Re-land: [lldb] Use vFlash commands when writing to target's flash memory regions

The difference between this and the previous patch is that now we use
ELF physical addresses only for loading objects into the target (and the
rest of the module load address logic still uses virtual addresses).

Summary:
When writing an object file over gdb-remote, use the vFlashErase, vFlashWrite, and vFlashDone commands if the write address is in a flash memory region.  A bare metal target may have this kind of setup.

- Update ObjectFileELF to set load addresses using physical addresses.  A typical case may be a data section with a physical address in ROM and a virtual address in RAM, which should be loaded to the ROM address.
- Add support for querying the target's qXfer:memory-map, which contains information about flash memory regions, leveraging MemoryRegionInfo data structures with minor modifications
- Update ProcessGDBRemote to use vFlash commands in DoWriteMemory when the target address is in a flash region

Original discussion at http://lists.llvm.org/pipermail/lldb-dev/2018-January/013093.html

Reviewers: clayborg, labath

Reviewed By: labath

Subscribers: llvm-commits, arichardson, emaste, mgorny, lldb-commits

Differential Revision: https://reviews.llvm.org/D42145
Patch by Owen Shaw <llvm@owenpshaw.net>.

llvm-svn: 327970

1 files changed, 169 insertions, 5 deletions

diff --git a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
index 0823add538d..93e08b5ce5b 100644
--- a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -59,6 +59,7 @@
 #include "lldb/Symbol/ObjectFile.h"
 #include "lldb/Target/ABI.h"
 #include "lldb/Target/DynamicLoader.h"
+#include "lldb/Target/MemoryRegionInfo.h"
 #include "lldb/Target/SystemRuntime.h"
 #include "lldb/Target/Target.h"
 #include "lldb/Target/TargetList.h"
@@ -256,7 +257,8 @@ ProcessGDBRemote::ProcessGDBRemote(lldb::TargetSP target_sp,
       m_addr_to_mmap_size(), m_thread_create_bp_sp(),
       m_waiting_for_attach(false), m_destroy_tried_resuming(false),
       m_command_sp(), m_breakpoint_pc_offset(0),
-      m_initial_tid(LLDB_INVALID_THREAD_ID) {
+      m_initial_tid(LLDB_INVALID_THREAD_ID), m_allow_flash_writes(false),
+      m_erased_flash_ranges() {
   m_async_broadcaster.SetEventName(eBroadcastBitAsyncThreadShouldExit,
                                    "async thread should exit");
   m_async_broadcaster.SetEventName(eBroadcastBitAsyncContinue,
@@ -2798,6 +2800,145 @@ size_t ProcessGDBRemote::DoReadMemory(addr_t addr, void *buf, size_t size,
   return 0;
 }
 
+Status ProcessGDBRemote::WriteObjectFile(
+    std::vector<ObjectFile::LoadableData> entries) {
+  Status error;
+  // Sort the entries by address because some writes, like those to flash
+  // memory, must happen in order of increasing address.
+  std::stable_sort(
+      std::begin(entries), std::end(entries),
+      [](const ObjectFile::LoadableData a, const ObjectFile::LoadableData b) {
+        return a.Dest < b.Dest;
+      });
+  m_allow_flash_writes = true;
+  error = Process::WriteObjectFile(entries);
+  if (error.Success())
+    error = FlashDone();
+  else
+    // Even though some of the writing failed, try to send a flash done if
+    // some of the writing succeeded so the flash state is reset to normal,
+    // but don't stomp on the error status that was set in the write failure
+    // since that's the one we want to report back.
+    FlashDone();
+  m_allow_flash_writes = false;
+  return error;
+}
+
+bool ProcessGDBRemote::HasErased(FlashRange range) {
+  auto size = m_erased_flash_ranges.GetSize();
+  for (size_t i = 0; i < size; ++i)
+    if (m_erased_flash_ranges.GetEntryAtIndex(i)->Contains(range))
+      return true;
+  return false;
+}
+
+Status ProcessGDBRemote::FlashErase(lldb::addr_t addr, size_t size) {
+  Status status;
+
+  MemoryRegionInfo region;
+  status = GetMemoryRegionInfo(addr, region);
+  if (!status.Success())
+    return status;
+
+  // The gdb spec doesn't say if erasures are allowed across multiple regions,
+  // but we'll disallow it to be safe and to keep the logic simple by worring
+  // about only one region's block size.  DoMemoryWrite is this function's
+  // primary user, and it can easily keep writes within a single memory region
+  if (addr + size > region.GetRange().GetRangeEnd()) {
+    status.SetErrorString("Unable to erase flash in multiple regions");
+    return status;
+  }
+
+  uint64_t blocksize = region.GetBlocksize();
+  if (blocksize == 0) {
+    status.SetErrorString("Unable to erase flash because blocksize is 0");
+    return status;
+  }
+
+  // Erasures can only be done on block boundary adresses, so round down addr
+  // and round up size
+  lldb::addr_t block_start_addr = addr - (addr % blocksize);
+  size += (addr - block_start_addr);
+  if ((size % blocksize) != 0)
+    size += (blocksize - size % blocksize);
+
+  FlashRange range(block_start_addr, size);
+
+  if (HasErased(range))
+    return status;
+
+  // We haven't erased the entire range, but we may have erased part of it.
+  // (e.g., block A is already erased and range starts in A and ends in B).
+  // So, adjust range if necessary to exclude already erased blocks.
+  if (!m_erased_flash_ranges.IsEmpty()) {
+    // Assuming that writes and erasures are done in increasing addr order,
+    // because that is a requirement of the vFlashWrite command.  Therefore,
+    // we only need to look at the last range in the list for overlap.
+    const auto &last_range = *m_erased_flash_ranges.Back();
+    if (range.GetRangeBase() < last_range.GetRangeEnd()) {
+      auto overlap = last_range.GetRangeEnd() - range.GetRangeBase();
+      // overlap will be less than range.GetByteSize() or else HasErased() would
+      // have been true
+      range.SetByteSize(range.GetByteSize() - overlap);
+      range.SetRangeBase(range.GetRangeBase() + overlap);
+    }
+  }
+
+  StreamString packet;
+  packet.Printf("vFlashErase:%" PRIx64 ",%" PRIx64, range.GetRangeBase(),
+                (uint64_t)range.GetByteSize());
+
+  StringExtractorGDBRemote response;
+  if (m_gdb_comm.SendPacketAndWaitForResponse(packet.GetString(), response,
+                                              true) ==
+      GDBRemoteCommunication::PacketResult::Success) {
+    if (response.IsOKResponse()) {
+      m_erased_flash_ranges.Insert(range, true);
+    } else {
+      if (response.IsErrorResponse())
+        status.SetErrorStringWithFormat("flash erase failed for 0x%" PRIx64,
+                                        addr);
+      else if (response.IsUnsupportedResponse())
+        status.SetErrorStringWithFormat("GDB server does not support flashing");
+      else
+        status.SetErrorStringWithFormat(
+            "unexpected response to GDB server flash erase packet '%s': '%s'",
+            packet.GetData(), response.GetStringRef().c_str());
+    }
+  } else {
+    status.SetErrorStringWithFormat("failed to send packet: '%s'",
+                                    packet.GetData());
+  }
+  return status;
+}
+
+Status ProcessGDBRemote::FlashDone() {
+  Status status;
+  // If we haven't erased any blocks, then we must not have written anything
+  // either, so there is no need to actually send a vFlashDone command
+  if (m_erased_flash_ranges.IsEmpty())
+    return status;
+  StringExtractorGDBRemote response;
+  if (m_gdb_comm.SendPacketAndWaitForResponse("vFlashDone", response, true) ==
+      GDBRemoteCommunication::PacketResult::Success) {
+    if (response.IsOKResponse()) {
+      m_erased_flash_ranges.Clear();
+    } else {
+      if (response.IsErrorResponse())
+        status.SetErrorStringWithFormat("flash done failed");
+      else if (response.IsUnsupportedResponse())
+        status.SetErrorStringWithFormat("GDB server does not support flashing");
+      else
+        status.SetErrorStringWithFormat(
+            "unexpected response to GDB server flash done packet: '%s'",
+            response.GetStringRef().c_str());
+    }
+  } else {
+    status.SetErrorStringWithFormat("failed to send flash done packet");
+  }
+  return status;
+}
+
 size_t ProcessGDBRemote::DoWriteMemory(addr_t addr, const void *buf,
                                        size_t size, Status &error) {
   GetMaxMemorySize();
@@ -2810,10 +2951,33 @@ size_t ProcessGDBRemote::DoWriteMemory(addr_t addr, const void *buf,
     size = max_memory_size;
   }
 
-  StreamString packet;
-  packet.Printf("M%" PRIx64 ",%" PRIx64 ":", addr, (uint64_t)size);
-  packet.PutBytesAsRawHex8(buf, size, endian::InlHostByteOrder(),
-                           endian::InlHostByteOrder());
+  StreamGDBRemote packet;
+
+  MemoryRegionInfo region;
+  Status region_status = GetMemoryRegionInfo(addr, region);
+
+  bool is_flash =
+      region_status.Success() && region.GetFlash() == MemoryRegionInfo::eYes;
+
+  if (is_flash) {
+    if (!m_allow_flash_writes) {
+      error.SetErrorString("Writing to flash memory is not allowed");
+      return 0;
+    }
+    // Keep the write within a flash memory region
+    if (addr + size > region.GetRange().GetRangeEnd())
+      size = region.GetRange().GetRangeEnd() - addr;
+    // Flash memory must be erased before it can be written
+    error = FlashErase(addr, size);
+    if (!error.Success())
+      return 0;
+    packet.Printf("vFlashWrite:%" PRIx64 ":", addr);
+    packet.PutEscapedBytes(buf, size);
+  } else {
+    packet.Printf("M%" PRIx64 ",%" PRIx64 ":", addr, (uint64_t)size);
+    packet.PutBytesAsRawHex8(buf, size, endian::InlHostByteOrder(),
+                             endian::InlHostByteOrder());
+  }
   StringExtractorGDBRemote response;
   if (m_gdb_comm.SendPacketAndWaitForResponse(packet.GetString(), response,
                                               true) ==