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232d0b87e0
- Explicitly load an empty initial state into FP registers when taking the fault on the first FP instruction in a thread. Setting SSTATE.FS to INITIAL is just a marker to let context switch restore code know that it can load FP registers with zeroes instead of memory loads. It does not imply that the hardware will reset all registers to zero on first access. In addition, set the state to CLEAN instead of INITIAL after the first FP instruction. cpu_switch() doesn't do anything for INITIAL and only restores from the pcb if the state is CLEAN. We could perhaps change cpu_switch to call fpe_state_clear if the state was INITIAL and leave SSTATE.FS set to INITIAL instead of CLEAN after the first FP instruction. However, adding this complexity to cpu_switch() doesn't seem worth the supposed gain. - Only save the current FPU registers in fill_fpregs() if the request is made to save the current thread's registers. Previously if a debugger requested FP registers via ptrace() it was getting a copy of the debugger's FP registers rather than the debugee's. - Zero the entire FP register set structure returned for ptrace() if a thread hasn't used FP registers rather than leaking garbage in the fp_fcsr field. - If a debugger writes FP registers via ptrace(), always mark the pcb as having valid FP registers and set SSTATUS.FS_MASK to CLEAN so that the registers will be restored when the debugged thread resumes. - Be more explicit about clearing the SSTATUS.FS field before setting it to CLEAN on the first FP instruction trap. Submitted by: br, markj Approved by: re (rgrimes) Sponsored by: DARPA Differential Revision: https://reviews.freebsd.org/D17141
40 lines
1.7 KiB
C
40 lines
1.7 KiB
C
/*-
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* Copyright (c) 2016 Ruslan Bukin <br@bsdpad.com>
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* All rights reserved.
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*
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* This software was developed by SRI International and the University of
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* Cambridge Computer Laboratory under DARPA/AFRL contract FA8750-10-C-0237
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* ("CTSRD"), as part of the DARPA CRASH research programme.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _MACHINE_FPE_H_
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#define _MACHINE_FPE_H_
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void fpe_state_save(struct thread *td);
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void fpe_state_clear(void);
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#endif /* !_MACHINE_FPE_H_ */
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