selftests/powerpc: Don't run DSCR tests on old systems

The DSCR tests fail on systems that don't have DSCR, so check for the
DSCR in hwcap and skip if it's not present.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200819015727.1977134-5-mpe@ellerman.id.au

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

Based on 2 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

selftests/powerpc: Fix typos

Fix two typos in the file header. Replacing the word 'priviledged'
by 'privileged' and 'exuecuted' by 'executed'.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Gustavo Romero <gromero@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

selftests/powerpc: Fix strncpy usage

There is a buffer overflow in dscr_inherit_test.c test. In main(), strncpy()'s
third argument is the length of the source, not the size of the destination
buffer, which makes strncpy() behaves like strcpy(), causing a buffer overflow
if argv[0] is bigger than LEN_MAX (100).

This patch maps 'prog' to the argv[0] memory region, removing the static
allocation and the LEN_MAX size restriction.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc: Fix DSCR inheritance over fork()

Two DSCR tests have a hack in them:

/*
* XXX: Force a context switch out so that DSCR
* current value is copied into the thread struct
* which is required for the child to inherit the
* changed value.
*/
sleep(1);

We should not be working around this in the testcase, it is a kernel bug.
Fix it by copying the current DSCR to the child, instead of what we
had in the thread struct at last context switch.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

selftests/powerpc: Add test for DSCR inheritence across fork & exec

This patch adds a test case to verify that the changed DSCR value inside
any process would be inherited to it's child across the fork and exec
system call.

Acked-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>