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target/arm: Convert BRA[AB]Z, BLR[AB]Z, RETA[AB] to decodetree 

Convert the single-register pointer-authentication variants of BR,
BLR, RET to decodetree. (BRAA/BLRAA are in a different branch of
the legacy decoder and will be dealt with in the next commit.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230512144106.3608981-19-peter.maydell@linaro.org
master
Peter Maydell 2023-05-12 15:41:04 +01:00
parent c0b5e3943b
commit 0ebbe90212
2 changed files with 84 additions and 55 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
target/arm/tcg/a64.decode
View File

@ -131,3 +131,10 @@ B_cond 0101010 0 ................... 0 cond:4 imm=%imm19
BR 1101011 0000 11111 000000 rn:5 00000 &r
BLR 1101011 0001 11111 000000 rn:5 00000 &r
RET 1101011 0010 11111 000000 rn:5 00000 &r
&braz rn m
BRAZ 1101011 0000 11111 00001 m:1 rn:5 11111 &braz # BRAAZ, BRABZ
BLRAZ 1101011 0001 11111 00001 m:1 rn:5 11111 &braz # BLRAAZ, BLRABZ
&reta m
RETA 1101011 0010 11111 00001 m:1 11111 11111 &reta # RETAA, RETAB

132
target/arm/tcg/translate-a64.c
View File

@ -1435,6 +1435,75 @@ static bool trans_RET(DisasContext *s, arg_r *a)
return true;
}
static TCGv_i64 auth_branch_target(DisasContext *s, TCGv_i64 dst,
TCGv_i64 modifier, bool use_key_a)
{
TCGv_i64 truedst;
/*
* Return the branch target for a BRAA/RETA/etc, which is either
* just the destination dst, or that value with the pauth check
* done and the code removed from the high bits.
*/
if (!s->pauth_active) {
return dst;
}
truedst = tcg_temp_new_i64();
if (use_key_a) {
gen_helper_autia(truedst, cpu_env, dst, modifier);
} else {
gen_helper_autib(truedst, cpu_env, dst, modifier);
}
return truedst;
}
static bool trans_BRAZ(DisasContext *s, arg_braz *a)
{
TCGv_i64 dst;
if (!dc_isar_feature(aa64_pauth, s)) {
return false;
}
dst = auth_branch_target(s, cpu_reg(s, a->rn), tcg_constant_i64(0), !a->m);
gen_a64_set_pc(s, dst);
set_btype_for_br(s, a->rn);
s->base.is_jmp = DISAS_JUMP;
return true;
}
static bool trans_BLRAZ(DisasContext *s, arg_braz *a)
{
TCGv_i64 dst, lr;
if (!dc_isar_feature(aa64_pauth, s)) {
return false;
}
dst = auth_branch_target(s, cpu_reg(s, a->rn), tcg_constant_i64(0), !a->m);
lr = cpu_reg(s, 30);
if (dst == lr) {
TCGv_i64 tmp = tcg_temp_new_i64();
tcg_gen_mov_i64(tmp, dst);
dst = tmp;
}
gen_pc_plus_diff(s, lr, curr_insn_len(s));
gen_a64_set_pc(s, dst);
set_btype_for_blr(s);
s->base.is_jmp = DISAS_JUMP;
return true;
}
static bool trans_RETA(DisasContext *s, arg_reta *a)
{
TCGv_i64 dst;
dst = auth_branch_target(s, cpu_reg(s, 30), cpu_X[31], !a->m);
gen_a64_set_pc(s, dst);
s->base.is_jmp = DISAS_JUMP;
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)
@ -2227,61 +2296,14 @@ static void disas_uncond_b_reg(DisasContext *s, uint32_t insn)
}
switch (opc) {
case 0: /* BR */
case 1: /* BLR */
case 2: /* RET */
btype_mod = opc;
switch (op3) {
case 0:
/* BR, BLR, RET : handled in decodetree */
goto do_unallocated;
case 2:
case 3:
if (!dc_isar_feature(aa64_pauth, s)) {
goto do_unallocated;
}
if (opc == 2) {
/* RETAA, RETAB */
if (rn != 0x1f || op4 != 0x1f) {
goto do_unallocated;
}
rn = 30;
modifier = cpu_X[31];
} else {
/* BRAAZ, BRABZ, BLRAAZ, BLRABZ */
if (op4 != 0x1f) {
goto do_unallocated;
}
modifier = tcg_constant_i64(0);
}
if (s->pauth_active) {
dst = tcg_temp_new_i64();
if (op3 == 2) {
gen_helper_autia(dst, cpu_env, cpu_reg(s, rn), modifier);
} else {
gen_helper_autib(dst, cpu_env, cpu_reg(s, rn), modifier);
}
} else {
dst = cpu_reg(s, rn);
}
break;
default:
goto do_unallocated;
}
/* BLR also needs to load return address */
if (opc == 1) {
TCGv_i64 lr = cpu_reg(s, 30);
if (dst == lr) {
TCGv_i64 tmp = tcg_temp_new_i64();
tcg_gen_mov_i64(tmp, dst);
dst = tmp;
}
gen_pc_plus_diff(s, lr, curr_insn_len(s));
}
gen_a64_set_pc(s, dst);
break;
case 0:
case 1:
case 2:
/*
* BR, BLR, RET, RETAA, RETAB, BRAAZ, BRABZ, BLRAAZ, BLRABZ:
* handled in decodetree
*/
goto do_unallocated;
case 8: /* BRAA */
case 9: /* BLRAA */