cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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patch.c (2976B)

      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
     14struct patch {
     15	void *addr;
     16	unsigned int insn;
     17};
     18
     19#ifdef CONFIG_MMU
     20static DEFINE_RAW_SPINLOCK(patch_lock);
     21
     22static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
     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
     38	set_fixmap(fixmap, page_to_phys(page));
     39
     40	return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
     41}
     42
     43static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
     44{
     45	clear_fixmap(fixmap);
     46
     47	if (flags)
     48		raw_spin_unlock_irqrestore(&patch_lock, *flags);
     49}
     50#else
     51static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
     52{
     53	return addr;
     54}
     55static void __kprobes patch_unmap(int fixmap, unsigned long *flags) { }
     56#endif
     57
     58void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
     59{
     60	bool thumb2 = IS_ENABLED(CONFIG_THUMB2_KERNEL);
     61	unsigned int uintaddr = (uintptr_t) addr;
     62	bool twopage = false;
     63	unsigned long flags;
     64	void *waddr = addr;
     65	int size;
     66
     67	if (remap)
     68		waddr = patch_map(addr, FIX_TEXT_POKE0, &flags);
     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	}
    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_cpuslocked(patch_text_stop_machine, &patch, NULL);
    128}