From 0126eaab7077162eb9c62a9a21fc359db8711372 Mon Sep 17 00:00:00 2001
From: Dave Martin <Dave.Martin@arm.com>
Date: Wed, 6 Dec 2017 16:45:46 +0000
Subject: [PATCH] arm64: fpsimd: Abstract out binding of task's fpsimd context
 to the cpu.

Git-commit: 8884b7bd7e52de20a801c5f457954ed212c0f625
Patch-mainline: v4.15-rc3
References: fate#325866

There is currently some duplicate logic to associate current's
FPSIMD context with the cpu when loading FPSIMD state into the cpu
regs.

Subsequent patches will update that logic, so in order to ensure it
only needs to be done in one place, this patch factors the relevant
code out into a new function fpsimd_bind_to_cpu().

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
 arch/arm64/kernel/fpsimd.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index e8f2529c264a..01a74f27f028 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -992,6 +992,18 @@ void fpsimd_signal_preserve_current_state(void)
 }
 
 /*
+ * Associate current's FPSIMD context with this cpu
+ * Preemption must be disabled when calling this function.
+ */
+static void fpsimd_bind_to_cpu(void)
+{
+	struct fpsimd_state *st = &current->thread.fpsimd_state;
+
+	__this_cpu_write(fpsimd_last_state, st);
+	st->cpu = smp_processor_id();
+}
+
+/*
  * Load the userland FPSIMD state of 'current' from memory, but only if the
  * FPSIMD state already held in the registers is /not/ the most recent FPSIMD
  * state of 'current'
@@ -1004,11 +1016,8 @@ void fpsimd_restore_current_state(void)
 	local_bh_disable();
 
 	if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
-		struct fpsimd_state *st = &current->thread.fpsimd_state;
-
 		task_fpsimd_load();
-		__this_cpu_write(fpsimd_last_state, st);
-		st->cpu = smp_processor_id();
+		fpsimd_bind_to_cpu();
 	}
 
 	local_bh_enable();
@@ -1032,12 +1041,8 @@ void fpsimd_update_current_state(struct fpsimd_state *state)
 
 	task_fpsimd_load();
 
-	if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
-		struct fpsimd_state *st = &current->thread.fpsimd_state;
-
-		__this_cpu_write(fpsimd_last_state, st);
-		st->cpu = smp_processor_id();
-	}
+	if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE))
+		fpsimd_bind_to_cpu();
 
 	local_bh_enable();
 }
-- 
2.11.0