MIPS: FPU: Fix conflict of register usage

In _restore_fp_context/_restore_fp_context32, t0 is used for both
CP0_Status and CP1_FCSR. This is a mistake and cause FP exeception on
boot, so fix it.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Tested-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Tested-by: Andreas Barth <aba@ayous.org>
Cc: John Crispin <john@phrozen.org>
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: linux-mips@linux-mips.org
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/6507/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/kernel/r4k_fpu.S b/arch/mips/kernel/r4k_fpu.S
index 841ffc2..73b0ddf 100644 (file)
--- a/arch/mips/kernel/r4k_fpu.S
+++ b/arch/mips/kernel/r4k_fpu.S
@@ -146,7 +146,7 @@ LEAF(_save_fp_context32)
  *  - cp1 status/control register
  */
 LEAF(_restore_fp_context)
-       EX      lw t0, SC_FPC_CSR(a0)
+       EX      lw t1, SC_FPC_CSR(a0)
 
 #if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPS32_R2)
        .set    push
@@ -191,7 +191,7 @@ LEAF(_restore_fp_context)
        EX      ldc1 $f26, SC_FPREGS+208(a0)
        EX      ldc1 $f28, SC_FPREGS+224(a0)
        EX      ldc1 $f30, SC_FPREGS+240(a0)
-       ctc1    t0, fcr31
+       ctc1    t1, fcr31
        jr      ra
         li     v0, 0                                   # success
        END(_restore_fp_context)
@@ -199,7 +199,7 @@ LEAF(_restore_fp_context)
 #ifdef CONFIG_MIPS32_COMPAT
 LEAF(_restore_fp_context32)
        /* Restore an o32 sigcontext.  */
-       EX      lw t0, SC32_FPC_CSR(a0)
+       EX      lw t1, SC32_FPC_CSR(a0)
 
        mfc0    t0, CP0_STATUS
        sll     t0, t0, 5
@@ -239,7 +239,7 @@ LEAF(_restore_fp_context32)
        EX      ldc1 $f26, SC32_FPREGS+208(a0)
        EX      ldc1 $f28, SC32_FPREGS+224(a0)
        EX      ldc1 $f30, SC32_FPREGS+240(a0)
-       ctc1    t0, fcr31
+       ctc1    t1, fcr31
        jr      ra
         li     v0, 0                                   # success
        END(_restore_fp_context32)