ARM: 9491/1: alignment: restore uaccess state on emulation fault

The alignment handlers enable access to user memory while emulating
unaligned instructions. If a checked access faults, its exception table
fixup jumps to the handler's fault label and bypasses uaccess_restore().
This leaves DOMAIN_USER as DOMAIN_CLIENT with SW domain PAN, or leaves
TTBR0 page table walks enabled with TTBR0 PAN, while the fault is handled.

An ARM926 QEMU test using LDMIA across an unmapped page boundary reports
DOMAIN_USER=1 at TYPE_FAULT before this change and DOMAIN_USER=0 after it.
SW domain PAN is the default on ARMv5, ARMv6, and non-LPAE ARMv7 builds.

Keep the saved uaccess state at function scope and track whether it was
saved. Restore it at the fault label only when needed. Paths that did not
enable user access continue to skip the restore.

Assisted-by: Codex:gpt-5.6-sol

Fixes: 274e91b81ed2 ("ARM: alignment: fix alignment handling for uaccess changes")
Cc: stable@vger.kernel.org
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

0 files changed, 0 insertions, 0 deletions