Convert the exception-return insns ERET, ERETA and ERETB to
decodetree. These were the last insns left in the legacy
decoder function disas_uncond_reg_b(), which allows us to
remove it.
The old decoder explicitly decoded the DRPS instruction,
only in order to call unallocated_encoding() on it, exactly
as would have happened if it hadn't decoded it. This is
because this insn always UNDEFs unless the CPU is in
halting-debug state, which we don't emulate. So we list
the pattern in a comment in a64.decode, but don't actively
decode it.
Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
Message-id: 20230512144106.3608981-21-peter.mayd...@linaro.org
---
target/arm/tcg/a64.decode | 8 ++
target/arm/tcg/translate-a64.c | 163 +++++++++++----------------------
2 files changed, 63 insertions(+), 108 deletions(-)
diff --git a/target/arm/tcg/a64.decode b/target/arm/tcg/a64.decode
index 2fd435b6317..12a310d0a31 100644
--- a/target/arm/tcg/a64.decode
+++ b/target/arm/tcg/a64.decode
@@ -142,3 +142,11 @@ RETA 1101011 0010 11111 00001 m:1 11111 11111
&reta # RETAA, RETAB
&bra rn rm m
BRA 1101011 1000 11111 00001 m:1 rn:5 rm:5 &bra # BRAA, BRAB
BLRA 1101011 1001 11111 00001 m:1 rn:5 rm:5 &bra # BLRAA, BLRAB
+
+ERET 1101011 0100 11111 000000 11111 00000
+ERETA 1101011 0100 11111 00001 m:1 11111 11111 &reta # ERETAA,
ERETAB
+
+# We don't need to decode DRPS because it always UNDEFs except when
+# the processor is in halting debug state (which we don't implement).
+# The pattern is listed here as documentation.
+# DRPS 1101011 0101 11111 000000 11111 00000
diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c
index 40a6e59a609..741a6087399 100644
--- a/target/arm/tcg/translate-a64.c
+++ b/target/arm/tcg/translate-a64.c
@@ -1539,6 +1539,61 @@ static bool trans_BLRA(DisasContext *s, arg_bra *a)
return true;
}
+static bool trans_ERET(DisasContext *s, arg_ERET *a)
+{
+ TCGv_i64 dst;
+
+ if (s->current_el == 0) {
+ return false;
+ }
+ if (s->fgt_eret) {
+ gen_exception_insn_el(s, 0, EXCP_UDEF, 0, 2);
+ return true;
+ }
+ dst = tcg_temp_new_i64();
+ tcg_gen_ld_i64(dst, cpu_env,
+ offsetof(CPUARMState, elr_el[s->current_el]));
+
+ if (tb_cflags(s->base.tb) & CF_USE_ICOUNT) {
+ gen_io_start();
+ }
+
+ gen_helper_exception_return(cpu_env, dst);
+ /* Must exit loop to check un-masked IRQs */
+ s->base.is_jmp = DISAS_EXIT;
+ return true;
+}
+
+static bool trans_ERETA(DisasContext *s, arg_reta *a)
+{
+ TCGv_i64 dst;
+
+ if (!dc_isar_feature(aa64_pauth, s)) {
+ return false;
+ }
+ if (s->current_el == 0) {
+ return false;
+ }
+ /* The FGT trap takes precedence over an auth trap. */
+ if (s->fgt_eret) {
+ gen_exception_insn_el(s, 0, EXCP_UDEF, a->m ? 3 : 2, 2);
+ return true;
+ }
+ dst = tcg_temp_new_i64();
+ tcg_gen_ld_i64(dst, cpu_env,
+ offsetof(CPUARMState, elr_el[s->current_el]));
+
+ dst = auth_branch_target(s, dst, cpu_X[31], !a->m);
+ if (tb_cflags(s->base.tb) & CF_USE_ICOUNT) {
+ gen_io_start();
+ }
+
+ gen_helper_exception_return(cpu_env, dst);
+ /* Must exit loop to check un-masked IRQs */
+ s->base.is_jmp = DISAS_EXIT;
+ return true;
+}
+
/* HINT instruction group, including various allocated HINTs */
static void handle_hint(DisasContext *s, uint32_t insn,
unsigned int op1, unsigned int op2, unsigned int crm)
@@ -2307,111 +2362,6 @@ static void disas_exc(DisasContext *s, uint32_t insn)
}
}
-/* Unconditional branch (register)
- * 31 25 24 21 20 16 15 10 9 5 4 0
- * +---------------+-------+-------+-------+------+-------+
- * | 1 1 0 1 0 1 1 | opc | op2 | op3 | Rn | op4 |
- * +---------------+-------+-------+-------+------+-------+
- */
-static void disas_uncond_b_reg(DisasContext *s, uint32_t insn)
-{
- unsigned int opc, op2, op3, rn, op4;
- TCGv_i64 dst;
- TCGv_i64 modifier;
-
- opc = extract32(insn, 21, 4);
- op2 = extract32(insn, 16, 5);
- op3 = extract32(insn, 10, 6);
- rn = extract32(insn, 5, 5);
- op4 = extract32(insn, 0, 5);
-
- if (op2 != 0x1f) {
- goto do_unallocated;
- }
-
- switch (opc) {
- case 0:
- case 1:
- case 2:
- case 8:
- case 9:
- /*
- * BR, BLR, RET, RETAA, RETAB, BRAAZ, BRABZ, BLRAAZ, BLRABZ,
- * BRAA, BLRAA: handled in decodetree
- */
- goto do_unallocated;
-
- case 4: /* ERET */
- if (s->current_el == 0) {
- goto do_unallocated;
- }
- switch (op3) {
- case 0: /* ERET */
- if (op4 != 0) {
- goto do_unallocated;
- }
- if (s->fgt_eret) {
- gen_exception_insn_el(s, 0, EXCP_UDEF, syn_erettrap(op3), 2);
- return;
- }
- dst = tcg_temp_new_i64();
- tcg_gen_ld_i64(dst, cpu_env,
- offsetof(CPUARMState, elr_el[s->current_el]));
- break;
-
- case 2: /* ERETAA */
- case 3: /* ERETAB */
- if (!dc_isar_feature(aa64_pauth, s)) {
- goto do_unallocated;
- }
- if (rn != 0x1f || op4 != 0x1f) {
- goto do_unallocated;
- }
- /* The FGT trap takes precedence over an auth trap. */
- if (s->fgt_eret) {
- gen_exception_insn_el(s, 0, EXCP_UDEF, syn_erettrap(op3), 2);
- return;
- }
- dst = tcg_temp_new_i64();
- tcg_gen_ld_i64(dst, cpu_env,
- offsetof(CPUARMState, elr_el[s->current_el]));
- if (s->pauth_active) {
- modifier = cpu_X[31];
- if (op3 == 2) {
- gen_helper_autia(dst, cpu_env, dst, modifier);
- } else {
- gen_helper_autib(dst, cpu_env, dst, modifier);
- }
- }
- break;
-
- default:
- goto do_unallocated;
- }
- if (tb_cflags(s->base.tb) & CF_USE_ICOUNT) {
- gen_io_start();
- }
-
- gen_helper_exception_return(cpu_env, dst);
- /* Must exit loop to check un-masked IRQs */
- s->base.is_jmp = DISAS_EXIT;
- return;
-
- case 5: /* DRPS */
- if (op3 != 0 || op4 != 0 || rn != 0x1f) {
- goto do_unallocated;
- } else {
- unallocated_encoding(s);
- }
- return;
-
- default:
- do_unallocated:
- unallocated_encoding(s);
- return;
- }
-}
-
/* Branches, exception generating and system instructions */
static void disas_b_exc_sys(DisasContext *s, uint32_t insn)
{
@@ -2427,9 +2377,6 @@ static void disas_b_exc_sys(DisasContext *s, uint32_t
insn)
disas_exc(s, insn);
}
break;
- case 0x6b: /* Unconditional branch (register) */
- disas_uncond_b_reg(s, insn);
- break;
default:
unallocated_encoding(s);
break;
--
2.34.1
