parisc: entry: set W bit for !compat tasks in syscall_restore_rfi()

When the kernel leaves to userspace via syscall_restore_rfi(), the
W bit is not set in the new PSW. This doesn't cause any problems
because there's no 64 bit userspace for parisc. Simple static binaries
are usually loaded at addresses way below the 32 bit limit so the W bit
doesn't matter.

Fix this by setting the W bit when TIF_32BIT is not set.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
Cc: stable@vger.kernel.org
Signed-off-by: Helge Deller <deller@gmx.de>

Author: Sven Schnelle

arch/parisc/kernel/asm-offsets.c

@@ -258,6 +258,8 @@ int main(void)
 	BLANK();
 	DEFINE(TIF_BLOCKSTEP_PA_BIT, 31-TIF_BLOCKSTEP);
 	DEFINE(TIF_SINGLESTEP_PA_BIT, 31-TIF_SINGLESTEP);
+	DEFINE(TIF_32BIT_PA_BIT, 31-TIF_32BIT);
+
 	BLANK();
 	DEFINE(ASM_PMD_SHIFT, PMD_SHIFT);
 	DEFINE(ASM_PGDIR_SHIFT, PGDIR_SHIFT);

arch/parisc/kernel/entry.S

@@ -1841,6 +1841,10 @@ syscall_restore_rfi:
 	extru,= %r19,TIF_BLOCKSTEP_PA_BIT,1,%r0
 	depi	-1,7,1,%r20			   /* T bit */
 
+#ifdef CONFIG_64BIT
+	extru,<> %r19,TIF_32BIT_PA_BIT,1,%r0
+	depi	-1,4,1,%r20			   /* W bit */
+#endif
 	STREG	%r20,TASK_PT_PSW(%r1)
 
 	/* Always store space registers, since sr3 can be changed (e.g. fork) */
@@ -1854,7 +1858,6 @@ syscall_restore_rfi:
 	STREG   %r25,TASK_PT_IASQ0(%r1)
 	STREG   %r25,TASK_PT_IASQ1(%r1)
 
-	/* XXX W bit??? */
 	/* Now if old D bit is clear, it means we didn't save all registers
 	 * on syscall entry, so do that now.  This only happens on TRACEME
 	 * calls, or if someone attached to us while we were on a syscall.