Commit 75969686 authored by Wang Kefeng's avatar Wang Kefeng Committed by Russell King (Oracle)
Browse files

ARM: 9166/1: Support KFENCE for ARM 



Add architecture specific implementation details for KFENCE and enable
KFENCE on ARM. In particular, this implements the required interface in
 <asm/kfence.h>.

KFENCE requires that attributes for pages from its memory pool can
individually be set. Therefore, force the kfence pool to be mapped
at page granularity.

Testing this patch using the testcases in kfence_test.c and all passed
with or without ARM_LPAE.

Acked-by: default avatarMarco Elver <elver@google.com>
Signed-off-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarRussell King (Oracle) <rmk+kernel@armlinux.org.uk>
parent 3c341b21

arch/arm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -69,6 +69,7 @@ config ARM 
	select HAVE_ARCH_AUDITSYSCALL if AEABI && !OABI_COMPAT

	select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6

	select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU

	select HAVE_ARCH_KFENCE if MMU && !XIP_KERNEL

	select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU

	select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL

	select HAVE_ARCH_MMAP_RND_BITS if MMU

arch/arm/include/asm/kfence.h

0 → 100644
+53 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */



#ifndef __ASM_ARM_KFENCE_H

#define __ASM_ARM_KFENCE_H



#include <linux/kfence.h>



#include <asm/pgalloc.h>

#include <asm/set_memory.h>



static inline int split_pmd_page(pmd_t *pmd, unsigned long addr)

{

	int i;

	unsigned long pfn = PFN_DOWN(__pa(addr));

	pte_t *pte = pte_alloc_one_kernel(&init_mm);



	if (!pte)

		return -ENOMEM;



	for (i = 0; i < PTRS_PER_PTE; i++)

		set_pte_ext(pte + i, pfn_pte(pfn + i, PAGE_KERNEL), 0);

	pmd_populate_kernel(&init_mm, pmd, pte);



	flush_tlb_kernel_range(addr, addr + PMD_SIZE);

	return 0;

}



static inline bool arch_kfence_init_pool(void)

{

	unsigned long addr;

	pmd_t *pmd;



	for (addr = (unsigned long)__kfence_pool; is_kfence_address((void *)addr);

	     addr += PAGE_SIZE) {

		pmd = pmd_off_k(addr);



		if (pmd_leaf(*pmd)) {

			if (split_pmd_page(pmd, addr & PMD_MASK))

				return false;

		}

	}



	return true;

}



static inline bool kfence_protect_page(unsigned long addr, bool protect)

{

	set_memory_valid(addr, 1, !protect);



	return true;

}



#endif /* __ASM_ARM_KFENCE_H */

arch/arm/mm/fault.c

+7 −2
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/sched/debug.h>

#include <linux/highmem.h>

#include <linux/perf_event.h>

#include <linux/kfence.h>



#include <asm/system_misc.h>

#include <asm/system_info.h>
@@ -136,10 +137,14 @@ __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, 
	/*

	 * No handler, we'll have to terminate things with extreme prejudice.

	 */

	if (addr < PAGE_SIZE)

	if (addr < PAGE_SIZE) {

		msg = "NULL pointer dereference";

	else

	} else {

		if (kfence_handle_page_fault(addr, is_write_fault(fsr), regs))

			return;



		msg = "paging request";

	}



	die_kernel_fault(msg, mm, addr, fsr, regs);

}