After commit 4b9d2a731c3d ("parisc: Switch user access functions
to signal errors in r29 instead of r8") bash suddenly started
to report those warnings after login:

-bash: cannot set terminal process group (-1): Bad file descriptor
-bash: no job control in this shell

It turned out, that a function call inside a put_user(), e.g.:
put_user(vt_do_kdgkbmode(console), (int __user *)arg);
clobbered the error register (r29) and thus the put_user() call itself
seem to have failed.

Rearrange the C-code to pre-calculate the intermediate value
and then do the put_user().
Additionally prefer the "+" constraint on pu_err and gu_err registers
to tell the compiler that those operands are both read and written by
the assembly instruction.

Reported-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Fixes: 4b9d2a731c3d ("parisc: Switch user access functions to signal errors in r29 instead of r8")
Signed-off-by: Helge Deller <deller@gmx.de>

It happens quite often that people use the wrong compiler to build the
kernel:

make ARCH=parisc   -> builds the 32-bit kernel
make ARCH=parisc64 -> builds the 64-bit kernel

This patch adds a sanity check which errors out with an instruction how
use the correct ARCH= option.

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org # v5.15+

Pull bitmap updates from Yury Norov:

 - introduce for_each_set_bitrange()

 - use find_first_*_bit() instead of find_next_*_bit() where possible

 - unify for_each_bit() macros

* tag 'bitmap-5.17-rc1' of git://github.com/norov/linux:
  vsprintf: rework bitmap_list_string
  lib: bitmap: add performance test for bitmap_print_to_pagebuf
  bitmap: unify find_bit operations
  mm/percpu: micro-optimize pcpu_is_populated()
  Replace for_each_*_bit_from() with for_each_*_bit() where appropriate
  find: micro-optimize for_each_{set,clear}_bit()
  include/linux: move for_each_bit() macros from bitops.h to find.h
  cpumask: replace cpumask_next_* with cpumask_first_* where appropriate
  tools: sync tools/bitmap with mother linux
  all: replace find_next{,_zero}_bit with find_first{,_zero}_bit where appropriate
  cpumask: use find_first_and_bit()
  lib: add find_first_and_bit()
  arch: remove GENERIC_FIND_FIRST_BIT entirely
  include: move find.h from asm_generic to linux
  bitops: move find_bit_*_le functions from le.h to find.h
  bitops: protect find_first_{,zero}_bit properly

Fix a missing prototype warning noticed by the kernel test robot.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Helge Deller <deller@gmx.de>

find_bit API and bitmap API are closely related, but inclusion paths
are different - include/asm-generic and include/linux, correspondingly.
In the past it made a lot of troubles due to circular dependencies
and/or undefined symbols. Fix this by moving find.h under include/linux.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>

This patch fixes the following build error for source file
drivers/scsi/pcmcia/sym53c500_cs.c:

In file included from ./include/linux/bug.h:5,
                 from ./include/linux/cpumask.h:14,
                 from ./include/linux/mm_types_task.h:14,
                 from ./include/linux/mm_types.h:5,
                 from ./include/linux/buildid.h:5,
                 from ./include/linux/module.h:14,
                 from drivers/scsi/pcmcia/sym53c500_cs.c:42:
drivers/scsi/pcmcia/sym53c500_cs.c: In function ‘SYM53C500_intr’:
./arch/parisc/include/asm/bug.h:28:2: error: expected expression before ‘do’
   28 |  do {        \
      |  ^~
./arch/parisc/include/asm/io.h:276:20: note: in expansion of macro ‘BUG’
  276 | #define outb(x, y) BUG()
      |                    ^~~
drivers/scsi/pcmcia/sym53c500_cs.c:124:19: note: in expansion of macro ‘outb’
  124 | #define REG0(x)  (outb(C4_IMG, (x) + CONFIG4))
      |                   ^~~~
drivers/scsi/pcmcia/sym53c500_cs.c:362:2: note: in expansion of macro ‘REG0’
  362 |  REG0(port_base);
      |  ^~~~

Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: linux-parisc@vger.kernel.org
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Helge Deller <deller@gmx.de>

The definitions for pdc_toc_pim_11 and pdc_toc_pim_20 are wrong since they
include an entry for a hversion field which doesn't exist in the specification.

Fix this and clean up some whitespaces so that the whole file will be in
sync with it's copy in the SeaBIOS-hppa sources.

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org # v5.16

The parisc architecture lacks general hardware support for compare and swap.
Particularly for userspace, it is difficult to implement software atomic
support. Page faults in critical regions can cause processes to sleep and
block the forward progress of other processes.  Thus, it is essential that
page faults be disabled in critical regions. For performance reasons, we
also need to disable external interrupts in critical regions.

In order to do this, we need a mechanism to trigger COW breaks outside the
critical region. Fortunately, parisc has the "stbys,e" instruction. When
the leftmost byte of a word is addressed, this instruction triggers all
the exceptions of a normal store but it does not write to memory. Thus,
we can use it to trigger COW breaks outside the critical region without
modifying the data that is to be updated atomically.

COW breaks occur randomly.  So even if we have priviously executed a "stbys,e"
instruction, we still need to disable pagefaults around the critical region.
If a fault occurs in the critical region, we return -EAGAIN. I had to add
a wrapper around _arch_futex_atomic_op_inuser() as I found in testing that
returning -EAGAIN caused problems for some processes even though it is
listed as a possible return value.

The patch implements the above. The code no longer attempts to sleep with
interrupts disabled and I haven't seen any stalls with the change.

I have attempted to merge common code and streamline the fast path.  In the
futex code, we only compute the spinlock address once.

I eliminated some debug code in the original CAS routine that just made the
flow more complicated.

I don't clip the arguments when called from wide mode. As a result, the LWS
routines should work when called from 64-bit processes.

I defined TASK_PAGEFAULT_DISABLED offset for use in the lws_pagefault_disable
and lws_pagefault_enable macros.

Since we now disable interrupts on the gateway page where necessary, it
might be possible to allow processes to be scheduled when they are on the
gateway page.

Change has been tested on c8000 and rp3440. It improves glibc build and test
time by about 10%.

In v2, I removed the lws_atomic_xchg and and lws_atomic_store calls. I
also removed the bug fixes that were not directly related to this patch.

In v3, I removed the code to force interruptions from
arch_futex_atomic_op_inuser(). It is always called with page faults
disabled, so this code had no effect.

In v4, I fixed a typo in depi_safe line.

In v5, I moved the code to disable/enable page faults inside the spinlocks.

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

Use register r29 instead of register r8 to signal faults when accessing
user memory. In case of faults, the fixup routine will store -EFAULT in
this register.

This change saves up to 752 bytes on a 32bit kernel, partly because the
compiler doesn't need to save and restore the old r8 value on the stack.

bloat-o-meter results for usage with r29 register:
add/remove: 0/0 grow/shrink: 23/86 up/down: 228/-980 (-752)

bloat-o-meter results for usage with r28 register:
add/remove: 0/0 grow/shrink: 28/83 up/down: 296/-956 (-660)

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

While working on the rewrite to the light-weight syscall and futex code, I
experimented with using a hash index based on the user physical address of
atomic variable. This exposed two problems with the lpa and lpa_user defines.

Because of the copy instruction, the pa argument needs to be an early clobber
argument. This prevents gcc from allocating the va and pa arguments to the same
register.

Secondly, the lpa instruction can cause a page fault so we need to catch
exceptions.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Fixes: 116d753308cf ("parisc: Use lpa instruction to load physical addresses in driver code")
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org # v5.2+