target-arm: Add support for generating exceptions with syndrome information

Add new helpers exception_with_syndrome (for generating an exception
with syndrome information) and exception_uncategorized (for generating
an exception with "Unknown or Uncategorized Reason", which have a syndrome
register value of zero), and use them to generate the correct syndrome
information for exceptions which are raised directly from generated code.

This patch includes moving the A32/T32 gen_exception_insn functions
further up in the source file; they will be needed for "VFP/Neon disabled"
exception generation later.

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

6 files changed, 138 insertions, 54 deletions

diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 3ec752e7f..bf8b7d504 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -52,6 +52,20 @@
 #define EXCP_KERNEL_TRAP     9   /* Jumped to kernel code page.  */
 #define EXCP_STREX          10
 
+static inline bool excp_is_internal(int excp)
+{
+    /* Return true if this exception number represents a QEMU-internal
+     * exception that will not be passed to the guest.
+     */
+    return excp == EXCP_INTERRUPT
+        || excp == EXCP_HLT
+        || excp == EXCP_DEBUG
+        || excp == EXCP_HALTED
+        || excp == EXCP_EXCEPTION_EXIT
+        || excp == EXCP_KERNEL_TRAP
+        || excp == EXCP_STREX;
+}
+
 #define ARMV7M_EXCP_RESET   1
 #define ARMV7M_EXCP_NMI     2
 #define ARMV7M_EXCP_HARD    3
diff --git a/target-arm/helper.h b/target-arm/helper.h
index 174c6159e..8986fcd6c 100644
--- a/target-arm/helper.h
+++ b/target-arm/helper.h
@@ -48,7 +48,8 @@ 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, void, env, i32)
+DEF_HELPER_2(exception_internal, void, env, i32)
+DEF_HELPER_3(exception_with_syndrome, void, env, i32, i32)
 DEF_HELPER_1(wfi, void, env)
 
 DEF_HELPER_3(cpsr_write, void, env, i32, i32)
diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
index fa383b3ef..0149e2f2f 100644
--- a/target-arm/op_helper.c
+++ b/target-arm/op_helper.c
@@ -225,9 +225,26 @@ void HELPER(wfi)(CPUARMState *env)
     cpu_loop_exit(env);
 }
 
-void HELPER(exception)(CPUARMState *env, uint32_t excp)
+/* Raise an internal-to-QEMU exception. This is limited to only
+ * those EXCP values which are special cases for QEMU to interrupt
+ * execution and not to be used for exceptions which are passed to
+ * the guest (those must all have syndrome information and thus should
+ * use exception_with_syndrome).
+ */
+void HELPER(exception_internal)(CPUARMState *env, uint32_t excp)
+{
+    assert(excp_is_internal(excp));
+    env->exception_index = excp;
+    cpu_loop_exit(env);
+}
+
+/* Raise an exception with the specified syndrome register value */
+void HELPER(exception_with_syndrome)(CPUARMState *env, uint32_t excp,
+                                     uint32_t syndrome)
 {
+    assert(!excp_is_internal(excp));
     env->exception_index = excp;
+    env->exception.syndrome = syndrome;
     cpu_loop_exit(env);
 }
 
diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index 88adb1925..6783b6ac7 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -172,18 +172,37 @@ void gen_a64_set_pc_im(uint64_t val)
     tcg_gen_movi_i64(cpu_pc, val);
 }
 
-static void gen_exception(int excp)
+static void gen_exception_internal(int excp)
 {
-    TCGv_i32 tmp = tcg_temp_new_i32();
-    tcg_gen_movi_i32(tmp, excp);
-    gen_helper_exception(cpu_env, tmp);
-    tcg_temp_free_i32(tmp);
+    TCGv_i32 tcg_excp = tcg_const_i32(excp);
+
+    assert(excp_is_internal(excp));
+    gen_helper_exception_internal(cpu_env, tcg_excp);
+    tcg_temp_free_i32(tcg_excp);
+}
+
+static void gen_exception(int excp, uint32_t syndrome)
+{
+    TCGv_i32 tcg_excp = tcg_const_i32(excp);
+    TCGv_i32 tcg_syn = tcg_const_i32(syndrome);
+
+    gen_helper_exception_with_syndrome(cpu_env, tcg_excp, tcg_syn);
+    tcg_temp_free_i32(tcg_syn);
+    tcg_temp_free_i32(tcg_excp);
+}
+
+static void gen_exception_internal_insn(DisasContext *s, int offset, int excp)
+{
+    gen_a64_set_pc_im(s->pc - offset);
+    gen_exception_internal(excp);
+    s->is_jmp = DISAS_EXC;
 }
 
-static void gen_exception_insn(DisasContext *s, int offset, int excp)
+static void gen_exception_insn(DisasContext *s, int offset, int excp,
+                               uint32_t syndrome)
 {
     gen_a64_set_pc_im(s->pc - offset);
-    gen_exception(excp);
+    gen_exception(excp, syndrome);
     s->is_jmp = DISAS_EXC;
 }
 
@@ -215,7 +234,7 @@ static inline void gen_goto_tb(DisasContext *s, int n, uint64_t dest)
     } else {
         gen_a64_set_pc_im(dest);
         if (s->singlestep_enabled) {
-            gen_exception(EXCP_DEBUG);
+            gen_exception_internal(EXCP_DEBUG);
         }
         tcg_gen_exit_tb(0);
         s->is_jmp = DISAS_JUMP;
@@ -224,7 +243,8 @@ static inline void gen_goto_tb(DisasContext *s, int n, uint64_t dest)
 
 static void unallocated_encoding(DisasContext *s)
 {
-    gen_exception_insn(s, 4, EXCP_UDEF);
+    /* Unallocated and reserved encodings are uncategorized */
+    gen_exception_insn(s, 4, EXCP_UDEF, syn_uncategorized());
 }
 
 #define unsupported_encoding(s, insn)                                    \
@@ -1369,6 +1389,7 @@ static void disas_exc(DisasContext *s, uint32_t insn)
 {
     int opc = extract32(insn, 21, 3);
     int op2_ll = extract32(insn, 0, 5);
+    int imm16 = extract32(insn, 5, 16);
 
     switch (opc) {
     case 0:
@@ -1379,7 +1400,7 @@ static void disas_exc(DisasContext *s, uint32_t insn)
             unallocated_encoding(s);
             break;
         }
-        gen_exception_insn(s, 0, EXCP_SWI);
+        gen_exception_insn(s, 0, EXCP_SWI, syn_aa64_svc(imm16));
         break;
     case 1:
         if (op2_ll != 0) {
@@ -1387,7 +1408,7 @@ static void disas_exc(DisasContext *s, uint32_t insn)
             break;
         }
         /* BRK */
-        gen_exception_insn(s, 0, EXCP_BKPT);
+        gen_exception_insn(s, 0, EXCP_BKPT, syn_aa64_bkpt(imm16));
         break;
     case 2:
         if (op2_ll != 0) {
@@ -1536,7 +1557,7 @@ static void gen_store_exclusive(DisasContext *s, int rd, int rt, int rt2,
     tcg_gen_mov_i64(cpu_exclusive_test, addr);
     tcg_gen_movi_i32(cpu_exclusive_info,
                      size | is_pair << 2 | (rd << 4) | (rt << 9) | (rt2 << 14));
-    gen_exception_insn(s, 4, EXCP_STREX);
+    gen_exception_internal_insn(s, 4, EXCP_STREX);
 }
 #else
 static void gen_store_exclusive(DisasContext *s, int rd, int rt, int rt2,
@@ -9107,7 +9128,7 @@ void gen_intermediate_code_internal_a64(ARMCPU *cpu,
         if (unlikely(!QTAILQ_EMPTY(&env->breakpoints))) {
             QTAILQ_FOREACH(bp, &env->breakpoints, entry) {
                 if (bp->pc == dc->pc) {
-                    gen_exception_insn(dc, 0, EXCP_DEBUG);
+                    gen_exception_internal_insn(dc, 0, EXCP_DEBUG);
                     /* Advance PC so that clearing the breakpoint will
                        invalidate this TB.  */
                     dc->pc += 2;
@@ -9170,7 +9191,7 @@ void gen_intermediate_code_internal_a64(ARMCPU *cpu,
         if (dc->is_jmp != DISAS_JUMP) {
             gen_a64_set_pc_im(dc->pc);
         }
-        gen_exception(EXCP_DEBUG);
+        gen_exception_internal(EXCP_DEBUG);
     } else {
         switch (dc->is_jmp) {
         case DISAS_NEXT:
diff --git a/target-arm/translate.c b/target-arm/translate.c
index 2c2c2fe10..42b64f496 100644
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -182,12 +182,23 @@ static inline void gen_set_cpsr(TCGv_i32 var, uint32_t mask)
 /* Set NZCV flags from the high 4 bits of var.  */
 #define gen_set_nzcv(var) gen_set_cpsr(var, CPSR_NZCV)
 
-static void gen_exception(int excp)
+static void gen_exception_internal(int excp)
 {
-    TCGv_i32 tmp = tcg_temp_new_i32();
-    tcg_gen_movi_i32(tmp, excp);
-    gen_helper_exception(cpu_env, tmp);
-    tcg_temp_free_i32(tmp);
+    TCGv_i32 tcg_excp = tcg_const_i32(excp);
+
+    assert(excp_is_internal(excp));
+    gen_helper_exception_internal(cpu_env, tcg_excp);
+    tcg_temp_free_i32(tcg_excp);
+}
+
+static void gen_exception(int excp, uint32_t syndrome)
+{
+    TCGv_i32 tcg_excp = tcg_const_i32(excp);
+    TCGv_i32 tcg_syn = tcg_const_i32(syndrome);
+
+    gen_helper_exception_with_syndrome(cpu_env, tcg_excp, tcg_syn);
+    tcg_temp_free_i32(tcg_syn);
+    tcg_temp_free_i32(tcg_excp);
 }
 
 static void gen_smul_dual(TCGv_i32 a, TCGv_i32 b)
@@ -899,6 +910,33 @@ static inline void gen_set_pc_im(DisasContext *s, target_ulong val)
     tcg_gen_movi_i32(cpu_R[15], val);
 }
 
+static inline void
+gen_set_condexec (DisasContext *s)
+{
+    if (s->condexec_mask) {
+        uint32_t val = (s->condexec_cond << 4) | (s->condexec_mask >> 1);
+        TCGv_i32 tmp = tcg_temp_new_i32();
+        tcg_gen_movi_i32(tmp, val);
+        store_cpu_field(tmp, condexec_bits);
+    }
+}
+
+static void gen_exception_internal_insn(DisasContext *s, int offset, int excp)
+{
+    gen_set_condexec(s);
+    gen_set_pc_im(s, s->pc - offset);
+    gen_exception_internal(excp);
+    s->is_jmp = DISAS_JUMP;
+}
+
+static void gen_exception_insn(DisasContext *s, int offset, int excp, int syn)
+{
+    gen_set_condexec(s);
+    gen_set_pc_im(s, s->pc - offset);
+    gen_exception(excp, syn);
+    s->is_jmp = DISAS_JUMP;
+}
+
 /* Force a TB lookup after an instruction that changes the CPU state.  */
 static inline void gen_lookup_tb(DisasContext *s)
 {
@@ -3912,25 +3950,6 @@ static void gen_rfe(DisasContext *s, TCGv_i32 pc, TCGv_i32 cpsr)
     s->is_jmp = DISAS_UPDATE;
 }
 
-static inline void
-gen_set_condexec (DisasContext *s)
-{
-    if (s->condexec_mask) {
-        uint32_t val = (s->condexec_cond << 4) | (s->condexec_mask >> 1);
-        TCGv_i32 tmp = tcg_temp_new_i32();
-        tcg_gen_movi_i32(tmp, val);
-        store_cpu_field(tmp, condexec_bits);
-    }
-}
-
-static void gen_exception_insn(DisasContext *s, int offset, int excp)
-{
-    gen_set_condexec(s);
-    gen_set_pc_im(s, s->pc - offset);
-    gen_exception(excp);
-    s->is_jmp = DISAS_JUMP;
-}
-
 static void gen_nop_hint(DisasContext *s, int val)
 {
     switch (val) {
@@ -7140,7 +7159,7 @@ static void gen_store_exclusive(DisasContext *s, int rd, int rt, int rt2,
     tcg_gen_extu_i32_i64(cpu_exclusive_test, addr);
     tcg_gen_movi_i32(cpu_exclusive_info,
                      size | (rd << 4) | (rt << 8) | (rt2 << 12));
-    gen_exception_insn(s, 4, EXCP_STREX);
+    gen_exception_internal_insn(s, 4, EXCP_STREX);
 }
 #else
 static void gen_store_exclusive(DisasContext *s, int rd, int rt, int rt2,
@@ -7620,6 +7639,8 @@ static void disas_arm_insn(CPUARMState * env, DisasContext *s)
             store_reg(s, rd, tmp);
             break;
         case 7:
+        {
+            int imm16 = extract32(insn, 0, 4) | (extract32(insn, 8, 12) << 4);
             /* SMC instruction (op1 == 3)
                and undefined instructions (op1 == 0 || op1 == 2)
                will trap */
@@ -7628,8 +7649,9 @@ static void disas_arm_insn(CPUARMState * env, DisasContext *s)
             }
             /* bkpt */
             ARCH(5);
-            gen_exception_insn(s, 4, EXCP_BKPT);
+            gen_exception_insn(s, 4, EXCP_BKPT, syn_aa32_bkpt(imm16, false));
             break;
+        }
         case 0x8: /* signed multiply */
         case 0xa:
         case 0xc:
@@ -8636,11 +8658,12 @@ static void disas_arm_insn(CPUARMState * env, DisasContext *s)
         case 0xf:
             /* swi */
             gen_set_pc_im(s, s->pc);
+            s->svc_imm = extract32(insn, 0, 24);
             s->is_jmp = DISAS_SWI;
             break;
         default:
         illegal_op:
-            gen_exception_insn(s, 4, EXCP_UDEF);
+            gen_exception_insn(s, 4, EXCP_UDEF, syn_uncategorized());
             break;
         }
     }
@@ -10425,9 +10448,12 @@ static void disas_thumb_insn(CPUARMState *env, DisasContext *s)
             break;
 
         case 0xe: /* bkpt */
+        {
+            int imm8 = extract32(insn, 0, 8);
             ARCH(5);
-            gen_exception_insn(s, 2, EXCP_BKPT);
+            gen_exception_insn(s, 2, EXCP_BKPT, syn_aa32_bkpt(imm8, true));
             break;
+        }
 
         case 0xa: /* rev */
             ARCH(6);
@@ -10544,6 +10570,7 @@ static void disas_thumb_insn(CPUARMState *env, DisasContext *s)
         if (cond == 0xf) {
             /* swi */
             gen_set_pc_im(s, s->pc);
+            s->svc_imm = extract32(insn, 0, 8);
             s->is_jmp = DISAS_SWI;
             break;
         }
@@ -10579,11 +10606,11 @@ static void disas_thumb_insn(CPUARMState *env, DisasContext *s)
     }
     return;
 undef32:
-    gen_exception_insn(s, 4, EXCP_UDEF);
+    gen_exception_insn(s, 4, EXCP_UDEF, syn_uncategorized());
     return;
 illegal_op:
 undef:
-    gen_exception_insn(s, 2, EXCP_UDEF);
+    gen_exception_insn(s, 2, EXCP_UDEF, syn_uncategorized());
 }
 
 /* generate intermediate code in gen_opc_buf and gen_opparam_buf for
@@ -10704,7 +10731,7 @@ static inline void gen_intermediate_code_internal(ARMCPU *cpu,
         if (dc->pc >= 0xffff0000) {
             /* We always get here via a jump, so know we are not in a
                conditional execution block.  */
-            gen_exception(EXCP_KERNEL_TRAP);
+            gen_exception_internal(EXCP_KERNEL_TRAP);
             dc->is_jmp = DISAS_UPDATE;
             break;
         }
@@ -10712,7 +10739,7 @@ static inline void gen_intermediate_code_internal(ARMCPU *cpu,
         if (dc->pc >= 0xfffffff0 && IS_M(env)) {
             /* We always get here via a jump, so know we are not in a
                conditional execution block.  */
-            gen_exception(EXCP_EXCEPTION_EXIT);
+            gen_exception_internal(EXCP_EXCEPTION_EXIT);
             dc->is_jmp = DISAS_UPDATE;
             break;
         }
@@ -10721,7 +10748,7 @@ static inline void gen_intermediate_code_internal(ARMCPU *cpu,
         if (unlikely(!QTAILQ_EMPTY(&env->breakpoints))) {
             QTAILQ_FOREACH(bp, &env->breakpoints, entry) {
                 if (bp->pc == dc->pc) {
-                    gen_exception_insn(dc, 0, EXCP_DEBUG);
+                    gen_exception_internal_insn(dc, 0, EXCP_DEBUG);
                     /* Advance PC so that clearing the breakpoint will
                        invalidate this TB.  */
                     dc->pc += 2;
@@ -10801,9 +10828,9 @@ static inline void gen_intermediate_code_internal(ARMCPU *cpu,
         if (dc->condjmp) {
             gen_set_condexec(dc);
             if (dc->is_jmp == DISAS_SWI) {
-                gen_exception(EXCP_SWI);
+                gen_exception(EXCP_SWI, syn_aa32_svc(dc->svc_imm, dc->thumb));
             } else {
-                gen_exception(EXCP_DEBUG);
+                gen_exception_internal(EXCP_DEBUG);
             }
             gen_set_label(dc->condlabel);
         }
@@ -10813,11 +10840,11 @@ static inline void gen_intermediate_code_internal(ARMCPU *cpu,
         }
         gen_set_condexec(dc);
         if (dc->is_jmp == DISAS_SWI && !dc->condjmp) {
-            gen_exception(EXCP_SWI);
+            gen_exception(EXCP_SWI, syn_aa32_svc(dc->svc_imm, dc->thumb));
         } else {
             /* FIXME: Single stepping a WFI insn will not halt
                the CPU.  */
-            gen_exception(EXCP_DEBUG);
+            gen_exception_internal(EXCP_DEBUG);
         }
     } else {
         /* While branches must always occur at the end of an IT block,
@@ -10846,7 +10873,7 @@ static inline void gen_intermediate_code_internal(ARMCPU *cpu,
             gen_helper_wfi(cpu_env);
             break;
         case DISAS_SWI:
-            gen_exception(EXCP_SWI);
+            gen_exception(EXCP_SWI, syn_aa32_svc(dc->svc_imm, dc->thumb));
             break;
         }
         if (dc->condjmp) {
diff --git a/target-arm/translate.h b/target-arm/translate.h
index 889a0316f..4d3d3636a 100644
--- a/target-arm/translate.h
+++ b/target-arm/translate.h
@@ -23,6 +23,10 @@ typedef struct DisasContext {
     int vfp_enabled;
     int vec_len;
     int vec_stride;
+    /* Immediate value in AArch32 SVC insn; must be set if is_jmp == DISAS_SWI
+     * so that top level loop can generate correct syndrome information.
+     */
+    uint32_t svc_imm;
     int aarch64;
     int current_pl;
     GHashTable *cp_regs;