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| 2 | |
| 3 | * Copyright (C) 2025 Chen Miao
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| 4 |
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| 5 |
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| 6 | #include <linux/mm.h>
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| 7 | #include <linux/kernel.h>
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| 8 | #include <linux/spinlock.h>
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| 9 | #include <linux/uaccess.h>
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| 10 |
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| 11 | #include <asm/insn-def.h>
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| 12 | #include <asm/cacheflush.h>
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| 13 | #include <asm/page.h>
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| 14 | #include <asm/fixmap.h>
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| 15 | #include <asm/text-patching.h>
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| 16 | #include <asm/sections.h>
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| 17 |
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| 18 | static DEFINE_RAW_SPINLOCK(patch_lock);
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| 19 |
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| 20 | static __always_inline void *patch_map(void *addr, int fixmap)
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| 21 | {
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| 22 | uintptr_t uaddr = (uintptr_t) addr;
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| 23 | phys_addr_t phys;
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| 24 |
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| 25 | if (core_kernel_text(uaddr)) {
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| 26 | phys = __pa_symbol(addr);
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| 27 | } else {
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| 28 | struct page *page = vmalloc_to_page(addr);
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| 29 | BUG_ON(!page);
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| 30 | phys = page_to_phys(page) + offset_in_page(addr);
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| 31 | }
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| 32 |
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| 33 | return (void *)set_fixmap_offset(fixmap, phys);
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| 34 | }
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| 35 |
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| 36 | static void patch_unmap(int fixmap)
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| 37 | {
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| 38 | clear_fixmap(fixmap);
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| 39 | }
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| 40 |
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| 41 | static int __patch_insn_write(void *addr, u32 insn)
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| 42 | {
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| 43 | void *waddr = addr;
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| 44 | unsigned long flags = 0;
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| 45 | int ret;
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| 46 |
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| 47 | raw_spin_lock_irqsave(&patch_lock, flags);
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| 48 |
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| 49 | waddr = patch_map(addr, FIX_TEXT_POKE0);
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| 50 |
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| 51 | ret = copy_to_kernel_nofault(waddr, &insn, OPENRISC_INSN_SIZE);
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| 52 | if (!IS_ENABLED(CONFIG_DCACHE_WRITETHROUGH))
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| 53 | local_dcache_range_flush((unsigned long)waddr,
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| 54 | (unsigned long)waddr + OPENRISC_INSN_SIZE);
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| 55 | local_icache_range_inv((unsigned long)waddr,
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| 56 | (unsigned long)waddr + OPENRISC_INSN_SIZE);
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| 57 |
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| 58 | patch_unmap(FIX_TEXT_POKE0);
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| 59 |
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| 60 | raw_spin_unlock_irqrestore(&patch_lock, flags);
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| 61 |
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| 62 | return ret;
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| 63 | }
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| 64 |
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| 65 | |
| 66 | * patch_insn_write - Write a single instruction to a specified memory location
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| 67 | * This API provides a single-instruction patching, primarily used for runtime
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| 68 | * code modification.
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| 69 | * By the way, the insn size must be 4 bytes.
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| 70 |
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| 71 | int patch_insn_write(void *addr, u32 insn)
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| 72 | {
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| 73 | u32 *tp = addr;
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| 74 | int ret;
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| 75 |
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| 76 | if ((uintptr_t) tp & 0x3)
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| 77 | return -EINVAL;
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| 78 |
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| 79 | ret = __patch_insn_write(tp, insn);
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| 80 |
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| 81 | return ret;
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| 82 | }
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