patch_text_nosync(patch->addr, &patch->insn,
110 GET_INSN_LENGTH(patch->insn));
111 atomic_inc(&patch->cpu_count);
112 } else {
113 while (atomic_read(&patch->cpu_count) <= num_online_cpus())
114 cpu_relax();
115 smp_mb();
116 }
117
118 return ret;
119}
120NOKPROBE_SYMBOL(patch_text_cb);
121
122int patch_text(void *addr, u32 insn)
123{
124 struct patch_insn patch = {
125 .addr = addr,
126 .insn = insn,
127 .cpu_count = ATOMIC_INIT(0),
128 };
129
130 return stop_machine_cpuslocked(patch_text_cb,
131 &patch, cpu_online_mask);
132}
133NOKPROBE_SYMBOL(patch_text);