[PATCH v3 10/11] s390/mm: Get rid of fault type switch statements

Claudio Imbrenda
2024-10-15T16:43:34Z

From: Heiko Carstens <hca@linux.ibm.com>

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.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
---
arch/s390/mm/fault.c | 70 ++++++++++++++------------------------------
1 file changed, 22 insertions(+), 48 deletions(-)

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 6e96fc7905fc..93ae097ef0e0 100644
--- 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);
--
2.47.0