[Qemu-devel] [PATCH v2 1/9] target-arm: Add exception target el infrastructure

[Greg Bellows <greg.bellows@linaro.org>]

Add a CPU state exception target EL field that will be used for communicating
the EL to which an exception should be routed.

Add a disassembly context field for tracking the EL3 architecture needed for
determining the target exception EL.

Add a target EL argument to the generic exception helper for callers to specify
the EL to which the exception should be routed.  Extended the helper to set
the newly added CPU state exception target el.

Added a function for setting the target exception EL and updated calls to helpers
to call it.

Signed-off-by: Greg Bellows <greg.bellows@linaro.org>

---

v1 -> v2
- Add translate utility function for determining the default exception target
  EL and replaced uses of MAX with it.
---
 target-arm/cpu.h           |  1 +
 target-arm/helper.h        |  2 +-
 target-arm/op_helper.c     |  3 ++-
 target-arm/translate-a64.c | 34 +++++++++++++++---------
 target-arm/translate.c     | 65 ++++++++++++++++++++++++++++++----------------
 target-arm/translate.h     | 15 +++++++++++
 6 files changed, 83 insertions(+), 37 deletions(-)

diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 083211c..0b232ba 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -401,6 +401,7 @@ typedef struct CPUARMState {
         uint32_t syndrome; /* AArch64 format syndrome register */
         uint32_t fsr; /* AArch32 format fault status register info */
         uint64_t vaddress; /* virtual addr associated with exception, if any */
+        uint32_t target_el; /* EL the exception should be targeted for */
         /* If we implement EL2 we will also need to store information
          * about the intermediate physical address for stage 2 faults.
          */
diff --git a/target-arm/helper.h b/target-arm/helper.h
index dec3728..fc885de 100644
--- a/target-arm/helper.h
+++ b/target-arm/helper.h
@@ -47,7 +47,7 @@ DEF_HELPER_FLAGS_2(usad8, TCG_CALL_NO_RWG_SE, i32, i32, i32)
 DEF_HELPER_FLAGS_3(sel_flags, TCG_CALL_NO_RWG_SE,
                    i32, i32, i32, i32)
 DEF_HELPER_2(exception_internal, void, env, i32)
-DEF_HELPER_3(exception_with_syndrome, void, env, i32, i32)
+DEF_HELPER_4(exception_with_syndrome, void, env, i32, i32, i32)
 DEF_HELPER_1(wfi, void, env)
 DEF_HELPER_1(wfe, void, env)
 DEF_HELPER_1(pre_hvc, void, env)
diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
index 7713022..72a973a 100644
--- a/target-arm/op_helper.c
+++ b/target-arm/op_helper.c
@@ -246,13 +246,14 @@ void HELPER(exception_internal)(CPUARMState *env, uint32_t excp)
 
 /* Raise an exception with the specified syndrome register value */
 void HELPER(exception_with_syndrome)(CPUARMState *env, uint32_t excp,
-                                     uint32_t syndrome)
+                                     uint32_t syndrome, uint32_t target_el)
 {
     CPUState *cs = CPU(arm_env_get_cpu(env));
 
     assert(!excp_is_internal(excp));
     cs->exception_index = excp;
     env->exception.syndrome = syndrome;
+    env->exception.target_el = target_el;
     cpu_loop_exit(cs);
 }
 
diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index 0b192a1..b1f44c9 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -197,12 +197,15 @@ static void gen_exception_internal(int excp)
     tcg_temp_free_i32(tcg_excp);
 }
 
-static void gen_exception(int excp, uint32_t syndrome)
+static void gen_exception(int excp, uint32_t syndrome, uint32_t target_el)
 {
     TCGv_i32 tcg_excp = tcg_const_i32(excp);
     TCGv_i32 tcg_syn = tcg_const_i32(syndrome);
+    TCGv_i32 tcg_el = tcg_const_i32(target_el);
 
-    gen_helper_exception_with_syndrome(cpu_env, tcg_excp, tcg_syn);
+    gen_helper_exception_with_syndrome(cpu_env, tcg_excp,
+                                       tcg_syn, tcg_el);
+    tcg_temp_free_i32(tcg_el);
     tcg_temp_free_i32(tcg_syn);
     tcg_temp_free_i32(tcg_excp);
 }
@@ -215,10 +218,10 @@ static void gen_exception_internal_insn(DisasContext *s, int offset, int excp)
 }
 
 static void gen_exception_insn(DisasContext *s, int offset, int excp,
-                               uint32_t syndrome)
+                               uint32_t syndrome, uint32_t target_el)
 {
     gen_a64_set_pc_im(s->pc - offset);
-    gen_exception(excp, syndrome);
+    gen_exception(excp, syndrome, target_el);
     s->is_jmp = DISAS_EXC;
 }
 
@@ -245,7 +248,8 @@ static void gen_step_complete_exception(DisasContext *s)
      * of the exception, and our syndrome information is always correct.
      */
     gen_ss_advance(s);
-    gen_exception(EXCP_UDEF, syn_swstep(s->ss_same_el, 1, s->is_ldex));
+    gen_exception(EXCP_UDEF, syn_swstep(s->ss_same_el, 1, s->is_ldex),
+                  default_exception_el(s));
     s->is_jmp = DISAS_EXC;
 }
 
@@ -292,7 +296,8 @@ static inline void gen_goto_tb(DisasContext *s, int n, uint64_t dest)
 static void unallocated_encoding(DisasContext *s)
 {
     /* Unallocated and reserved encodings are uncategorized */
-    gen_exception_insn(s, 4, EXCP_UDEF, syn_uncategorized());
+    gen_exception_insn(s, 4, EXCP_UDEF, syn_uncategorized(),
+                       default_exception_el(s));
 }
 
 #define unsupported_encoding(s, insn)                                    \
@@ -971,7 +976,8 @@ static inline bool fp_access_check(DisasContext *s)
         return true;
     }
 
-    gen_exception_insn(s, 4, EXCP_UDEF, syn_fp_access_trap(1, 0xe, false));
+    gen_exception_insn(s, 4, EXCP_UDEF, syn_fp_access_trap(1, 0xe, false),
+                       default_exception_el(s));
     return false;
 }
 
@@ -1498,7 +1504,8 @@ static void disas_exc(DisasContext *s, uint32_t insn)
         switch (op2_ll) {
         case 1:
             gen_ss_advance(s);
-            gen_exception_insn(s, 0, EXCP_SWI, syn_aa64_svc(imm16));
+            gen_exception_insn(s, 0, EXCP_SWI, syn_aa64_svc(imm16),
+                               default_exception_el(s));
             break;
         case 2:
             if (s->current_el == 0) {
@@ -1511,7 +1518,7 @@ static void disas_exc(DisasContext *s, uint32_t insn)
             gen_a64_set_pc_im(s->pc - 4);
             gen_helper_pre_hvc(cpu_env);
             gen_ss_advance(s);
-            gen_exception_insn(s, 0, EXCP_HVC, syn_aa64_hvc(imm16));
+            gen_exception_insn(s, 0, EXCP_HVC, syn_aa64_hvc(imm16), 2);
             break;
         case 3:
             if (s->current_el == 0) {
@@ -1523,7 +1530,7 @@ static void disas_exc(DisasContext *s, uint32_t insn)
             gen_helper_pre_smc(cpu_env, tmp);
             tcg_temp_free_i32(tmp);
             gen_ss_advance(s);
-            gen_exception_insn(s, 0, EXCP_SMC, syn_aa64_smc(imm16));
+            gen_exception_insn(s, 0, EXCP_SMC, syn_aa64_smc(imm16), 3);
             break;
         default:
             unallocated_encoding(s);
@@ -1536,7 +1543,8 @@ static void disas_exc(DisasContext *s, uint32_t insn)
             break;
         }
         /* BRK */
-        gen_exception_insn(s, 4, EXCP_BKPT, syn_aa64_bkpt(imm16));
+        gen_exception_insn(s, 4, EXCP_BKPT, syn_aa64_bkpt(imm16),
+                           default_exception_el(s));
         break;
     case 2:
         if (op2_ll != 0) {
@@ -10936,6 +10944,7 @@ void gen_intermediate_code_internal_a64(ARMCPU *cpu,
     dc->condjmp = 0;
 
     dc->aarch64 = 1;
+    dc->el3_is_aa64 = arm_el_is_aa64(env, 3);
     dc->thumb = 0;
     dc->bswap_code = 0;
     dc->condexec_mask = 0;
@@ -11031,7 +11040,8 @@ void gen_intermediate_code_internal_a64(ARMCPU *cpu,
              * bits should be zero.
              */
             assert(num_insns == 0);
-            gen_exception(EXCP_UDEF, syn_swstep(dc->ss_same_el, 0, 0));
+            gen_exception(EXCP_UDEF, syn_swstep(dc->ss_same_el, 0, 0),
+                          default_exception_el(dc));
             dc->is_jmp = DISAS_EXC;
             break;
         }
diff --git a/target-arm/translate.c b/target-arm/translate.c
index 9116529..2bd5733 100644
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -217,12 +217,16 @@ static void gen_exception_internal(int excp)
     tcg_temp_free_i32(tcg_excp);
 }
 
-static void gen_exception(int excp, uint32_t syndrome)
+static void gen_exception(int excp, uint32_t syndrome, uint32_t target_el)
 {
     TCGv_i32 tcg_excp = tcg_const_i32(excp);
     TCGv_i32 tcg_syn = tcg_const_i32(syndrome);
+    TCGv_i32 tcg_el = tcg_const_i32(target_el);
 
-    gen_helper_exception_with_syndrome(cpu_env, tcg_excp, tcg_syn);
+    gen_helper_exception_with_syndrome(cpu_env, tcg_excp,
+                                       tcg_syn, tcg_el);
+
+    tcg_temp_free_i32(tcg_el);
     tcg_temp_free_i32(tcg_syn);
     tcg_temp_free_i32(tcg_excp);
 }
@@ -250,7 +254,8 @@ static void gen_step_complete_exception(DisasContext *s)
      * of the exception, and our syndrome information is always correct.
      */
     gen_ss_advance(s);
-    gen_exception(EXCP_UDEF, syn_swstep(s->ss_same_el, 1, s->is_ldex));
+    gen_exception(EXCP_UDEF, syn_swstep(s->ss_same_el, 1, s->is_ldex),
+                  default_exception_el(s));
     s->is_jmp = DISAS_EXC;
 }
 
@@ -1013,11 +1018,12 @@ static void gen_exception_internal_insn(DisasContext *s, int offset, int excp)
     s->is_jmp = DISAS_JUMP;
 }
 
-static void gen_exception_insn(DisasContext *s, int offset, int excp, int syn)
+static void gen_exception_insn(DisasContext *s, int offset, int excp,
+                               int syn, uint32_t target_el)
 {
     gen_set_condexec(s);
     gen_set_pc_im(s, s->pc - offset);
-    gen_exception(excp, syn);
+    gen_exception(excp, syn, target_el);
     s->is_jmp = DISAS_JUMP;
 }
 
@@ -3040,7 +3046,8 @@ static int disas_vfp_insn(DisasContext *s, uint32_t insn)
      */
     if (!s->cpacr_fpen) {
         gen_exception_insn(s, 4, EXCP_UDEF,
-                           syn_fp_access_trap(1, 0xe, s->thumb));
+                           syn_fp_access_trap(1, 0xe, s->thumb),
+                           default_exception_el(s));
         return 0;
     }
 
@@ -4358,7 +4365,8 @@ static int disas_neon_ls_insn(DisasContext *s, uint32_t insn)
      */
     if (!s->cpacr_fpen) {
         gen_exception_insn(s, 4, EXCP_UDEF,
-                           syn_fp_access_trap(1, 0xe, s->thumb));
+                           syn_fp_access_trap(1, 0xe, s->thumb),
+                           default_exception_el(s));
         return 0;
     }
 
@@ -5096,7 +5104,8 @@ static int disas_neon_data_insn(DisasContext *s, uint32_t insn)
      */
     if (!s->cpacr_fpen) {
         gen_exception_insn(s, 4, EXCP_UDEF,
-                           syn_fp_access_trap(1, 0xe, s->thumb));
+                           syn_fp_access_trap(1, 0xe, s->thumb),
+                           default_exception_el(s));
         return 0;
     }
 
@@ -7960,7 +7969,8 @@ static void disas_arm_insn(DisasContext *s, unsigned int insn)
                 /* bkpt */
                 ARCH(5);
                 gen_exception_insn(s, 4, EXCP_BKPT,
-                                   syn_aa32_bkpt(imm16, false));
+                                   syn_aa32_bkpt(imm16, false),
+                                   default_exception_el(s));
                 break;
             case 2:
                 /* Hypervisor call (v7) */
@@ -9021,7 +9031,8 @@ static void disas_arm_insn(DisasContext *s, unsigned int insn)
             break;
         default:
         illegal_op:
-            gen_exception_insn(s, 4, EXCP_UDEF, syn_uncategorized());
+            gen_exception_insn(s, 4, EXCP_UDEF, syn_uncategorized(),
+                               default_exception_el(s));
             break;
         }
     }
@@ -10858,7 +10869,8 @@ static void disas_thumb_insn(CPUARMState *env, DisasContext *s)
         {
             int imm8 = extract32(insn, 0, 8);
             ARCH(5);
-            gen_exception_insn(s, 2, EXCP_BKPT, syn_aa32_bkpt(imm8, true));
+            gen_exception_insn(s, 2, EXCP_BKPT, syn_aa32_bkpt(imm8, true),
+                               default_exception_el(s));
             break;
         }
 
@@ -11013,11 +11025,13 @@ static void disas_thumb_insn(CPUARMState *env, DisasContext *s)
     }
     return;
 undef32:
-    gen_exception_insn(s, 4, EXCP_UDEF, syn_uncategorized());
+    gen_exception_insn(s, 4, EXCP_UDEF, syn_uncategorized(),
+                       default_exception_el(s));
     return;
 illegal_op:
 undef:
-    gen_exception_insn(s, 2, EXCP_UDEF, syn_uncategorized());
+    gen_exception_insn(s, 2, EXCP_UDEF, syn_uncategorized(),
+                       default_exception_el(s));
 }
 
 /* generate intermediate code in gen_opc_buf and gen_opparam_buf for
@@ -11057,6 +11071,7 @@ static inline void gen_intermediate_code_internal(ARMCPU *cpu,
     dc->condjmp = 0;
 
     dc->aarch64 = 0;
+    dc->el3_is_aa64 = arm_el_is_aa64(env, 3);
     dc->thumb = ARM_TBFLAG_THUMB(tb->flags);
     dc->bswap_code = ARM_TBFLAG_BSWAP_CODE(tb->flags);
     dc->condexec_mask = (ARM_TBFLAG_CONDEXEC(tb->flags) & 0xf) << 1;
@@ -11216,7 +11231,8 @@ static inline void gen_intermediate_code_internal(ARMCPU *cpu,
              * bits should be zero.
              */
             assert(num_insns == 0);
-            gen_exception(EXCP_UDEF, syn_swstep(dc->ss_same_el, 0, 0));
+            gen_exception(EXCP_UDEF, syn_swstep(dc->ss_same_el, 0, 0),
+                          default_exception_el(dc));
             goto done_generating;
         }
 
@@ -11276,13 +11292,14 @@ static inline void gen_intermediate_code_internal(ARMCPU *cpu,
             gen_set_condexec(dc);
             if (dc->is_jmp == DISAS_SWI) {
                 gen_ss_advance(dc);
-                gen_exception(EXCP_SWI, syn_aa32_svc(dc->svc_imm, dc->thumb));
+                gen_exception(EXCP_SWI, syn_aa32_svc(dc->svc_imm, dc->thumb),
+                              default_exception_el(dc));
             } else if (dc->is_jmp == DISAS_HVC) {
                 gen_ss_advance(dc);
-                gen_exception(EXCP_HVC, syn_aa32_hvc(dc->svc_imm));
+                gen_exception(EXCP_HVC, syn_aa32_hvc(dc->svc_imm), 2);
             } else if (dc->is_jmp == DISAS_SMC) {
                 gen_ss_advance(dc);
-                gen_exception(EXCP_SMC, syn_aa32_smc());
+                gen_exception(EXCP_SMC, syn_aa32_smc(), 3);
             } else if (dc->ss_active) {
                 gen_step_complete_exception(dc);
             } else {
@@ -11297,13 +11314,14 @@ static inline void gen_intermediate_code_internal(ARMCPU *cpu,
         gen_set_condexec(dc);
         if (dc->is_jmp == DISAS_SWI && !dc->condjmp) {
             gen_ss_advance(dc);
-            gen_exception(EXCP_SWI, syn_aa32_svc(dc->svc_imm, dc->thumb));
+            gen_exception(EXCP_SWI, syn_aa32_svc(dc->svc_imm, dc->thumb),
+                          default_exception_el(dc));
         } else if (dc->is_jmp == DISAS_HVC && !dc->condjmp) {
             gen_ss_advance(dc);
-            gen_exception(EXCP_HVC, syn_aa32_hvc(dc->svc_imm));
+            gen_exception(EXCP_HVC, syn_aa32_hvc(dc->svc_imm), 2);
         } else if (dc->is_jmp == DISAS_SMC && !dc->condjmp) {
             gen_ss_advance(dc);
-            gen_exception(EXCP_SMC, syn_aa32_smc());
+            gen_exception(EXCP_SMC, syn_aa32_smc(), 3);
         } else if (dc->ss_active) {
             gen_step_complete_exception(dc);
         } else {
@@ -11341,13 +11359,14 @@ static inline void gen_intermediate_code_internal(ARMCPU *cpu,
             gen_helper_wfe(cpu_env);
             break;
         case DISAS_SWI:
-            gen_exception(EXCP_SWI, syn_aa32_svc(dc->svc_imm, dc->thumb));
+            gen_exception(EXCP_SWI, syn_aa32_svc(dc->svc_imm, dc->thumb),
+                          default_exception_el(dc));
             break;
         case DISAS_HVC:
-            gen_exception(EXCP_HVC, syn_aa32_hvc(dc->svc_imm));
+            gen_exception(EXCP_HVC, syn_aa32_hvc(dc->svc_imm), 2);
             break;
         case DISAS_SMC:
-            gen_exception(EXCP_SMC, syn_aa32_smc());
+            gen_exception(EXCP_SMC, syn_aa32_smc(), 3);
             break;
         }
         if (dc->condjmp) {
diff --git a/target-arm/translate.h b/target-arm/translate.h
index 9829576..2eadcb7 100644
--- a/target-arm/translate.h
+++ b/target-arm/translate.h
@@ -23,6 +23,7 @@ typedef struct DisasContext {
     ARMMMUIdx mmu_idx; /* MMU index to use for normal loads/stores */
     bool ns;        /* Use non-secure CPREG bank on access */
     bool cpacr_fpen; /* FP enabled via CPACR.FPEN */
+    bool el3_is_aa64;  /* Flag indicating whether EL3 is AArch64 or not */
     bool vfp_enabled; /* FP enabled via FPSCR.EN */
     int vec_len;
     int vec_stride;
@@ -73,6 +74,20 @@ static inline int get_mem_index(DisasContext *s)
     return s->mmu_idx;
 }
 
+/* Function used to determine the target exception EL when otherwise not known
+ * or default.
+ */
+static inline int default_exception_el(DisasContext *s)
+{
+    /* If we are coming from secure EL0 in a system with a 32-bit EL3, then
+     * there is no secure EL1, so we route exceptions to EL3.  Otherwise,
+     * exceptions can only be routed to ELs above 1, so we target the higher of
+     * 1 or the current EL.
+     */
+    return (s->mmu_idx == ARMMMUIdx_S1SE0 && !s->el3_is_aa64)
+            ? 3 : MAX(1, s->current_el);
+}
+
 /* target-specific extra values for is_jmp */
 /* These instructions trap after executing, so the A32/T32 decoder must
  * defer them until after the conditional execution state has been updated.
-- 
1.8.3.2