[PATCH v2 3/7] plugins: extend API to get latest memory value accessed

[Pierrick Bouvier]

Two functions are added to plugins API:
- qemu_plugin_mem_get_value_upper_bits
- qemu_plugin_mem_get_value_lower_bits

This value can be accessed only during a memory callback.

Signed-off-by: Pierrick Bouvier <pierrick.bouv...@linaro.org>
---
 include/qemu/qemu-plugin.h   | 20 ++++++++++++++++++++
 plugins/api.c                | 21 +++++++++++++++++++++
 plugins/qemu-plugins.symbols |  2 ++
 3 files changed, 43 insertions(+)

diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h
index c71c705b699..5945f256949 100644
--- a/include/qemu/qemu-plugin.h
+++ b/include/qemu/qemu-plugin.h
@@ -551,6 +551,26 @@ bool qemu_plugin_mem_is_big_endian(qemu_plugin_meminfo_t 
info);
 QEMU_PLUGIN_API
 bool qemu_plugin_mem_is_store(qemu_plugin_meminfo_t info);
 
+/**
+ * qemu_plugin_mem_get_value_lower_bits() - return 64 lower bits of latest
+ * accessed memory value
+ * @info: opaque memory transaction handle
+ *
+ * Returns: lower bits for value accessed
+ */
+QEMU_PLUGIN_API
+uint64_t qemu_plugin_mem_get_value_lower_bits(qemu_plugin_meminfo_t info);
+
+/**
+ * qemu_plugin_mem_get_value_upper_bits() - return 64 upper bits of latest
+ * accessed memory value
+ * @info: opaque memory transaction handle
+ *
+ * Returns: upper bits for value accessed
+ */
+QEMU_PLUGIN_API
+uint64_t qemu_plugin_mem_get_value_upper_bits(qemu_plugin_meminfo_t info);
+
 /**
  * qemu_plugin_get_hwaddr() - return handle for memory operation
  * @info: opaque memory info structure
diff --git a/plugins/api.c b/plugins/api.c
index 2ff13d09de6..89e9f6ba5b4 100644
--- a/plugins/api.c
+++ b/plugins/api.c
@@ -351,6 +351,27 @@ bool qemu_plugin_mem_is_store(qemu_plugin_meminfo_t info)
     return get_plugin_meminfo_rw(info) & QEMU_PLUGIN_MEM_W;
 }
 
+uint64_t qemu_plugin_mem_get_value_upper_bits(qemu_plugin_meminfo_t info)
+{
+    return current_cpu->plugin_state->mem_value_upper_bits;
+}
+
+uint64_t qemu_plugin_mem_get_value_lower_bits(qemu_plugin_meminfo_t info)
+{
+    uint64_t value = current_cpu->plugin_state->mem_value_lower_bits;
+    /* tcg values are sign extended, so we must clip them */
+    switch (qemu_plugin_mem_size_shift(info)) {
+    case 0:
+        return value & 0xff;
+    case 1:
+        return value & 0xffff;
+    case 2:
+        return value & 0xffffffff;
+    default:
+        return value;
+    }
+}
+
 /*
  * Virtual Memory queries
  */
diff --git a/plugins/qemu-plugins.symbols b/plugins/qemu-plugins.symbols
index ca773d8d9fe..9f2646fc812 100644
--- a/plugins/qemu-plugins.symbols
+++ b/plugins/qemu-plugins.symbols
@@ -13,6 +13,8 @@
   qemu_plugin_insn_size;
   qemu_plugin_insn_symbol;
   qemu_plugin_insn_vaddr;
+  qemu_plugin_mem_get_value_upper_bits;
+  qemu_plugin_mem_get_value_lower_bits;
   qemu_plugin_mem_is_big_endian;
   qemu_plugin_mem_is_sign_extended;
   qemu_plugin_mem_is_store;
-- 
2.39.2