Fix resembles implementation from Marc Gauthier and Piet Denaly:

In the Xtensa architecture, assembly generates literals which must always
precede the code (the L32R instruction that loads them only uses negative
PC-relative offsets).  For any *.text section, literals are placed in a
corresponding *.literal section.  The linker script (vmlinux.lds) must
place these in the correct order.  It must also combine them, when the
*.text section can be larger than L32R's 256 kB range.

For example, this doesn't work:  *(.literal) *(.text) because L32R
instructions at the end of .text can't reach the literals.

The linker can solve this if they are combined in parentheses, like this:
       *(.literal .text)
because it is now allowed mix literals in .text to bring them in range.

None of this is done by standard vmlinux.lds.h macros such as TEXT_TEXT
and INIT_TEXT.  To avoid replicating the logic of that header file, we
instead post-process the generated linker script to convert *(xxx.text)
to *(xxx.literal xxx.text) for the following text sections:
       .text .ref.text .*init.text .*exit.text .text.*
using a sed script.  To do this we must override the default rule for
vmlinux.lds (see scripts/Makefile.build and the top-level Makefile)
to insert this extra step.

Signed-off-by: Marc Gauthier <marc@tensilica.com>
Signed-off-by: Pete Delaney <piet@tensilica.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

Commit '28a0ce7 xtensa: use correct stack pointer for stack traces'
changed the stack tracer from always reading the stack pointer
register to always using the saved value in the task descriptor.

The author was too dense to consider the fact that the saved stack
value is stale for a running process und thus unusable for 'current'.

What we do now is to use the stack pointer register (a1) for when the
task is unknown - we can't help it then - or when the task is
'current'.  For everything else use the saved stack pointer value
contained in the task descriptor.

Signed-off-by: Johannes Weiner <jw@emlix.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

Signed-off-by: Tim Abbott <tabbott@mit.edu>
Cc: Chris Zankel <chris@zankel.net>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Move it from .text to .init.text to get rid of it after boot and
prevent illegal section references.

Signed-off-by: Daniel Glöckner <dg@emlix.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

Switch to GENERIC_TIME by using the ccount register as a clock source.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Chris Zankel <chris@zankel.net>

platform_get/set_rtc_time() is not implemented by any of the supported
xtensa platforms.  Remove the facility completely.

The initial seconds for xtime come from read_persistent_clock() which
returns just 0 in the generic implementation.  Platforms that sport a
persistent clock can implement this function.

This is needed to implement the ccount as a clock source.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Chris Zankel <chris@zankel.net>

Current xtensa implementation of sched_clock() is the same as the
generic one.  Just remove it, the weak symbol in kernel/sched_clock.c
will be used instead.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Chris Zankel <chris@zankel.net>

The linker script should not assume a fix offset in memory for the
kernel, this is platform-specific, so let the platform set it.

Signed-off-by: Johannes Weiner <jw@emlix.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

Allow the core variant code to provide irq enable/disable callbacks.

Signed-off-by: Johannes Weiner <jw@emlix.com>
Signed-off-by: Chris Zankel <chris@zankel.net>