[S390] No execute support cleanup.

Simplify the signal_return function that checks for the two special
system calls sigreturn and rt_sigreturn. No need to do a page table
walk, a call to copy_from_user while disabled page faults will work
as well.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 8bc35183db5943a62ae6c4ff9b552b3059210c18..2b76a879a7b5455f92c3ccd9e2009b98e8393b8c 100644 (file)
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -26,9 +26,9 @@
 #include <linux/module.h>
 #include <linux/hardirq.h>
 #include <linux/kprobes.h>
+#include <linux/uaccess.h>
 
 #include <asm/system.h>
-#include <asm/uaccess.h>
 #include <asm/pgtable.h>
 #include <asm/kdebug.h>
 #include <asm/s390_ext.h>
@@ -263,68 +263,38 @@ extern long sys_rt_sigreturn(struct pt_regs *regs);
 extern long sys32_sigreturn(struct pt_regs *regs);
 extern long sys32_rt_sigreturn(struct pt_regs *regs);
 
-static inline void do_sigreturn(struct mm_struct *mm, struct pt_regs *regs,
-                               int rt)
+static int signal_return(struct mm_struct *mm, struct pt_regs *regs,
+                        unsigned long address, unsigned long error_code)
 {
+       u16 instruction;
+       int rc, compat;
+
+       pagefault_disable();
+       rc = __get_user(instruction, (u16 __user *) regs->psw.addr);
+       pagefault_enable();
+       if (rc)
+               return -EFAULT;
+
        up_read(&mm->mmap_sem);
        clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
 #ifdef CONFIG_COMPAT
-       if (test_tsk_thread_flag(current, TIF_31BIT)) {
-               if (rt)
-                       sys32_rt_sigreturn(regs);
-               else
-                       sys32_sigreturn(regs);
-               return;
-       }
-#endif /* CONFIG_COMPAT */
-       if (rt)
-               sys_rt_sigreturn(regs);
+       compat = test_tsk_thread_flag(current, TIF_31BIT);
+       if (compat && instruction == 0x0a77)
+               sys32_sigreturn(regs);
+       else if (compat && instruction == 0x0aad)
+               sys32_rt_sigreturn(regs);
        else
+#endif
+       if (instruction == 0x0a77)
                sys_sigreturn(regs);
-       return;
-}
-
-static int signal_return(struct mm_struct *mm, struct pt_regs *regs,
-                        unsigned long address, unsigned long error_code)
-{
-       pgd_t *pgd;
-       pmd_t *pmd;
-       pte_t *pte;
-       u16 *instruction;
-       unsigned long pfn, uaddr = regs->psw.addr;
-
-       spin_lock(&mm->page_table_lock);
-       pgd = pgd_offset(mm, uaddr);
-       if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
-               goto out_fault;
-       pmd = pmd_offset(pgd, uaddr);
-       if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
-               goto out_fault;
-       pte = pte_offset_map(pmd_offset(pgd_offset(mm, uaddr), uaddr), uaddr);
-       if (!pte || !pte_present(*pte))
-               goto out_fault;
-       pfn = pte_pfn(*pte);
-       if (!pfn_valid(pfn))
-               goto out_fault;
-       spin_unlock(&mm->page_table_lock);
-
-       instruction = (u16 *) ((pfn << PAGE_SHIFT) + (uaddr & (PAGE_SIZE-1)));
-       if (*instruction == 0x0a77)
-               do_sigreturn(mm, regs, 0);
-       else if (*instruction == 0x0aad)
-               do_sigreturn(mm, regs, 1);
+       else if (instruction == 0x0aad)
+               sys_rt_sigreturn(regs);
        else {
-               printk("- XXX - do_exception: task = %s, primary, NO EXEC "
-                      "-> SIGSEGV\n", current->comm);
-               up_read(&mm->mmap_sem);
                current->thread.prot_addr = address;
                current->thread.trap_no = error_code;
                do_sigsegv(regs, error_code, SEGV_MAPERR, address);
        }
        return 0;
-out_fault:
-       spin_unlock(&mm->page_table_lock);
-       return -EFAULT;
 }
 #endif /* CONFIG_S390_EXEC_PROTECT */