Messages in this thread | | | Subject | Re: [PATCH -next] riscv: Enable KFENCE for riscv64 | From | Liu Shixin <> | Date | Wed, 9 Jun 2021 14:17:55 +0800 |
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Hi, everybody,
I perfected the patch based on the previous advice. How about this version?
Thanks,
On 2021/5/29 16:03, Liu Shixin wrote: > Add architecture specific implementation details for KFENCE and enable > KFENCE for the riscv64 architecture. 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. > > Signed-off-by: Liu Shixin <liushixin2@huawei.com> > --- > 1. Add helper function split_pmd_page() which is used to split a pmd to ptes. > 2. Add the judgment on the result of pte_alloc_one_kernel(). > > arch/riscv/Kconfig | 1 + > arch/riscv/include/asm/kfence.h | 63 +++++++++++++++++++++++++++++++++ > arch/riscv/mm/fault.c | 11 +++++- > 3 files changed, 74 insertions(+), 1 deletion(-) > create mode 100644 arch/riscv/include/asm/kfence.h > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > index 4982130064ef..2f4903a7730f 100644 > --- a/arch/riscv/Kconfig > +++ b/arch/riscv/Kconfig > @@ -65,6 +65,7 @@ config RISCV > select HAVE_ARCH_JUMP_LABEL_RELATIVE > select HAVE_ARCH_KASAN if MMU && 64BIT > select HAVE_ARCH_KASAN_VMALLOC if MMU && 64BIT > + select HAVE_ARCH_KFENCE if MMU && 64BIT > select HAVE_ARCH_KGDB > select HAVE_ARCH_KGDB_QXFER_PKT > select HAVE_ARCH_MMAP_RND_BITS if MMU > diff --git a/arch/riscv/include/asm/kfence.h b/arch/riscv/include/asm/kfence.h > new file mode 100644 > index 000000000000..d887a54042aa > --- /dev/null > +++ b/arch/riscv/include/asm/kfence.h > @@ -0,0 +1,63 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > + > +#ifndef _ASM_RISCV_KFENCE_H > +#define _ASM_RISCV_KFENCE_H > + > +#include <linux/kfence.h> > +#include <linux/pfn.h> > +#include <asm-generic/pgalloc.h> > +#include <asm/pgtable.h> > + > +static inline int split_pmd_page(unsigned long addr) > +{ > + int i; > + unsigned long pfn = PFN_DOWN(__pa((addr & PMD_MASK))); > + pmd_t *pmd = pmd_off_k(addr); > + pte_t *pte = pte_alloc_one_kernel(&init_mm); > + > + if (!pte) > + return -ENOMEM; > + > + for (i = 0; i < PTRS_PER_PTE; i++) > + set_pte(pte + i, pfn_pte(pfn + i, PAGE_KERNEL)); > + set_pmd(pmd, pfn_pmd(PFN_DOWN(__pa(pte)), PAGE_TABLE)); > + > + flush_tlb_kernel_range(addr, addr + PMD_SIZE); > + return 0; > +} > + > +static inline bool arch_kfence_init_pool(void) > +{ > + int ret; > + 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)) { > + ret = split_pmd_page(addr); > + if (ret) > + return false; > + } > + } > + > + return true; > +} > + > +static inline bool kfence_protect_page(unsigned long addr, bool protect) > +{ > + pte_t *pte = virt_to_kpte(addr); > + > + if (protect) > + set_pte(pte, __pte(pte_val(*pte) & ~_PAGE_PRESENT)); > + else > + set_pte(pte, __pte(pte_val(*pte) | _PAGE_PRESENT)); > + > + flush_tlb_kernel_range(addr, addr + PAGE_SIZE); > + > + return true; > +} > + > +#endif /* _ASM_RISCV_KFENCE_H */ > diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c > index 096463cc6fff..aa08dd2f8fae 100644 > --- a/arch/riscv/mm/fault.c > +++ b/arch/riscv/mm/fault.c > @@ -14,6 +14,7 @@ > #include <linux/signal.h> > #include <linux/uaccess.h> > #include <linux/kprobes.h> > +#include <linux/kfence.h> > > #include <asm/ptrace.h> > #include <asm/tlbflush.h> > @@ -45,7 +46,15 @@ static inline void no_context(struct pt_regs *regs, unsigned long addr) > * Oops. The kernel tried to access some bad page. We'll have to > * terminate things with extreme prejudice. > */ > - msg = (addr < PAGE_SIZE) ? "NULL pointer dereference" : "paging request"; > + if (addr < PAGE_SIZE) > + msg = "NULL pointer dereference"; > + else { > + if (kfence_handle_page_fault(addr, regs->cause == EXC_STORE_PAGE_FAULT, regs)) > + return; > + > + msg = "paging request"; > + } > + > die_kernel_fault(msg, addr, regs); > } >
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