LXR linux/arch/arm/kernel/patch.c

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