arm64: Floating point and SIMD

This patch adds support for FP/ASIMD register bank saving and restoring
during context switch and FP exception handling to generate SIGFPE.
There are 32 128-bit registers and the context switching is currently
done non-lazily. Benchmarks on real hardware are required before
implementing lazy FP state saving/restoring.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>

1 files changed, 80 insertions, 0 deletions

diff --git a/arch/arm64/kernel/entry-fpsimd.S b/arch/arm64/kernel/entry-fpsimd.S
new file mode 100644
index 00000000000..17988a6e7ea
--- /dev/null
+++ b/arch/arm64/kernel/entry-fpsimd.S
@@ -0,0 +1,80 @@
+/*
+ * FP/SIMD state saving and restoring
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ * Author: Catalin Marinas <catalin.marinas@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/linkage.h>
+
+#include <asm/assembler.h>
+
+/*
+ * Save the FP registers.
+ *
+ * x0 - pointer to struct fpsimd_state
+ */
+ENTRY(fpsimd_save_state)
+	stp	q0, q1, [x0, #16 * 0]
+	stp	q2, q3, [x0, #16 * 2]
+	stp	q4, q5, [x0, #16 * 4]
+	stp	q6, q7, [x0, #16 * 6]
+	stp	q8, q9, [x0, #16 * 8]
+	stp	q10, q11, [x0, #16 * 10]
+	stp	q12, q13, [x0, #16 * 12]
+	stp	q14, q15, [x0, #16 * 14]
+	stp	q16, q17, [x0, #16 * 16]
+	stp	q18, q19, [x0, #16 * 18]
+	stp	q20, q21, [x0, #16 * 20]
+	stp	q22, q23, [x0, #16 * 22]
+	stp	q24, q25, [x0, #16 * 24]
+	stp	q26, q27, [x0, #16 * 26]
+	stp	q28, q29, [x0, #16 * 28]
+	stp	q30, q31, [x0, #16 * 30]!
+	mrs	x8, fpsr
+	str	w8, [x0, #16 * 2]
+	mrs	x8, fpcr
+	str	w8, [x0, #16 * 2 + 4]
+	ret
+ENDPROC(fpsimd_save_state)
+
+/*
+ * Load the FP registers.
+ *
+ * x0 - pointer to struct fpsimd_state
+ */
+ENTRY(fpsimd_load_state)
+	ldp	q0, q1, [x0, #16 * 0]
+	ldp	q2, q3, [x0, #16 * 2]
+	ldp	q4, q5, [x0, #16 * 4]
+	ldp	q6, q7, [x0, #16 * 6]
+	ldp	q8, q9, [x0, #16 * 8]
+	ldp	q10, q11, [x0, #16 * 10]
+	ldp	q12, q13, [x0, #16 * 12]
+	ldp	q14, q15, [x0, #16 * 14]
+	ldp	q16, q17, [x0, #16 * 16]
+	ldp	q18, q19, [x0, #16 * 18]
+	ldp	q20, q21, [x0, #16 * 20]
+	ldp	q22, q23, [x0, #16 * 22]
+	ldp	q24, q25, [x0, #16 * 24]
+	ldp	q26, q27, [x0, #16 * 26]
+	ldp	q28, q29, [x0, #16 * 28]
+	ldp	q30, q31, [x0, #16 * 30]!
+	ldr	w8, [x0, #16 * 2]
+	ldr	w9, [x0, #16 * 2 + 4]
+	msr	fpsr, x8
+	msr	fpcr, x9
+	ret
+ENDPROC(fpsimd_load_state)