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

   1// SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * functions to patch RO kernel text during runtime
   4  *
   5  * Copyright (c) 2019 Sven Schnelle <svens@stackframe.org>
   6  */
   7
   8#include <linux/kernel.h>
   9#include <linux/spinlock.h>
  10#include <linux/kprobes.h>
  11#include <linux/mm.h>
  12#include <linux/stop_machine.h>
  13
  14#include <asm/cacheflush.h>
  15#include <asm/fixmap.h>
  16#include <asm/patch.h>
  17
  18struct patch {
  19        void *addr;
  20        unsigned int insn;
  21};
  22
  23static void __kprobes *patch_map(void *addr, int fixmap)
  24{
  25        unsigned long uintaddr = (uintptr_t) addr;
  26        bool module = !core_kernel_text(uintaddr);
  27        struct page *page;
  28
  29        if (module && IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
  30                page = vmalloc_to_page(addr);
  31        else if (!module && IS_ENABLED(CONFIG_STRICT_KERNEL_RWX))
  32                page = virt_to_page(addr);
  33        else
  34                return addr;
  35
  36        set_fixmap(fixmap, page_to_phys(page));
  37
  38        return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
  39}
  40
  41static void __kprobes patch_unmap(int fixmap)
  42{
  43        clear_fixmap(fixmap);
  44}
  45
  46void __kprobes __patch_text(void *addr, unsigned int insn)
  47{
  48        void *waddr = addr;
  49        int size;
  50
  51        waddr = patch_map(addr, FIX_TEXT_POKE0);
  52        *(u32 *)waddr = insn;
  53        size = sizeof(u32);
  54        flush_kernel_vmap_range(waddr, size);
  55        patch_unmap(FIX_TEXT_POKE0);
  56        flush_icache_range((uintptr_t)(addr),
  57                           (uintptr_t)(addr) + size);
  58}
  59
  60static int __kprobes patch_text_stop_machine(void *data)
  61{
  62        struct patch *patch = data;
  63
  64        __patch_text(patch->addr, patch->insn);
  65
  66        return 0;
  67}
  68
  69void __kprobes patch_text(void *addr, unsigned int insn)
  70{
  71        struct patch patch = {
  72                .addr = addr,
  73                .insn = insn,
  74        };
  75
  76        stop_machine_cpuslocked(patch_text_stop_machine, &patch, NULL);
  77}
  78