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author | Jonas Bonn <jonas@southpole.se> | 2011-06-04 11:06:11 +0300 |
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committer | Jonas Bonn <jonas@southpole.se> | 2011-07-22 18:46:28 +0200 |
commit | 61e85e367535a7b6385b404bef93928768140f96 (patch) | |
tree | a0b8cb40dff683d3d09268f55080b5539d25b9a5 /arch/openrisc/mm/fault.c | |
parent | 4f246ba30e1a9a31fcfd91d2ab8f5c75f1362bbf (diff) | |
download | linux-61e85e367535a7b6385b404bef93928768140f96.tar.bz2 |
OpenRISC: Memory management
Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'arch/openrisc/mm/fault.c')
-rw-r--r-- | arch/openrisc/mm/fault.c | 338 |
1 files changed, 338 insertions, 0 deletions
diff --git a/arch/openrisc/mm/fault.c b/arch/openrisc/mm/fault.c new file mode 100644 index 000000000000..a5dce82f864b --- /dev/null +++ b/arch/openrisc/mm/fault.c @@ -0,0 +1,338 @@ +/* + * OpenRISC fault.c + * + * Linux architectural port borrowing liberally from similar works of + * others. All original copyrights apply as per the original source + * declaration. + * + * Modifications for the OpenRISC architecture: + * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com> + * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include <linux/mm.h> +#include <linux/interrupt.h> +#include <linux/module.h> +#include <linux/sched.h> + +#include <asm/uaccess.h> +#include <asm/siginfo.h> +#include <asm/signal.h> + +#define NUM_TLB_ENTRIES 64 +#define TLB_OFFSET(add) (((add) >> PAGE_SHIFT) & (NUM_TLB_ENTRIES-1)) + +unsigned long pte_misses; /* updated by do_page_fault() */ +unsigned long pte_errors; /* updated by do_page_fault() */ + +/* __PHX__ :: - check the vmalloc_fault in do_page_fault() + * - also look into include/asm-or32/mmu_context.h + */ +volatile pgd_t *current_pgd; + +extern void die(char *, struct pt_regs *, long); + +/* + * This routine handles page faults. It determines the address, + * and the problem, and then passes it off to one of the appropriate + * routines. + * + * If this routine detects a bad access, it returns 1, otherwise it + * returns 0. + */ + +asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long address, + unsigned long vector, int write_acc) +{ + struct task_struct *tsk; + struct mm_struct *mm; + struct vm_area_struct *vma; + siginfo_t info; + int fault; + + tsk = current; + + /* + * 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. + * + * NOTE2: This is done so that, when updating the vmalloc + * mappings we don't have to walk all processes pgdirs and + * add the high mappings all at once. Instead we do it as they + * are used. However vmalloc'ed page entries have the PAGE_GLOBAL + * bit set so sometimes the TLB can use a lingering entry. + * + * This verifies that the fault happens in kernel space + * and that the fault was not a protection error. + */ + + if (address >= VMALLOC_START && + (vector != 0x300 && vector != 0x400) && + !user_mode(regs)) + goto vmalloc_fault; + + /* If exceptions were enabled, we can reenable them here */ + if (user_mode(regs)) { + /* Exception was in userspace: reenable interrupts */ + local_irq_enable(); + } else { + /* If exception was in a syscall, then IRQ's may have + * been enabled or disabled. If they were enabled, + * reenable them. + */ + if (regs->sr && (SPR_SR_IEE | SPR_SR_TEE)) + local_irq_enable(); + } + + mm = tsk->mm; + info.si_code = SEGV_MAPERR; + + /* + * 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); + 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 (user_mode(regs)) { + /* + * accessing the stack below usp is always a bug. + * we get page-aligned addresses so we can only check + * if we're within a page from usp, but that might be + * enough to catch brutal errors at least. + */ + if (address + PAGE_SIZE < regs->sp) + 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: + info.si_code = SEGV_ACCERR; + + /* first do some preliminary protection checks */ + + if (write_acc) { + if (!(vma->vm_flags & VM_WRITE)) + goto bad_area; + } else { + /* not present */ + if (!(vma->vm_flags & (VM_READ | VM_EXEC))) + goto bad_area; + } + + /* are we trying to execute nonexecutable area */ + if ((vector == 0x400) && !(vma->vm_page_prot.pgprot & _PAGE_EXEC)) + goto bad_area; + + /* + * 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, write_acc); + 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(); + } + /*RGD modeled on Cris */ + 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)) { + info.si_signo = SIGSEGV; + info.si_errno = 0; + /* info.si_code has been set above */ + info.si_addr = (void *)address; + force_sig_info(SIGSEGV, &info, tsk); + return; + } + +no_context: + + /* Are we prepared to handle this kernel fault? + * + * (The kernel has valid exception-points in the source + * when it acesses user-memory. When it fails in one + * of those points, we find it in a table and do a jump + * to some fixup code that loads an appropriate error + * code) + */ + + { + const struct exception_table_entry *entry; + + __asm__ __volatile__("l.nop 42"); + + if ((entry = search_exception_tables(regs->pc)) != NULL) { + /* Adjust the instruction pointer in the stackframe */ + regs->pc = entry->fixup; + return; + } + } + + /* + * Oops. The kernel tried to access some bad page. We'll have to + * terminate things with extreme prejudice. + */ + + if ((unsigned long)(address) < PAGE_SIZE) + printk(KERN_ALERT + "Unable to handle kernel NULL pointer dereference"); + else + printk(KERN_ALERT "Unable to handle kernel access"); + printk(" at virtual address 0x%08lx\n", address); + + die("Oops", regs, write_acc); + + do_exit(SIGKILL); + + /* + * 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: + __asm__ __volatile__("l.nop 42"); + __asm__ __volatile__("l.nop 1"); + + up_read(&mm->mmap_sem); + printk("VM: killing process %s\n", tsk->comm); + if (user_mode(regs)) + do_exit(SIGKILL); + goto no_context; + +do_sigbus: + up_read(&mm->mmap_sem); + + /* + * Send a sigbus, regardless of whether we were in kernel + * or user mode. + */ + info.si_signo = SIGBUS; + info.si_errno = 0; + info.si_code = BUS_ADRERR; + info.si_addr = (void *)address; + force_sig_info(SIGBUS, &info, tsk); + + /* Kernel mode? Handle exceptions or die */ + if (!user_mode(regs)) + goto no_context; + return; + +vmalloc_fault: + { + /* + * Synchronize this task's top level page-table + * with the 'reference' page table. + * + * Use current_pgd instead of tsk->active_mm->pgd + * since the latter might be unavailable if this + * code is executed in a misfortunately run irq + * (like inside schedule() between switch_mm and + * switch_to...). + */ + + int offset = pgd_index(address); + pgd_t *pgd, *pgd_k; + pud_t *pud, *pud_k; + pmd_t *pmd, *pmd_k; + pte_t *pte_k; + +/* + phx_warn("do_page_fault(): vmalloc_fault will not work, " + "since current_pgd assign a proper value somewhere\n" + "anyhow we don't need this at the moment\n"); + + phx_mmu("vmalloc_fault"); +*/ + pgd = (pgd_t *)current_pgd + offset; + pgd_k = init_mm.pgd + offset; + + /* Since we're two-level, we don't need to do both + * set_pgd and set_pmd (they do the same thing). If + * we go three-level at some point, do the right thing + * with pgd_present and set_pgd here. + * + * Also, since the vmalloc area is global, we don't + * need to copy individual PTE's, it is enough to + * copy the pgd pointer into the pte page of the + * root task. If that is there, we'll find our pte if + * it exists. + */ + + 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 bad_area_nosemaphore; + + set_pmd(pmd, *pmd_k); + + /* Make sure the actual PTE exists as well to + * catch kernel vmalloc-area accesses to non-mapped + * addresses. If we don't do this, this will just + * silently loop forever. + */ + + pte_k = pte_offset_kernel(pmd_k, address); + if (!pte_present(*pte_k)) + goto no_context; + + return; + } +} |