s390/mm: Get rid of fault type switch statements

With GMAP_FAULT fault type gone, there are only KERNEL_FAULT and
USER_FAULT fault types left. Therefore there is no need for any fault
type switch statements left.

Rename get_fault_type() into is_kernel_fault() and let it return a
boolean value. Change all switch statements to if statements. This
removes quite a bit of code.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Link: https://lore.kernel.org/r/20241022120601.167009-11-imbrenda@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 6e96fc7905fccbff684ead5e7956a2da94bf3be8..93ae097ef0e0801cefc1476690b0cae1810ce60c 100644 (file)
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -46,11 +46,6 @@
 #include <asm/uv.h>
 #include "../kernel/entry.h"
 
-enum fault_type {
-       KERNEL_FAULT,
-       USER_FAULT,
-};
-
 static DEFINE_STATIC_KEY_FALSE(have_store_indication);
 
 static int __init fault_init(void)
@@ -64,15 +59,15 @@ early_initcall(fault_init);
 /*
  * Find out which address space caused the exception.
  */
-static enum fault_type get_fault_type(struct pt_regs *regs)
+static bool is_kernel_fault(struct pt_regs *regs)
 {
        union teid teid = { .val = regs->int_parm_long };
 
        if (user_mode(regs))
-               return USER_FAULT;
+               return false;
        if (teid.as == PSW_BITS_AS_SECONDARY)
-               return USER_FAULT;
-       return KERNEL_FAULT;
+               return false;
+       return true;
 }
 
 static unsigned long get_fault_address(struct pt_regs *regs)
@@ -167,17 +162,12 @@ static void dump_fault_info(struct pt_regs *regs)
                break;
        }
        pr_cont("mode while using ");
-       switch (get_fault_type(regs)) {
-       case USER_FAULT:
-               asce = get_lowcore()->user_asce.val;
-               pr_cont("user ");
-               break;
-       case KERNEL_FAULT:
+       if (is_kernel_fault(regs)) {
                asce = get_lowcore()->kernel_asce.val;
                pr_cont("kernel ");
-               break;
-       default:
-               unreachable();
+       } else {
+               asce = get_lowcore()->user_asce.val;
+               pr_cont("user ");
        }
        pr_cont("ASCE.\n");
        dump_pagetable(asce, get_fault_address(regs));
@@ -212,7 +202,6 @@ static void do_sigsegv(struct pt_regs *regs, int si_code)
 
 static void handle_fault_error_nolock(struct pt_regs *regs, int si_code)
 {
-       enum fault_type fault_type;
        unsigned long address;
        bool is_write;
 
@@ -223,17 +212,15 @@ static void handle_fault_error_nolock(struct pt_regs *regs, int si_code)
        }
        if (fixup_exception(regs))
                return;
-       fault_type = get_fault_type(regs);
-       if (fault_type == KERNEL_FAULT) {
+       if (is_kernel_fault(regs)) {
                address = get_fault_address(regs);
                is_write = fault_is_write(regs);
                if (kfence_handle_page_fault(address, is_write, regs))
                        return;
-       }
-       if (fault_type == KERNEL_FAULT)
                pr_alert("Unable to handle kernel pointer dereference in virtual kernel address space\n");
-       else
+       } else {
                pr_alert("Unable to handle kernel paging request in virtual user address space\n");
+       }
        dump_fault_info(regs);
        die(regs, "Oops");
 }
@@ -267,7 +254,6 @@ static void do_exception(struct pt_regs *regs, int access)
        struct vm_area_struct *vma;
        unsigned long address;
        struct mm_struct *mm;
-       enum fault_type type;
        unsigned int flags;
        vm_fault_t fault;
        bool is_write;
@@ -282,15 +268,8 @@ static void do_exception(struct pt_regs *regs, int access)
        mm = current->mm;
        address = get_fault_address(regs);
        is_write = fault_is_write(regs);
-       type = get_fault_type(regs);
-       switch (type) {
-       case KERNEL_FAULT:
+       if (is_kernel_fault(regs) || faulthandler_disabled() || !mm)
                return handle_fault_error_nolock(regs, 0);
-       case USER_FAULT:
-               if (faulthandler_disabled() || !mm)
-                       return handle_fault_error_nolock(regs, 0);
-               break;
-       }
        perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
        flags = FAULT_FLAG_DEFAULT;
        if (user_mode(regs))
@@ -460,8 +439,15 @@ void do_secure_storage_access(struct pt_regs *regs)
                 */
                panic("Unexpected PGM 0x3d with TEID bit 61=0");
        }
-       switch (get_fault_type(regs)) {
-       case USER_FAULT:
+       if (is_kernel_fault(regs)) {
+               folio = phys_to_folio(addr);
+               if (unlikely(!folio_try_get(folio)))
+                       return;
+               rc = arch_make_folio_accessible(folio);
+               folio_put(folio);
+               if (rc)
+                       BUG();
+       } else {
                mm = current->mm;
                mmap_read_lock(mm);
                vma = find_vma(mm, addr);
@@ -470,7 +456,7 @@ void do_secure_storage_access(struct pt_regs *regs)
                folio = folio_walk_start(&fw, vma, addr, 0);
                if (!folio) {
                        mmap_read_unlock(mm);
-                       break;
+                       return;
                }
                /* arch_make_folio_accessible() needs a raised refcount. */
                folio_get(folio);
@@ -480,18 +466,6 @@ void do_secure_storage_access(struct pt_regs *regs)
                if (rc)
                        send_sig(SIGSEGV, current, 0);
                mmap_read_unlock(mm);
-               break;
-       case KERNEL_FAULT:
-               folio = phys_to_folio(addr);
-               if (unlikely(!folio_try_get(folio)))
-                       break;
-               rc = arch_make_folio_accessible(folio);
-               folio_put(folio);
-               if (rc)
-                       BUG();
-               break;
-       default:
-               unreachable();
        }
 }
 NOKPROBE_SYMBOL(do_secure_storage_access);