diff options
Diffstat (limited to 'arch/nios2/mm/fault.c')
| -rw-r--r-- | arch/nios2/mm/fault.c | 251 |
1 files changed, 251 insertions, 0 deletions
diff --git a/arch/nios2/mm/fault.c b/arch/nios2/mm/fault.c new file mode 100644 index 00000000000..15a0bb5fc06 --- /dev/null +++ b/arch/nios2/mm/fault.c @@ -0,0 +1,251 @@ +/* + * Copyright (C) 2009 Wind River Systems Inc + * Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com + * + * based on arch/mips/mm/fault.c which is: + * + * Copyright (C) 1995-2000 Ralf Baechle + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + */ + +#include <linux/signal.h> +#include <linux/sched.h> +#include <linux/interrupt.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/module.h> +#include <linux/uaccess.h> +#include <linux/ptrace.h> + +#include <asm/mmu_context.h> +#include <asm/traps.h> + +#define EXC_SUPERV_INSN_ACCESS 9 /* Supervisor only instruction address */ +#define EXC_SUPERV_DATA_ACCESS 11 /* Supervisor only data address */ +#define EXC_X_PROTECTION_FAULT 13 /* TLB permission violation (x) */ +#define EXC_R_PROTECTION_FAULT 14 /* TLB permission violation (r) */ +#define EXC_W_PROTECTION_FAULT 15 /* TLB permission violation (w) */ + +/* + * This routine handles page faults. It determines the address, + * and the problem, and then passes it off to one of the appropriate + * routines. + */ +asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long cause, + unsigned long address) +{ + struct vm_area_struct *vma = NULL; + struct task_struct *tsk = current; + struct mm_struct *mm = tsk->mm; + int code = SEGV_MAPERR; + int fault; + unsigned int flags = 0; + + cause >>= 2; + + /* Restart the instruction */ + regs->ea -= 4; + + /* + * We fault-in kernel-space virtual memory on-demand. The + * 'reference' page table is init_mm.pgd. + * + * 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. + */ + if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END)) { + if (user_mode(regs)) + goto bad_area_nosemaphore; + else + goto vmalloc_fault; + } + + if (unlikely(address >= TASK_SIZE)) + goto bad_area_nosemaphore; + + /* + * If we're in an interrupt or have no user + * context, we must not take the fault.. + */ + if (in_atomic() || !mm) + goto bad_area_nosemaphore; + + if (user_mode(regs)) + flags |= FAULT_FLAG_USER; + + if (!down_read_trylock(&mm->mmap_sem)) { + if (!user_mode(regs) && !search_exception_tables(regs->ea)) + goto bad_area_nosemaphore; + down_read(&mm->mmap_sem); + } + + vma = find_vma(mm, address); + if (!vma) + goto bad_area; + if (vma->vm_start <= address) + goto good_area; + if (!(vma->vm_flags & VM_GROWSDOWN)) + goto bad_area; + if (expand_stack(vma, address)) + goto bad_area; +/* + * Ok, we have a good vm_area for this memory access, so + * we can handle it.. + */ +good_area: + code = SEGV_ACCERR; + + switch (cause) { + case EXC_SUPERV_INSN_ACCESS: + goto bad_area; + case EXC_SUPERV_DATA_ACCESS: + goto bad_area; + case EXC_X_PROTECTION_FAULT: + if (!(vma->vm_flags & VM_EXEC)) + goto bad_area; + break; + case EXC_R_PROTECTION_FAULT: + if (!(vma->vm_flags & VM_READ)) + goto bad_area; + break; + case EXC_W_PROTECTION_FAULT: + if (!(vma->vm_flags & VM_WRITE)) + goto bad_area; + flags = FAULT_FLAG_WRITE; + break; + } + +survive: + /* + * If for any reason at all we couldn't handle the fault, + * make sure we exit gracefully rather than endlessly redo + * the fault. + */ + fault = handle_mm_fault(mm, vma, address, flags); + if (unlikely(fault & VM_FAULT_ERROR)) { + if (fault & VM_FAULT_OOM) + goto out_of_memory; + else if (fault & VM_FAULT_SIGBUS) + goto do_sigbus; + BUG(); + } + if (fault & VM_FAULT_MAJOR) + tsk->maj_flt++; + else + tsk->min_flt++; + + up_read(&mm->mmap_sem); + return; + +/* + * Something tried to access memory that isn't in our memory map.. + * Fix it, but check if it's kernel or user first.. + */ +bad_area: + up_read(&mm->mmap_sem); + +bad_area_nosemaphore: + /* User mode accesses just cause a SIGSEGV */ + if (user_mode(regs)) { + pr_alert("%s: unhandled page fault (%d) at 0x%08lx, " + "cause %ld\n", current->comm, SIGSEGV, address, cause); + show_regs(regs); + _exception(SIGSEGV, regs, code, address); + return; + } + +no_context: + /* Are we prepared to handle this kernel fault? */ + if (fixup_exception(regs)) + return; + + /* + * Oops. The kernel tried to access some bad page. We'll have to + * terminate things with extreme prejudice. + */ + bust_spinlocks(1); + + pr_alert("Unable to handle kernel %s at virtual address %08lx", + address < PAGE_SIZE ? "NULL pointer dereference" : + "paging request", address); + pr_alert("ea = %08lx, ra = %08lx, cause = %ld\n", regs->ea, regs->ra, + cause); + panic("Oops"); + return; + +/* + * We ran out of memory, or some other thing happened to us that made + * us unable to handle the page fault gracefully. + */ +out_of_memory: + up_read(&mm->mmap_sem); + if (is_global_init(tsk)) { + yield(); + down_read(&mm->mmap_sem); + goto survive; + } + if (!user_mode(regs)) + goto no_context; + pagefault_out_of_memory(); + return; + +do_sigbus: + up_read(&mm->mmap_sem); + + /* Kernel mode? Handle exceptions or die */ + if (!user_mode(regs)) + goto no_context; + + _exception(SIGBUS, regs, BUS_ADRERR, address); + return; + +vmalloc_fault: + { + /* + * Synchronize this task's top level page-table + * with the 'reference' page table. + * + * Do _not_ use "tsk" here. We might be inside + * an interrupt in the middle of a task switch.. + */ + int offset = pgd_index(address); + pgd_t *pgd, *pgd_k; + pud_t *pud, *pud_k; + pmd_t *pmd, *pmd_k; + pte_t *pte_k; + + pgd = pgd_current + offset; + pgd_k = init_mm.pgd + offset; + + if (!pgd_present(*pgd_k)) + goto no_context; + set_pgd(pgd, *pgd_k); + + pud = pud_offset(pgd, address); + pud_k = pud_offset(pgd_k, address); + if (!pud_present(*pud_k)) + goto no_context; + pmd = pmd_offset(pud, address); + pmd_k = pmd_offset(pud_k, address); + if (!pmd_present(*pmd_k)) + goto no_context; + set_pmd(pmd, *pmd_k); + + pte_k = pte_offset_kernel(pmd_k, address); + if (!pte_present(*pte_k)) + goto no_context; + + flush_tlb_one(address); + return; + } +} |