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: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 9ed9796906654f93a67528648e06e7126bda26bd..e0dbc231828c8f55d6acec425823eb18be54520a 100644 (file)
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -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);