FAILED: patch "[PATCH] MIPS: Fix MIPS64 FP save/restore on 32-bit kernels" failed to apply to 4.4-stable tree

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From: James Hogan <[email protected]>
Date: Mon, 3 Jul 2017 23:41:47 +0100
Subject: [PATCH] MIPS: Fix MIPS64 FP save/restore on 32-bit kernels

32-bit kernels can be configured to support MIPS64, in which case neither CONFIG_64BIT or CONFIG_CPU_MIPS32_R* will be set. This causes the CP0_Status.FR checks at the point of floating point register save and restore to be compiled out, which results in odd FP registers not being saved or restored to the task or signal context even when CP0_Status.FR is set.

Fix the ifdefs to use CONFIG_CPU_MIPSR2 and CONFIG_CPU_MIPSR6, which are enabled for the relevant revisions of either MIPS32 or MIPS64, along with some other CPUs such as Octeon (r2), Loongson1 (r2), XLP (r2), Loongson 3A R2.

The suspect code originates from commit 597ce1723e0f ("MIPS: Support for 64-bit FP with O32 binaries") in v3.14, however the code in __enable_fpu() was consistent and refused to set FR=1, falling back to software FPU emulation. This was suboptimal but should be functionally correct.

Commit fcc53b5f6c38 ("MIPS: fpu.h: Allow 64-bit FPU on a 64-bit MIPS R6 CPU") in v4.2 (and stable tagged back to 4.0) later introduced the bug by updating __enable_fpu() to set FR=1 but failing to update the other similar ifdefs to enable FR=1 state handling.

Patchwork: https://patchwork.linux-mips.org/patch/16739/

index 83054f79f72a..b815d7b3bd27 100644
@@ -126,8 +126,8 @@
 	.endm
 
 	.macro	fpu_save_double thread status tmp
-#if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPS32_R2) || \
-		defined(CONFIG_CPU_MIPS32_R6)
+#if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPSR2) || \
+		defined(CONFIG_CPU_MIPSR6)
 	sll	\tmp, \status, 5
 	bgez	\tmp, 10f
 	fpu_save_16odd \thread

@@ -184,8 +184,8 @@
 	.endm
 
 	.macro	fpu_restore_double thread status tmp
-#if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPS32_R2) || \
-		defined(CONFIG_CPU_MIPS32_R6)
+#if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPSR2) || \
+		defined(CONFIG_CPU_MIPSR6)
 	sll	\tmp, \status, 5
 	bgez	\tmp, 10f				# 16 register mode?
 

index 0a83b1708b3c..8e3a6020c613 100644
@@ -40,8 +40,8 @@
  */
 LEAF(_save_fp)
 EXPORT_SYMBOL(_save_fp)
-#if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPS32_R2) || \
-		defined(CONFIG_CPU_MIPS32_R6)
+#if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPSR2) || \
+		defined(CONFIG_CPU_MIPSR6)
 	mfc0	t0, CP0_STATUS
 #endif
 	fpu_save_double a0 t0 t1		# clobbers t1

@@ -52,8 +52,8 @@ EXPORT_SYMBOL(_save_fp)
  * Restore a thread's fp context.
  */
 LEAF(_restore_fp)
-#if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPS32_R2) || \
-		defined(CONFIG_CPU_MIPS32_R6)
+#if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPSR2) || \
+		defined(CONFIG_CPU_MIPSR6)
 	mfc0	t0, CP0_STATUS
 #endif
 	fpu_restore_double a0 t0 t1		# clobbers t1

@@ -246,11 +246,11 @@ LEAF(_save_fp_context)
 	cfc1	t1, fcr31
 	.set	pop
 
-#if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPS32_R2) || \
-		defined(CONFIG_CPU_MIPS32_R6)
+#if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPSR2) || \
+		defined(CONFIG_CPU_MIPSR6)
 	.set	push
 	SET_HARDFLOAT
-#ifdef CONFIG_CPU_MIPS32_R2
+#ifdef CONFIG_CPU_MIPSR2
 	.set	mips32r2
 	.set	fp=64
 	mfc0	t0, CP0_STATUS

@@ -314,11 +314,11 @@ LEAF(_save_fp_context)
 LEAF(_restore_fp_context)
 	EX	lw t1, 0(a1)
 
-#if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPS32_R2)  || \
-		defined(CONFIG_CPU_MIPS32_R6)
+#if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPSR2)  || \
+		defined(CONFIG_CPU_MIPSR6)
 	.set	push
 	SET_HARDFLOAT
-#ifdef CONFIG_CPU_MIPS32_R2
+#ifdef CONFIG_CPU_MIPSR2
 	.set	mips32r2
 	.set	fp=64
 	mfc0	t0, CP0_STATUS