fix WFI/WFE length in syndrome register

WFI/E are often, but not always, 4 bytes long. When they are, we need to
set ARM_EL_IL_SHIFT in the syndrome register.

Pass the instruction length to HELPER(wfi), use it to decrement pc
appropriately and to pass an is_16bit flag to syn_wfx, which sets
ARM_EL_IL_SHIFT if needed.

Set dc->insn in both arm_tr_translate_insn and thumb_tr_translate_insn.

Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
Message-id: alpine.DEB.2.10.1710241055160.574@sstabellini-ThinkPad-X260
[PMM: move setting of dc->insn for Thumb so it is correct for 32 bit insns]
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/helper.h

@@ -48,7 +48,7 @@ DEF_HELPER_FLAGS_3(sel_flags, TCG_CALL_NO_RWG_SE,
 DEF_HELPER_2(exception_internal, void, env, i32)
 DEF_HELPER_4(exception_with_syndrome, void, env, i32, i32, i32)
 DEF_HELPER_1(setend, void, env)
-DEF_HELPER_1(wfi, void, env)
+DEF_HELPER_2(wfi, void, env, i32)
 DEF_HELPER_1(wfe, void, env)
 DEF_HELPER_1(yield, void, env)
 DEF_HELPER_1(pre_hvc, void, env)

target/arm/internals.h

@@ -428,9 +428,10 @@ static inline uint32_t syn_breakpoint(int same_el)
         | ARM_EL_IL | 0x22;
 }
 
-static inline uint32_t syn_wfx(int cv, int cond, int ti)
+static inline uint32_t syn_wfx(int cv, int cond, int ti, bool is_16bit)
 {
     return (EC_WFX_TRAP << ARM_EL_EC_SHIFT) |
+           (is_16bit ? 0 : (1 << ARM_EL_IL_SHIFT)) |
            (cv << 24) | (cond << 20) | ti;
 }
 

target/arm/op_helper.c

@@ -463,7 +463,7 @@ static inline int check_wfx_trap(CPUARMState *env, bool is_wfe)
     return 0;
 }
 
-void HELPER(wfi)(CPUARMState *env)
+void HELPER(wfi)(CPUARMState *env, uint32_t insn_len)
 {
     CPUState *cs = CPU(arm_env_get_cpu(env));
     int target_el = check_wfx_trap(env, false);
@@ -476,8 +476,9 @@ void HELPER(wfi)(CPUARMState *env)
     }
 
     if (target_el) {
-        env->pc -= 4;
-        raise_exception(env, EXCP_UDEF, syn_wfx(1, 0xe, 0), target_el);
+        env->pc -= insn_len;
+        raise_exception(env, EXCP_UDEF, syn_wfx(1, 0xe, 0, insn_len == 2),
+                        target_el);
     }
 
     cs->exception_index = EXCP_HLT;

target/arm/psci.c

@@ -189,7 +189,7 @@ void arm_handle_psci_call(ARMCPU *cpu)
         } else {
             env->regs[0] = 0;
         }
-        helper_wfi(env);
+        helper_wfi(env, 4);
         break;
     case QEMU_PSCI_0_1_FN_MIGRATE:
     case QEMU_PSCI_0_2_FN_MIGRATE:

target/arm/translate-a64.c

@@ -11400,17 +11400,22 @@ static void aarch64_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
             gen_helper_yield(cpu_env);
             break;
         case DISAS_WFI:
+        {
             /* This is a special case because we don't want to just halt the CPU
              * if trying to debug across a WFI.
              */
+            TCGv_i32 tmp = tcg_const_i32(4);
+
             gen_a64_set_pc_im(dc->pc);
-            gen_helper_wfi(cpu_env);
+            gen_helper_wfi(cpu_env, tmp);
+            tcg_temp_free_i32(tmp);
             /* The helper doesn't necessarily throw an exception, but we
              * must go back to the main loop to check for interrupts anyway.
              */
             tcg_gen_exit_tb(0);
             break;
         }
+        }
     }
 
     /* Functions above can change dc->pc, so re-align db->pc_next */

target/arm/translate.c

@@ -12125,6 +12125,7 @@ static void arm_tr_translate_insn(DisasContextBase *dcbase, CPUState *cpu)
     }
 
     insn = arm_ldl_code(env, dc->pc, dc->sctlr_b);
+    dc->insn = insn;
     dc->pc += 4;
     disas_arm_insn(dc, insn);
 
@@ -12200,6 +12201,7 @@ static void thumb_tr_translate_insn(DisasContextBase *dcbase, CPUState *cpu)
         insn = insn << 16 | insn2;
         dc->pc += 2;
     }
+    dc->insn = insn;
 
     if (dc->condexec_mask && !thumb_insn_is_unconditional(dc, insn)) {
         uint32_t cond = dc->condexec_cond;
@@ -12326,12 +12328,18 @@ static void arm_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
             /* nothing more to generate */
             break;
         case DISAS_WFI:
-            gen_helper_wfi(cpu_env);
+        {
+            TCGv_i32 tmp = tcg_const_i32((dc->thumb &&
+                                          !(dc->insn & (1U << 31))) ? 2 : 4);
+
+            gen_helper_wfi(cpu_env, tmp);
+            tcg_temp_free_i32(tmp);
             /* The helper doesn't necessarily throw an exception, but we
              * must go back to the main loop to check for interrupts anyway.
              */
             tcg_gen_exit_tb(0);
             break;
+        }
         case DISAS_WFE:
             gen_helper_wfe(cpu_env);
             break;