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qemu/target/arm/vfp.decode
Peter Maydell fa856736b6 target/arm: Don't NOCP fault for FPCXT_NS accesses 
The M-profile architecture requires that accesses to FPCXT_NS when
there is no active FP state must not take a NOCP fault even if the
FPU is disabled. We were not implementing this correctly, because
in our decode we catch the NOCP faults early in m-nocp.decode.

Fix this bug by moving all the handling of M-profile FP system
register accesses from vfp.decode into m-nocp.decode and putting
it above the NOCP blocks. This provides the correct behaviour:
 * for accesses other than FPCXT_NS the trans functions call
   vfp_access_check(), which will check for FPU disabled and
   raise a NOCP exception if necessary
 * for FPCXT_NS we have the special case code that doesn't
   call vfp_access_check()
 * when these trans functions want to raise an UNDEF they return
   false, so the decoder will fall through into the NOCP blocks.
   This means that NOCP correctly takes precedence over UNDEF
   for these insns. (This is a difference from the other insns
   handled by m-nocp.decode, where UNDEF takes precedence and
   which we implement by having those trans functions call
   unallocated_encoding() in the appropriate places.)

[Note for backport to stable: this commit has a semantic dependency
on commit 9a486856e9, which was not marked as cc-stable because
we didn't know we'd need it for a for-stable bugfix.]

Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210618141019.10671-4-peter.maydell@linaro.org
2021-06-21 16:49:37 +01:00

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# AArch32 VFP instruction descriptions (conditional insns)
#
# Copyright (c) 2019 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
#
# Encodings for the conditional VFP instructions are here:
# generally anything matching A32
# cccc 11.. .... .... .... 101. .... ....
# and T32
# 1110 110. .... .... .... 101. .... ....
# 1110 1110 .... .... .... 101. .... ....
# (but those patterns might also cover some Neon instructions,
# which do not live in this file.)
# VFP registers have an odd encoding with a four-bit field
# and a one-bit field which are assembled in different orders
# depending on whether the register is double or single precision.
# Each individual instruction function must do the checks for
# "double register selected but CPU does not have double support"
# and "double register number has bit 4 set but CPU does not
# support D16-D31" (which should UNDEF).
%vm_dp 5:1 0:4
%vm_sp 0:4 5:1
%vn_dp 7:1 16:4
%vn_sp 16:4 7:1
%vd_dp 22:1 12:4
%vd_sp 12:4 22:1
%vmov_idx_b 21:1 5:2
%vmov_idx_h 21:1 6:1
%vmov_imm 16:4 0:4
@vfp_dnm_s ................................ vm=%vm_sp vn=%vn_sp vd=%vd_sp
@vfp_dnm_d ................................ vm=%vm_dp vn=%vn_dp vd=%vd_dp
@vfp_dm_ss ................................ vm=%vm_sp vd=%vd_sp
@vfp_dm_dd ................................ vm=%vm_dp vd=%vd_dp
@vfp_dm_ds ................................ vm=%vm_sp vd=%vd_dp
@vfp_dm_sd ................................ vm=%vm_dp vd=%vd_sp
# VMOV scalar to general-purpose register; note that this does
# include some Neon cases.
VMOV_to_gp ---- 1110 u:1 1. 1 .... rt:4 1011 ... 1 0000 \
vn=%vn_dp size=0 index=%vmov_idx_b
VMOV_to_gp ---- 1110 u:1 0. 1 .... rt:4 1011 ..1 1 0000 \
vn=%vn_dp size=1 index=%vmov_idx_h
VMOV_to_gp ---- 1110 0 0 index:1 1 .... rt:4 1011 .00 1 0000 \
vn=%vn_dp size=2 u=0
VMOV_from_gp ---- 1110 0 1. 0 .... rt:4 1011 ... 1 0000 \
vn=%vn_dp size=0 index=%vmov_idx_b
VMOV_from_gp ---- 1110 0 0. 0 .... rt:4 1011 ..1 1 0000 \
vn=%vn_dp size=1 index=%vmov_idx_h
VMOV_from_gp ---- 1110 0 0 index:1 0 .... rt:4 1011 .00 1 0000 \
vn=%vn_dp size=2
VDUP ---- 1110 1 b:1 q:1 0 .... rt:4 1011 . 0 e:1 1 0000 \
vn=%vn_dp
VMSR_VMRS ---- 1110 111 l:1 reg:4 rt:4 1010 0001 0000
VMOV_half ---- 1110 000 l:1 .... rt:4 1001 . 001 0000 vn=%vn_sp
VMOV_single ---- 1110 000 l:1 .... rt:4 1010 . 001 0000 vn=%vn_sp
VMOV_64_sp ---- 1100 010 op:1 rt2:4 rt:4 1010 00.1 .... vm=%vm_sp
VMOV_64_dp ---- 1100 010 op:1 rt2:4 rt:4 1011 00.1 .... vm=%vm_dp
VLDR_VSTR_hp ---- 1101 u:1 .0 l:1 rn:4 .... 1001 imm:8 vd=%vd_sp
VLDR_VSTR_sp ---- 1101 u:1 .0 l:1 rn:4 .... 1010 imm:8 vd=%vd_sp
VLDR_VSTR_dp ---- 1101 u:1 .0 l:1 rn:4 .... 1011 imm:8 vd=%vd_dp
# We split the load/store multiple up into two patterns to avoid
# overlap with other insns in the "Advanced SIMD load/store and 64-bit move"
# grouping:
# P=0 U=0 W=0 is 64-bit VMOV
# P=1 W=0 is VLDR/VSTR
# P=U W=1 is UNDEF
# leaving P=0 U=1 W=x and P=1 U=0 W=1 for load/store multiple.
# These include FSTM/FLDM.
VLDM_VSTM_sp ---- 1100 1 . w:1 l:1 rn:4 .... 1010 imm:8 \
vd=%vd_sp p=0 u=1
VLDM_VSTM_dp ---- 1100 1 . w:1 l:1 rn:4 .... 1011 imm:8 \
vd=%vd_dp p=0 u=1
VLDM_VSTM_sp ---- 1101 0.1 l:1 rn:4 .... 1010 imm:8 \
vd=%vd_sp p=1 u=0 w=1
VLDM_VSTM_dp ---- 1101 0.1 l:1 rn:4 .... 1011 imm:8 \
vd=%vd_dp p=1 u=0 w=1
# 3-register VFP data-processing; bits [23,21:20,6] identify the operation.
VMLA_hp ---- 1110 0.00 .... .... 1001 .0.0 .... @vfp_dnm_s
VMLA_sp ---- 1110 0.00 .... .... 1010 .0.0 .... @vfp_dnm_s
VMLA_dp ---- 1110 0.00 .... .... 1011 .0.0 .... @vfp_dnm_d
VMLS_hp ---- 1110 0.00 .... .... 1001 .1.0 .... @vfp_dnm_s
VMLS_sp ---- 1110 0.00 .... .... 1010 .1.0 .... @vfp_dnm_s
VMLS_dp ---- 1110 0.00 .... .... 1011 .1.0 .... @vfp_dnm_d
VNMLS_hp ---- 1110 0.01 .... .... 1001 .0.0 .... @vfp_dnm_s
VNMLS_sp ---- 1110 0.01 .... .... 1010 .0.0 .... @vfp_dnm_s
VNMLS_dp ---- 1110 0.01 .... .... 1011 .0.0 .... @vfp_dnm_d
VNMLA_hp ---- 1110 0.01 .... .... 1001 .1.0 .... @vfp_dnm_s
VNMLA_sp ---- 1110 0.01 .... .... 1010 .1.0 .... @vfp_dnm_s
VNMLA_dp ---- 1110 0.01 .... .... 1011 .1.0 .... @vfp_dnm_d
VMUL_hp ---- 1110 0.10 .... .... 1001 .0.0 .... @vfp_dnm_s
VMUL_sp ---- 1110 0.10 .... .... 1010 .0.0 .... @vfp_dnm_s
VMUL_dp ---- 1110 0.10 .... .... 1011 .0.0 .... @vfp_dnm_d
VNMUL_hp ---- 1110 0.10 .... .... 1001 .1.0 .... @vfp_dnm_s
VNMUL_sp ---- 1110 0.10 .... .... 1010 .1.0 .... @vfp_dnm_s
VNMUL_dp ---- 1110 0.10 .... .... 1011 .1.0 .... @vfp_dnm_d
VADD_hp ---- 1110 0.11 .... .... 1001 .0.0 .... @vfp_dnm_s
VADD_sp ---- 1110 0.11 .... .... 1010 .0.0 .... @vfp_dnm_s
VADD_dp ---- 1110 0.11 .... .... 1011 .0.0 .... @vfp_dnm_d
VSUB_hp ---- 1110 0.11 .... .... 1001 .1.0 .... @vfp_dnm_s
VSUB_sp ---- 1110 0.11 .... .... 1010 .1.0 .... @vfp_dnm_s
VSUB_dp ---- 1110 0.11 .... .... 1011 .1.0 .... @vfp_dnm_d
VDIV_hp ---- 1110 1.00 .... .... 1001 .0.0 .... @vfp_dnm_s
VDIV_sp ---- 1110 1.00 .... .... 1010 .0.0 .... @vfp_dnm_s
VDIV_dp ---- 1110 1.00 .... .... 1011 .0.0 .... @vfp_dnm_d
VFMA_hp ---- 1110 1.10 .... .... 1001 .0. 0 .... @vfp_dnm_s
VFMS_hp ---- 1110 1.10 .... .... 1001 .1. 0 .... @vfp_dnm_s
VFNMA_hp ---- 1110 1.01 .... .... 1001 .0. 0 .... @vfp_dnm_s
VFNMS_hp ---- 1110 1.01 .... .... 1001 .1. 0 .... @vfp_dnm_s
VFMA_sp ---- 1110 1.10 .... .... 1010 .0. 0 .... @vfp_dnm_s
VFMS_sp ---- 1110 1.10 .... .... 1010 .1. 0 .... @vfp_dnm_s
VFNMA_sp ---- 1110 1.01 .... .... 1010 .0. 0 .... @vfp_dnm_s
VFNMS_sp ---- 1110 1.01 .... .... 1010 .1. 0 .... @vfp_dnm_s
VFMA_dp ---- 1110 1.10 .... .... 1011 .0.0 .... @vfp_dnm_d
VFMS_dp ---- 1110 1.10 .... .... 1011 .1.0 .... @vfp_dnm_d
VFNMA_dp ---- 1110 1.01 .... .... 1011 .0.0 .... @vfp_dnm_d
VFNMS_dp ---- 1110 1.01 .... .... 1011 .1.0 .... @vfp_dnm_d
VMOV_imm_hp ---- 1110 1.11 .... .... 1001 0000 .... \
vd=%vd_sp imm=%vmov_imm
VMOV_imm_sp ---- 1110 1.11 .... .... 1010 0000 .... \
vd=%vd_sp imm=%vmov_imm
VMOV_imm_dp ---- 1110 1.11 .... .... 1011 0000 .... \
vd=%vd_dp imm=%vmov_imm
VMOV_reg_sp ---- 1110 1.11 0000 .... 1010 01.0 .... @vfp_dm_ss
VMOV_reg_dp ---- 1110 1.11 0000 .... 1011 01.0 .... @vfp_dm_dd
VABS_hp ---- 1110 1.11 0000 .... 1001 11.0 .... @vfp_dm_ss
VABS_sp ---- 1110 1.11 0000 .... 1010 11.0 .... @vfp_dm_ss
VABS_dp ---- 1110 1.11 0000 .... 1011 11.0 .... @vfp_dm_dd
VNEG_hp ---- 1110 1.11 0001 .... 1001 01.0 .... @vfp_dm_ss
VNEG_sp ---- 1110 1.11 0001 .... 1010 01.0 .... @vfp_dm_ss
VNEG_dp ---- 1110 1.11 0001 .... 1011 01.0 .... @vfp_dm_dd
VSQRT_hp ---- 1110 1.11 0001 .... 1001 11.0 .... @vfp_dm_ss
VSQRT_sp ---- 1110 1.11 0001 .... 1010 11.0 .... @vfp_dm_ss
VSQRT_dp ---- 1110 1.11 0001 .... 1011 11.0 .... @vfp_dm_dd
VCMP_hp ---- 1110 1.11 010 z:1 .... 1001 e:1 1.0 .... \
vd=%vd_sp vm=%vm_sp
VCMP_sp ---- 1110 1.11 010 z:1 .... 1010 e:1 1.0 .... \
vd=%vd_sp vm=%vm_sp
VCMP_dp ---- 1110 1.11 010 z:1 .... 1011 e:1 1.0 .... \
vd=%vd_dp vm=%vm_dp
# VCVTT and VCVTB from f16: Vd format depends on size bit; Vm is always vm_sp
VCVT_f32_f16 ---- 1110 1.11 0010 .... 1010 t:1 1.0 .... \
vd=%vd_sp vm=%vm_sp
VCVT_f64_f16 ---- 1110 1.11 0010 .... 1011 t:1 1.0 .... \
vd=%vd_dp vm=%vm_sp
# VCVTB and VCVTT to f16: Vd format is always vd_sp;
# Vm format depends on size bit
VCVT_b16_f32 ---- 1110 1.11 0011 .... 1001 t:1 1.0 .... \
vd=%vd_sp vm=%vm_sp
VCVT_f16_f32 ---- 1110 1.11 0011 .... 1010 t:1 1.0 .... \
vd=%vd_sp vm=%vm_sp
VCVT_f16_f64 ---- 1110 1.11 0011 .... 1011 t:1 1.0 .... \
vd=%vd_sp vm=%vm_dp
VRINTR_hp ---- 1110 1.11 0110 .... 1001 01.0 .... @vfp_dm_ss
VRINTR_sp ---- 1110 1.11 0110 .... 1010 01.0 .... @vfp_dm_ss
VRINTR_dp ---- 1110 1.11 0110 .... 1011 01.0 .... @vfp_dm_dd
VRINTZ_hp ---- 1110 1.11 0110 .... 1001 11.0 .... @vfp_dm_ss
VRINTZ_sp ---- 1110 1.11 0110 .... 1010 11.0 .... @vfp_dm_ss
VRINTZ_dp ---- 1110 1.11 0110 .... 1011 11.0 .... @vfp_dm_dd
VRINTX_hp ---- 1110 1.11 0111 .... 1001 01.0 .... @vfp_dm_ss
VRINTX_sp ---- 1110 1.11 0111 .... 1010 01.0 .... @vfp_dm_ss
VRINTX_dp ---- 1110 1.11 0111 .... 1011 01.0 .... @vfp_dm_dd
# VCVT between single and double:
# Vm precision depends on size; Vd is its reverse
VCVT_sp ---- 1110 1.11 0111 .... 1010 11.0 .... @vfp_dm_ds
VCVT_dp ---- 1110 1.11 0111 .... 1011 11.0 .... @vfp_dm_sd
# VCVT from integer to floating point: Vm always single; Vd depends on size
VCVT_int_hp ---- 1110 1.11 1000 .... 1001 s:1 1.0 .... \
vd=%vd_sp vm=%vm_sp
VCVT_int_sp ---- 1110 1.11 1000 .... 1010 s:1 1.0 .... \
vd=%vd_sp vm=%vm_sp
VCVT_int_dp ---- 1110 1.11 1000 .... 1011 s:1 1.0 .... \
vd=%vd_dp vm=%vm_sp
# VJCVT is always dp to sp
VJCVT ---- 1110 1.11 1001 .... 1011 11.0 .... @vfp_dm_sd
# VCVT between floating-point and fixed-point. The immediate value
# is in the same format as a Vm single-precision register number.
# We assemble bits 18 (op), 16 (u) and 7 (sx) into a single opc field
# for the convenience of the trans_VCVT_fix functions.
%vcvt_fix_op 18:1 16:1 7:1
VCVT_fix_hp ---- 1110 1.11 1.1. .... 1001 .1.0 .... \
vd=%vd_sp imm=%vm_sp opc=%vcvt_fix_op
VCVT_fix_sp ---- 1110 1.11 1.1. .... 1010 .1.0 .... \
vd=%vd_sp imm=%vm_sp opc=%vcvt_fix_op
VCVT_fix_dp ---- 1110 1.11 1.1. .... 1011 .1.0 .... \
vd=%vd_dp imm=%vm_sp opc=%vcvt_fix_op
# VCVT float to integer (VCVT and VCVTR): Vd always single; Vd depends on size
VCVT_hp_int ---- 1110 1.11 110 s:1 .... 1001 rz:1 1.0 .... \
vd=%vd_sp vm=%vm_sp
VCVT_sp_int ---- 1110 1.11 110 s:1 .... 1010 rz:1 1.0 .... \
vd=%vd_sp vm=%vm_sp
VCVT_dp_int ---- 1110 1.11 110 s:1 .... 1011 rz:1 1.0 .... \
vd=%vd_sp vm=%vm_dp
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