target-s390x: PER storage-alteration event support

For the PER storage-alteration event we can use the QEMU watchpoint
infrastructure. When PER is enabled or PER control register changed we
enable the corresponding watchpoints. When a watchpoint arises we can
save the event. Unfortunately the current code does not provide the
address space used to trigger the watchpoint. For now we assume it comes
from the default ASC.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 75 insertions, 0 deletions

diff --git a/target-s390x/helper.c b/target-s390x/helper.c
index ec847a2645..615cccf53f 100644
--- a/target-s390x/helper.c
+++ b/target-s390x/helper.c
@@ -181,12 +181,18 @@ hwaddr s390_cpu_get_phys_addr_debug(CPUState *cs, vaddr vaddr)
 
 void load_psw(CPUS390XState *env, uint64_t mask, uint64_t addr)
 {
+    uint64_t old_mask = env->psw.mask;
+
     env->psw.addr = addr;
     env->psw.mask = mask;
     if (tcg_enabled()) {
         env->cc_op = (mask >> 44) & 3;
     }
 
+    if ((old_mask ^ mask) & PSW_MASK_PER) {
+        s390_cpu_recompute_watchpoints(CPU(s390_env_get_cpu(env)));
+    }
+
     if (mask & PSW_MASK_WAIT) {
         S390CPU *cpu = s390_env_get_cpu(env);
         if (s390_cpu_halt(cpu) == 0) {
@@ -573,4 +579,73 @@ bool s390_cpu_exec_interrupt(CPUState *cs, int interrupt_request)
     }
     return false;
 }
+
+void s390_cpu_recompute_watchpoints(CPUState *cs)
+{
+    const int wp_flags = BP_CPU | BP_MEM_WRITE | BP_STOP_BEFORE_ACCESS;
+    S390CPU *cpu = S390_CPU(cs);
+    CPUS390XState *env = &cpu->env;
+
+    /* We are called when the watchpoints have changed. First
+       remove them all.  */
+    cpu_watchpoint_remove_all(cs, BP_CPU);
+
+    /* Return if PER is not enabled */
+    if (!(env->psw.mask & PSW_MASK_PER)) {
+        return;
+    }
+
+    /* Return if storage-alteration event is not enabled.  */
+    if (!(env->cregs[9] & PER_CR9_EVENT_STORE)) {
+        return;
+    }
+
+    if (env->cregs[10] == 0 && env->cregs[11] == -1LL) {
+        /* We can't create a watchoint spanning the whole memory range, so
+           split it in two parts.   */
+        cpu_watchpoint_insert(cs, 0, 1ULL << 63, wp_flags, NULL);
+        cpu_watchpoint_insert(cs, 1ULL << 63, 1ULL << 63, wp_flags, NULL);
+    } else if (env->cregs[10] > env->cregs[11]) {
+        /* The address range loops, create two watchpoints.  */
+        cpu_watchpoint_insert(cs, env->cregs[10], -env->cregs[10],
+                              wp_flags, NULL);
+        cpu_watchpoint_insert(cs, 0, env->cregs[11] + 1, wp_flags, NULL);
+
+    } else {
+        /* Default case, create a single watchpoint.  */
+        cpu_watchpoint_insert(cs, env->cregs[10],
+                              env->cregs[11] - env->cregs[10] + 1,
+                              wp_flags, NULL);
+    }
+}
+
+void s390x_cpu_debug_excp_handler(CPUState *cs)
+{
+    S390CPU *cpu = S390_CPU(cs);
+    CPUS390XState *env = &cpu->env;
+    CPUWatchpoint *wp_hit = cs->watchpoint_hit;
+
+    if (wp_hit && wp_hit->flags & BP_CPU) {
+        /* FIXME: When the storage-alteration-space control bit is set,
+           the exception should only be triggered if the memory access
+           is done using an address space with the storage-alteration-event
+           bit set.  We have no way to detect that with the current
+           watchpoint code.  */
+        cs->watchpoint_hit = NULL;
+
+        env->per_address = env->psw.addr;
+        env->per_perc_atmid |= PER_CODE_EVENT_STORE | get_per_atmid(env);
+        /* FIXME: We currently no way to detect the address space used
+           to trigger the watchpoint.  For now just consider it is the
+           current default ASC. This turn to be true except when MVCP
+           and MVCS instrutions are not used.  */
+        env->per_perc_atmid |= env->psw.mask & (PSW_MASK_ASC) >> 46;
+
+        /* Remove all watchpoints to re-execute the code.  A PER exception
+           will be triggered, it will call load_psw which will recompute
+           the watchpoints.  */
+        cpu_watchpoint_remove_all(cs, BP_CPU);
+        cpu_resume_from_signal(cs, NULL);
+    }
+}
 #endif /* CONFIG_USER_ONLY */