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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131// SPDX-License-Identifier: GPL-2.0 /* * functions to patch RO kernel text during runtime * * Copyright (c) 2019 Sven Schnelle <svens@stackframe.org> */
#include <linux/kernel.h>#include <linux/spinlock.h>#include <linux/kprobes.h>#include <linux/mm.h>#include <linux/stop_machine.h>
#include <asm/cacheflush.h>#include <asm/fixmap.h>#include <asm/text-patching.h>
struct patch { void *addr; u32 *insn; unsigned int len;};
static DEFINE_RAW_SPINLOCK(patch_lock);
static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags, int *need_unmap){ unsigned long uintaddr = (uintptr_t) addr; bool module = !core_kernel_text(uintaddr); struct page *page;
*need_unmap = 0; if (module && IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) page = vmalloc_to_page(addr); else if (!module && IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)) page = virt_to_page(addr); else return addr;
*need_unmap = 1; set_fixmap(fixmap, page_to_phys(page)); raw_spin_lock_irqsave(&patch_lock, *flags);
return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));}
static void __kprobes patch_unmap(int fixmap, unsigned long *flags){ clear_fixmap(fixmap);
raw_spin_unlock_irqrestore(&patch_lock, *flags);}
void __kprobes __patch_text_multiple(void *addr, u32 *insn, unsigned int len){ unsigned long start = (unsigned long)addr; unsigned long end = (unsigned long)addr + len; unsigned long flags; u32 *p, *fixmap; int mapped;
/* Make sure we don't have any aliases in cache */ flush_kernel_dcache_range_asm(start, end); flush_kernel_icache_range_asm(start, end); flush_tlb_kernel_range(start, end);
p = fixmap = patch_map(addr, FIX_TEXT_POKE0, &flags, &mapped);
while (len >= 4) { *p++ = *insn++; addr += sizeof(u32); len -= sizeof(u32); if (len && offset_in_page(addr) == 0) { /* * We're crossing a page boundary, so * need to remap */ flush_kernel_dcache_range_asm((unsigned long)fixmap, (unsigned long)p); flush_tlb_kernel_range((unsigned long)fixmap, (unsigned long)p); if (mapped) patch_unmap(FIX_TEXT_POKE0, &flags); p = fixmap = patch_map(addr, FIX_TEXT_POKE0, &flags, &mapped); } }
flush_kernel_dcache_range_asm((unsigned long)fixmap, (unsigned long)p); flush_tlb_kernel_range((unsigned long)fixmap, (unsigned long)p); if (mapped) patch_unmap(FIX_TEXT_POKE0, &flags);}
void __kprobes __patch_text(void *addr, u32 insn){ __patch_text_multiple(addr, &insn, sizeof(insn));}
static int __kprobes patch_text_stop_machine(void *data){ struct patch *patch = data;
__patch_text_multiple(patch->addr, patch->insn, patch->len); return 0;}
void __kprobes patch_text(void *addr, unsigned int insn){ struct patch patch = { .addr = addr, .insn = &insn, .len = sizeof(insn), };
stop_machine_cpuslocked(patch_text_stop_machine, &patch, NULL);}
void __kprobes patch_text_multiple(void *addr, u32 *insn, unsigned int len){
struct patch patch = { .addr = addr, .insn = insn, .len = len };
stop_machine_cpuslocked(patch_text_stop_machine, &patch, NULL);}