diff options
Diffstat (limited to 'arch/arm26/mm/fault.c')
| -rw-r--r-- | arch/arm26/mm/fault.c | 318 |
1 files changed, 318 insertions, 0 deletions
diff --git a/arch/arm26/mm/fault.c b/arch/arm26/mm/fault.c new file mode 100644 index 000000000000..dacca8bb7744 --- /dev/null +++ b/arch/arm26/mm/fault.c @@ -0,0 +1,318 @@ +/* + * linux/arch/arm26/mm/fault.c + * + * Copyright (C) 1995 Linus Torvalds + * Modifications for ARM processor (c) 1995-2001 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 <linux/config.h> +#include <linux/signal.h> +#include <linux/sched.h> +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/string.h> +#include <linux/types.h> +#include <linux/ptrace.h> +#include <linux/mman.h> +#include <linux/mm.h> +#include <linux/interrupt.h> +#include <linux/proc_fs.h> +#include <linux/init.h> + +#include <asm/system.h> +#include <asm/pgtable.h> +#include <asm/uaccess.h> //FIXME this header may be bogusly included + +#include "fault.h" + +#define FAULT_CODE_LDRSTRPOST 0x80 +#define FAULT_CODE_LDRSTRPRE 0x40 +#define FAULT_CODE_LDRSTRREG 0x20 +#define FAULT_CODE_LDMSTM 0x10 +#define FAULT_CODE_LDCSTC 0x08 +#define FAULT_CODE_PREFETCH 0x04 +#define FAULT_CODE_WRITE 0x02 +#define FAULT_CODE_FORCECOW 0x01 + +#define DO_COW(m) ((m) & (FAULT_CODE_WRITE|FAULT_CODE_FORCECOW)) +#define READ_FAULT(m) (!((m) & FAULT_CODE_WRITE)) +#define DEBUG +/* + * 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; + + printk(KERN_ALERT "pgd = %p\n", mm->pgd); + pgd = pgd_offset(mm, addr); + printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd)); + + do { + pmd_t *pmd; + pte_t *pte; + + pmd = pmd_offset(pgd, addr); + + if (pmd_none(*pmd)) + break; + + if (pmd_bad(*pmd)) { + printk("(bad)"); + break; + } + + /* We must not map this if we have highmem enabled */ + /* FIXME */ + pte = pte_offset_map(pmd, addr); + printk(", *pte=%08lx", pte_val(*pte)); + pte_unmap(pte); + } while(0); + + printk("\n"); +} + +/* + * 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); + printk(KERN_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, int code, struct pt_regs *regs) +{ + struct siginfo si; + +#ifdef CONFIG_DEBUG_USER + printk("%s: unhandled page fault at 0x%08lx, code 0x%03x\n", + tsk->comm, addr, fsr); + show_pte(tsk->mm, addr); + show_regs(regs); + //dump_backtrace(regs, tsk); // FIXME ARM32 dropped this - why? + while(1); //FIXME - hack to stop debug going nutso +#endif + + tsk->thread.address = addr; + tsk->thread.error_code = fsr; + tsk->thread.trap_no = 14; + si.si_signo = SIGSEGV; + si.si_errno = 0; + si.si_code = code; + si.si_addr = (void *)addr; + force_sig_info(SIGSEGV, &si, tsk); +} + +static int +__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, + struct task_struct *tsk) +{ + struct vm_area_struct *vma; + int fault, mask; + + vma = find_vma(mm, addr); + fault = -2; /* bad map area */ + if (!vma) + goto out; + if (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 (READ_FAULT(fsr)) /* read? */ + mask = VM_READ|VM_EXEC; + else + mask = VM_WRITE; + + fault = -1; /* bad access type */ + if (!(vma->vm_flags & mask)) + goto out; + + /* + * If for any reason at all we couldn't handle + * the fault, make sure we exit gracefully rather + * than endlessly redo the fault. + */ +survive: + fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, DO_COW(fsr)); + + /* + * Handle the "normal" cases first - successful and sigbus + */ + switch (fault) { + case 2: + tsk->maj_flt++; + return fault; + case 1: + tsk->min_flt++; + case 0: + return fault; + } + + fault = -3; /* out of memory */ + if (tsk->pid != 1) + goto out; + + /* + * If we are out of memory for pid1, + * sleep for a while and retry + */ + yield(); + goto survive; + +check_stack: + if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr)) + goto good_area; +out: + return fault; +} + +int do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) +{ + struct task_struct *tsk; + struct mm_struct *mm; + int fault; + + tsk = current; + mm = tsk->mm; + + /* + * If we're in an interrupt or have no user + * context, we must not take the fault.. + */ + if (in_interrupt() || !mm) + goto no_context; + + down_read(&mm->mmap_sem); + fault = __do_page_fault(mm, addr, fsr, tsk); + up_read(&mm->mmap_sem); + + /* + * Handle the "normal" case first + */ + if (fault > 0) + return 0; + + /* + * We had some memory, but were unable to + * successfully fix up this page fault. + */ + if (fault == 0){ + goto do_sigbus; + } + + /* + * If we are in kernel mode at this point, we + * have no context to handle this fault with. + * FIXME - is this test right? + */ + if (!user_mode(regs)){ + goto no_context; + } + + if (fault == -3) { + /* + * We ran out of memory, or some other thing happened to + * us that made us unable to handle the page fault gracefully. + */ + printk("VM: killing process %s\n", tsk->comm); + do_exit(SIGKILL); + } + else{ + __do_user_fault(tsk, addr, fsr, fault == -1 ? SEGV_ACCERR : SEGV_MAPERR, regs); + } + + return 0; + + +/* + * We ran out of memory, or some other thing happened to us that made + * us unable to handle the page fault gracefully. + */ +do_sigbus: + /* + * Send a sigbus, regardless of whether we were in kernel + * or user mode. + */ + tsk->thread.address = addr; //FIXME - need other bits setting? + tsk->thread.error_code = fsr; + tsk->thread.trap_no = 14; + force_sig(SIGBUS, tsk); +#ifdef CONFIG_DEBUG_USER + printk(KERN_DEBUG "%s: sigbus at 0x%08lx, pc=0x%08lx\n", + current->comm, addr, instruction_pointer(regs)); +#endif + + /* Kernel mode? Handle exceptions or die */ + if (user_mode(regs)) + return 0; + +no_context: + __do_kernel_fault(mm, addr, fsr, regs); + return 0; +} + +/* + * Handle a data abort. Note that we have to handle a range of addresses + * on ARM2/3 for ldm. If both pages are zero-mapped, then we have to force + * a copy-on-write. However, on the second page, we always force COW. + */ +asmlinkage void +do_DataAbort(unsigned long min_addr, unsigned long max_addr, int mode, struct pt_regs *regs) +{ + do_page_fault(min_addr, mode, regs); + + if ((min_addr ^ max_addr) >> PAGE_SHIFT){ + do_page_fault(max_addr, mode | FAULT_CODE_FORCECOW, regs); + } +} + +asmlinkage int +do_PrefetchAbort(unsigned long addr, struct pt_regs *regs) +{ +#if 0 + if (the memc mapping for this page exists) { + printk ("Page in, but got abort (undefined instruction?)\n"); + return 0; + } +#endif + do_page_fault(addr, FAULT_CODE_PREFETCH, regs); + return 1; +} + |