linux/arch/powerpc/kernel/fpu.S

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 *  FPU support code, moved here from head.S so that it can be used
 *  by chips which use other head-whatever.S files.
 *
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *    Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
 *    Copyright (C) 1996 Paul Mackerras.
 *    Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
 */

#include <asm/reg.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/cputable.h>
#include <asm/cache.h>
#include <asm/thread_info.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
#include <asm/ptrace.h>
#include <asm/export.h>
#include <asm/asm-compat.h>
#include <asm/feature-fixups.h>

#ifdef CONFIG_VSX
#define __REST_32FPVSRS(n,c,base)					\
BEGIN_FTR_SECTION							\
	b	2f;							\
END_FTR_SECTION_IFSET(CPU_FTR_VSX);					\
	REST_32FPRS(n,base);						\
	b	3f;							\
2:	REST_32VSRS(n,c,base);						\
3:

#define __SAVE_32FPVSRS(n,c,base)					\
BEGIN_FTR_SECTION							\
	b	2f;							\
END_FTR_SECTION_IFSET(CPU_FTR_VSX);					\
	SAVE_32FPRS(n,base);						\
	b	3f;							\
2:	SAVE_32VSRS(n,c,base);						\
3:
#else
#define __REST_32FPVSRS(n,b,base)	REST_32FPRS(n, base)
#define __SAVE_32FPVSRS(n,b,base)	SAVE_32FPRS(n, base)
#endif
#define REST_32FPVSRS(n,c,base) __REST_32FPVSRS(n,__REG_##c,__REG_##base)
#define SAVE_32FPVSRS(n,c,base) __SAVE_32FPVSRS(n,__REG_##c,__REG_##base)

/*
 * Load state from memory into FP registers including FPSCR.
 * Assumes the caller has enabled FP in the MSR.
 */
_GLOBAL(load_fp_state)
	lfd	fr0,FPSTATE_FPSCR(r3)
	MTFSF_L(fr0)
	REST_32FPVSRS(0, R4, R3)
	blr
EXPORT_SYMBOL(load_fp_state)
_ASM_NOKPROBE_SYMBOL(load_fp_state); /* used by restore_math */

/*
 * Store FP state into memory, including FPSCR
 * Assumes the caller has enabled FP in the MSR.
 */
_GLOBAL(store_fp_state)
	SAVE_32FPVSRS(0, R4, R3)
	mffs	fr0
	stfd	fr0,FPSTATE_FPSCR(r3)
	blr
EXPORT_SYMBOL(store_fp_state)

/*
 * This task wants to use the FPU now.
 * On UP, disable FP for the task which had the FPU previously,
 * and save its floating-point registers in its thread_struct.
 * Load up this task's FP registers from its thread_struct,
 * enable the FPU for the current task and return to the task.
 * Note that on 32-bit this can only use registers that will be
 * restored by fast_exception_return, i.e. r3 - r6, r10 and r11.
 */
_GLOBAL(load_up_fpu)
	mfmsr	r5
	ori	r5,r5,MSR_FP
#ifdef CONFIG_VSX
BEGIN_FTR_SECTION
	oris	r5,r5,MSR_VSX@h
END_FTR_SECTION_IFSET(CPU_FTR_VSX)
#endif
	MTMSRD(r5)			/* enable use of fpu now */
	isync
	/* enable use of FP after return */
#ifdef CONFIG_PPC32
	mfspr	r5,SPRN_SPRG_THREAD	/* current task's THREAD (phys) */
#ifdef CONFIG_VMAP_STACK
	tovirt(r5, r5)
#endif
	lwz	r4,THREAD_FPEXC_MODE(r5)
	ori	r9,r9,MSR_FP		/* enable FP for current */
	or	r9,r9,r4
#else
	ld	r4,PACACURRENT(r13)
	addi	r5,r4,THREAD		/* Get THREAD */
	lwz	r4,THREAD_FPEXC_MODE(r5)
	ori	r12,r12,MSR_FP
	or	r12,r12,r4
	std	r12,_MSR(r1)
#endif
	li	r4,1
	stb	r4,THREAD_LOAD_FP(r5)
	addi	r10,r5,THREAD_FPSTATE
	lfd	fr0,FPSTATE_FPSCR(r10)
	MTFSF_L(fr0)
	REST_32FPVSRS(0, R4, R10)
	/* restore registers and return */
	/* we haven't used ctr or xer or lr */
	blr
_ASM_NOKPROBE_SYMBOL(load_up_fpu)

/*
 * save_fpu(tsk)
 * Save the floating-point registers in its thread_struct.
 * Enables the FPU for use in the kernel on return.
 */
_GLOBAL(save_fpu)
	addi	r3,r3,THREAD	        /* want THREAD of task */
	PPC_LL	r6,THREAD_FPSAVEAREA(r3)
	PPC_LL	r5,PT_REGS(r3)
	PPC_LCMPI	0,r6,0
	bne	2f
	addi	r6,r3,THREAD_FPSTATE
2:	SAVE_32FPVSRS(0, R4, R6)
	mffs	fr0
	stfd	fr0,FPSTATE_FPSCR(r6)
	blr