Revert "exec.c: Fix breakpoint invalidation race"

Now that we have proper locking after MTTCG patches have landed, we
can revert the commit.  This reverts commit

a9353fe8.

CC: Peter Maydell <peter.maydell@linaro.org>
CC: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: NPranith Kumar <bobby.prani@gmail.com>
Message-Id: <20170712215143.19594-1-bobby.prani@gmail.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

exec.c

@@ -775,15 +775,28 @@ void cpu_exec_realizefn(CPUState *cpu, Error **errp)
 #endif
 }
 
+#if defined(CONFIG_USER_ONLY)
 static void breakpoint_invalidate(CPUState *cpu, target_ulong pc)
 {
-    /* Flush the whole TB as this will not have race conditions
-     * even if we don't have proper locking yet.
-     * Ideally we would just invalidate the TBs for the
-     * specified PC.
-     */
-    tb_flush(cpu);
+    mmap_lock();
+    tb_lock();
+    tb_invalidate_phys_page_range(pc, pc + 1, 0);
+    tb_unlock();
+    mmap_unlock();
 }
+#else
+static void breakpoint_invalidate(CPUState *cpu, target_ulong pc)
+{
+    MemTxAttrs attrs;
+    hwaddr phys = cpu_get_phys_page_attrs_debug(cpu, pc, &attrs);
+    int asidx = cpu_asidx_from_attrs(cpu, attrs);
+    if (phys != -1) {
+        /* Locks grabbed by tb_invalidate_phys_addr */
+        tb_invalidate_phys_addr(cpu->cpu_ases[asidx].as,
+                                phys | (pc & ~TARGET_PAGE_MASK));
+    }
+}
+#endif
 
 #if defined(CONFIG_USER_ONLY)
 void cpu_watchpoint_remove_all(CPUState *cpu, int mask)

include/exec/exec-all.h

@@ -290,6 +290,9 @@ static inline void tlb_flush_by_mmuidx_all_cpus_synced(CPUState *cpu,
                                                        uint16_t idxmap)
 {
 }
+static inline void tb_invalidate_phys_addr(AddressSpace *as, hwaddr addr)
+{
+}
 #endif
 
 #define CODE_GEN_ALIGN           16 /* must be >= of the size of a icache line */