tracing/syscalls: combined patches from cyanogenmod

tracing/syscalls: Fix perf syscall tracing when syscall_nr == -1
syscall_get_nr can return -1 in the case that the task is not executing
a system call.

This patch fixes perf_syscall_{enter,exit} to check that the syscall
number is valid before using it as an index into a bitmap.

Link: http://lkml.kernel.org/r/1345137254-7377-1-git-send-email-
will.deacon@arm.com

Change-Id: Ie730f03d82ed3e44b53a6fe42b97172b435f04eb
Cc: Jason Baron <jbaron@redhat.com>
Cc: Wade Farnsworth <wade_farnsworth@mentor.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

tracing/syscalls: Ignore numbers outside NR_syscalls' range
ARM has some private syscalls (for example, set_tls(2)) which lie
outside the range of NR_syscalls.  If any of these are called while
syscall tracing is being performed, out-of-bounds array access will
occur in the ftrace and perf sys_{enter,exit} handlers.

...
true-653   [000]   384.675777: sys_enter:            NR 192 (0, 1000,
3, 4000022, ffffffff, 0)
true-653   [000]   384.675812: sys_exit:             NR 192 =
1995915264
true-653   [000]   384.675971: sys_enter:            NR 983045
(76f74480, 76f74000, 76f74b28, 76f74480, 76f76f74, 1)
true-653   [000]   384.675988: sys_exit:             NR 983045 = 0
...

[   17.289329] Unable to handle kernel paging request at virtual
address aaaaaace
[   17.289590] pgd = 9e71c000
[   17.289696] [aaaaaace] *pgd=00000000
[   17.289985] Internal error: Oops: 5 [#1] PREEMPT SMP ARM
[   17.290169] Modules linked in:
[   17.290391] CPU: 0 PID: 704 Comm: true Not tainted 3.18.0-rc2+ #21
[   17.290585] task: 9f4dab00 ti: 9e710000 task.ti: 9e710000
[   17.290747] PC is at ftrace_syscall_enter+0x48/0x1f8
[   17.290866] LR is at syscall_trace_enter+0x124/0x184

Fix this by ignoring out-of-NR_syscalls-bounds syscall numbers.

Commit cd0980f "tracing: Check invalid syscall nr while tracing
syscalls"
added the check for less than zero, but it should have also checked
for greater than NR_syscalls.

Link: http://lkml.kernel.org/p/1414620418-29472-1-git-send-email-
rabin@rab.in

Fixes: cd0980f "tracing: Check invalid syscall nr while tracing
syscalls"
Cc: stable@vger.kernel.org # 2.6.33+
Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
frandom: now builtin
stweaks: use deltas for cpu & gpu voltage control