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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * Memory fault handling for Hexagon
- *
- * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
- */
- /*
- * Page fault handling for the Hexagon Virtual Machine.
- * Can also be called by a native port emulating the HVM
- * execptions.
- */
- #include <asm/traps.h>
- #include <linux/uaccess.h>
- #include <linux/mm.h>
- #include <linux/sched/signal.h>
- #include <linux/signal.h>
- #include <linux/extable.h>
- #include <linux/hardirq.h>
- #include <linux/perf_event.h>
- /*
- * Decode of hardware exception sends us to one of several
- * entry points. At each, we generate canonical arguments
- * for handling by the abstract memory management code.
- */
- #define FLT_IFETCH -1
- #define FLT_LOAD 0
- #define FLT_STORE 1
- /*
- * Canonical page fault handler
- */
- void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
- {
- struct vm_area_struct *vma;
- struct mm_struct *mm = current->mm;
- int si_signo;
- int si_code = SEGV_MAPERR;
- vm_fault_t fault;
- const struct exception_table_entry *fixup;
- unsigned int flags = FAULT_FLAG_DEFAULT;
- /*
- * If we're in an interrupt or have no user context,
- * then must not take the fault.
- */
- if (unlikely(in_interrupt() || !mm))
- goto no_context;
- local_irq_enable();
- if (user_mode(regs))
- flags |= FAULT_FLAG_USER;
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
- retry:
- vma = lock_mm_and_find_vma(mm, address, regs);
- if (unlikely(!vma))
- goto bad_area_nosemaphore;
- /* Address space is OK. Now check access rights. */
- si_code = SEGV_ACCERR;
- switch (cause) {
- case FLT_IFETCH:
- if (!(vma->vm_flags & VM_EXEC))
- goto bad_area;
- break;
- case FLT_LOAD:
- if (!(vma->vm_flags & VM_READ))
- goto bad_area;
- break;
- case FLT_STORE:
- if (!(vma->vm_flags & VM_WRITE))
- goto bad_area;
- flags |= FAULT_FLAG_WRITE;
- break;
- }
- fault = handle_mm_fault(vma, address, flags, regs);
- if (fault_signal_pending(fault, regs))
- return;
- /* The fault is fully completed (including releasing mmap lock) */
- if (fault & VM_FAULT_COMPLETED)
- return;
- /* The most common case -- we are done. */
- if (likely(!(fault & VM_FAULT_ERROR))) {
- if (fault & VM_FAULT_RETRY) {
- flags |= FAULT_FLAG_TRIED;
- goto retry;
- }
- mmap_read_unlock(mm);
- return;
- }
- mmap_read_unlock(mm);
- /* Handle copyin/out exception cases */
- if (!user_mode(regs))
- goto no_context;
- if (fault & VM_FAULT_OOM) {
- pagefault_out_of_memory();
- return;
- }
- /* User-mode address is in the memory map, but we are
- * unable to fix up the page fault.
- */
- if (fault & VM_FAULT_SIGBUS) {
- si_signo = SIGBUS;
- si_code = BUS_ADRERR;
- }
- /* Address is not in the memory map */
- else {
- si_signo = SIGSEGV;
- si_code = SEGV_ACCERR;
- }
- force_sig_fault(si_signo, si_code, (void __user *)address);
- return;
- bad_area:
- mmap_read_unlock(mm);
- bad_area_nosemaphore:
- if (user_mode(regs)) {
- force_sig_fault(SIGSEGV, si_code, (void __user *)address);
- return;
- }
- /* Kernel-mode fault falls through */
- no_context:
- fixup = search_exception_tables(pt_elr(regs));
- if (fixup) {
- pt_set_elr(regs, fixup->fixup);
- return;
- }
- /* Things are looking very, very bad now */
- bust_spinlocks(1);
- printk(KERN_EMERG "Unable to handle kernel paging request at "
- "virtual address 0x%08lx, regs %p\n", address, regs);
- die("Bad Kernel VA", regs, SIGKILL);
- }
- void read_protection_fault(struct pt_regs *regs)
- {
- unsigned long badvadr = pt_badva(regs);
- do_page_fault(badvadr, FLT_LOAD, regs);
- }
- void write_protection_fault(struct pt_regs *regs)
- {
- unsigned long badvadr = pt_badva(regs);
- do_page_fault(badvadr, FLT_STORE, regs);
- }
- void execute_protection_fault(struct pt_regs *regs)
- {
- unsigned long badvadr = pt_badva(regs);
- do_page_fault(badvadr, FLT_IFETCH, regs);
- }
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