The RTAS device-tree node's refcount has been increased by one in
the function call of_find_node_by_name(), but it's missed to be
decreased by one in the error path. It leads to unbalanced refcount
on RTAS device-tree node.

This fixes above issue by decreasing RTAS device-tree node's refcount
in error path.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This uses of_property_read_u32() in rtas_initialize() so that we
needn't explicitly care the CPU's endian.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This removes the unnecessary nested if statements in function
rtas_initialize(), to simplify the code. No functional changes
introduced.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This was entirely automated, using the script by Al:

  PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
  sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
        $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.

Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

powernv marks it's halt and restart calls as __noreturn. However,
ppc_md does not have this annotation. Add the annotation to ppc_md,
and then to every halt/restart function that is missing it.

Additionally, I have verified that all of these functions do not
return. Occasionally I have added a spin loop to be sure.

Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

The test is unnecessary, the FW_FEATURE_LPAR is sufficient as there
exist no other LPAR type that has RTAS.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

If ppc_rtas() is called with args.nargs == 16 and args.nret == 0,
args.rets is set to point to &args.args[16], which is beyond the end of
the args.args array. This results in a minor read overrun of the array
when we check the first return code (which, per PAPR, is a required
output of all RTAS calls) to see if there's been a hardware error.

Change the nargs/nret check to ensure nargs is <= 15, allowing room for
the status code. Users shouldn't be calling with nret == 0, but there's
no real harm if they do, so we don't stop them.

Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

There are no longer any users of enter_rtas() outside of rtas.c, so make
it "private", by moving the declaration inside rtas.c. Hopefully this
will encourage people to use one of the wrappers which takes the sharp
edges off the RTAS calling sequence.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Although call_rtas_display_status() does actually want to use the
regular RTAS locking, it doesn't want the extra logic that is in
rtas_call(), so currently it open codes the logic.

Instead we can use rtas_call_unlocked(), after taking the RTAS lock.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Most users of RTAS (Run-Time Abstraction Services) use rtas_call(),
which deals with locking as well as endian handling.

However we have two users outside of rtas.c that can't use rtas_call()
because they have different locking requirements.

The hotplug CPU code can't take the RTAS lock because the CPU would go
offline with the lock held and no other CPUs would be able to call RTAS
until the CPU came back online.

The xmon code doesn't want to take the lock because it would risk dead
locking when we are trying to recover from a crash.

Both sites required multiple patches when we added little endian
support, proving that programmers can't do endian right.

Although that ship has sailed, we can still clean the code up by
providing an unlocked version of rtas_call() which avoids the need to
open code the logic elsewhere.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>