Since at least kernel 6.1, flush_dcache_page() is called with IRQs
disabled, e.g. from aio_complete().

But the current implementation for flush_dcache_page() on parisc
unintentionally re-enables IRQs, which may lead to deadlocks.

Fix it by using xa_lock_irqsave() and xa_unlock_irqrestore()
for the flush_dcache_mmap_*lock() macros instead.

Cc: linux-parisc@vger.kernel.org
Cc: stable@kernel.org # 5.18+
Signed-off-by: Helge Deller <deller@gmx.de>

The kernel kgdb break instructions should only be handled when running
in kernel context.

Cc: <stable@vger.kernel.org> # v5.4+
Signed-off-by: Helge Deller <deller@gmx.de>

The kernel kprobes break instructions should only be handled when running
in kernel context.

Cc: <stable@vger.kernel.org> # v5.18+
Signed-off-by: Helge Deller <deller@gmx.de>

In case a machine can't power-off itself on system shutdown,
allow the user to reboot it by pressing the RETURN key.

Cc: <stable@vger.kernel.org> # v4.14+
Signed-off-by: Helge Deller <deller@gmx.de>

Add a lightweight spinlock check which uses only two instructions
per spinlock call. It detects if a spinlock has been trashed by
some memory corruption and then halts the kernel. It will not detect
uninitialized spinlocks, for which CONFIG_DEBUG_SPINLOCK needs to
be enabled.

This lightweight spinlock check shouldn't influence runtime, so it's
safe to enable it by default.

The __ARCH_SPIN_LOCK_UNLOCKED_VAL constant has been choosen small enough
to be able to be loaded by one LDI assembler statement.

Signed-off-by: Helge Deller <deller@gmx.de>

When patching the kernel code some alternatives depend on SMP vs. !SMP.
Use the value of num_present_cpus() instead of num_online_cpus() to
decide, otherwise we may run into issues if and additional CPU is
enabled after having loaded a module while only one CPU was enabled.

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org> # v6.1+

Add comment in arch_sync_dma_for_device() and handle the direction flag in
arch_sync_dma_for_cpu().

When receiving data from the device (DMA_FROM_DEVICE) unconditionally
purge the data cache in arch_sync_dma_for_cpu().

Signed-off-by: Helge Deller <deller@gmx.de>

Include reboot.h in machine_kexec.c for declaration of
machine_crash_shutdown and machine_shutdown.

gcc-12 with W=1 reports:

 arch/parisc/kernel/kexec.c:57:6: warning: no previous prototype for 'machine_crash_shutdown' [-Wmissing-prototypes]
    57 | void machine_crash_shutdown(struct pt_regs *regs)
       |      ^~~~~~~~~~~~~~~~~~~~~~
 arch/parisc/kernel/kexec.c:61:6: warning: no previous prototype for 'machine_shutdown' [-Wmissing-prototypes]
    61 | void machine_shutdown(void)
       |      ^~~~~~~~~~~~~~~~

No functional changes intended.
Compile tested only.

Signed-off-by: Simon Horman <horms@kernel.org>
Acked-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Helge Deller <deller@gmx.de>

Fix the argument pointer (ap) to point to real-mode memory
instead of virtual memory.

It's interesting that this issue hasn't shown up earlier, as this could
have happened with any 64-bit PDC ROM code.

I just noticed it because I suddenly faced a HPMC while trying to execute
the 64-bit STI ROM code of an Visualize-FXe graphics card for the STI
text console.

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

This change simplifies the randomization of file mapping regions. It
reworks the code to remove duplication. The flow is now similar to
that for mips. Finally, we consistently use the do_color_align variable
to determine when color alignment is needed.

Tested on rp3440.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>