ARM: 7809/1: perf: fix event validation for software group leaders

It is possible to construct an event group with a software event as a
group leader and then subsequently add a hardware event to the group.
This results in the event group being validated by adding all members
of the group to a fake PMU and attempting to allocate each event on
their respective PMU.

Unfortunately, for software events wthout a corresponding arm_pmu, this
results in a kernel crash attempting to dereference the ->get_event_idx
function pointer.

This patch fixes the problem by checking explicitly for software events
and ignoring those in event validation (since they can always be
scheduled). We will probably want to revisit this for 3.12, since the
validation checks don't appear to work correctly when dealing with
multiple hardware PMUs anyway.

Change-Id: Ic1722ba7463c9836f1ff595d7e8da1d0fc0e32b0
Cc: <stable@vger.kernel.org>
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Git-commit: c95eb3184ea1a3a2551df57190c81da695e2144b
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
[joonwoop@codeaurora.org: fixed merge conflict]
CRs-fixed: 529735
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>

Conflicts:
	arch/arm/kernel/perf_event.c
ARM: 7810/1: perf: Fix array out of bounds access in armpmu_map_hw_event()

Vince Weaver reports an oops in the ARM perf event code while
running his perf_fuzzer tool on a pandaboard running v3.11-rc4.

Unable to handle kernel paging request at virtual address 73fd14cc
pgd = eca6c000
[73fd14cc] *pgd=00000000
Internal error: Oops: 5 [#1] SMP ARM
Modules linked in: snd_soc_omap_hdmi omapdss snd_soc_omap_abe_twl6040 snd_soc_twl6040 snd_soc_omap snd_soc_omap_hdmi_card snd_soc_omap_mcpdm snd_soc_omap_mcbsp snd_soc_core snd_compress regmap_spi snd_pcm snd_page_alloc snd_timer snd soundcore
CPU: 1 PID: 2790 Comm: perf_fuzzer Not tainted 3.11.0-rc4 #6
task: eddcab80 ti: ed892000 task.ti: ed892000
PC is at armpmu_map_event+0x20/0x88
LR is at armpmu_event_init+0x38/0x280
pc : [<c001c3e4>]    lr : [<c001c17c>]    psr: 60000013
sp : ed893e40  ip : ecececec  fp : edfaec00
r10: 00000000  r9 : 00000000  r8 : ed8c3ac0
r7 : ed8c3b5c  r6 : edfaec00  r5 : 00000000  r4 : 00000000
r3 : 000000ff  r2 : c0496144  r1 : c049611c  r0 : edfaec00
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
Control: 10c5387d  Table: aca6c04a  DAC: 00000015
Process perf_fuzzer (pid: 2790, stack limit = 0xed892240)
Stack: (0xed893e40 to 0xed894000)
3e40: 00000800 c001c17c 00000002 c008a748 00000001 00000000 00000000 c00bf078
3e60: 00000000 edfaee50 00000000 00000000 00000000 edfaec00 ed8c3ac0 edfaec00
3e80: 00000000 c073ffac ed893f20 c00bf180 00000001 00000000 c00bf078 ed893f20
3ea0: 00000000 ed8c3ac0 00000000 00000000 00000000 c0cb0818 eddcab80 c00bf440
3ec0: ed893f20 00000000 eddcab80 eca76800 00000000 eca76800 00000000 00000000
3ee0: 00000000 ec984c80 eddcab80 c00bfe68 00000000 00000000 00000000 00000080
3f00: 00000000 ed892000 00000000 ed892030 00000004 ecc7e3c8 ecc7e3c8 00000000
3f20: 00000000 00000048 ecececec 00000000 00000000 00000000 00000000 00000000
3f40: 00000000 00000000 00297810 00000000 00000000 00000000 00000000 00000000
3f60: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
3f80: 00000002 00000002 000103a4 00000002 0000016c c00128e8 ed892000 00000000
3fa0: 00090998 c0012700 00000002 000103a4 00090ab8 00000000 00000000 0000000f
3fc0: 00000002 000103a4 00000002 0000016c 00090ab0 00090ab8 000107a0 00090998
3fe0: bed92be0 bed92bd0 0000b785 b6e8f6d0 40000010 00090ab8 00000000 00000000
[<c001c3e4>] (armpmu_map_event+0x20/0x88) from [<c001c17c>] (armpmu_event_init+0x38/0x280)
[<c001c17c>] (armpmu_event_init+0x38/0x280) from [<c00bf180>] (perf_init_event+0x108/0x180)
[<c00bf180>] (perf_init_event+0x108/0x180) from [<c00bf440>] (perf_event_alloc+0x248/0x40c)
[<c00bf440>] (perf_event_alloc+0x248/0x40c) from [<c00bfe68>] (SyS_perf_event_open+0x4f4/0x8fc)
[<c00bfe68>] (SyS_perf_event_open+0x4f4/0x8fc) from [<c0012700>] (ret_fast_syscall+0x0/0x48)
Code: 0a000005 e3540004 0a000016 e3540000 (0791010c)

This is because event->attr.config in armpmu_event_init()
contains a very large number copied directly from userspace and
is never checked against the size of the array indexed in
armpmu_map_hw_event(). Fix the problem by checking the value of
config before indexing the array and rejecting invalid config
values.

Change-Id: I77c21164fc0f57f8a44dd0bcc7d00b51998669f6
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Vince Weaver <vincent.weaver@maine.edu>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Git-commit: d9f966357b14e356dbd83b8f4a197a287ab4ff83
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
CRs-fixed: 561044
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>

Conflicts:
	arch/arm/kernel/perf_event.c