[v5,05/22] target/arm: Suppress tag check for sp+offset

Message ID 20191011134744.2477-6-richard.henderson@linaro.org
State New
Headers show
Series
  • [v5,01/22] target/arm: Add MTE_ACTIVE to tb_flags
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Commit Message

Richard Henderson Oct. 11, 2019, 1:47 p.m.
R0078 specifies that base register, or base register plus immediate
offset, is unchecked when the base register is SP.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

---
v2: Include writeback addresses as checked.
---
 target/arm/translate-a64.c | 36 ++++++++++++++++++------------------
 1 file changed, 18 insertions(+), 18 deletions(-)

-- 
2.17.1

Comments

Peter Maydell Dec. 3, 2019, 2:07 p.m. | #1
On Fri, 11 Oct 2019 at 14:49, Richard Henderson
<richard.henderson@linaro.org> wrote:
>

> R0078 specifies that base register, or base register plus immediate

> offset, is unchecked when the base register is SP.


It looks like rule-numbers didn't make it into the final Arm ARM,
so I guess the reference here would just be to section D6.8.1 ?

Also, this phrasing is slightly ambiguous about whether the
"when base is SP" condition applies to both "base register"
and "base register + immediate", or just to the last of the two;
the correct reading is the latter of these (and the D6.8.1
Arm ARM text is in error; trust the pseudocode here).

We could perhaps say something like:

D6.8.1 specifies that accesses are tag-unchecked for loads and
stores (including exclusives, compare-and-swap, etc) whose addresses are:
 * base-register only, where the base register is SP
 * base-register plus immediate, where the base register is SP
   (not including reg+imm with writeback addressing forms)
and also that literal (pc-relative) loads are tag-unchecked.

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

> ---

> v2: Include writeback addresses as checked.


The load-literal case is implicitly tag-unchecked because
the address calculation doesn't go via clean_data_tbi(), right?

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>


thanks
-- PMM
Richard Henderson Feb. 17, 2020, 9:32 p.m. | #2
On 12/3/19 6:07 AM, Peter Maydell wrote:
> The load-literal case is implicitly tag-unchecked because

> the address calculation doesn't go via clean_data_tbi(), right?


Yes.


r~

Patch

diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index 8e4fea6b4c..18d45fba87 100644
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -211,12 +211,12 @@  static void gen_a64_set_pc(DisasContext *s, TCGv_i64 src)
  * This is always a fresh temporary, as we need to be able to
  * increment this independently of a dirty write-back address.
  */
-static TCGv_i64 clean_data_tbi(DisasContext *s, TCGv_i64 addr)
+static TCGv_i64 clean_data_tbi(DisasContext *s, TCGv_i64 addr, bool check)
 {
     TCGv_i64 clean = new_tmp_a64(s);
 
     /* Note that s->mte_active already includes a check for s->tbid != 0. */
-    if (!s->mte_active) {
+    if (!check || !s->mte_active) {
         gen_top_byte_ignore(s, clean, addr, s->tbid);
     } else if (!regime_has_2_ranges(s->mmu_idx)) {
         gen_helper_mte_check1(clean, cpu_env, addr);
@@ -2334,7 +2334,7 @@  static void gen_compare_and_swap(DisasContext *s, int rs, int rt,
     if (rn == 31) {
         gen_check_sp_alignment(s);
     }
-    clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn));
+    clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn), rn != 31);
     tcg_gen_atomic_cmpxchg_i64(tcg_rs, clean_addr, tcg_rs, tcg_rt, memidx,
                                size | MO_ALIGN | s->be_data);
 }
@@ -2352,7 +2352,7 @@  static void gen_compare_and_swap_pair(DisasContext *s, int rs, int rt,
     if (rn == 31) {
         gen_check_sp_alignment(s);
     }
-    clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn));
+    clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn), rn != 31);
 
     if (size == 2) {
         TCGv_i64 cmp = tcg_temp_new_i64();
@@ -2477,7 +2477,7 @@  static void disas_ldst_excl(DisasContext *s, uint32_t insn)
         if (is_lasr) {
             tcg_gen_mb(TCG_MO_ALL | TCG_BAR_STRL);
         }
-        clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn));
+        clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn), rn != 31);
         gen_store_exclusive(s, rs, rt, rt2, clean_addr, size, false);
         return;
 
@@ -2486,7 +2486,7 @@  static void disas_ldst_excl(DisasContext *s, uint32_t insn)
         if (rn == 31) {
             gen_check_sp_alignment(s);
         }
-        clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn));
+        clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn), rn != 31);
         s->is_ldex = true;
         gen_load_exclusive(s, rt, rt2, clean_addr, size, false);
         if (is_lasr) {
@@ -2506,7 +2506,7 @@  static void disas_ldst_excl(DisasContext *s, uint32_t insn)
             gen_check_sp_alignment(s);
         }
         tcg_gen_mb(TCG_MO_ALL | TCG_BAR_STRL);
-        clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn));
+        clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn), rn != 31);
         do_gpr_st(s, cpu_reg(s, rt), clean_addr, size, true, rt,
                   disas_ldst_compute_iss_sf(size, false, 0), is_lasr);
         return;
@@ -2522,7 +2522,7 @@  static void disas_ldst_excl(DisasContext *s, uint32_t insn)
         if (rn == 31) {
             gen_check_sp_alignment(s);
         }
-        clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn));
+        clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn), rn != 31);
         do_gpr_ld(s, cpu_reg(s, rt), clean_addr, size, false, false, true, rt,
                   disas_ldst_compute_iss_sf(size, false, 0), is_lasr);
         tcg_gen_mb(TCG_MO_ALL | TCG_BAR_LDAQ);
@@ -2536,7 +2536,7 @@  static void disas_ldst_excl(DisasContext *s, uint32_t insn)
             if (is_lasr) {
                 tcg_gen_mb(TCG_MO_ALL | TCG_BAR_STRL);
             }
-            clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn));
+            clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn), rn != 31);
             gen_store_exclusive(s, rs, rt, rt2, clean_addr, size, true);
             return;
         }
@@ -2554,7 +2554,7 @@  static void disas_ldst_excl(DisasContext *s, uint32_t insn)
             if (rn == 31) {
                 gen_check_sp_alignment(s);
             }
-            clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn));
+            clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn), rn != 31);
             s->is_ldex = true;
             gen_load_exclusive(s, rt, rt2, clean_addr, size, true);
             if (is_lasr) {
@@ -2744,7 +2744,7 @@  static void disas_ldst_pair(DisasContext *s, uint32_t insn)
     if (!postindex) {
         tcg_gen_addi_i64(dirty_addr, dirty_addr, offset);
     }
-    clean_addr = clean_data_tbi(s, dirty_addr);
+    clean_addr = clean_data_tbi(s, dirty_addr, wback || rn != 31);
 
     if (is_vector) {
         if (is_load) {
@@ -2882,7 +2882,7 @@  static void disas_ldst_reg_imm9(DisasContext *s, uint32_t insn,
     if (!post_index) {
         tcg_gen_addi_i64(dirty_addr, dirty_addr, imm9);
     }
-    clean_addr = clean_data_tbi(s, dirty_addr);
+    clean_addr = clean_data_tbi(s, dirty_addr, writeback || rn != 31);
 
     if (is_vector) {
         if (is_store) {
@@ -2989,7 +2989,7 @@  static void disas_ldst_reg_roffset(DisasContext *s, uint32_t insn,
     ext_and_shift_reg(tcg_rm, tcg_rm, opt, shift ? size : 0);
 
     tcg_gen_add_i64(dirty_addr, dirty_addr, tcg_rm);
-    clean_addr = clean_data_tbi(s, dirty_addr);
+    clean_addr = clean_data_tbi(s, dirty_addr, true);
 
     if (is_vector) {
         if (is_store) {
@@ -3074,7 +3074,7 @@  static void disas_ldst_reg_unsigned_imm(DisasContext *s, uint32_t insn,
     dirty_addr = read_cpu_reg_sp(s, rn, 1);
     offset = imm12 << size;
     tcg_gen_addi_i64(dirty_addr, dirty_addr, offset);
-    clean_addr = clean_data_tbi(s, dirty_addr);
+    clean_addr = clean_data_tbi(s, dirty_addr, rn != 31);
 
     if (is_vector) {
         if (is_store) {
@@ -3158,7 +3158,7 @@  static void disas_ldst_atomic(DisasContext *s, uint32_t insn,
     if (rn == 31) {
         gen_check_sp_alignment(s);
     }
-    clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn));
+    clean_addr = clean_data_tbi(s, cpu_reg_sp(s, rn), rn != 31);
     tcg_rs = read_cpu_reg(s, rs, true);
 
     if (o3_opc == 1) { /* LDCLR */
@@ -3220,7 +3220,7 @@  static void disas_ldst_pac(DisasContext *s, uint32_t insn,
     tcg_gen_addi_i64(dirty_addr, dirty_addr, offset);
 
     /* Note that "clean" and "dirty" here refer to TBI not PAC.  */
-    clean_addr = clean_data_tbi(s, dirty_addr);
+    clean_addr = clean_data_tbi(s, dirty_addr, is_wback || rn != 31);
 
     tcg_rt = cpu_reg(s, rt);
     do_gpr_ld(s, tcg_rt, clean_addr, size, /* is_signed */ false,
@@ -3380,7 +3380,7 @@  static void disas_ldst_multiple_struct(DisasContext *s, uint32_t insn)
     elements = (is_q ? 16 : 8) / ebytes;
 
     tcg_rn = cpu_reg_sp(s, rn);
-    clean_addr = clean_data_tbi(s, tcg_rn);
+    clean_addr = clean_data_tbi(s, tcg_rn, is_postidx || rn != 31);
     tcg_ebytes = tcg_const_i64(ebytes);
 
     for (r = 0; r < rpt; r++) {
@@ -3523,7 +3523,7 @@  static void disas_ldst_single_struct(DisasContext *s, uint32_t insn)
     }
 
     tcg_rn = cpu_reg_sp(s, rn);
-    clean_addr = clean_data_tbi(s, tcg_rn);
+    clean_addr = clean_data_tbi(s, tcg_rn, is_postidx || rn != 31);
     tcg_ebytes = tcg_const_i64(ebytes);
 
     for (xs = 0; xs < selem; xs++) {