/* SPDX-License-Identifier: GPL-2.0 */ /* * x86 KFENCE support. * * Copyright (C) 2020, Google LLC. */ #ifndef _ASM_X86_KFENCE_H #define _ASM_X86_KFENCE_H #include <linux/bug.h> #include <linux/kfence.h> #include <asm/pgalloc.h> #include <asm/pgtable.h> #include <asm/set_memory.h> #include <asm/tlbflush.h> /* Force 4K pages for __kfence_pool. */ static inline bool arch_kfence_init_pool(void) { unsigned long addr; for (addr = (unsigned long)__kfence_pool; is_kfence_address((void *)addr); addr += PAGE_SIZE) { unsigned int level; if (!lookup_address(addr, &level)) return false; if (level != PG_LEVEL_4K) set_memory_4k(addr, 1); } return true; } /* Protect the given page and flush TLB. */ static inline bool kfence_protect_page(unsigned long addr, bool protect) { unsigned int level; pte_t *pte = lookup_address(addr, &level); if (WARN_ON(!pte || level != PG_LEVEL_4K)) return false; /* * We need to avoid IPIs, as we may get KFENCE allocations or faults * with interrupts disabled. Therefore, the below is best-effort, and * does not flush TLBs on all CPUs. We can tolerate some inaccuracy; * lazy fault handling takes care of faults after the page is PRESENT. */ if (protect) set_pte(pte, __pte(pte_val(*pte) & ~_PAGE_PRESENT)); else set_pte(pte, __pte(pte_val(*pte) | _PAGE_PRESENT)); /* * Flush this CPU's TLB, assuming whoever did the allocation/free is * likely to continue running on this CPU. */ preempt_disable(); flush_tlb_one_kernel(addr); preempt_enable(); return true; } #endif /* _ASM_X86_KFENCE_H */