GCC-4.6 can find more unused code than previous versions could.

In the case of protected_restore_fp_context{,32}, the variable tmp is
really used.  Its use is tricky in that we really care about the side
effects of the __put_user() calls.  So we must mark tmp with
__maybe_unused to quiet the warning.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2035/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

o32 compat does the right thing, native and n32 compat do not...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/1700/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Put the original syscall number into ->regs[0] when we leave syscall
with error.  Use it in restart logics.  Everything else will have
it 0 since we pass through SAVE_SOME on all the ways in.  Note that
in places like bad_stack and inllegal_syscall we leave it 0 - it's not
restartable.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/1698/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/1696/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

This is a follow on to the vdso patch.

Since all processes now have signal trampolines permanently mapped, we
can use those instead of putting the trampoline on the stack and
invalidating the corresponding icache across all CPUs.  We also get rid
of a bunch of ICACHE_REFILLS_WORKAROUND_WAR code.

[Ralf: GDB 7.1 which has the necessary modifications to allow backtracing
over signal frames will supposedly be released tomorrow.  The old signal
frame format obsoleted by this patch exists in two variations, for sane
processors and for those requiring ICACHE_REFILLS_WORKAROUND_WAR.  So
there was never a GDB which did support backtracing over signal frames
on all MIPS systems.  This convinved me this series should be applied and
pushed upstream as soon as possible.]

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/974/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/709/

Add #inclusions of linux/tracehook.h to those arch files that had the tracehook
call for TIF_NOTIFY_RESUME added when support for that flag was added to that
arch.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

Add a keyctl to install a process's session keyring onto its parent.  This
replaces the parent's session keyring.  Because the COW credential code does
not permit one process to change another process's credentials directly, the
change is deferred until userspace next starts executing again.  Normally this
will be after a wait*() syscall.

To support this, three new security hooks have been provided:
cred_alloc_blank() to allocate unset security creds, cred_transfer() to fill in
the blank security creds and key_session_to_parent() - which asks the LSM if
the process may replace its parent's session keyring.

The replacement may only happen if the process has the same ownership details
as its parent, and the process has LINK permission on the session keyring, and
the session keyring is owned by the process, and the LSM permits it.

Note that this requires alteration to each architecture's notify_resume path.
This has been done for all arches barring blackfin, m68k* and xtensa, all of
which need assembly alteration to support TIF_NOTIFY_RESUME.  This allows the
replacement to be performed at the point the parent process resumes userspace
execution.

This allows the userspace AFS pioctl emulation to fully emulate newpag() and
the VIOCSETTOK and VIOCSETTOK2 pioctls, all of which require the ability to
alter the parent process's PAG membership.  However, since kAFS doesn't use
PAGs per se, but rather dumps the keys into the session keyring, the session
keyring of the parent must be replaced if, for example, VIOCSETTOK is passed
the newpag flag.

This can be tested with the following program:

	#include <stdio.h>
	#include <stdlib.h>
	#include <keyutils.h>

	#define KEYCTL_SESSION_TO_PARENT	18

	#define OSERROR(X, S) do { if ((long)(X) == -1) { perror(S); exit(1); } } while(0)

	int main(int argc, char **argv)
	{
		key_serial_t keyring, key;
		long ret;

		keyring = keyctl_join_session_keyring(argv[1]);
		OSERROR(keyring, "keyctl_join_session_keyring");

		key = add_key("user", "a", "b", 1, keyring);
		OSERROR(key, "add_key");

		ret = keyctl(KEYCTL_SESSION_TO_PARENT);
		OSERROR(ret, "KEYCTL_SESSION_TO_PARENT");

		return 0;
	}

Compiled and linked with -lkeyutils, you should see something like:

	[dhowells@andromeda ~]$ keyctl show
	Session Keyring
	       -3 --alswrv   4043  4043  keyring: _ses
	355907932 --alswrv   4043    -1   \_ keyring: _uid.4043
	[dhowells@andromeda ~]$ /tmp/newpag
	[dhowells@andromeda ~]$ keyctl show
	Session Keyring
	       -3 --alswrv   4043  4043  keyring: _ses
	1055658746 --alswrv   4043  4043   \_ user: a
	[dhowells@andromeda ~]$ /tmp/newpag hello
	[dhowells@andromeda ~]$ keyctl show
	Session Keyring
	       -3 --alswrv   4043  4043  keyring: hello
	340417692 --alswrv   4043  4043   \_ user: a

Where the test program creates a new session keyring, sticks a user key named
'a' into it and then installs it on its parent.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

Implement TIF_NOTIFY_RESUME for most of those architectures in which isn't yet
available, and, whilst we're at it, have it call the appropriate tracehook.

After this patch, blackfin, m68k* and xtensa still lack support and need
alteration of assembly code to make it work.

Resume notification can then be used (by a later patch) to install a new
session keyring on the parent of a process.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>

cc: linux-arch@vger.kernel.org
Signed-off-by: James Morris <jmorris@namei.org>

Thanks to David Daney helping with debugging and testing.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: David Daney <ddaney@caviumnetworks.com>