Mark Rutland 46b0567c85 arm64: entry: fix context tracking for el0_sp_pc ... Commit 6c81fe7925 ("arm64: enable context tracking") did not update el0_sp_pc to use ct_user_exit, but this appears to have been unintentional. In commit 6ab6463aeb ("arm64: adjust el0_sync so that a function can be called") we made x0 available, and in the return to userspace we call ct_user_enter in the kernel_exit macro. Due to this, we currently don't correctly inform RCU of the user->kernel transition, and may erroneously account for time spent in the kernel as if we were in an extended quiescent state when CONFIG_CONTEXT_TRACKING is enabled. As we do record the kernel->user transition, a userspace application making accesses from an unaligned stack pointer can demonstrate the imbalance, provoking the following warning: ------------[ cut here ]------------ WARNING: CPU: 2 PID: 3660 at kernel/context_tracking.c:75 context_tracking_enter+0xd8/0xe4() Modules linked in: CPU: 2 PID: 3660 Comm: a.out Not tainted 4.1.0-rc7+ #8 Hardware name: ARM Juno development board (r0) (DT) Call trace: [<ffffffc000089914>] dump_backtrace+0x0/0x124 [<ffffffc000089a48>] show_stack+0x10/0x1c [<ffffffc0005b3cbc>] dump_stack+0x84/0xc8 [<ffffffc0000b3214>] warn_slowpath_common+0x98/0xd0 [<ffffffc0000b330c>] warn_slowpath_null+0x14/0x20 [<ffffffc00013ada4>] context_tracking_enter+0xd4/0xe4 [<ffffffc0005b534c>] preempt_schedule_irq+0xd4/0x114 [<ffffffc00008561c>] el1_preempt+0x4/0x28 [<ffffffc0001b8040>] exit_files+0x38/0x4c [<ffffffc0000b5b94>] do_exit+0x430/0x978 [<ffffffc0000b614c>] do_group_exit+0x40/0xd4 [<ffffffc0000c0208>] get_signal+0x23c/0x4f4 [<ffffffc0000890b4>] do_signal+0x1ac/0x518 [<ffffffc000089650>] do_notify_resume+0x5c/0x68 ---[ end trace 963c192600337066 ]--- This patch adds the missing ct_user_exit to the el0_sp_pc entry path, correcting the context tracking for this case. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Fixes: 6c81fe7925 ("arm64: enable context tracking") Cc: <stable@vger.kernel.org> # v3.17+ Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>		2015-06-17 11:53:19 +01:00
..
boot	ARM64: juno: add sp810 support and fix sp804 clock frequency	2015-05-12 16:39:28 +02:00
configs	arm64: defconfig: enable memtest	2015-06-15 16:57:46 +01:00
crypto	Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6	2015-05-11 11:05:13 -07:00
include	arm64: mm: remove reference to tlb.S from comment block	2015-06-12 15:36:52 +01:00
kernel	arm64: entry: fix context tracking for el0_sp_pc	2015-06-17 11:53:19 +01:00
kvm	arm64: KVM: Switch vgic save/restore to alternative_insn	2015-06-12 15:12:08 +01:00
lib	arm64: __clear_user: handle exceptions on strb	2014-11-13 15:21:26 +00:00
mm	arm64: Do not attempt to use init_mm in reset_context()	2015-06-12 15:36:18 +01:00
net	arm64: bpf: fix signedness bug in loading 64-bit immediate	2015-05-08 16:15:07 +01:00
xen	arm: xen: implement multicall hypercall support.	2014-04-24 13:09:46 +01:00
Kconfig	arm64: Allow forced irq threading	2015-05-19 15:27:42 +01:00
Kconfig.debug	coresight: moving to new "hwtracing" directory	2015-04-03 16:17:04 +02:00
Makefile	arm64: Adjust EFI libstub object include logic	2015-03-17 16:59:47 +00:00