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Diffstat (limited to '')
| -rw-r--r-- | arch/riscv/mm/fault.c | 299 |
1 files changed, 299 insertions, 0 deletions
diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c new file mode 100644 index 000000000..523dbfbac --- /dev/null +++ b/arch/riscv/mm/fault.c @@ -0,0 +1,299 @@ +/* + * Copyright (C) 2009 Sunplus Core Technology Co., Ltd. + * Lennox Wu <lennox.wu@sunplusct.com> + * Chen Liqin <liqin.chen@sunplusct.com> + * Copyright (C) 2012 Regents of the University of California + * + * 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. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see the file COPYING, or write + * to the Free Software Foundation, Inc., + */ + + +#include <linux/mm.h> +#include <linux/kernel.h> +#include <linux/interrupt.h> +#include <linux/perf_event.h> +#include <linux/signal.h> +#include <linux/uaccess.h> + +#include <asm/pgalloc.h> +#include <asm/ptrace.h> +#include <asm/tlbflush.h> + +/* + * 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) +{ + struct task_struct *tsk; + struct vm_area_struct *vma; + struct mm_struct *mm; + unsigned long addr, cause; + unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; + int code = SEGV_MAPERR; + vm_fault_t fault; + + cause = regs->scause; + addr = regs->sbadaddr; + + tsk = current; + mm = tsk->mm; + + /* + * 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((addr >= VMALLOC_START) && (addr <= VMALLOC_END))) + goto vmalloc_fault; + + /* Enable interrupts if they were enabled in the parent context. */ + if (likely(regs->sstatus & SR_SPIE)) + local_irq_enable(); + + /* + * If we're in an interrupt, have no user context, or are running + * in an atomic region, then we must not take the fault. + */ + if (unlikely(faulthandler_disabled() || !mm)) + goto no_context; + + if (user_mode(regs)) + flags |= FAULT_FLAG_USER; + + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr); + +retry: + down_read(&mm->mmap_sem); + vma = find_vma(mm, addr); + if (unlikely(!vma)) + goto bad_area; + if (likely(vma->vm_start <= addr)) + goto good_area; + if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) + goto bad_area; + if (unlikely(expand_stack(vma, addr))) + 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_INST_PAGE_FAULT: + if (!(vma->vm_flags & VM_EXEC)) + goto bad_area; + break; + case EXC_LOAD_PAGE_FAULT: + if (!(vma->vm_flags & VM_READ)) + goto bad_area; + break; + case EXC_STORE_PAGE_FAULT: + if (!(vma->vm_flags & VM_WRITE)) + goto bad_area; + flags |= FAULT_FLAG_WRITE; + break; + default: + panic("%s: unhandled cause %lu", __func__, cause); + } + + /* + * If for any reason at all we could not handle the fault, + * make sure we exit gracefully rather than endlessly redo + * the fault. + */ + fault = handle_mm_fault(vma, addr, flags); + + /* + * 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(tsk)) + return; + + 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(); + } + + /* + * 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. + */ + if (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; + + /* + * No need to up_read(&mm->mmap_sem) as we would + * have already released it in __lock_page_or_retry + * in mm/filemap.c. + */ + goto retry; + } + } + + 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); + /* User mode accesses just cause a SIGSEGV */ + if (user_mode(regs)) { + do_trap(regs, SIGSEGV, code, addr, tsk); + 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 " REG_FMT "\n", + (addr < PAGE_SIZE) ? "NULL pointer dereference" : + "paging request", addr); + die(regs, "Oops"); + do_exit(SIGKILL); + + /* + * We ran out of memory, call the OOM killer, and return the userspace + * (which will retry the fault, or kill us if we got oom-killed). + */ +out_of_memory: + up_read(&mm->mmap_sem); + 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; + do_trap(regs, SIGBUS, BUS_ADRERR, addr, tsk); + return; + +vmalloc_fault: + { + pgd_t *pgd, *pgd_k; + pud_t *pud, *pud_k; + p4d_t *p4d, *p4d_k; + pmd_t *pmd, *pmd_k; + pte_t *pte_k; + int index; + + if (user_mode(regs)) + goto bad_area; + + /* + * Synchronize this task's top level page-table + * with the 'reference' page table. + * + * Do _not_ use "tsk->active_mm->pgd" here. + * We might be inside an interrupt in the middle + * of a task switch. + * + * Note: Use the old spbtr name instead of using the current + * satp name to support binutils 2.29 which doesn't know about + * the privileged ISA 1.10 yet. + */ + index = pgd_index(addr); + pgd = (pgd_t *)pfn_to_virt(csr_read(sptbr)) + index; + pgd_k = init_mm.pgd + index; + + if (!pgd_present(*pgd_k)) + goto no_context; + set_pgd(pgd, *pgd_k); + + p4d = p4d_offset(pgd, addr); + p4d_k = p4d_offset(pgd_k, addr); + if (!p4d_present(*p4d_k)) + goto no_context; + + pud = pud_offset(p4d, addr); + pud_k = pud_offset(p4d_k, addr); + if (!pud_present(*pud_k)) + goto no_context; + + /* + * Since the vmalloc area is global, it is unnecessary + * to copy individual PTEs + */ + pmd = pmd_offset(pud, addr); + pmd_k = pmd_offset(pud_k, addr); + if (!pmd_present(*pmd_k)) + goto no_context; + 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, addr); + if (!pte_present(*pte_k)) + goto no_context; + + /* + * The kernel assumes that TLBs don't cache invalid + * entries, but in RISC-V, SFENCE.VMA specifies an + * ordering constraint, not a cache flush; it is + * necessary even after writing invalid entries. + * Relying on flush_tlb_fix_spurious_fault would + * suffice, but the extra traps reduce + * performance. So, eagerly SFENCE.VMA. + */ + local_flush_tlb_page(addr); + + return; + } +} |