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597ce1723e
CPUs implementing MIPS32 R2 may include a 64-bit FPU, just as MIPS64 CPUs do. In order to preserve backwards compatibility a 64-bit FPU will act like a 32-bit FPU (by accessing doubles from the least significant 32 bits of an even-odd pair of FP registers) when the Status.FR bit is zero, again just like a mips64 CPU. The standard O32 ABI is defined expecting a 32-bit FPU, however recent toolchains support use of a 64-bit FPU from an O32 MIPS32 executable. When an ELF executable is built to use a 64-bit FPU a new flag (EF_MIPS_FP64) is set in the ELF header. With this patch the kernel will check the EF_MIPS_FP64 flag when executing an O32 binary, and set Status.FR accordingly. The addition of O32 64-bit FP support lessens the opportunity for optimisation in the FPU emulator, so a CONFIG_MIPS_O32_FP64_SUPPORT Kconfig option is introduced to allow this support to be disabled for those that don't require it. Inspired by an earlier patch by Leonid Yegoshin, but implemented more cleanly & correctly. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Cc: Paul Burton <paul.burton@imgtec.com> Patchwork: https://patchwork.linux-mips.org/patch/6154/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
118 lines
2.8 KiB
C
118 lines
2.8 KiB
C
/*
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* Kevin D. Kissell, kevink@mips and Carsten Langgaard, carstenl@mips.com
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* Copyright (C) 2000 MIPS Technologies, Inc. All rights reserved.
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*
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* This program is free software; you can distribute it and/or modify it
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* under the terms of the GNU General Public License (Version 2) as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
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*
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* Routines corresponding to Linux kernel FP context
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* manipulation primitives for the Algorithmics MIPS
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* FPU Emulator
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*/
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#include <linux/sched.h>
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#include <asm/processor.h>
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#include <asm/signal.h>
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#include <asm/uaccess.h>
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#include <asm/fpu.h>
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#include <asm/fpu_emulator.h>
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#define SIGNALLING_NAN 0x7ff800007ff80000LL
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void fpu_emulator_init_fpu(void)
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{
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static int first = 1;
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int i;
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if (first) {
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first = 0;
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printk("Algorithmics/MIPS FPU Emulator v1.5\n");
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}
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current->thread.fpu.fcr31 = 0;
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for (i = 0; i < 32; i++) {
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current->thread.fpu.fpr[i] = SIGNALLING_NAN;
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}
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}
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/*
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* Emulator context save/restore to/from a signal context
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* presumed to be on the user stack, and therefore accessed
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* with appropriate macros from uaccess.h
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*/
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int fpu_emulator_save_context(struct sigcontext __user *sc)
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{
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int i;
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int err = 0;
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for (i = 0; i < 32; i++) {
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err |=
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__put_user(current->thread.fpu.fpr[i], &sc->sc_fpregs[i]);
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}
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err |= __put_user(current->thread.fpu.fcr31, &sc->sc_fpc_csr);
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return err;
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}
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int fpu_emulator_restore_context(struct sigcontext __user *sc)
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{
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int i;
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int err = 0;
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for (i = 0; i < 32; i++) {
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err |=
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__get_user(current->thread.fpu.fpr[i], &sc->sc_fpregs[i]);
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}
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err |= __get_user(current->thread.fpu.fcr31, &sc->sc_fpc_csr);
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return err;
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}
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#ifdef CONFIG_64BIT
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/*
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* This is the o32 version
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*/
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int fpu_emulator_save_context32(struct sigcontext32 __user *sc)
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{
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int i;
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int err = 0;
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int inc = test_thread_flag(TIF_32BIT_FPREGS) ? 2 : 1;
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for (i = 0; i < 32; i += inc) {
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err |=
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__put_user(current->thread.fpu.fpr[i], &sc->sc_fpregs[i]);
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}
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err |= __put_user(current->thread.fpu.fcr31, &sc->sc_fpc_csr);
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return err;
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}
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int fpu_emulator_restore_context32(struct sigcontext32 __user *sc)
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{
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int i;
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int err = 0;
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int inc = test_thread_flag(TIF_32BIT_FPREGS) ? 2 : 1;
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for (i = 0; i < 32; i += inc) {
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err |=
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__get_user(current->thread.fpu.fpr[i], &sc->sc_fpregs[i]);
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}
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err |= __get_user(current->thread.fpu.fcr31, &sc->sc_fpc_csr);
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return err;
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}
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#endif
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