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