[S390] cleanup lowcore access from program checks

Read all required fields for program checks from the lowcore in the
first level interrupt handler in entry[64].S. If the context that
caused the fault was enabled for interrupts we can now re-enable the
irqs in entry[64].S.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 14 insertions, 22 deletions

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index bae2c282221..b6570069b12 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -333,12 +333,6 @@ static inline int do_exception(struct pt_regs *regs, int access,
                 goto out;
 
         address = trans_exc_code & __FAIL_ADDR_MASK;
-        /*
-         * When we get here, the fault happened in the current
-         * task's user address space, so we can switch on the
-         * interrupts again and then search the VMAs
-         */
-        local_irq_enable();
         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);
         down_read(&mm->mmap_sem);
 
@@ -397,20 +391,20 @@ out:
         return fault;
 }
 
-void __kprobes do_protection_exception(struct pt_regs *regs, long int_code)
+void __kprobes do_protection_exception(struct pt_regs *regs, long pgm_int_code,
+                                       unsigned long trans_exc_code)
 {
-        unsigned long trans_exc_code = S390_lowcore.trans_exc_code;
         int fault;
 
         /* Protection exception is supressing, decrement psw address. */
-        regs->psw.addr -= (int_code >> 16);
+        regs->psw.addr -= (pgm_int_code >> 16);
         /*
          * Check for low-address protection.  This needs to be treated
          * as a special case because the translation exception code
          * field is not guaranteed to contain valid data in this case.
          */
         if (unlikely(!(trans_exc_code & 4))) {
-                do_low_address(regs, int_code, trans_exc_code);
+                do_low_address(regs, pgm_int_code, trans_exc_code);
                 return;
         }
         fault = do_exception(regs, VM_WRITE, trans_exc_code);
@@ -418,9 +412,9 @@ void __kprobes do_protection_exception(struct pt_regs *regs, long int_code)
                 do_fault_error(regs, 4, trans_exc_code, fault);
 }
 
-void __kprobes do_dat_exception(struct pt_regs *regs, long int_code)
+void __kprobes do_dat_exception(struct pt_regs *regs, long pgm_int_code,
+                                unsigned long trans_exc_code)
 {
-        unsigned long trans_exc_code = S390_lowcore.trans_exc_code;
         int access, fault;
 
         access = VM_READ | VM_EXEC | VM_WRITE;
@@ -431,21 +425,19 @@ void __kprobes do_dat_exception(struct pt_regs *regs, long int_code)
 #endif
         fault = do_exception(regs, access, trans_exc_code);
         if (unlikely(fault))
-                do_fault_error(regs, int_code & 255, trans_exc_code, fault);
+                do_fault_error(regs, pgm_int_code & 255, trans_exc_code, fault);
 }
 
 #ifdef CONFIG_64BIT
-void __kprobes do_asce_exception(struct pt_regs *regs, long int_code)
+void __kprobes do_asce_exception(struct pt_regs *regs, long pgm_int_code,
+                                 unsigned long trans_exc_code)
 {
-        unsigned long trans_exc_code = S390_lowcore.trans_exc_code;
         struct mm_struct *mm = current->mm;
         struct vm_area_struct *vma;
 
         if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
                 goto no_context;
 
-        local_irq_enable();
-
         down_read(&mm->mmap_sem);
         vma = find_vma(mm, trans_exc_code & __FAIL_ADDR_MASK);
         up_read(&mm->mmap_sem);
@@ -457,16 +449,16 @@ void __kprobes do_asce_exception(struct pt_regs *regs, long int_code)
 
         /* User mode accesses just cause a SIGSEGV */
         if (regs->psw.mask & PSW_MASK_PSTATE) {
-                do_sigsegv(regs, int_code, SEGV_MAPERR, trans_exc_code);
+                do_sigsegv(regs, pgm_int_code, SEGV_MAPERR, trans_exc_code);
                 return;
         }
 
 no_context:
-        do_no_context(regs, int_code, trans_exc_code);
+        do_no_context(regs, pgm_int_code, trans_exc_code);
 }
 #endif
 
-int __handle_fault(unsigned long uaddr, unsigned long int_code, int write_user)
+int __handle_fault(unsigned long uaddr, unsigned long pgm_int_code, int write)
 {
         struct pt_regs regs;
         int access, fault;
@@ -477,14 +469,14 @@ int __handle_fault(unsigned long uaddr, unsigned long int_code, int write_user)
         regs.psw.addr = (unsigned long) __builtin_return_address(0);
         regs.psw.addr |= PSW_ADDR_AMODE;
         uaddr &= PAGE_MASK;
-        access = write_user ? VM_WRITE : VM_READ;
+        access = write ? VM_WRITE : VM_READ;
         fault = do_exception(&regs, access, uaddr | 2);
         if (unlikely(fault)) {
                 if (fault & VM_FAULT_OOM) {
                         pagefault_out_of_memory();
                         fault = 0;
                 } else if (fault & VM_FAULT_SIGBUS)
-                        do_sigbus(&regs, int_code, uaddr);
+                        do_sigbus(&regs, pgm_int_code, uaddr);
         }
         return fault ? -EFAULT : 0;
 }