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Commit a36d8225 authored by David Daney's avatar David Daney Committed by Ralf Baechle
Browse files

MIPS: OCTEON: Enable use of FPU 



Some versions of the assembler will not assemble CFC1 for OCTEON, so
override the ISA for these.

Add r4k_fpu.o to handle low level FPU initialization.

Modify octeon_switch.S to save the FPU registers.  And include
r4k_switch.S to pick up more FPU support.

Get rid of "#define cpu_has_fpu		0"

Signed-off-by: default avatarDavid Daney <david.daney@cavium.com>
Signed-off-by: default avatarAndreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Cc: James Hogan <james.hogan@imgtec.com>
Cc: kvm@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/7006/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent dadaa1c2

arch/mips/include/asm/mach-cavium-octeon/cpu-feature-overrides.h

+0 −1
Original line number Diff line number Diff line
@@ -22,7 +22,6 @@ 
#define cpu_has_3k_cache	0

#define cpu_has_4k_cache	0

#define cpu_has_tx39_cache	0

#define cpu_has_fpu		0

#define cpu_has_counter		1

#define cpu_has_watch		1

#define cpu_has_divec		1

arch/mips/kernel/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -41,7 +41,7 @@ obj-$(CONFIG_CPU_R4K_FPU) += r4k_fpu.o r4k_switch.o 
obj-$(CONFIG_CPU_R3000)		+= r2300_fpu.o r2300_switch.o

obj-$(CONFIG_CPU_R6000)		+= r6000_fpu.o r4k_switch.o

obj-$(CONFIG_CPU_TX39XX)	+= r2300_fpu.o r2300_switch.o

obj-$(CONFIG_CPU_CAVIUM_OCTEON) += octeon_switch.o

obj-$(CONFIG_CPU_CAVIUM_OCTEON)	+= r4k_fpu.o octeon_switch.o



obj-$(CONFIG_SMP)		+= smp.o

obj-$(CONFIG_SMP_UP)		+= smp-up.o

arch/mips/kernel/branch.c

+5 −1
Original line number Diff line number Diff line
@@ -562,7 +562,11 @@ int __compute_return_epc_for_insn(struct pt_regs *regs, 
	case cop1_op:

		preempt_disable();

		if (is_fpu_owner())

			asm volatile("cfc1\t%0,$31" : "=r" (fcr31));

			asm volatile(

				".set push\n"

				"\t.set mips1\n"

				"\tcfc1\t%0,$31\n"

				"\t.set pop" : "=r" (fcr31));

		else

			fcr31 = current->thread.fpu.fcr31;

		preempt_enable();

arch/mips/kernel/octeon_switch.S

+61 −23
Original line number Diff line number Diff line
@@ -10,24 +10,12 @@ 
 * Copyright (C) 2000 MIPS Technologies, Inc.

 *    written by Carsten Langgaard, carstenl@mips.com

 */

#include <asm/asm.h>

#include <asm/cachectl.h>

#include <asm/fpregdef.h>

#include <asm/mipsregs.h>

#include <asm/asm-offsets.h>

#include <asm/pgtable-bits.h>

#include <asm/regdef.h>

#include <asm/stackframe.h>

#include <asm/thread_info.h>



#include <asm/asmmacro.h>



/*

 * Offset to the current process status flags, the first 32 bytes of the

 * stack are not used.

 */

#define ST_OFF (_THREAD_SIZE - 32 - PT_SIZE + PT_STATUS)



#define USE_ALTERNATE_RESUME_IMPL 1

	.set push

	.set arch=mips64r2

#include "r4k_switch.S"

	.set pop

/*

 * task_struct *resume(task_struct *prev, task_struct *next,

 *		       struct thread_info *next_ti, int usedfpu)
@@ -40,6 +28,61 @@ 
	cpu_save_nonscratch a0

	LONG_S	ra, THREAD_REG31(a0)



	/*

	 * check if we need to save FPU registers

	 */

	PTR_L	t3, TASK_THREAD_INFO(a0)

	LONG_L	t0, TI_FLAGS(t3)

	li	t1, _TIF_USEDFPU

	and	t2, t0, t1

	beqz	t2, 1f

	nor	t1, zero, t1



	and	t0, t0, t1

	LONG_S	t0, TI_FLAGS(t3)



	/*

	 * clear saved user stack CU1 bit

	 */

	LONG_L	t0, ST_OFF(t3)

	li	t1, ~ST0_CU1

	and	t0, t0, t1

	LONG_S	t0, ST_OFF(t3)



	.set push

	.set arch=mips64r2

	fpu_save_double a0 t0 t1		# c0_status passed in t0

						# clobbers t1

	.set pop

1:



	/* check if we need to save COP2 registers */

	PTR_L	t2, TASK_THREAD_INFO(a0)

	LONG_L	t0, ST_OFF(t2)

	bbit0	t0, 30, 1f



	/* Disable COP2 in the stored process state */

	li	t1, ST0_CU2

	xor	t0, t1

	LONG_S	t0, ST_OFF(t2)



	/* Enable COP2 so we can save it */

	mfc0	t0, CP0_STATUS

	or	t0, t1

	mtc0	t0, CP0_STATUS



	/* Save COP2 */

	daddu	a0, THREAD_CP2

	jal octeon_cop2_save

	dsubu	a0, THREAD_CP2



	/* Disable COP2 now that we are done */

	mfc0	t0, CP0_STATUS

	li	t1, ST0_CU2

	xor	t0, t1

	mtc0	t0, CP0_STATUS



1:

#if CONFIG_CAVIUM_OCTEON_CVMSEG_SIZE > 0

	/* Check if we need to store CVMSEG state */

	mfc0	t0, $11,7	/* CvmMemCtl */
@@ -85,12 +128,7 @@ 
	move	$28, a2

	cpu_restore_nonscratch a1



#if (_THREAD_SIZE - 32) < 0x8000

	PTR_ADDIU	t0, $28, _THREAD_SIZE - 32

#else

	PTR_LI		t0, _THREAD_SIZE - 32

	PTR_ADDU	t0, $28

#endif

	PTR_ADDU	t0, $28, _THREAD_SIZE - 32

	set_saved_sp	t0, t1, t2



	mfc0	t1, CP0_STATUS		/* Do we really need this? */

arch/mips/kernel/r4k_switch.S

+3 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
 */

#define ST_OFF (_THREAD_SIZE - 32 - PT_SIZE + PT_STATUS)



#ifndef USE_ALTERNATE_RESUME_IMPL

/*

 * task_struct *resume(task_struct *prev, task_struct *next,

 *		       struct thread_info *next_ti, s32 fp_save)
@@ -99,6 +100,8 @@ 
	jr	ra

	END(resume)



#endif /* USE_ALTERNATE_RESUME_IMPL */



/*

 * Save a thread's fp context.

 */