1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (C) 2020 SiFive
3 * Copyright (C) 2025 Chen Miao
4 */
5
6 #include <linux/mm.h>
7 #include <linux/kernel.h>
8 #include <linux/spinlock.h>
9 #include <linux/uaccess.h>
10
11 #include <asm/insn-def.h>
12 #include <asm/cacheflush.h>
13 #include <asm/page.h>
14 #include <asm/fixmap.h>
15 #include <asm/text-patching.h>
16 #include <asm/sections.h>
17
18 static DEFINE_RAW_SPINLOCK(patch_lock);
19
patch_map(void * addr,int fixmap)20 static __always_inline void *patch_map(void *addr, int fixmap)
21 {
22 uintptr_t uaddr = (uintptr_t) addr;
23 phys_addr_t phys;
24
25 if (core_kernel_text(uaddr)) {
26 phys = __pa_symbol(addr);
27 } else {
28 struct page *page = vmalloc_to_page(addr);
29 BUG_ON(!page);
30 phys = page_to_phys(page) + offset_in_page(addr);
31 }
32
33 return (void *)set_fixmap_offset(fixmap, phys);
34 }
35
patch_unmap(int fixmap)36 static void patch_unmap(int fixmap)
37 {
38 clear_fixmap(fixmap);
39 }
40
__patch_insn_write(void * addr,u32 insn)41 static int __patch_insn_write(void *addr, u32 insn)
42 {
43 void *waddr = addr;
44 unsigned long flags = 0;
45 int ret;
46
47 raw_spin_lock_irqsave(&patch_lock, flags);
48
49 waddr = patch_map(addr, FIX_TEXT_POKE0);
50
51 ret = copy_to_kernel_nofault(waddr, &insn, OPENRISC_INSN_SIZE);
52 local_icache_range_inv((unsigned long)waddr,
53 (unsigned long)waddr + OPENRISC_INSN_SIZE);
54
55 patch_unmap(FIX_TEXT_POKE0);
56
57 raw_spin_unlock_irqrestore(&patch_lock, flags);
58
59 return ret;
60 }
61
62 /*
63 * patch_insn_write - Write a single instruction to a specified memory location
64 * This API provides a single-instruction patching, primarily used for runtime
65 * code modification.
66 * By the way, the insn size must be 4 bytes.
67 */
patch_insn_write(void * addr,u32 insn)68 int patch_insn_write(void *addr, u32 insn)
69 {
70 u32 *tp = addr;
71 int ret;
72
73 if ((uintptr_t) tp & 0x3)
74 return -EINVAL;
75
76 ret = __patch_insn_write(tp, insn);
77
78 return ret;
79 }
80