[PATCH v3 10/10] exec: Use address_space_rw to handle reads and wirtes

[Andrey Smirnov <andrew.smirnov@gmail.com>]

Use address_space_rw to handle reads and wirtes in cpu_memory_rw_debug()
this way it becomes possible to modify memory mapped registers through
GDB connection.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---
 exec.c            | 55 ++++++++++++++++++++++++++++++++++++++++---------------
 gdbstub.c         |  2 +-
 include/qom/cpu.h |  3 ++-
 3 files changed, 43 insertions(+), 17 deletions(-)

diff --git a/exec.c b/exec.c
index 5557cc9..565d494 100644
--- a/exec.c
+++ b/exec.c
@@ -2444,7 +2444,8 @@ int cpu_memory_rw_debug(CPUState *cpu, target_ulong addr,
     uint8_t *buf = b;
 
     g_assert(access_type == MEM_DATA_STORE ||
-             access_type == MEM_DATA_LOAD);
+             access_type == MEM_DATA_LOAD  ||
+             access_type == MEM_DEBUG_STORE);
 
     while (len > 0) {
         page = addr & TARGET_PAGE_MASK;
@@ -2556,7 +2557,8 @@ static MemTxResult address_space_write_continue(AddressSpace *as, hwaddr addr,
                                                 MemTxAttrs attrs,
                                                 const uint8_t *buf,
                                                 int len, hwaddr addr1,
-                                                hwaddr l, MemoryRegion *mr)
+                                                hwaddr l, MemoryRegion *mr,
+                                                bool debug)
 {
     uint8_t *ptr;
     uint64_t val;
@@ -2564,7 +2566,15 @@ static MemTxResult address_space_write_continue(AddressSpace *as, hwaddr addr,
     bool release_lock = false;
 
     for (;;) {
-        if (!memory_access_is_direct(mr, true)) {
+        /*
+         * debug_direct is used to copy the semantics of
+         * cpu_physical_memory_write_rom() which was originally used
+         * to handle writes to memory with GDBStub
+         */
+        const bool debug_direct = (debug && !(memory_region_is_ram(mr) ||
+                                              memory_region_is_romd(mr)));
+
+        if (!memory_access_is_direct(mr, true) || !debug_direct) {
             release_lock |= prepare_mmio_access(mr);
             l = memory_access_size(mr, l, addr1);
             /* XXX: could force current_cpu to NULL to avoid
@@ -2615,8 +2625,10 @@ static MemTxResult address_space_write_continue(AddressSpace *as, hwaddr addr,
     return result;
 }
 
-MemTxResult address_space_write(AddressSpace *as, hwaddr addr, MemTxAttrs attrs,
-                                const void *buf, int len)
+static MemTxResult address_space_write_combined(AddressSpace *as, hwaddr addr,
+                                                MemTxAttrs attrs,
+                                                const void *buf, int len,
+                                                bool debug)
 {
     hwaddr l;
     hwaddr addr1;
@@ -2628,11 +2640,25 @@ MemTxResult address_space_write(AddressSpace *as, hwaddr addr, MemTxAttrs attrs,
         l = len;
         mr = address_space_translate(as, addr, &addr1, &l, true);
         result = address_space_write_continue(as, addr, attrs, buf, len,
-                                              addr1, l, mr);
+                                              addr1, l, mr, debug);
         rcu_read_unlock();
     }
 
     return result;
+
+}
+
+MemTxResult address_space_write(AddressSpace *as, hwaddr addr, MemTxAttrs attrs,
+                                const void *buf, int len)
+{
+    return address_space_write_combined(as, addr, attrs, buf, len, false);
+}
+
+static MemTxResult address_space_write_debug(AddressSpace *as, hwaddr addr,
+                                             MemTxAttrs attrs,
+                                             const void *buf, int len)
+{
+    return address_space_write_combined(as, addr, attrs, buf, len, true);
 }
 
 /* Called within RCU critical section.  */
@@ -2734,6 +2760,8 @@ MemTxResult address_space_rw(AddressSpace *as, hwaddr addr, MemTxAttrs attrs,
         return address_space_write(as, addr, attrs, buf, len);
     case MEM_DATA_LOAD:
         return address_space_read(as, addr, attrs, buf, len);
+    case MEM_DEBUG_STORE:
+        return address_space_write_debug(as, addr, attrs, buf, len);
     default:
         abort();
     }
@@ -3633,7 +3661,8 @@ int cpu_memory_rw_debug(CPUState *cpu, target_ulong addr,
     uint8_t *buf = b;
 
     g_assert(access_type == MEM_DATA_STORE ||
-             access_type == MEM_DATA_LOAD);
+             access_type == MEM_DATA_LOAD  ||
+             access_type == MEM_DEBUG_STORE);
 
     while (len > 0) {
         int asidx;
@@ -3649,14 +3678,10 @@ int cpu_memory_rw_debug(CPUState *cpu, target_ulong addr,
         if (l > len)
             l = len;
         phys_addr += (addr & ~TARGET_PAGE_MASK);
-        if (access_type == MEM_DATA_STORE) {
-            cpu_physical_memory_write_rom(cpu->cpu_ases[asidx].as,
-                                          phys_addr, buf, l);
-        } else {
-            address_space_rw(cpu->cpu_ases[asidx].as, phys_addr,
-                             MEMTXATTRS_UNSPECIFIED,
-                             buf, l, access_type);
-        }
+        address_space_rw(cpu->cpu_ases[asidx].as, phys_addr,
+                         MEMTXATTRS_UNSPECIFIED,
+                         buf, l, access_type);
+
         len -= l;
         buf += l;
         addr += l;
diff --git a/gdbstub.c b/gdbstub.c
index c215672..03d45f7 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -991,7 +991,7 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
         }
         hextomem(mem_buf, p, len);
         if (target_memory_rw_debug(s->g_cpu, addr, mem_buf, len,
-                                   MEM_DATA_STORE) != 0) {
+                                   MEM_DEBUG_STORE) != 0) {
             put_packet(s, "E14");
         } else {
             put_packet(s, "OK");
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index b23b4b1..28e30a1 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -63,7 +63,8 @@ typedef uint64_t vaddr;
 typedef enum MemoryAccessType {
     MEM_DATA_LOAD  = 0,
     MEM_DATA_STORE = 1,
-    MEM_INST_FETCH = 2
+    MEM_INST_FETCH = 2,
+    MEM_DEBUG_STORE = 3,
 } MemoryAccessType;
 
 typedef struct CPUWatchpoint CPUWatchpoint;
-- 
2.5.5