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qemu/target/arm/m-nocp.decode

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# M-profile UserFault.NOCP exception handling
#
# Copyright (c) 2020 Linaro, Ltd
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, see <http://www.gnu.org/licenses/>.
#
# This file is processed by scripts/decodetree.py
#
# For M-profile, the architecture specifies that NOCP UsageFaults
# should take precedence over UNDEF faults over the whole wide
# range of coprocessor-space encodings, with the exception of
# VLLDM and VLSTM. (Compare v8.1M IsCPInstruction() pseudocode and
# v8M Arm ARM rule R_QLGM.) This isn't mandatory for v8.0M but we choose
# to behave the same as v8.1M.
# This decode is handled before any others (and in particular before
# decoding FP instructions which are in the coprocessor space).
# If the coprocessor is not present or disabled then we will generate
# the NOCP exception; otherwise we let the insn through to the main decode.
%vd_dp 22:1 12:4
%vd_sp 12:4 22:1
&nocp cp
# M-profile VLDR/VSTR to sysreg
%vldr_sysreg 22:1 13:3
%imm7_0x4 0:7 !function=times_4
&vldr_sysreg rn reg imm a w p
@vldr_sysreg .... ... . a:1 . . . rn:4 ... . ... .. ....... \
reg=%vldr_sysreg imm=%imm7_0x4 &vldr_sysreg
{
# Special cases which do not take an early NOCP: VLLDM and VLSTM
VLLDM_VLSTM 1110 1100 001 l:1 rn:4 0000 1010 op:1 000 0000
# VSCCLRM (new in v8.1M) is similar:
VSCCLRM 1110 1100 1.01 1111 .... 1011 imm:7 0 vd=%vd_dp size=3
VSCCLRM 1110 1100 1.01 1111 .... 1010 imm:8 vd=%vd_sp size=2
# FP system register accesses: these are a special case because accesses
# to FPCXT_NS succeed even if the FPU is disabled. We therefore need
# to handle them before the big NOCP blocks. Note that within these
# insns NOCP still has higher priority than UNDEFs; this is implemented
# by their returning 'false' for UNDEF so as to fall through into the
# NOCP check (in contrast to VLLDM etc, which call unallocated_encoding()
# for the UNDEFs there that must take precedence over NOCP.)
VMSR_VMRS ---- 1110 111 l:1 reg:4 rt:4 1010 0001 0000
# P=0 W=0 is SEE "Related encodings", so split into two patterns
VLDR_sysreg ---- 110 1 . . w:1 1 .... ... 0 111 11 ....... @vldr_sysreg p=1
VLDR_sysreg ---- 110 0 . . 1 1 .... ... 0 111 11 ....... @vldr_sysreg p=0 w=1
VSTR_sysreg ---- 110 1 . . w:1 0 .... ... 0 111 11 ....... @vldr_sysreg p=1
VSTR_sysreg ---- 110 0 . . 1 0 .... ... 0 111 11 ....... @vldr_sysreg p=0 w=1
NOCP 111- 1110 ---- ---- ---- cp:4 ---- ---- &nocp
NOCP 111- 110- ---- ---- ---- cp:4 ---- ---- &nocp
# From v8.1M onwards this range will also NOCP:
NOCP_8_1 111- 1111 ---- ---- ---- ---- ---- ---- &nocp cp=10
}