[Qemu-devel] [PULL 25/26] target-s390x: PER: add Breaking-Event-Address register

[Alexander Graf <agraf@suse.de>]

From: Aurelien Jarno <aurelien@aurel32.net>

This patch adds support for PER Breaking-Event-Address register. Like
real hardware, it save the current PSW address when the PSW address is
changed by an instruction. We have to take care of optimizations QEMU
does, a branch to the next instruction is still a branch.

This register is copied to low core memory when a program exception
happens.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Alexander Graf <agraf@suse.de>
---
 target-s390x/cpu.c       |  6 ++++++
 target-s390x/cpu.h       | 12 +++++++-----
 target-s390x/helper.c    |  1 +
 target-s390x/translate.c | 29 +++++++++++++++++++++++------
 4 files changed, 37 insertions(+), 11 deletions(-)

diff --git a/target-s390x/cpu.c b/target-s390x/cpu.c
index 4daf643..69bac35 100644
--- a/target-s390x/cpu.c
+++ b/target-s390x/cpu.c
@@ -117,6 +117,9 @@ static void s390_cpu_initial_reset(CPUState *s)
     env->cregs[0] = CR0_RESET;
     env->cregs[14] = CR14_RESET;
 
+    /* architectured initial value for Breaking-Event-Address register */
+    env->gbea = 1;
+
     env->pfault_token = -1UL;
     env->ext_index = -1;
     for (i = 0; i < ARRAY_SIZE(env->io_index); i++) {
@@ -152,6 +155,9 @@ static void s390_cpu_full_reset(CPUState *s)
     env->cregs[0] = CR0_RESET;
     env->cregs[14] = CR14_RESET;
 
+    /* architectured initial value for Breaking-Event-Address register */
+    env->gbea = 1;
+
     env->pfault_token = -1UL;
     env->ext_index = -1;
     for (i = 0; i < ARRAY_SIZE(env->io_index); i++) {
diff --git a/target-s390x/cpu.h b/target-s390x/cpu.h
index 68321f5..7b87c7d 100644
--- a/target-s390x/cpu.h
+++ b/target-s390x/cpu.h
@@ -789,14 +789,16 @@ typedef struct LowCore
     uint8_t         pad5[0xf4-0xf0];          /* 0x0f0 */
     uint32_t        external_damage_code;     /* 0x0f4 */
     uint64_t        failing_storage_address;  /* 0x0f8 */
-    uint8_t         pad6[0x120-0x100];        /* 0x100 */
+    uint8_t         pad6[0x110-0x100];        /* 0x100 */
+    uint64_t        per_breaking_event_addr;  /* 0x110 */
+    uint8_t         pad7[0x120-0x118];        /* 0x118 */
     PSW             restart_old_psw;          /* 0x120 */
     PSW             external_old_psw;         /* 0x130 */
     PSW             svc_old_psw;              /* 0x140 */
     PSW             program_old_psw;          /* 0x150 */
     PSW             mcck_old_psw;             /* 0x160 */
     PSW             io_old_psw;               /* 0x170 */
-    uint8_t         pad7[0x1a0-0x180];        /* 0x180 */
+    uint8_t         pad8[0x1a0-0x180];        /* 0x180 */
     PSW             restart_new_psw;          /* 0x1a0 */
     PSW             external_new_psw;         /* 0x1b0 */
     PSW             svc_new_psw;              /* 0x1c0 */
@@ -814,10 +816,10 @@ typedef struct LowCore
     uint64_t        last_update_clock;        /* 0x280 */
     uint64_t        steal_clock;              /* 0x288 */
     PSW             return_mcck_psw;          /* 0x290 */
-    uint8_t         pad8[0xc00-0x2a0];        /* 0x2a0 */
+    uint8_t         pad9[0xc00-0x2a0];        /* 0x2a0 */
     /* System info area */
     uint64_t        save_area[16];            /* 0xc00 */
-    uint8_t         pad9[0xd40-0xc80];        /* 0xc80 */
+    uint8_t         pad10[0xd40-0xc80];       /* 0xc80 */
     uint64_t        kernel_stack;             /* 0xd40 */
     uint64_t        thread_info;              /* 0xd48 */
     uint64_t        async_stack;              /* 0xd50 */
@@ -825,7 +827,7 @@ typedef struct LowCore
     uint64_t        user_asce;                /* 0xd60 */
     uint64_t        panic_stack;              /* 0xd68 */
     uint64_t        user_exec_asce;           /* 0xd70 */
-    uint8_t         pad10[0xdc0-0xd78];       /* 0xd78 */
+    uint8_t         pad11[0xdc0-0xd78];       /* 0xd78 */
 
     /* SMP info area: defined by DJB */
     uint64_t        clock_comparator;         /* 0xdc0 */
diff --git a/target-s390x/helper.c b/target-s390x/helper.c
index 615cccf..d887006 100644
--- a/target-s390x/helper.c
+++ b/target-s390x/helper.c
@@ -293,6 +293,7 @@ static void do_program_interrupt(CPUS390XState *env)
     lowcore->program_old_psw.addr = cpu_to_be64(env->psw.addr);
     mask = be64_to_cpu(lowcore->program_new_psw.mask);
     addr = be64_to_cpu(lowcore->program_new_psw.addr);
+    lowcore->per_breaking_event_addr = cpu_to_be64(env->gbea);
 
     cpu_unmap_lowcore(lowcore);
 
diff --git a/target-s390x/translate.c b/target-s390x/translate.c
index d69fb5c..42f52c7 100644
--- a/target-s390x/translate.c
+++ b/target-s390x/translate.c
@@ -150,6 +150,7 @@ void s390_cpu_dump_state(CPUState *cs, FILE *f, fprintf_function cpu_fprintf,
 
 static TCGv_i64 psw_addr;
 static TCGv_i64 psw_mask;
+static TCGv_i64 gbea;
 
 static TCGv_i32 cc_op;
 static TCGv_i64 cc_src;
@@ -173,6 +174,9 @@ void s390x_translate_init(void)
     psw_mask = tcg_global_mem_new_i64(TCG_AREG0,
                                       offsetof(CPUS390XState, psw.mask),
                                       "psw_mask");
+    gbea = tcg_global_mem_new_i64(TCG_AREG0,
+                                  offsetof(CPUS390XState, gbea),
+                                  "gbea");
 
     cc_op = tcg_global_mem_new_i32(TCG_AREG0, offsetof(CPUS390XState, cc_op),
                                    "cc_op");
@@ -252,14 +256,14 @@ static void update_psw_addr(DisasContext *s)
 static void per_branch(DisasContext *s, bool to_next)
 {
 #ifndef CONFIG_USER_ONLY
+    tcg_gen_movi_i64(gbea, s->pc);
+
     if (s->tb->flags & FLAG_MASK_PER) {
-        TCGv_i64 pc = tcg_const_i64(s->pc);
         TCGv_i64 next_pc = to_next ? tcg_const_i64(s->next_pc) : psw_addr;
-        gen_helper_per_branch(cpu_env, pc, next_pc);
+        gen_helper_per_branch(cpu_env, gbea, next_pc);
         if (to_next) {
             tcg_temp_free_i64(next_pc);
         }
-        tcg_temp_free_i64(pc);
     }
 #endif
 }
@@ -272,15 +276,23 @@ static void per_branch_cond(DisasContext *s, TCGCond cond,
         TCGLabel *lab = gen_new_label();
         tcg_gen_brcond_i64(tcg_invert_cond(cond), arg1, arg2, lab);
 
-        TCGv_i64 pc = tcg_const_i64(s->pc);
-        gen_helper_per_branch(cpu_env, pc, psw_addr);
-        tcg_temp_free_i64(pc);
+        tcg_gen_movi_i64(gbea, s->pc);
+        gen_helper_per_branch(cpu_env, gbea, psw_addr);
 
         gen_set_label(lab);
+    } else {
+        TCGv_i64 pc = tcg_const_i64(s->pc);
+        tcg_gen_movcond_i64(cond, gbea, arg1, arg2, gbea, pc);
+        tcg_temp_free_i64(pc);
     }
 #endif
 }
 
+static void per_breaking_event(DisasContext *s)
+{
+    tcg_gen_movi_i64(gbea, s->pc);
+}
+
 static void update_cc_op(DisasContext *s)
 {
     if (s->cc_op != CC_OP_DYNAMIC && s->cc_op != CC_OP_STATIC) {
@@ -1220,6 +1232,7 @@ static ExitStatus help_goto_direct(DisasContext *s, uint64_t dest)
     }
     if (use_goto_tb(s, dest)) {
         update_cc_op(s);
+        per_breaking_event(s);
         tcg_gen_goto_tb(0);
         tcg_gen_movi_i64(psw_addr, dest);
         tcg_gen_exit_tb((uintptr_t)s->tb);
@@ -1287,6 +1300,7 @@ static ExitStatus help_branch(DisasContext *s, DisasCompare *c,
 
             /* Branch taken.  */
             gen_set_label(lab);
+            per_breaking_event(s);
             tcg_gen_goto_tb(1);
             tcg_gen_movi_i64(psw_addr, dest);
             tcg_gen_exit_tb((uintptr_t)s->tb + 1);
@@ -1318,6 +1332,7 @@ static ExitStatus help_branch(DisasContext *s, DisasCompare *c,
             if (is_imm) {
                 tcg_gen_movi_i64(psw_addr, dest);
             }
+            per_breaking_event(s);
             ret = EXIT_PC_UPDATED;
         }
     } else {
@@ -2550,6 +2565,7 @@ static ExitStatus op_lpsw(DisasContext *s, DisasOps *o)
     TCGv_i64 t1, t2;
 
     check_privileged(s);
+    per_breaking_event(s);
 
     t1 = tcg_temp_new_i64();
     t2 = tcg_temp_new_i64();
@@ -2569,6 +2585,7 @@ static ExitStatus op_lpswe(DisasContext *s, DisasOps *o)
     TCGv_i64 t1, t2;
 
     check_privileged(s);
+    per_breaking_event(s);
 
     t1 = tcg_temp_new_i64();
     t2 = tcg_temp_new_i64();
-- 
1.7.12.4