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7e923369b1
If multiple CPUs are patching code we need the spinlock to protect against parallel fixmap maps/unmap calls. Signed-off-by: Sven Schnelle <svens@stackframe.org> Signed-off-by: Helge Deller <deller@gmx.de>
133 lines
2.9 KiB
C
133 lines
2.9 KiB
C
// 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 <svens@stackframe.org>
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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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