arch/mips/mm/fault.c

Source file repositories/reference/linux-study-clean/arch/mips/mm/fault.c

File Facts

System
Linux kernel
Corpus path
arch/mips/mm/fault.c
Extension
.c
Size
8504 bytes
Lines
334
Domain
Architecture Layer
Bucket
arch/mips
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

fault = handle_mm_fault(vma, address, flags, regs);

	if (fault_signal_pending(fault, regs)) {
		if (!user_mode(regs))
			goto no_context;
		return;
	}

	/* The fault is fully completed (including releasing mmap lock) */
	if (fault & VM_FAULT_COMPLETED)
		return;

	if (unlikely(fault & VM_FAULT_ERROR)) {
		if (fault & VM_FAULT_OOM)
			goto out_of_memory;
		else if (fault & VM_FAULT_SIGSEGV)
			goto bad_area;
		else if (fault & VM_FAULT_SIGBUS)
			goto do_sigbus;
		BUG();
	}

	if (fault & VM_FAULT_RETRY) {
		flags |= FAULT_FLAG_TRIED;

		/*
		 * No need to mmap_read_unlock(mm) as we would
		 * have already released it in __lock_page_or_retry
		 * in mm/filemap.c.
		 */

		goto retry;
	}

	mmap_read_unlock(mm);
	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:
	mmap_read_unlock(mm);

bad_area_nosemaphore:
	/* User mode accesses just cause a SIGSEGV */
	if (user_mode(regs)) {
		tsk->thread.cp0_badvaddr = address;
		tsk->thread.error_code = write;
		if (show_unhandled_signals &&
		    unhandled_signal(tsk, SIGSEGV) &&
		    __ratelimit(&ratelimit_state)) {
			pr_info("do_page_fault(): sending SIGSEGV to %s for invalid %s %0*lx\n",
				tsk->comm,
				write ? "write access to" : "read access from",
				field, address);
			pr_info("epc = %0*lx in", field,
				(unsigned long) regs->cp0_epc);
			print_vma_addr(KERN_CONT " ", regs->cp0_epc);
			pr_cont("\n");
			pr_info("ra  = %0*lx in", field,
				(unsigned long) regs->regs[31]);
			print_vma_addr(KERN_CONT " ", regs->regs[31]);
			pr_cont("\n");
		}
		current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
		force_sig_fault(SIGSEGV, si_code, (void __user *)address);
		return;
	}

no_context:
	/* Are we prepared to handle this kernel fault?	 */
	if (fixup_exception(regs)) {
		current->thread.cp0_baduaddr = address;
		return;
	}

	/*
	 * Oops. The kernel tried to access some bad page. We'll have to
	 * terminate things with extreme prejudice.
	 */
	bust_spinlocks(1);

	printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
	       "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
	       raw_smp_processor_id(), field, address, field, regs->cp0_epc,
	       field,  regs->regs[31]);
	die("Oops", regs);

out_of_memory:

Annotation

Implementation Notes