[S390] addressing mode limits and psw address wrapping

An instruction with an address right below the adress limit for the
current addressing mode will wrap. The instruction restart logic in
the protection fault handler and the signal code need to follow the
wrapping rules to find the correct instruction address.

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

1 files changed, 21 insertions, 1 deletions

diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index a4b6229e5d4b..306c93c1b184 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -187,7 +187,6 @@ static inline void __load_psw(psw_t psw)
  * Set PSW mask to specified value, while leaving the
  * PSW addr pointing to the next instruction.
  */
-
 static inline void __load_psw_mask (unsigned long mask)
 {
         unsigned long addr;
@@ -212,6 +211,27 @@ static inline void __load_psw_mask (unsigned long mask)
                 : "=&d" (addr), "=Q" (psw) : "Q" (psw) : "memory", "cc");
 #endif /* __s390x__ */
 }
+
+/*
+ * Rewind PSW instruction address by specified number of bytes.
+ */
+static inline unsigned long __rewind_psw(psw_t psw, unsigned long ilc)
+{
+#ifndef __s390x__
+        if (psw.addr & PSW_ADDR_AMODE)
+                /* 31 bit mode */
+                return (psw.addr - ilc) | PSW_ADDR_AMODE;
+        /* 24 bit mode */
+        return (psw.addr - ilc) & ((1UL << 24) - 1);
+#else
+        unsigned long mask;
+
+        mask = (psw.mask & PSW_MASK_EA) ? -1UL :
+               (psw.mask & PSW_MASK_BA) ? (1UL << 31) - 1 :
+                                          (1UL << 24) - 1;
+        return (psw.addr - ilc) & mask;
+#endif
+}
  
 /*
  * Function to stop a processor until an interruption occurred