1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/kernel.h> 3 #include <linux/spinlock.h> 4 #include <linux/kprobes.h> 5 #include <linux/mm.h> 6 #include <linux/stop_machine.h> 7 8 #include <asm/cacheflush.h> 9 #include <asm/fixmap.h> 10 #include <asm/smp_plat.h> 11 #include <asm/opcodes.h> 12 #include <asm/patch.h> 13 14 struct patch { 15 void *addr; 16 unsigned int insn; 17 }; 18 19 static DEFINE_RAW_SPINLOCK(patch_lock); 20 21 static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags) 22 __acquires(&patch_lock) 23 { 24 unsigned int uintaddr = (uintptr_t) addr; 25 bool module = !core_kernel_text(uintaddr); 26 struct page *page; 27 28 if (module && IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) 29 page = vmalloc_to_page(addr); 30 else if (!module && IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)) 31 page = virt_to_page(addr); 32 else 33 return addr; 34 35 if (flags) 36 raw_spin_lock_irqsave(&patch_lock, *flags); 37 else 38 __acquire(&patch_lock); 39 40 set_fixmap(fixmap, page_to_phys(page)); 41 42 return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK)); 43 } 44 45 static void __kprobes patch_unmap(int fixmap, unsigned long *flags) 46 __releases(&patch_lock) 47 { 48 clear_fixmap(fixmap); 49 50 if (flags) 51 raw_spin_unlock_irqrestore(&patch_lock, *flags); 52 else 53 __release(&patch_lock); 54 } 55 56 void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap) 57 { 58 bool thumb2 = IS_ENABLED(CONFIG_THUMB2_KERNEL); 59 unsigned int uintaddr = (uintptr_t) addr; 60 bool twopage = false; 61 unsigned long flags; 62 void *waddr = addr; 63 int size; 64 65 if (remap) 66 waddr = patch_map(addr, FIX_TEXT_POKE0, &flags); 67 else 68 __acquire(&patch_lock); 69 70 if (thumb2 && __opcode_is_thumb16(insn)) { 71 *(u16 *)waddr = __opcode_to_mem_thumb16(insn); 72 size = sizeof(u16); 73 } else if (thumb2 && (uintaddr & 2)) { 74 u16 first = __opcode_thumb32_first(insn); 75 u16 second = __opcode_thumb32_second(insn); 76 u16 *addrh0 = waddr; 77 u16 *addrh1 = waddr + 2; 78 79 twopage = (uintaddr & ~PAGE_MASK) == PAGE_SIZE - 2; 80 if (twopage && remap) 81 addrh1 = patch_map(addr + 2, FIX_TEXT_POKE1, NULL); 82 83 *addrh0 = __opcode_to_mem_thumb16(first); 84 *addrh1 = __opcode_to_mem_thumb16(second); 85 86 if (twopage && addrh1 != addr + 2) { 87 flush_kernel_vmap_range(addrh1, 2); 88 patch_unmap(FIX_TEXT_POKE1, NULL); 89 } 90 91 size = sizeof(u32); 92 } else { 93 if (thumb2) 94 insn = __opcode_to_mem_thumb32(insn); 95 else 96 insn = __opcode_to_mem_arm(insn); 97 98 *(u32 *)waddr = insn; 99 size = sizeof(u32); 100 } 101 102 if (waddr != addr) { 103 flush_kernel_vmap_range(waddr, twopage ? size / 2 : size); 104 patch_unmap(FIX_TEXT_POKE0, &flags); 105 } else 106 __release(&patch_lock); 107 108 flush_icache_range((uintptr_t)(addr), 109 (uintptr_t)(addr) + size); 110 } 111 112 static int __kprobes patch_text_stop_machine(void *data) 113 { 114 struct patch *patch = data; 115 116 __patch_text(patch->addr, patch->insn); 117 118 return 0; 119 } 120 121 void __kprobes patch_text(void *addr, unsigned int insn) 122 { 123 struct patch patch = { 124 .addr = addr, 125 .insn = insn, 126 }; 127 128 stop_machine_cpuslocked(patch_text_stop_machine, &patch, NULL); 129 } 130