MIPS: Loongson-3: Enable COP2 usage in kernel

Loongson-3's COP2 is Multi-Media coprocessor, it is disabled in kernel
mode by default. However, gslq/gssq (16-bytes load/store instructions)
overrides the instruction format of lwc2/swc2. If we wan't to use gslq/
gssq for optimization in kernel, we should enable COP2 usage in kernel.

Please pay attention that in this patch we only enable COP2 in kernel,
which means it will lose ST0_CU2 when a process go to user space (try
to use COP2 in user space will trigger an exception and then grab COP2,
which is similar to FPU). And as a result, we need to modify the context
switching code because the new scheduled process doesn't contain ST0_CU2
in its THERAD_STATUS probably.

For zboot, we disable gslq/gssq be generated by toolchain.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

diff --git a/arch/mips/boot/compressed/Makefile b/arch/mips/boot/compressed/Makefile
index 9a9ba77..d665118 100644 (file)
--- a/arch/mips/boot/compressed/Makefile
+++ b/arch/mips/boot/compressed/Makefile
@@ -22,6 +22,11 @@ KBUILD_CFLAGS := $(filter-out -pg, $(KBUILD_CFLAGS))
 
 KBUILD_CFLAGS := $(filter-out -fstack-protector, $(KBUILD_CFLAGS))
 
+# Disable lq/sq in zboot
+ifdef CONFIG_CPU_LOONGSON64
+KBUILD_CFLAGS := $(filter-out -march=loongson3a, $(KBUILD_CFLAGS)) -march=mips64r2
+endif
+
 KBUILD_CFLAGS := $(KBUILD_CFLAGS) -D__KERNEL__ -D__DISABLE_EXPORTS \
        -DBOOT_HEAP_SIZE=$(BOOT_HEAP_SIZE) -D"VMLINUX_LOAD_ADDRESS_ULL=$(VMLINUX_LOAD_ADDRESS)ull"
 

diff --git a/arch/mips/include/asm/mipsregs.h b/arch/mips/include/asm/mipsregs.h
index 3a7379b..a0e8ae5 100644 (file)
--- a/arch/mips/include/asm/mipsregs.h
+++ b/arch/mips/include/asm/mipsregs.h
@@ -389,6 +389,13 @@
 #define ST0_CU3                        0x80000000
 #define ST0_XX                 0x80000000      /* MIPS IV naming */
 
+/* in-kernel enabled CUs */
+#ifdef CONFIG_CPU_LOONGSON64
+#define ST0_KERNEL_CUMASK      (ST0_CU0 | ST0_CU2)
+#else
+#define ST0_KERNEL_CUMASK      ST0_CU0
+#endif
+
 /*
  * Bitfields and bit numbers in the coprocessor 0 IntCtl register. (MIPSR2)
  */

diff --git a/arch/mips/include/asm/stackframe.h b/arch/mips/include/asm/stackframe.h
index 3e8d2aa..aa430a6 100644 (file)
--- a/arch/mips/include/asm/stackframe.h
+++ b/arch/mips/include/asm/stackframe.h
@@ -450,7 +450,7 @@
  */
                .macro  CLI
                mfc0    t0, CP0_STATUS
-               li      t1, ST0_CU0 | STATMASK
+               li      t1, ST0_KERNEL_CUMASK | STATMASK
                or      t0, t1
                xori    t0, STATMASK
                mtc0    t0, CP0_STATUS
@@ -463,7 +463,7 @@
  */
                .macro  STI
                mfc0    t0, CP0_STATUS
-               li      t1, ST0_CU0 | STATMASK
+               li      t1, ST0_KERNEL_CUMASK | STATMASK
                or      t0, t1
                xori    t0, STATMASK & ~1
                mtc0    t0, CP0_STATUS
@@ -477,7 +477,7 @@
  */
                .macro  KMODE
                mfc0    t0, CP0_STATUS
-               li      t1, ST0_CU0 | (STATMASK & ~1)
+               li      t1, ST0_KERNEL_CUMASK | (STATMASK & ~1)
 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
                andi    t2, t0, ST0_IEP
                srl     t2, 2

diff --git a/arch/mips/kernel/head.S b/arch/mips/kernel/head.S
index 7dd234e..61b7358 100644 (file)
--- a/arch/mips/kernel/head.S
+++ b/arch/mips/kernel/head.S
@@ -35,7 +35,7 @@
        .macro  setup_c0_status set clr
        .set    push
        mfc0    t0, CP0_STATUS
-       or      t0, ST0_CU0|\set|0x1f|\clr
+       or      t0, ST0_KERNEL_CUMASK|\set|0x1f|\clr
        xor     t0, 0x1f|\clr
        mtc0    t0, CP0_STATUS
        .set    noreorder

diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index f5dc316..b36297e 100644 (file)
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -68,7 +68,7 @@ void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
        unsigned long status;
 
        /* New thread loses kernel privileges. */
-       status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
+       status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_CU2|ST0_FR|KU_MASK);
        status |= KU_USER;
        regs->cp0_status = status;
        lose_fpu(0);
@@ -133,7 +133,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
        childregs = (struct pt_regs *) childksp - 1;
        /*  Put the stack after the struct pt_regs.  */
        childksp = (unsigned long) childregs;
-       p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
+       p->thread.cp0_status = (read_c0_status() & ~(ST0_CU2|ST0_CU1)) | ST0_KERNEL_CUMASK;
        if (unlikely(p->flags & PF_KTHREAD)) {
                /* kernel thread */
                unsigned long status = p->thread.cp0_status;

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 38aa07c..14225b6 100644 (file)
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -2192,7 +2192,7 @@ static void configure_status(void)
         * flag that some firmware may have left set and the TS bit (for
         * IP27).  Set XX for ISA IV code to work.
         */
-       unsigned int status_set = ST0_CU0;
+       unsigned int status_set = ST0_KERNEL_CUMASK;
 #ifdef CONFIG_64BIT
        status_set |= ST0_FR|ST0_KX|ST0_SX|ST0_UX;
 #endif