As noticed by Dave Anglin, the last commit introduced a small bug where
the potentially uninitialized r struct is used instead of the regs
pointer as input for unwind_frame_init(). Fix it.

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

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

Commit c8921d72e390 ("parisc: Fix and improve kernel stack unwinding")
broke booting of 64-bit kernels. On 64-bit kernels function pointers are
actually function descriptors which require dereferencing. In this patch
we instead declare functions in assembly code which are referenced from
C-code as external data pointers with the ENTRY() macro and thus can use
a simple external reference to the functions.

Signed-off-by: Helge Deller <deller@gmx.de>
Fixes: c8921d72e390 ("parisc: Fix and improve kernel stack unwinding")

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

We do support running 64-bit userspace processes, although there isn't
yet full gcc and glibc support. Anyway, fix the comments to reflect the
reality.

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

Fix the strace code path to call 64-bit syscalls in case we are
executing by a 64-bit application.

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

Executing 64-bit applications was broken. This patch restores this
support and cleans up some code paths.

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

This patchset fixes and improves stack unwinding a lot:
1. Show backward stack traces with up to 30 callsites
2. Add callinfo to ENTRY_CFI() such that every assembler function will get an
   entry in the unwind table
3. Use constants instead of numbers in call_on_stack()
4. Do not depend on CONFIG_KALLSYMS to generate backtraces.
5. Speed up backtrace generation

Make sure you have this patch to GNU as installed:
https://sourceware.org/ml/binutils/2018-07/msg00474.html
Without this patch, unwind info in the kernel is often wrong for various
functions.

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

Now that we use a sync prior to releasing the locks in syscall.S, we don't need
the PA 2.0 ordered stores used to release some locks.  Using an ordered store,
potentially slows the release and subsequent code.

There are a number of other ordered stores and loads that serve no purpose.  I
have converted these to normal stores.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org # 4.0+
Signed-off-by: Helge Deller <deller@gmx.de>

As part of the effort to reduce the code duplication between _THIS_IP_
and current_text_addr(), let's consolidate callers of
current_text_addr() to use _THIS_IP_.

Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Helge Deller <deller@gmx.de>