fe6fa228a7
v8.1M adds new encodings of VLLDM and VLSTM (where bit 7 is set). The only difference is that: * the old T1 encodings UNDEF if the implementation implements 32 Dregs (this is currently architecturally impossible for M-profile) * the new T2 encodings have the implementation-defined option to read from memory (discarding the data) or write UNKNOWN values to memory for the stack slots that would be D16-D31 We choose not to make those accesses, so for us the two instructions behave identically assuming they don't UNDEF. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20201119215617.29887-21-peter.maydell@linaro.org
49 lines
2 KiB
Plaintext
49 lines
2 KiB
Plaintext
# M-profile UserFault.NOCP exception handling
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#
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# Copyright (c) 2020 Linaro, Ltd
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, see <http://www.gnu.org/licenses/>.
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#
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# This file is processed by scripts/decodetree.py
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#
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# For M-profile, the architecture specifies that NOCP UsageFaults
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# should take precedence over UNDEF faults over the whole wide
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# range of coprocessor-space encodings, with the exception of
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# VLLDM and VLSTM. (Compare v8.1M IsCPInstruction() pseudocode and
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# v8M Arm ARM rule R_QLGM.) This isn't mandatory for v8.0M but we choose
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# to behave the same as v8.1M.
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# This decode is handled before any others (and in particular before
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# decoding FP instructions which are in the coprocessor space).
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# If the coprocessor is not present or disabled then we will generate
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# the NOCP exception; otherwise we let the insn through to the main decode.
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%vd_dp 22:1 12:4
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%vd_sp 12:4 22:1
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&nocp cp
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{
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# Special cases which do not take an early NOCP: VLLDM and VLSTM
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VLLDM_VLSTM 1110 1100 001 l:1 rn:4 0000 1010 op:1 000 0000
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# VSCCLRM (new in v8.1M) is similar:
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VSCCLRM 1110 1100 1.01 1111 .... 1011 imm:7 0 vd=%vd_dp size=3
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VSCCLRM 1110 1100 1.01 1111 .... 1010 imm:8 vd=%vd_sp size=2
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NOCP 111- 1110 ---- ---- ---- cp:4 ---- ---- &nocp
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NOCP 111- 110- ---- ---- ---- cp:4 ---- ---- &nocp
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# From v8.1M onwards this range will also NOCP:
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NOCP_8_1 111- 1111 ---- ---- ---- ---- ---- ---- &nocp cp=10
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}
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