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