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[Qemu-arm] [PATCH v2] fix WFI/WFE length in syndrome register


From: Stefano Stabellini
Subject: [Qemu-arm] [PATCH v2] fix WFI/WFE length in syndrome register
Date: Sat, 21 Oct 2017 11:09:33 -0700 (PDT)
User-agent: Alpine 2.10 (DEB 1266 2009-07-14)

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.

Signed-off-by: Stefano Stabellini <address@hidden>

diff --git a/target/arm/helper.h b/target/arm/helper.h
index 2cf6f74..439d228 100644
--- a/target/arm/helper.h
+++ b/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)
diff --git a/target/arm/internals.h b/target/arm/internals.h
index 5a5af38..6792df2 100644
--- a/target/arm/internals.h
+++ b/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;
 }
 
diff --git a/target/arm/op_helper.c b/target/arm/op_helper.c
index 045c312..30039c5 100644
--- a/target/arm/op_helper.c
+++ b/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;
diff --git a/target/arm/psci.c b/target/arm/psci.c
index fc34b26..eb7b88e 100644
--- a/target/arm/psci.c
+++ b/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:
diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index a39b9d3..6f74589 100644
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -11380,17 +11380,20 @@ static void aarch64_tr_tb_stop(DisasContextBase 
*dcbase, CPUState *cpu)
             gen_helper_yield(cpu_env);
             break;
         case DISAS_WFI:
+        {
+            TCGv_i32 tmp = tcg_const_i32((dc->insn & (1U << 31)) ? 4 : 2);
             /* This is a special case because we don't want to just halt the 
CPU
              * if trying to debug across a WFI.
              */
             gen_a64_set_pc_im(dc->pc);
-            gen_helper_wfi(cpu_env);
+            gen_helper_wfi(cpu_env, 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 */
diff --git a/target/arm/translate.c b/target/arm/translate.c
index 4da1a4c..a89518f 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -12325,12 +12325,15 @@ 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->insn & (1U << 31)) ? 4 : 2);
+            gen_helper_wfi(cpu_env, 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;



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