Messages in this thread | | | Subject | Re: [PATCH 3/4] ARM: Support KFENCE for ARM | From | ownia <> | Date | Wed, 25 Aug 2021 21:18:49 +0800 |
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On 2021/8/25 17:21, Kefeng Wang wrote: > 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. > > Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> > --- > arch/arm/Kconfig | 1 + > arch/arm/include/asm/kfence.h | 52 +++++++++++++++++++++++++++++++++++ > arch/arm/mm/fault.c | 9 ++++-- > 3 files changed, 60 insertions(+), 2 deletions(-) > create mode 100644 arch/arm/include/asm/kfence.h > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index 7a8059ff6bb0..3798f82a0c0d 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -73,6 +73,7 @@ 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 > 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 > diff --git a/arch/arm/include/asm/kfence.h b/arch/arm/include/asm/kfence.h > new file mode 100644 > index 000000000000..eae7a12ab2a9 > --- /dev/null > +++ b/arch/arm/include/asm/kfence.h > @@ -0,0 +1,52 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > + > +#ifndef __ASM_ARM_KFENCE_H > +#define __ASM_ARM_KFENCE_H > + > +#include <linux/kfence.h> > +#include <asm/set_memory.h> > +#include <asm/pgalloc.h> > + > +static inline int split_pmd_page(pmd_t *pmd, unsigned long addr) > +{ > + int i; > + unsigned long pfn = PFN_DOWN(__pa((addr & PMD_MASK))); > + 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)) > + 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 */ > diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c > index f7ab6dabe89f..9fa221ffa1b9 100644 > --- a/arch/arm/mm/fault.c > +++ b/arch/arm/mm/fault.c > @@ -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> > @@ -131,10 +132,14 @@ __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"; > + }
I think here should do some fixup to follow upstream mainline code.
> > die_kernel_fault(msg, mm, addr, fsr, regs); > }
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