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ARM: 9166/1: Support KFENCE for ARM

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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: Marco Elver <elver@google.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Wang Kefeng 2021-12-03 10:26:33 +01:00 committed by Russell King (Oracle)
parent 3c341b2174
commit 75969686ec
3 changed files with 61 additions and 2 deletions
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1
arch/arm/Kconfig
View File

@ -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

53
arch/arm/include/asm/kfence.h Normal file
View File

@ -0,0 +1,53 @@
/* 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 */

9
arch/arm/mm/fault.c
View File

@ -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);
}