From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- arch/arm/mm/fault.c | 619 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 619 insertions(+) create mode 100644 arch/arm/mm/fault.c (limited to 'arch/arm/mm/fault.c') diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c new file mode 100644 index 000000000..6333d9c17 --- /dev/null +++ b/arch/arm/mm/fault.c @@ -0,0 +1,619 @@ +/* + * linux/arch/arm/mm/fault.c + * + * Copyright (C) 1995 Linus Torvalds + * Modifications for ARM processor (c) 1995-2004 Russell King + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include + +#include "fault.h" + +#ifdef CONFIG_MMU + +#ifdef CONFIG_KPROBES +static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr) +{ + int ret = 0; + + if (!user_mode(regs)) { + /* kprobe_running() needs smp_processor_id() */ + preempt_disable(); + if (kprobe_running() && kprobe_fault_handler(regs, fsr)) + ret = 1; + preempt_enable(); + } + + return ret; +} +#else +static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr) +{ + return 0; +} +#endif + +/* + * This is useful to dump out the page tables associated with + * 'addr' in mm 'mm'. + */ +void show_pte(struct mm_struct *mm, unsigned long addr) +{ + pgd_t *pgd; + + if (!mm) + mm = &init_mm; + + pr_alert("pgd = %p\n", mm->pgd); + pgd = pgd_offset(mm, addr); + pr_alert("[%08lx] *pgd=%08llx", + addr, (long long)pgd_val(*pgd)); + + do { + pud_t *pud; + pmd_t *pmd; + pte_t *pte; + + if (pgd_none(*pgd)) + break; + + if (pgd_bad(*pgd)) { + pr_cont("(bad)"); + break; + } + + pud = pud_offset(pgd, addr); + if (PTRS_PER_PUD != 1) + pr_cont(", *pud=%08llx", (long long)pud_val(*pud)); + + if (pud_none(*pud)) + break; + + if (pud_bad(*pud)) { + pr_cont("(bad)"); + break; + } + + pmd = pmd_offset(pud, addr); + if (PTRS_PER_PMD != 1) + pr_cont(", *pmd=%08llx", (long long)pmd_val(*pmd)); + + if (pmd_none(*pmd)) + break; + + if (pmd_bad(*pmd)) { + pr_cont("(bad)"); + break; + } + + /* We must not map this if we have highmem enabled */ + if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT))) + break; + + pte = pte_offset_map(pmd, addr); + pr_cont(", *pte=%08llx", (long long)pte_val(*pte)); +#ifndef CONFIG_ARM_LPAE + pr_cont(", *ppte=%08llx", + (long long)pte_val(pte[PTE_HWTABLE_PTRS])); +#endif + pte_unmap(pte); + } while(0); + + pr_cont("\n"); +} +#else /* CONFIG_MMU */ +void show_pte(struct mm_struct *mm, unsigned long addr) +{ } +#endif /* CONFIG_MMU */ + +/* + * Oops. The kernel tried to access some page that wasn't present. + */ +static void +__do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, + struct pt_regs *regs) +{ + /* + * Are we prepared to handle this kernel fault? + */ + if (fixup_exception(regs)) + return; + + /* + * No handler, we'll have to terminate things with extreme prejudice. + */ + bust_spinlocks(1); + pr_alert("Unable to handle kernel %s at virtual address %08lx\n", + (addr < PAGE_SIZE) ? "NULL pointer dereference" : + "paging request", addr); + + show_pte(mm, addr); + die("Oops", regs, fsr); + bust_spinlocks(0); + do_exit(SIGKILL); +} + +/* + * Something tried to access memory that isn't in our memory map.. + * User mode accesses just cause a SIGSEGV + */ +static void +__do_user_fault(struct task_struct *tsk, unsigned long addr, + unsigned int fsr, unsigned int sig, int code, + struct pt_regs *regs) +{ + struct siginfo si; + +#ifdef CONFIG_DEBUG_USER + if (((user_debug & UDBG_SEGV) && (sig == SIGSEGV)) || + ((user_debug & UDBG_BUS) && (sig == SIGBUS))) { + printk(KERN_DEBUG "%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n", + tsk->comm, sig, addr, fsr); + show_pte(tsk->mm, addr); + show_regs(regs); + } +#endif + + tsk->thread.address = addr; + tsk->thread.error_code = fsr; + tsk->thread.trap_no = 14; + si.si_signo = sig; + si.si_errno = 0; + si.si_code = code; + si.si_addr = (void __user *)addr; + force_sig_info(sig, &si, tsk); +} + +void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs) +{ + struct task_struct *tsk = current; + struct mm_struct *mm = tsk->active_mm; + + /* + * If we are in kernel mode at this point, we + * have no context to handle this fault with. + */ + if (user_mode(regs)) + __do_user_fault(tsk, addr, fsr, SIGSEGV, SEGV_MAPERR, regs); + else + __do_kernel_fault(mm, addr, fsr, regs); +} + +#ifdef CONFIG_MMU +#define VM_FAULT_BADMAP 0x010000 +#define VM_FAULT_BADACCESS 0x020000 + +/* + * Check that the permissions on the VMA allow for the fault which occurred. + * If we encountered a write fault, we must have write permission, otherwise + * we allow any permission. + */ +static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma) +{ + unsigned int mask = VM_READ | VM_WRITE | VM_EXEC; + + if (fsr & FSR_WRITE) + mask = VM_WRITE; + if (fsr & FSR_LNX_PF) + mask = VM_EXEC; + + return vma->vm_flags & mask ? false : true; +} + +static int __kprobes +__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, + unsigned int flags, struct task_struct *tsk) +{ + struct vm_area_struct *vma; + int fault; + + vma = find_vma(mm, addr); + fault = VM_FAULT_BADMAP; + if (unlikely(!vma)) + goto out; + if (unlikely(vma->vm_start > addr)) + goto check_stack; + + /* + * Ok, we have a good vm_area for this + * memory access, so we can handle it. + */ +good_area: + if (access_error(fsr, vma)) { + fault = VM_FAULT_BADACCESS; + goto out; + } + + return handle_mm_fault(mm, vma, addr & PAGE_MASK, flags); + +check_stack: + /* Don't allow expansion below FIRST_USER_ADDRESS */ + if (vma->vm_flags & VM_GROWSDOWN && + addr >= FIRST_USER_ADDRESS && !expand_stack(vma, addr)) + goto good_area; +out: + return fault; +} + +static int __kprobes +do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) +{ + struct task_struct *tsk; + struct mm_struct *mm; + int fault, sig, code; + unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; + + if (notify_page_fault(regs, fsr)) + return 0; + + tsk = current; + mm = tsk->mm; + + /* Enable interrupts if they were enabled in the parent context. */ + if (interrupts_enabled(regs)) + local_irq_enable(); + + /* + * If we're in an interrupt or have no user + * context, we must not take the fault.. + */ + if (in_atomic() || !mm) + goto no_context; + + if (user_mode(regs)) + flags |= FAULT_FLAG_USER; + if (fsr & FSR_WRITE) + flags |= FAULT_FLAG_WRITE; + + /* + * As per x86, we may deadlock here. However, since the kernel only + * validly references user space from well defined areas of the code, + * we can bug out early if this is from code which shouldn't. + */ + if (!down_read_trylock(&mm->mmap_sem)) { + if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc)) + goto no_context; +retry: + down_read(&mm->mmap_sem); + } else { + /* + * The above down_read_trylock() might have succeeded in + * which case, we'll have missed the might_sleep() from + * down_read() + */ + might_sleep(); +#ifdef CONFIG_DEBUG_VM + if (!user_mode(regs) && + !search_exception_tables(regs->ARM_pc)) + goto no_context; +#endif + } + + fault = __do_page_fault(mm, addr, fsr, flags, tsk); + + /* If we need to retry but a fatal signal is pending, handle the + * signal first. We do not need to release the mmap_sem because + * it would already be released in __lock_page_or_retry in + * mm/filemap.c. */ + if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) + return 0; + + /* + * Major/minor page fault accounting is only done on the + * initial attempt. If we go through a retry, it is extremely + * likely that the page will be found in page cache at that point. + */ + + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr); + if (!(fault & VM_FAULT_ERROR) && flags & FAULT_FLAG_ALLOW_RETRY) { + if (fault & VM_FAULT_MAJOR) { + tsk->maj_flt++; + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, + regs, addr); + } else { + tsk->min_flt++; + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, + regs, addr); + } + if (fault & VM_FAULT_RETRY) { + /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk + * of starvation. */ + flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; + goto retry; + } + } + + up_read(&mm->mmap_sem); + + /* + * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR + */ + if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS)))) + return 0; + + /* + * If we are in kernel mode at this point, we + * have no context to handle this fault with. + */ + if (!user_mode(regs)) + goto no_context; + + if (fault & VM_FAULT_OOM) { + /* + * We ran out of memory, call the OOM killer, and return to + * userspace (which will retry the fault, or kill us if we + * got oom-killed) + */ + pagefault_out_of_memory(); + return 0; + } + + if (fault & VM_FAULT_SIGBUS) { + /* + * We had some memory, but were unable to + * successfully fix up this page fault. + */ + sig = SIGBUS; + code = BUS_ADRERR; + } else { + /* + * Something tried to access memory that + * isn't in our memory map.. + */ + sig = SIGSEGV; + code = fault == VM_FAULT_BADACCESS ? + SEGV_ACCERR : SEGV_MAPERR; + } + + __do_user_fault(tsk, addr, fsr, sig, code, regs); + return 0; + +no_context: + __do_kernel_fault(mm, addr, fsr, regs); + return 0; +} +#else /* CONFIG_MMU */ +static int +do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) +{ + return 0; +} +#endif /* CONFIG_MMU */ + +/* + * First Level Translation Fault Handler + * + * We enter here because the first level page table doesn't contain + * a valid entry for the address. + * + * If the address is in kernel space (>= TASK_SIZE), then we are + * probably faulting in the vmalloc() area. + * + * If the init_task's first level page tables contains the relevant + * entry, we copy the it to this task. If not, we send the process + * a signal, fixup the exception, or oops the kernel. + * + * NOTE! We MUST NOT take any locks for this case. We may be in an + * interrupt or a critical region, and should only copy the information + * from the master page table, nothing more. + */ +#ifdef CONFIG_MMU +static int __kprobes +do_translation_fault(unsigned long addr, unsigned int fsr, + struct pt_regs *regs) +{ + unsigned int index; + pgd_t *pgd, *pgd_k; + pud_t *pud, *pud_k; + pmd_t *pmd, *pmd_k; + + if (addr < TASK_SIZE) + return do_page_fault(addr, fsr, regs); + + if (user_mode(regs)) + goto bad_area; + + index = pgd_index(addr); + + pgd = cpu_get_pgd() + index; + pgd_k = init_mm.pgd + index; + + if (pgd_none(*pgd_k)) + goto bad_area; + if (!pgd_present(*pgd)) + set_pgd(pgd, *pgd_k); + + pud = pud_offset(pgd, addr); + pud_k = pud_offset(pgd_k, addr); + + if (pud_none(*pud_k)) + goto bad_area; + if (!pud_present(*pud)) + set_pud(pud, *pud_k); + + pmd = pmd_offset(pud, addr); + pmd_k = pmd_offset(pud_k, addr); + +#ifdef CONFIG_ARM_LPAE + /* + * Only one hardware entry per PMD with LPAE. + */ + index = 0; +#else + /* + * On ARM one Linux PGD entry contains two hardware entries (see page + * tables layout in pgtable.h). We normally guarantee that we always + * fill both L1 entries. But create_mapping() doesn't follow the rule. + * It can create inidividual L1 entries, so here we have to call + * pmd_none() check for the entry really corresponded to address, not + * for the first of pair. + */ + index = (addr >> SECTION_SHIFT) & 1; +#endif + if (pmd_none(pmd_k[index])) + goto bad_area; + + copy_pmd(pmd, pmd_k); + return 0; + +bad_area: + do_bad_area(addr, fsr, regs); + return 0; +} +#else /* CONFIG_MMU */ +static int +do_translation_fault(unsigned long addr, unsigned int fsr, + struct pt_regs *regs) +{ + return 0; +} +#endif /* CONFIG_MMU */ + +/* + * Some section permission faults need to be handled gracefully. + * They can happen due to a __{get,put}_user during an oops. + */ +#ifndef CONFIG_ARM_LPAE +static int +do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) +{ + do_bad_area(addr, fsr, regs); + return 0; +} +#endif /* CONFIG_ARM_LPAE */ + +/* + * This abort handler always returns "fault". + */ +static int +do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs) +{ + return 1; +} + +struct fsr_info { + int (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs); + int sig; + int code; + const char *name; +}; + +/* FSR definition */ +#ifdef CONFIG_ARM_LPAE +#include "fsr-3level.c" +#else +#include "fsr-2level.c" +#endif + +void __init +hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *), + int sig, int code, const char *name) +{ + if (nr < 0 || nr >= ARRAY_SIZE(fsr_info)) + BUG(); + + fsr_info[nr].fn = fn; + fsr_info[nr].sig = sig; + fsr_info[nr].code = code; + fsr_info[nr].name = name; +} + +/* + * Dispatch a data abort to the relevant handler. + */ +asmlinkage void __exception +do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs) +{ + const struct fsr_info *inf = fsr_info + fsr_fs(fsr); + struct siginfo info; + + if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs)) + return; + + pr_alert("Unhandled fault: %s (0x%03x) at 0x%08lx\n", + inf->name, fsr, addr); + show_pte(current->mm, addr); + + info.si_signo = inf->sig; + info.si_errno = 0; + info.si_code = inf->code; + info.si_addr = (void __user *)addr; + arm_notify_die("", regs, &info, fsr, 0); +} + +void __init +hook_ifault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *), + int sig, int code, const char *name) +{ + if (nr < 0 || nr >= ARRAY_SIZE(ifsr_info)) + BUG(); + + ifsr_info[nr].fn = fn; + ifsr_info[nr].sig = sig; + ifsr_info[nr].code = code; + ifsr_info[nr].name = name; +} + +asmlinkage void __exception +do_PrefetchAbort(unsigned long addr, unsigned int ifsr, struct pt_regs *regs) +{ + const struct fsr_info *inf = ifsr_info + fsr_fs(ifsr); + struct siginfo info; + + if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs)) + return; + + pr_alert("Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n", + inf->name, ifsr, addr); + + info.si_signo = inf->sig; + info.si_errno = 0; + info.si_code = inf->code; + info.si_addr = (void __user *)addr; + arm_notify_die("", regs, &info, ifsr, 0); +} + +#ifndef CONFIG_ARM_LPAE +static int __init exceptions_init(void) +{ + if (cpu_architecture() >= CPU_ARCH_ARMv6) { + hook_fault_code(4, do_translation_fault, SIGSEGV, SEGV_MAPERR, + "I-cache maintenance fault"); + } + + if (cpu_architecture() >= CPU_ARCH_ARMv7) { + /* + * TODO: Access flag faults introduced in ARMv6K. + * Runtime check for 'K' extension is needed + */ + hook_fault_code(3, do_bad, SIGSEGV, SEGV_MAPERR, + "section access flag fault"); + hook_fault_code(6, do_bad, SIGSEGV, SEGV_MAPERR, + "section access flag fault"); + } + + return 0; +} + +arch_initcall(exceptions_init); +#endif -- cgit v1.2.3-54-g00ecf