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Diffstat (limited to '')
| -rw-r--r-- | arch/arc/mm/fault.c | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c new file mode 100644 index 000000000..f5657cb68 --- /dev/null +++ b/arch/arc/mm/fault.c @@ -0,0 +1,188 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Page Fault Handling for ARC (TLB Miss / ProtV) + * + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + */ + +#include <linux/signal.h> +#include <linux/interrupt.h> +#include <linux/sched/signal.h> +#include <linux/errno.h> +#include <linux/ptrace.h> +#include <linux/uaccess.h> +#include <linux/kdebug.h> +#include <linux/perf_event.h> +#include <linux/mm_types.h> +#include <asm/mmu.h> + +/* + * kernel virtual address is required to implement vmalloc/pkmap/fixmap + * Refer to asm/processor.h for System Memory Map + * + * It simply copies the PMD entry (pointer to 2nd level page table or hugepage) + * from swapper pgdir to task pgdir. The 2nd level table/page is thus shared + */ +noinline static int handle_kernel_vaddr_fault(unsigned long address) +{ + /* + * Synchronize this task's top level page-table + * with the 'reference' page table. + */ + pgd_t *pgd, *pgd_k; + p4d_t *p4d, *p4d_k; + pud_t *pud, *pud_k; + pmd_t *pmd, *pmd_k; + + pgd = pgd_offset_fast(current->active_mm, address); + pgd_k = pgd_offset_k(address); + + if (!pgd_present(*pgd_k)) + goto bad_area; + + p4d = p4d_offset(pgd, address); + p4d_k = p4d_offset(pgd_k, address); + if (!p4d_present(*p4d_k)) + goto bad_area; + + pud = pud_offset(p4d, address); + pud_k = pud_offset(p4d_k, address); + if (!pud_present(*pud_k)) + goto bad_area; + + pmd = pmd_offset(pud, address); + pmd_k = pmd_offset(pud_k, address); + if (!pmd_present(*pmd_k)) + goto bad_area; + + set_pmd(pmd, *pmd_k); + + /* XXX: create the TLB entry here */ + return 0; + +bad_area: + return 1; +} + +void do_page_fault(unsigned long address, struct pt_regs *regs) +{ + struct vm_area_struct *vma = NULL; + struct task_struct *tsk = current; + struct mm_struct *mm = tsk->mm; + int sig, si_code = SEGV_MAPERR; + unsigned int write = 0, exec = 0, mask; + vm_fault_t fault = VM_FAULT_SIGSEGV; /* handle_mm_fault() output */ + unsigned int flags; /* handle_mm_fault() input */ + + /* + * 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 (address >= VMALLOC_START && !user_mode(regs)) { + if (unlikely(handle_kernel_vaddr_fault(address))) + goto no_context; + else + return; + } + + /* + * If we're in an interrupt or have no user + * context, we must not take the fault.. + */ + if (faulthandler_disabled() || !mm) + goto no_context; + + if (regs->ecr_cause & ECR_C_PROTV_STORE) /* ST/EX */ + write = 1; + else if ((regs->ecr_vec == ECR_V_PROTV) && + (regs->ecr_cause == ECR_C_PROTV_INST_FETCH)) + exec = 1; + + flags = FAULT_FLAG_DEFAULT; + if (user_mode(regs)) + flags |= FAULT_FLAG_USER; + if (write) + flags |= FAULT_FLAG_WRITE; + + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); +retry: + mmap_read_lock(mm); + + vma = find_vma(mm, address); + if (!vma) + goto bad_area; + if (unlikely(address < vma->vm_start)) { + if (!(vma->vm_flags & VM_GROWSDOWN) || expand_stack(vma, address)) + goto bad_area; + } + + /* + * vm_area is good, now check permissions for this memory access + */ + mask = VM_READ; + if (write) + mask = VM_WRITE; + if (exec) + mask = VM_EXEC; + + if (!(vma->vm_flags & mask)) { + si_code = SEGV_ACCERR; + goto bad_area; + } + + fault = handle_mm_fault(vma, address, flags, regs); + + /* Quick path to respond to signals */ + if (fault_signal_pending(fault, regs)) { + if (!user_mode(regs)) + goto no_context; + return; + } + + /* + * Fault retry nuances, mmap_lock already relinquished by core mm + */ + if (unlikely((fault & VM_FAULT_RETRY) && + (flags & FAULT_FLAG_ALLOW_RETRY))) { + flags |= FAULT_FLAG_TRIED; + goto retry; + } + +bad_area: + mmap_read_unlock(mm); + + /* + * Major/minor page fault accounting + * (in case of retry we only land here once) + */ + if (likely(!(fault & VM_FAULT_ERROR))) + /* Normal return path: fault Handled Gracefully */ + return; + + if (!user_mode(regs)) + goto no_context; + + if (fault & VM_FAULT_OOM) { + pagefault_out_of_memory(); + return; + } + + if (fault & VM_FAULT_SIGBUS) { + sig = SIGBUS; + si_code = BUS_ADRERR; + } + else { + sig = SIGSEGV; + } + + tsk->thread.fault_address = address; + force_sig_fault(sig, si_code, (void __user *)address); + return; + +no_context: + if (fixup_exception(regs)) + return; + + die("Oops", regs, address); +} |