// 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/patch.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));	if (flags)		raw_spin_lock_irqsave(&patch_lock, *flags);	else		__acquire(&patch_lock); 	return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));} static void __kprobes patch_unmap(int fixmap, unsigned long *flags){	clear_fixmap(fixmap); 	if (flags)		raw_spin_unlock_irqrestore(&patch_lock, *flags);	else		__release(&patch_lock);} 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_vmap_range(addr, len);	flush_icache_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_vmap_range((void *)fixmap,						(p-fixmap) * sizeof(*p));			if (mapped)				patch_unmap(FIX_TEXT_POKE0, &flags);			p = fixmap = patch_map(addr, FIX_TEXT_POKE0, &flags,						&mapped);		}	} 	flush_kernel_vmap_range((void *)fixmap, (p-fixmap) * sizeof(*p));	if (mapped)		patch_unmap(FIX_TEXT_POKE0, &flags);	flush_icache_range(start, end);} 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);}