[PATCH 6.12 392/567] parisc: entry: set W bit for !compat tasks in syscall_restore_rfi()

Greg Kroah-Hartman
2026-01-06T17:37:44Z

From: Sven Schnelle <svens@stackframe.org>

commit 5fb1d3ce3e74a4530042795e1e065422295f1371 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/parisc/kernel/asm-offsets.c | 2 ++
arch/parisc/kernel/entry.S | 5 ++++-
2 files changed, 6 insertions(+), 1 deletion(-)

--- a/arch/parisc/kernel/asm-offsets.c
+++ b/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);
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -1846,6 +1846,10 @@ 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) */
@@ -1859,7 +1863,6 @@ 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.