Commit 0f1a14e0 authored by Heiko Carstens's avatar Heiko Carstens Committed by Vasily Gorbik
Browse files

s390/mm,fault: simplify kfence fault handling 



do_no_context() can be simplified by removing its fault parameter,
which is only used to decide if kfence_handle_page_fault() should be
called.

If the fault happened within the kernel space it is ok to always check
if this happened on a page which was unmapped because of the kfence
feature. Limiting the check to the VM_FAULT_BADCONTEXT case doesn't
add any value.

Reviewed-by: default avatarClaudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 64ea33fb

arch/s390/mm/fault.c

+8 −8
Original line number Diff line number Diff line
@@ -234,7 +234,7 @@ static void do_sigsegv(struct pt_regs *regs, int si_code) 
	force_sig_fault(SIGSEGV, si_code, (void __user *)get_fault_address(regs));

}



static void do_no_context(struct pt_regs *regs, vm_fault_t fault)

static void do_no_context(struct pt_regs *regs)

{

	enum fault_type fault_type;

	unsigned long address;
@@ -243,7 +243,7 @@ static void do_no_context(struct pt_regs *regs, vm_fault_t fault) 
	if (fixup_exception(regs))

		return;

	fault_type = get_fault_type(regs);

	if ((fault_type == KERNEL_FAULT) && (fault == VM_FAULT_BADCONTEXT)) {

	if (fault_type == KERNEL_FAULT) {

		address = get_fault_address(regs);

		is_write = fault_is_write(regs);

		if (kfence_handle_page_fault(address, is_write, regs))
@@ -279,28 +279,28 @@ static void do_fault_error(struct pt_regs *regs, vm_fault_t fault) 
		}

		fallthrough;

	case VM_FAULT_BADCONTEXT:

		do_no_context(regs, fault);

		do_no_context(regs);

		break;

	case VM_FAULT_SIGNAL:

		if (!user_mode(regs))

			do_no_context(regs, fault);

			do_no_context(regs);

		break;

	default: /* fault & VM_FAULT_ERROR */

		if (fault & VM_FAULT_OOM) {

			if (!user_mode(regs))

				do_no_context(regs, fault);

				do_no_context(regs);

			else

				pagefault_out_of_memory();

		} else if (fault & VM_FAULT_SIGSEGV) {

			/* Kernel mode? Handle exceptions or die */

			if (!user_mode(regs))

				do_no_context(regs, fault);

				do_no_context(regs);

			else

				do_sigsegv(regs, SEGV_MAPERR);

		} else if (fault & VM_FAULT_SIGBUS) {

			/* Kernel mode? Handle exceptions or die */

			if (!user_mode(regs))

				do_no_context(regs, fault);

				do_no_context(regs);

			else

				do_sigbus(regs);

		} else {
@@ -497,7 +497,7 @@ void do_protection_exception(struct pt_regs *regs) 
		 * Low-address protection in kernel mode means

		 * NULL pointer write access in kernel mode.

		 */

		return do_no_context(regs, VM_FAULT_BADACCESS);

		return do_no_context(regs);

	}

	if (unlikely(MACHINE_HAS_NX && teid.b56)) {

		regs->int_parm_long = (teid.addr * PAGE_SIZE) | (regs->psw.addr & PAGE_MASK);