arm64: drop already applied reg leak patch

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

2 files changed, 0 insertions, 95 deletions

diff --git a/queue/arm64-fpsimd-Prevent-registers-leaking-from-dead-tas.patch b/queue/arm64-fpsimd-Prevent-registers-leaking-from-dead-tas.patch
deleted file mode 100644
index cfaebd8..0000000
--- a/queue/arm64-fpsimd-Prevent-registers-leaking-from-dead-tas.patch
+++ /dev/null
@@ -1,94 +0,0 @@
-From 071b6d4a5d343046f253a5a8835d477d93992002 Mon Sep 17 00:00:00 2001
-From: Dave Martin <Dave.Martin@arm.com>
-Date: Tue, 5 Dec 2017 14:56:42 +0000
-Subject: [PATCH] arm64: fpsimd: Prevent registers leaking from dead tasks
-
-commit 071b6d4a5d343046f253a5a8835d477d93992002 upstream.
-
-Currently, loading of a task's fpsimd state into the CPU registers
-is skipped if that task's state is already present in the registers
-of that CPU.
-
-However, the code relies on the struct fpsimd_state * (and by
-extension struct task_struct *) to unambiguously identify a task.
-
-There is a particular case in which this doesn't work reliably:
-when a task exits, its task_struct may be recycled to describe a
-new task.
-
-Consider the following scenario:
-
- 1) Task P loads its fpsimd state onto cpu C.
-        per_cpu(fpsimd_last_state, C) := P;
-        P->thread.fpsimd_state.cpu := C;
-
- 2) Task X is scheduled onto C and loads its fpsimd state on C.
-        per_cpu(fpsimd_last_state, C) := X;
-        X->thread.fpsimd_state.cpu := C;
-
- 3) X exits, causing X's task_struct to be freed.
-
- 4) P forks a new child T, which obtains X's recycled task_struct.
-	T == X.
-	T->thread.fpsimd_state.cpu == C (inherited from P).
-
- 5) T is scheduled on C.
-	T's fpsimd state is not loaded, because
-	per_cpu(fpsimd_last_state, C) == T (== X) &&
-	T->thread.fpsimd_state.cpu == C.
-
-        (This is the check performed by fpsimd_thread_switch().)
-
-So, T gets X's registers because the last registers loaded onto C
-were those of X, in (2).
-
-This patch fixes the problem by ensuring that the sched-in check
-fails in (5): fpsimd_flush_task_state(T) is called when T is
-forked, so that T->thread.fpsimd_state.cpu == C cannot be true.
-This relies on the fact that T is not schedulable until after
-copy_thread() completes.
-
-Once T's fpsimd state has been loaded on some CPU C there may still
-be other cpus D for which per_cpu(fpsimd_last_state, D) ==
-&X->thread.fpsimd_state.  But D is necessarily != C in this case,
-and the check in (5) must fail.
-
-An alternative fix would be to do refcounting on task_struct.  This
-would result in each CPU holding a reference to the last task whose
-fpsimd state was loaded there.  It's not clear whether this is
-preferable, and it involves higher overhead than the fix proposed
-in this patch.  It would also move all the task_struct freeing
-work into the context switch critical section, or otherwise some
-deferred cleanup mechanism would need to be introduced, neither of
-which seems obviously justified.
-
-Cc: <stable@vger.kernel.org>
-Fixes: 005f78cd8849 ("arm64: defer reloading a task's FPSIMD state to userland resume")
-Signed-off-by: Dave Martin <Dave.Martin@arm.com>
-Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
-[will: word-smithed the comment so it makes more sense]
-Signed-off-by: Will Deacon <will.deacon@arm.com>
-
-diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
-index b2adcce7bc18..6b7dcf4310ac 100644
---- a/arch/arm64/kernel/process.c
-+++ b/arch/arm64/kernel/process.c
-@@ -314,6 +314,15 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start,
- 	clear_tsk_thread_flag(p, TIF_SVE);
- 	p->thread.sve_state = NULL;
- 
-+	/*
-+	 * In case p was allocated the same task_struct pointer as some
-+	 * other recently-exited task, make sure p is disassociated from
-+	 * any cpu that may have run that now-exited task recently.
-+	 * Otherwise we could erroneously skip reloading the FPSIMD
-+	 * registers for p.
-+	 */
-+	fpsimd_flush_task_state(p);
-+
- 	if (likely(!(p->flags & PF_KTHREAD))) {
- 		*childregs = *current_pt_regs();
- 		childregs->regs[0] = 0;
--- 
-2.15.0
-
diff --git a/queue/series b/queue/series
index 2ea0c86..90436ba 100644
--- a/queue/series
+++ b/queue/series
@@ -51,7 +51,6 @@ kdb-Fix-handling-of-kallsyms_symbol_next-return-valu.patch
 drm-bridge-analogix-dp-Fix-runtime-PM-state-in-get_m.patch
 drm-exynos-gem-Drop-NONCONTIG-flag-for-buffers-alloc.patch
 media-dvb-i2c-transfers-over-usb-cannot-be-done-from.patch
-arm64-fpsimd-Prevent-registers-leaking-from-dead-tas.patch
 arm64-SW-PAN-Point-saved-ttbr0-at-the-zero-page-when.patch
 arm64-SW-PAN-Update-saved-ttbr0-value-on-enter_lazy_.patch
 Revert-ARM-dts-imx53-add-srtc-node.patch