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target/arm: Implement v8.3-RCPC

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The v8.3-RCPC extension implements three new load instructions
which provide slightly weaker consistency guarantees than the
existing load-acquire operations. For QEMU we choose to simply
implement them with a full LDAQ barrier.

Backports commit 2677cf9f92a5319bb995927f9225940414ce879d from qemu
This commit is contained in:
Peter Maydell 2020-03-22 00:11:32 -04:00 committed by Lioncash
parent 8d12309fd8
commit f72582bb7a
3 changed files with 31 additions and 0 deletions
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5
qemu/target/arm/cpu.h
View file

@ -3647,6 +3647,11 @@ static inline bool isar_feature_aa64_pmu_8_4(const ARMISARegisters *id)
FIELD_EX64(id->id_aa64dfr0, ID_AA64DFR0, PMUVER) != 0xf;
}
static inline bool isar_feature_aa64_rcpc_8_3(const ARMISARegisters *id)
{
return FIELD_EX64(id->id_aa64isar1, ID_AA64ISAR1, LRCPC) != 0;
}
/*
* Feature tests for "does this exist in either 32-bit or 64-bit?"
*/

1
qemu/target/arm/cpu64.c
View file

@ -298,6 +298,7 @@ static void aarch64_max_initfn(struct uc_struct *uc, Object *obj, void *opaque)
t = FIELD_DP64(t, ID_AA64ISAR1, SB, 1);
t = FIELD_DP64(t, ID_AA64ISAR1, SPECRES, 1);
t = FIELD_DP64(t, ID_AA64ISAR1, FRINTTS, 1);
t = FIELD_DP64(t, ID_AA64ISAR1, LRCPC, 1); /* ARMv8.3-RCPC */
cpu->isar.id_aa64isar1 = t;
t = cpu->isar.id_aa64pfr0;

25
qemu/target/arm/translate-a64.c
View file

@ -3335,6 +3335,8 @@ static void disas_ldst_atomic(DisasContext *s, uint32_t insn,
int rs = extract32(insn, 16, 5);
int rn = extract32(insn, 5, 5);
int o3_opc = extract32(insn, 12, 4);
bool r = extract32(insn, 22, 1);
bool a = extract32(insn, 23, 1);
TCGv_i64 tcg_rs, clean_addr;
AtomicThreeOpFn *fn;
@ -3370,6 +3372,13 @@ static void disas_ldst_atomic(DisasContext *s, uint32_t insn,
case 010: /* SWP */
fn = tcg_gen_atomic_xchg_i64;
break;
case 014: /* LDAPR, LDAPRH, LDAPRB */
if (!dc_isar_feature(aa64_rcpc_8_3, s) ||
rs != 31 || a != 1 || r != 0) {
unallocated_encoding(s);
return;
}
break;
default:
unallocated_encoding(s);
return;
@ -3379,6 +3388,22 @@ static void disas_ldst_atomic(DisasContext *s, uint32_t insn,
gen_check_sp_alignment(s);
}
clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn));
if (o3_opc == 014) {
/*
* LDAPR* are a special case because they are a simple load, not a
* fetch-and-do-something op.
* The architectural consistency requirements here are weaker than
* full load-acquire (we only need "load-acquire processor consistent"),
* but we choose to implement them as full LDAQ.
*/
do_gpr_ld(s, cpu_reg(s, rt), clean_addr, size, false, false,
true, rt, disas_ldst_compute_iss_sf(size, false, 0), true);
tcg_gen_mb(tcg_ctx, TCG_MO_ALL | TCG_BAR_LDAQ);
return;
}
tcg_rs = read_cpu_reg(s, rs, true);
if (o3_opc == 1) { /* LDCLR */