diff options
Diffstat (limited to 'arch/arm64/mm/fault.c')
-rw-r--r-- | arch/arm64/mm/fault.c | 186 |
1 files changed, 118 insertions, 68 deletions
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 2d115016feb4..115d7a0e4b08 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -8,6 +8,7 @@ */ #include <linux/acpi.h> +#include <linux/bitfield.h> #include <linux/extable.h> #include <linux/signal.h> #include <linux/mm.h> @@ -59,28 +60,6 @@ static inline const struct fault_info *esr_to_debug_fault_info(unsigned int esr) return debug_fault_info + DBG_ESR_EVT(esr); } -#ifdef CONFIG_KPROBES -static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr) -{ - int ret = 0; - - /* kprobe_running() needs smp_processor_id() */ - if (!user_mode(regs)) { - preempt_disable(); - if (kprobe_running() && kprobe_fault_handler(regs, esr)) - ret = 1; - preempt_enable(); - } - - return ret; -} -#else -static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr) -{ - return 0; -} -#endif - static void data_abort_decode(unsigned int esr) { pr_alert("Data abort info:\n"); @@ -108,8 +87,8 @@ static void mem_abort_decode(unsigned int esr) pr_alert("Mem abort info:\n"); pr_alert(" ESR = 0x%08x\n", esr); - pr_alert(" Exception class = %s, IL = %u bits\n", - esr_get_class_string(esr), + pr_alert(" EC = 0x%02lx: %s, IL = %u bits\n", + ESR_ELx_EC(esr), esr_get_class_string(esr), (esr & ESR_ELx_IL) ? 32 : 16); pr_alert(" SET = %lu, FnV = %lu\n", (esr & ESR_ELx_SET_MASK) >> ESR_ELx_SET_SHIFT, @@ -131,7 +110,7 @@ static inline bool is_ttbr0_addr(unsigned long addr) static inline bool is_ttbr1_addr(unsigned long addr) { /* TTBR1 addresses may have a tag if KASAN_SW_TAGS is in use */ - return arch_kasan_reset_tag(addr) >= VA_START; + return arch_kasan_reset_tag(addr) >= PAGE_OFFSET; } /* @@ -160,10 +139,9 @@ static void show_pte(unsigned long addr) return; } - pr_alert("%s pgtable: %luk pages, %u-bit VAs, pgdp=%016lx\n", + pr_alert("%s pgtable: %luk pages, %llu-bit VAs, pgdp=%016lx\n", mm == &init_mm ? "swapper" : "user", PAGE_SIZE / SZ_1K, - mm == &init_mm ? VA_BITS : (int)vabits_user, - (unsigned long)virt_to_phys(mm->pgd)); + vabits_actual, (unsigned long)virt_to_phys(mm->pgd)); pgdp = pgd_offset(mm, addr); pgd = READ_ONCE(*pgdp); pr_alert("[%016lx] pgd=%016llx", addr, pgd_val(pgd)); @@ -264,6 +242,34 @@ static inline bool is_el1_permission_fault(unsigned long addr, unsigned int esr, return false; } +static bool __kprobes is_spurious_el1_translation_fault(unsigned long addr, + unsigned int esr, + struct pt_regs *regs) +{ + unsigned long flags; + u64 par, dfsc; + + if (ESR_ELx_EC(esr) != ESR_ELx_EC_DABT_CUR || + (esr & ESR_ELx_FSC_TYPE) != ESR_ELx_FSC_FAULT) + return false; + + local_irq_save(flags); + asm volatile("at s1e1r, %0" :: "r" (addr)); + isb(); + par = read_sysreg(par_el1); + local_irq_restore(flags); + + if (!(par & SYS_PAR_EL1_F)) + return false; + + /* + * If we got a different type of fault from the AT instruction, + * treat the translation fault as spurious. + */ + dfsc = FIELD_PREP(SYS_PAR_EL1_FST, par); + return (dfsc & ESR_ELx_FSC_TYPE) != ESR_ELx_FSC_FAULT; +} + static void die_kernel_fault(const char *msg, unsigned long addr, unsigned int esr, struct pt_regs *regs) { @@ -292,6 +298,10 @@ static void __do_kernel_fault(unsigned long addr, unsigned int esr, if (!is_el1_instruction_abort(esr) && fixup_exception(regs)) return; + if (WARN_RATELIMIT(is_spurious_el1_translation_fault(addr, esr, regs), + "Ignoring spurious kernel translation fault at virtual address %016lx\n", addr)) + return; + if (is_el1_permission_fault(addr, esr, regs)) { if (esr & ESR_ELx_WNR) msg = "write to read-only memory"; @@ -384,40 +394,31 @@ static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *re #define VM_FAULT_BADACCESS 0x020000 static vm_fault_t __do_page_fault(struct mm_struct *mm, unsigned long addr, - unsigned int mm_flags, unsigned long vm_flags, - struct task_struct *tsk) + unsigned int mm_flags, unsigned long vm_flags) { - struct vm_area_struct *vma; - vm_fault_t fault; + struct vm_area_struct *vma = find_vma(mm, addr); - vma = find_vma(mm, addr); - fault = VM_FAULT_BADMAP; if (unlikely(!vma)) - goto out; - if (unlikely(vma->vm_start > addr)) - goto check_stack; + return VM_FAULT_BADMAP; /* * Ok, we have a good vm_area for this memory access, so we can handle * it. */ -good_area: + if (unlikely(vma->vm_start > addr)) { + if (!(vma->vm_flags & VM_GROWSDOWN)) + return VM_FAULT_BADMAP; + if (expand_stack(vma, addr)) + return VM_FAULT_BADMAP; + } + /* * Check that the permissions on the VMA allow for the fault which * occurred. */ - if (!(vma->vm_flags & vm_flags)) { - fault = VM_FAULT_BADACCESS; - goto out; - } - + if (!(vma->vm_flags & vm_flags)) + return VM_FAULT_BADACCESS; return handle_mm_fault(vma, addr & PAGE_MASK, mm_flags); - -check_stack: - if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr)) - goto good_area; -out: - return fault; } static bool is_el0_instruction_abort(unsigned int esr) @@ -425,22 +426,27 @@ static bool is_el0_instruction_abort(unsigned int esr) return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW; } +/* + * Note: not valid for EL1 DC IVAC, but we never use that such that it + * should fault. EL0 cannot issue DC IVAC (undef). + */ +static bool is_write_abort(unsigned int esr) +{ + return (esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM); +} + static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, struct pt_regs *regs) { const struct fault_info *inf; - struct task_struct *tsk; - struct mm_struct *mm; + struct mm_struct *mm = current->mm; vm_fault_t fault, major = 0; unsigned long vm_flags = VM_READ | VM_WRITE; unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; - if (notify_page_fault(regs, esr)) + if (kprobe_page_fault(regs, esr)) return 0; - tsk = current; - mm = tsk->mm; - /* * If we're in an interrupt or have no user context, we must not take * the fault. @@ -453,7 +459,8 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, if (is_el0_instruction_abort(esr)) { vm_flags = VM_EXEC; - } else if ((esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM)) { + mm_flags |= FAULT_FLAG_INSTRUCTION; + } else if (is_write_abort(esr)) { vm_flags = VM_WRITE; mm_flags |= FAULT_FLAG_WRITE; } @@ -492,12 +499,14 @@ retry: */ might_sleep(); #ifdef CONFIG_DEBUG_VM - if (!user_mode(regs) && !search_exception_tables(regs->pc)) + if (!user_mode(regs) && !search_exception_tables(regs->pc)) { + up_read(&mm->mmap_sem); goto no_context; + } #endif } - fault = __do_page_fault(mm, addr, mm_flags, vm_flags, tsk); + fault = __do_page_fault(mm, addr, mm_flags, vm_flags); major |= fault & VM_FAULT_MAJOR; if (fault & VM_FAULT_RETRY) { @@ -537,11 +546,11 @@ retry: * that point. */ if (major) { - tsk->maj_flt++; + current->maj_flt++; perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, addr); } else { - tsk->min_flt++; + current->min_flt++; perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, addr); } @@ -800,6 +809,53 @@ void __init hook_debug_fault_code(int nr, debug_fault_info[nr].name = name; } +/* + * In debug exception context, we explicitly disable preemption despite + * having interrupts disabled. + * This serves two purposes: it makes it much less likely that we would + * accidentally schedule in exception context and it will force a warning + * if we somehow manage to schedule by accident. + */ +static void debug_exception_enter(struct pt_regs *regs) +{ + /* + * Tell lockdep we disabled irqs in entry.S. Do nothing if they were + * already disabled to preserve the last enabled/disabled addresses. + */ + if (interrupts_enabled(regs)) + trace_hardirqs_off(); + + if (user_mode(regs)) { + RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); + } else { + /* + * We might have interrupted pretty much anything. In + * fact, if we're a debug exception, we can even interrupt + * NMI processing. We don't want this code makes in_nmi() + * to return true, but we need to notify RCU. + */ + rcu_nmi_enter(); + } + + preempt_disable(); + + /* This code is a bit fragile. Test it. */ + RCU_LOCKDEP_WARN(!rcu_is_watching(), "exception_enter didn't work"); +} +NOKPROBE_SYMBOL(debug_exception_enter); + +static void debug_exception_exit(struct pt_regs *regs) +{ + preempt_enable_no_resched(); + + if (!user_mode(regs)) + rcu_nmi_exit(); + + if (interrupts_enabled(regs)) + trace_hardirqs_on(); +} +NOKPROBE_SYMBOL(debug_exception_exit); + #ifdef CONFIG_ARM64_ERRATUM_1463225 DECLARE_PER_CPU(int, __in_cortex_a76_erratum_1463225_wa); @@ -840,12 +896,7 @@ asmlinkage void __exception do_debug_exception(unsigned long addr_if_watchpoint, if (cortex_a76_erratum_1463225_debug_handler(regs)) return; - /* - * Tell lockdep we disabled irqs in entry.S. Do nothing if they were - * already disabled to preserve the last enabled/disabled addresses. - */ - if (interrupts_enabled(regs)) - trace_hardirqs_off(); + debug_exception_enter(regs); if (user_mode(regs) && !is_ttbr0_addr(pc)) arm64_apply_bp_hardening(); @@ -855,7 +906,6 @@ asmlinkage void __exception do_debug_exception(unsigned long addr_if_watchpoint, inf->sig, inf->code, (void __user *)pc, esr); } - if (interrupts_enabled(regs)) - trace_hardirqs_on(); + debug_exception_exit(regs); } NOKPROBE_SYMBOL(do_debug_exception); |