// 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;	unsigned int insn;}; static void __kprobes *patch_map(void *addr, int fixmap){	unsigned long uintaddr = (uintptr_t) addr;	bool module = !core_kernel_text(uintaddr);	struct page *page; 	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; 	set_fixmap(fixmap, page_to_phys(page)); 	return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));} static void __kprobes patch_unmap(int fixmap){	clear_fixmap(fixmap);} void __kprobes __patch_text(void *addr, unsigned int insn){	void *waddr = addr;	int size; 	waddr = patch_map(addr, FIX_TEXT_POKE0);	*(u32 *)waddr = insn;	size = sizeof(u32);	flush_kernel_vmap_range(waddr, size);	patch_unmap(FIX_TEXT_POKE0);	flush_icache_range((uintptr_t)(addr),			   (uintptr_t)(addr) + size);} static int __kprobes patch_text_stop_machine(void *data){	struct patch *patch = data; 	__patch_text(patch->addr, patch->insn); 	return 0;} void __kprobes patch_text(void *addr, unsigned int insn){	struct patch patch = {		.addr = addr,		.insn = insn,	}; 	stop_machine_cpuslocked(patch_text_stop_machine, &patch, NULL);}