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.

Fixes: fcc53b5f6c38 ("MIPS: fpu.h: Allow 64-bit FPU on a 64-bit MIPS R6 CPU")
Signed-off-by: James Hogan <jhogan@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 4.0+
Patchwork: https://patchwork.linux-mips.org/patch/16739/

diff --git a/arch/mips/include/asm/asmmacro.h b/arch/mips/include/asm/asmmacro.h
index 83054f79f72aa62595923ca017936f6cd60075fd..b815d7b3bd27b08510dff89ae71bb4b6380304fd 100644 (file)
--- a/arch/mips/include/asm/asmmacro.h
+++ b/arch/mips/include/asm/asmmacro.h
@@ -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?
 

diff --git a/arch/mips/kernel/r4k_fpu.S b/arch/mips/kernel/r4k_fpu.S
index 0a83b1708b3cbed5bba0f4781107122cc0c77569..8e3a6020c613453fda948a33f4aa6435b9f79ad9 100644 (file)
--- a/arch/mips/kernel/r4k_fpu.S
+++ b/arch/mips/kernel/r4k_fpu.S
@@ -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