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8792468da5
This patch adds the ability to be able to save the FPU registers to the thread struct without giving up (disabling the facility) next time the process returns to userspace. This patch optimises the thread copy path (as a result of a fork() or clone()) so that the parent thread can return to userspace with hot registers avoiding a possibly pointless reload of FPU register state. Signed-off-by: Cyril Bur <cyrilbur@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
176 lines
4.4 KiB
ArmAsm
176 lines
4.4 KiB
ArmAsm
/*
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* FPU support code, moved here from head.S so that it can be used
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* by chips which use other head-whatever.S files.
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*
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* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
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* Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
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* Copyright (C) 1996 Paul Mackerras.
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* Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*/
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#include <asm/reg.h>
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#include <asm/page.h>
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#include <asm/mmu.h>
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#include <asm/pgtable.h>
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#include <asm/cputable.h>
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#include <asm/cache.h>
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#include <asm/thread_info.h>
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#include <asm/ppc_asm.h>
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#include <asm/asm-offsets.h>
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#include <asm/ptrace.h>
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#ifdef CONFIG_VSX
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#define __REST_32FPVSRS(n,c,base) \
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BEGIN_FTR_SECTION \
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b 2f; \
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END_FTR_SECTION_IFSET(CPU_FTR_VSX); \
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REST_32FPRS(n,base); \
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b 3f; \
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2: REST_32VSRS(n,c,base); \
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3:
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#define __SAVE_32FPVSRS(n,c,base) \
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BEGIN_FTR_SECTION \
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b 2f; \
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END_FTR_SECTION_IFSET(CPU_FTR_VSX); \
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SAVE_32FPRS(n,base); \
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b 3f; \
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2: SAVE_32VSRS(n,c,base); \
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3:
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#else
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#define __REST_32FPVSRS(n,b,base) REST_32FPRS(n, base)
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#define __SAVE_32FPVSRS(n,b,base) SAVE_32FPRS(n, base)
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#endif
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#define REST_32FPVSRS(n,c,base) __REST_32FPVSRS(n,__REG_##c,__REG_##base)
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#define SAVE_32FPVSRS(n,c,base) __SAVE_32FPVSRS(n,__REG_##c,__REG_##base)
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#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
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/* void do_load_up_transact_fpu(struct thread_struct *thread)
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*
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* This is similar to load_up_fpu but for the transactional version of the FP
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* register set. It doesn't mess with the task MSR or valid flags.
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* Furthermore, we don't do lazy FP with TM currently.
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*/
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_GLOBAL(do_load_up_transact_fpu)
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mfmsr r6
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ori r5,r6,MSR_FP
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#ifdef CONFIG_VSX
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BEGIN_FTR_SECTION
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oris r5,r5,MSR_VSX@h
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END_FTR_SECTION_IFSET(CPU_FTR_VSX)
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#endif
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SYNC
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MTMSRD(r5)
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addi r7,r3,THREAD_TRANSACT_FPSTATE
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lfd fr0,FPSTATE_FPSCR(r7)
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MTFSF_L(fr0)
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REST_32FPVSRS(0, R4, R7)
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blr
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#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
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/*
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* Load state from memory into FP registers including FPSCR.
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* Assumes the caller has enabled FP in the MSR.
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*/
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_GLOBAL(load_fp_state)
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lfd fr0,FPSTATE_FPSCR(r3)
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MTFSF_L(fr0)
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REST_32FPVSRS(0, R4, R3)
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blr
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/*
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* Store FP state into memory, including FPSCR
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* Assumes the caller has enabled FP in the MSR.
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*/
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_GLOBAL(store_fp_state)
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SAVE_32FPVSRS(0, R4, R3)
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mffs fr0
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stfd fr0,FPSTATE_FPSCR(r3)
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blr
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/*
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* This task wants to use the FPU now.
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* On UP, disable FP for the task which had the FPU previously,
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* and save its floating-point registers in its thread_struct.
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* Load up this task's FP registers from its thread_struct,
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* enable the FPU for the current task and return to the task.
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* Note that on 32-bit this can only use registers that will be
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* restored by fast_exception_return, i.e. r3 - r6, r10 and r11.
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*/
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_GLOBAL(load_up_fpu)
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mfmsr r5
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ori r5,r5,MSR_FP
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#ifdef CONFIG_VSX
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BEGIN_FTR_SECTION
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oris r5,r5,MSR_VSX@h
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END_FTR_SECTION_IFSET(CPU_FTR_VSX)
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#endif
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SYNC
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MTMSRD(r5) /* enable use of fpu now */
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isync
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/* enable use of FP after return */
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#ifdef CONFIG_PPC32
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mfspr r5,SPRN_SPRG_THREAD /* current task's THREAD (phys) */
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lwz r4,THREAD_FPEXC_MODE(r5)
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ori r9,r9,MSR_FP /* enable FP for current */
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or r9,r9,r4
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#else
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ld r4,PACACURRENT(r13)
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addi r5,r4,THREAD /* Get THREAD */
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lwz r4,THREAD_FPEXC_MODE(r5)
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ori r12,r12,MSR_FP
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or r12,r12,r4
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std r12,_MSR(r1)
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#endif
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/* Don't care if r4 overflows, this is desired behaviour */
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lbz r4,THREAD_LOAD_FP(r5)
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addi r4,r4,1
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stb r4,THREAD_LOAD_FP(r5)
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addi r10,r5,THREAD_FPSTATE
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lfd fr0,FPSTATE_FPSCR(r10)
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MTFSF_L(fr0)
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REST_32FPVSRS(0, R4, R10)
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/* restore registers and return */
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/* we haven't used ctr or xer or lr */
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blr
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/*
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* save_fpu(tsk)
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* Save the floating-point registers in its thread_struct.
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* Enables the FPU for use in the kernel on return.
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*/
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_GLOBAL(save_fpu)
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addi r3,r3,THREAD /* want THREAD of task */
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PPC_LL r6,THREAD_FPSAVEAREA(r3)
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PPC_LL r5,PT_REGS(r3)
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PPC_LCMPI 0,r6,0
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bne 2f
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addi r6,r3,THREAD_FPSTATE
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2: SAVE_32FPVSRS(0, R4, R6)
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mffs fr0
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stfd fr0,FPSTATE_FPSCR(r6)
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blr
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/*
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* These are used in the alignment trap handler when emulating
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* single-precision loads and stores.
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*/
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_GLOBAL(cvt_fd)
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lfs 0,0(r3)
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stfd 0,0(r4)
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blr
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_GLOBAL(cvt_df)
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lfd 0,0(r3)
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stfs 0,0(r4)
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blr
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