On Tue, Jul 25, 2023 at 2:15 PM Enze Li <lienze@xxxxxxxxxx> wrote: > > The LoongArch architecture is quite different from other architectures. > When the allocating of KFENCE itself is done, it is mapped to the direct > mapping configuration window [1] by default on LoongArch. It means that > it is not possible to use the page table mapped mode which required by > the KFENCE system and therefore it should be remapped to the appropriate > region. > > This patch adds architecture specific implementation details for KFENCE. > In particular, this implements the required interface in <asm/kfence.h>. > > Tested this patch by running the testcases and all passed. > > [1] https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#virtual-address-space-and-address-translation-mode > > Signed-off-by: Enze Li <lienze@xxxxxxxxxx> > --- > arch/loongarch/Kconfig | 1 + > arch/loongarch/include/asm/kfence.h | 62 ++++++++++++++++++++++++++++ > arch/loongarch/include/asm/pgtable.h | 14 ++++++- > arch/loongarch/mm/fault.c | 22 ++++++---- > 4 files changed, 90 insertions(+), 9 deletions(-) > create mode 100644 arch/loongarch/include/asm/kfence.h > > diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig > index 70635ea3d1e4..5b63b16be49e 100644 > --- a/arch/loongarch/Kconfig > +++ b/arch/loongarch/Kconfig > @@ -91,6 +91,7 @@ config LOONGARCH > select HAVE_ARCH_AUDITSYSCALL > select HAVE_ARCH_JUMP_LABEL > select HAVE_ARCH_JUMP_LABEL_RELATIVE > + select HAVE_ARCH_KFENCE > select HAVE_ARCH_MMAP_RND_BITS if MMU > select HAVE_ARCH_SECCOMP_FILTER > select HAVE_ARCH_TRACEHOOK > diff --git a/arch/loongarch/include/asm/kfence.h b/arch/loongarch/include/asm/kfence.h > new file mode 100644 > index 000000000000..fb39076fe4d7 > --- /dev/null > +++ b/arch/loongarch/include/asm/kfence.h > @@ -0,0 +1,62 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * KFENCE support for LoongArch. > + * > + * Author: Enze Li <lienze@xxxxxxxxxx> > + * Copyright (C) 2022-2023 KylinSoft Corporation. > + */ > + > +#ifndef _ASM_LOONGARCH_KFENCE_H > +#define _ASM_LOONGARCH_KFENCE_H > + > +#include <linux/kfence.h> > +#include <asm/pgtable.h> > +#include <asm/tlb.h> > + > +static inline bool arch_kfence_init_pool(void) > +{ > + char *kfence_pool = __kfence_pool; > + struct vm_struct *area; > + int err; > + > + area = __get_vm_area_caller(KFENCE_POOL_SIZE, VM_IOREMAP, > + KFENCE_AREA_START, KFENCE_AREA_END, > + __builtin_return_address(0)); > + if (!area) > + return false; > + > + __kfence_pool = (char *)area->addr; > + err = ioremap_page_range((unsigned long)__kfence_pool, > + (unsigned long)__kfence_pool + KFENCE_POOL_SIZE, > + virt_to_phys((void *)kfence_pool), > + PAGE_KERNEL); > + if (err) { > + free_vm_area(area); > + return false; > + } > + > + return true; > +} > + > +/* Protect the given page and flush TLB. */ > +static inline bool kfence_protect_page(unsigned long addr, bool protect) > +{ > + pte_t *pte = virt_to_kpte(addr); > + > + if (WARN_ON(!pte) || pte_none(*pte)) > + return false; > + > + if (protect) > + set_pte(pte, __pte(pte_val(*pte) & ~(_PAGE_VALID | _PAGE_PRESENT))); > + else > + set_pte(pte, __pte(pte_val(*pte) | (_PAGE_VALID | _PAGE_PRESENT))); > + > + /* Flush this CPU's TLB. */ > + preempt_disable(); > + local_flush_tlb_one(addr); > + preempt_enable(); > + > + return true; > +} > + > +#endif /* _ASM_LOONGARCH_KFENCE_H */ > diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h > index 98a0c98de9d1..2702a6ba7122 100644 > --- a/arch/loongarch/include/asm/pgtable.h > +++ b/arch/loongarch/include/asm/pgtable.h > @@ -77,6 +77,13 @@ extern unsigned long zero_page_mask; > (virt_to_page((void *)(empty_zero_page + (((unsigned long)(vaddr)) & zero_page_mask)))) > #define __HAVE_COLOR_ZERO_PAGE > > +#ifdef CONFIG_KFENCE > +#define KFENCE_AREA_SIZE \ > + (((CONFIG_KFENCE_NUM_OBJECTS + 1) * 2 + 2) * PAGE_SIZE) Another question: Why define KFENCE_AREA_SIZE while there is already KFENCE_POOL_SIZE? And why is KFENCE_AREA_SIZE a little larger than KFENCE_POOL_SIZE? If we can reuse KFENCE_POOL_SIZE, KFENCE_AREA_START/KFENCE_AREA_END can be renamed to KFENCE_POOL_START/KFENCE_POOL_END. Huacai > +#else > +#define KFENCE_AREA_SIZE 0 > +#endif > + > /* > * TLB refill handlers may also map the vmalloc area into xkvrange. > * Avoid the first couple of pages so NULL pointer dereferences will > @@ -88,11 +95,16 @@ extern unsigned long zero_page_mask; > #define VMALLOC_START MODULES_END > #define VMALLOC_END \ > (vm_map_base + \ > - min(PTRS_PER_PGD * PTRS_PER_PUD * PTRS_PER_PMD * PTRS_PER_PTE * PAGE_SIZE, (1UL << cpu_vabits)) - PMD_SIZE - VMEMMAP_SIZE) > + min(PTRS_PER_PGD * PTRS_PER_PUD * PTRS_PER_PMD * PTRS_PER_PTE * PAGE_SIZE, (1UL << cpu_vabits)) - PMD_SIZE - VMEMMAP_SIZE - KFENCE_AREA_SIZE) > > #define vmemmap ((struct page *)((VMALLOC_END + PMD_SIZE) & PMD_MASK)) > #define VMEMMAP_END ((unsigned long)vmemmap + VMEMMAP_SIZE - 1) > > +#ifdef CONFIG_KFENCE > +#define KFENCE_AREA_START VMEMMAP_END > +#define KFENCE_AREA_END (KFENCE_AREA_START + KFENCE_AREA_SIZE) > +#endif > + > #define pte_ERROR(e) \ > pr_err("%s:%d: bad pte %016lx.\n", __FILE__, __LINE__, pte_val(e)) > #ifndef __PAGETABLE_PMD_FOLDED > diff --git a/arch/loongarch/mm/fault.c b/arch/loongarch/mm/fault.c > index da5b6d518cdb..c0319128b221 100644 > --- a/arch/loongarch/mm/fault.c > +++ b/arch/loongarch/mm/fault.c > @@ -23,6 +23,7 @@ > #include <linux/kprobes.h> > #include <linux/perf_event.h> > #include <linux/uaccess.h> > +#include <linux/kfence.h> > > #include <asm/branch.h> > #include <asm/mmu_context.h> > @@ -30,7 +31,8 @@ > > int show_unhandled_signals = 1; > > -static void __kprobes no_context(struct pt_regs *regs, unsigned long address) > +static void __kprobes no_context(struct pt_regs *regs, unsigned long address, > + unsigned long write) > { > const int field = sizeof(unsigned long) * 2; > > @@ -38,6 +40,9 @@ static void __kprobes no_context(struct pt_regs *regs, unsigned long address) > if (fixup_exception(regs)) > return; > > + if (kfence_handle_page_fault(address, write, regs)) > + return; > + > /* > * Oops. The kernel tried to access some bad page. We'll have to > * terminate things with extreme prejudice. > @@ -51,14 +56,15 @@ static void __kprobes no_context(struct pt_regs *regs, unsigned long address) > die("Oops", regs); > } > > -static void __kprobes do_out_of_memory(struct pt_regs *regs, unsigned long address) > +static void __kprobes do_out_of_memory(struct pt_regs *regs, unsigned long address, > + unsigned long write) > { > /* > * We ran out of memory, call the OOM killer, and return the userspace > * (which will retry the fault, or kill us if we got oom-killed). > */ > if (!user_mode(regs)) { > - no_context(regs, address); > + no_context(regs, address, write); > return; > } > pagefault_out_of_memory(); > @@ -69,7 +75,7 @@ static void __kprobes do_sigbus(struct pt_regs *regs, > { > /* Kernel mode? Handle exceptions or die */ > if (!user_mode(regs)) { > - no_context(regs, address); > + no_context(regs, address, write); > return; > } > > @@ -90,7 +96,7 @@ static void __kprobes do_sigsegv(struct pt_regs *regs, > > /* Kernel mode? Handle exceptions or die */ > if (!user_mode(regs)) { > - no_context(regs, address); > + no_context(regs, address, write); > return; > } > > @@ -149,7 +155,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, > */ > if (address & __UA_LIMIT) { > if (!user_mode(regs)) > - no_context(regs, address); > + no_context(regs, address, write); > else > do_sigsegv(regs, write, address, si_code); > return; > @@ -211,7 +217,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, > > if (fault_signal_pending(fault, regs)) { > if (!user_mode(regs)) > - no_context(regs, address); > + no_context(regs, address, write); > return; > } > > @@ -232,7 +238,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, > if (unlikely(fault & VM_FAULT_ERROR)) { > mmap_read_unlock(mm); > if (fault & VM_FAULT_OOM) { > - do_out_of_memory(regs, address); > + do_out_of_memory(regs, address, write); > return; > } else if (fault & VM_FAULT_SIGSEGV) { > do_sigsegv(regs, write, address, si_code); > -- > 2.34.1 > >
