[Qemu-devel] [PATCH v4 7/8] scripts/dump-guest-memory.py: add vmcoreinfo

[Marc-André Lureau]

Add vmcoreinfo ELF note if vmcoreinfo device is ready.

To help the python script, add a static vmcoreinfo_gdb_helper value to
be looked up to get vmcoreinfo device singleton.

Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
Acked-by: Laszlo Ersek <ler...@redhat.com>
---
 scripts/dump-guest-memory.py | 47 ++++++++++++++++++++++++++++++++++++++++++++
 hw/acpi/vmcoreinfo.c         |  3 +++
 2 files changed, 50 insertions(+)

diff --git a/scripts/dump-guest-memory.py b/scripts/dump-guest-memory.py
index f7c6635f15..e0589e5b7c 100644
--- a/scripts/dump-guest-memory.py
+++ b/scripts/dump-guest-memory.py
@@ -14,6 +14,7 @@ the COPYING file in the top-level directory.
 """
 
 import ctypes
+import struct
 
 UINTPTR_T = gdb.lookup_type("uintptr_t")
 
@@ -120,6 +121,22 @@ class ELF(object):
         self.segments[0].p_filesz += ctypes.sizeof(note)
         self.segments[0].p_memsz += ctypes.sizeof(note)
 
+
+    def add_vmcoreinfo_note(self, vmcoreinfo):
+        """Adds a vmcoreinfo note to the ELF dump."""
+        # compute the header size, and copy that many bytes from the note
+        header = get_arch_note(self.endianness, 0, 0)
+        ctypes.memmove(ctypes.pointer(header),
+                       vmcoreinfo, ctypes.sizeof(header))
+        # now get the full note
+        note = get_arch_note(self.endianness,
+                             header.n_namesz - 1, header.n_descsz)
+        ctypes.memmove(ctypes.pointer(note), vmcoreinfo, ctypes.sizeof(note))
+
+        self.notes.append(note)
+        self.segments[0].p_filesz += ctypes.sizeof(note)
+        self.segments[0].p_memsz += ctypes.sizeof(note)
+
     def add_segment(self, p_type, p_paddr, p_size):
         """Adds a segment to the elf."""
 
@@ -505,6 +522,35 @@ shape and this command should mostly work."""
                 cur += chunk_size
                 left -= chunk_size
 
+    def phys_memory_read(self, addr, size):
+        qemu_core = gdb.inferiors()[0]
+        for block in self.guest_phys_blocks:
+            if block["target_start"] <= addr \
+               and addr + size <= block["target_end"]:
+                haddr = block["host_addr"] + (addr - block["target_start"])
+                return qemu_core.read_memory(haddr, size)
+        return None
+
+    def add_vmcoreinfo(self):
+        if not gdb.parse_and_eval("vmcoreinfo_realize::vmcoreinfo_gdb_helper"):
+            return
+
+        addr = gdb.parse_and_eval("vmcoreinfo_realize::vmcoreinfo_gdb_helper->"
+                                  "vmcoreinfo_addr_le")
+        addr = bytes([addr[i] for i in range(4)])
+        addr = struct.unpack("<I", addr)[0]
+
+        mem = self.phys_memory_read(addr, 16)
+        if not mem:
+            return
+        (version, addr, size) = struct.unpack("<IQI", mem)
+        if version != 0:
+            return
+
+        vmcoreinfo = self.phys_memory_read(addr, size)
+        if vmcoreinfo:
+            self.elf.add_vmcoreinfo_note(vmcoreinfo.tobytes())
+
     def invoke(self, args, from_tty):
         """Handles command invocation from gdb."""
 
@@ -518,6 +564,7 @@ shape and this command should mostly work."""
 
         self.elf = ELF(argv[1])
         self.guest_phys_blocks = get_guest_phys_blocks()
+        self.add_vmcoreinfo()
 
         with open(argv[0], "wb") as vmcore:
             self.dump_init(vmcore)
diff --git a/hw/acpi/vmcoreinfo.c b/hw/acpi/vmcoreinfo.c
index 0ea41de8d9..78aaa03570 100644
--- a/hw/acpi/vmcoreinfo.c
+++ b/hw/acpi/vmcoreinfo.c
@@ -165,6 +165,8 @@ static void vmcoreinfo_handle_reset(void *opaque)
 
 static void vmcoreinfo_realize(DeviceState *dev, Error **errp)
 {
+    static volatile VMCoreInfoState *vmcoreinfo_gdb_helper G_GNUC_UNUSED;
+
     if (!bios_linker_loader_can_write_pointer()) {
         error_setg(errp, "%s requires DMA write support in fw_cfg, "
                    "which this machine type does not provide",
@@ -181,6 +183,7 @@ static void vmcoreinfo_realize(DeviceState *dev, Error 
**errp)
         return;
     }
 
+    vmcoreinfo_gdb_helper = VMCOREINFO(dev);
     qemu_register_reset(vmcoreinfo_handle_reset, dev);
 }
 
-- 
2.13.1.395.gf7b71de06