Use partial register read/writes in transfer_regset

This avoids assert failures when the register is bigger than the
slot size. This happens on Aarch64 when truncating Z registers
into an fpsimd structure. This can be triggered by running
gdb command "generate-core-file".

Also, when the register is smaller then the slot size, then
zero pad when writing to the slot, and truncate when writing
to the regcache. This happens on Aarch64 with the CPSR register.

Continue to ensure registers are invalidated when both buffers
are null.

gdb/
	* regcache.c (readable_regcache::read_part): Fix asserts.
	(reg_buffer::raw_collect_part): New function.
	(regcache::write_part): Fix asserts.
	(reg_buffer::raw_supply_part): New function.
	(regcache::transfer_regset_register): New helper function.
	(regcache::transfer_regset): Call new functions.
	(regcache_supply_regset): Use gdb_byte*.
	(regcache::supply_regset): Likewise.
	(regcache_collect_regset): Likewise.
	(regcache::collect_regset): Likewise.
	* regcache.h (reg_buffer::raw_collect_part): New declaration.
	(reg_buffer::raw_supply_part): Likewise.
	(regcache::transfer_regset_register): Likewise.
	(regcache::transfer_regset): Use gdb_byte*.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index de9127f70fe1417e9a012756c5da19f298514ebd..9539c87ca18f6a7973d3096890c4f6ffa19066bf 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,20 @@
+2018-06-22  Alan Hayward  <alan.hayward@arm.com>
+
+       * regcache.c (readable_regcache::read_part): Fix asserts.
+       (reg_buffer::raw_collect_part): New function.
+       (regcache::write_part): Fix asserts.
+       (reg_buffer::raw_supply_part): New function.
+       (regcache::transfer_regset_register): New helper function.
+       (regcache::transfer_regset): Call new functions.
+       (regcache_supply_regset): Use gdb_byte*.
+       (regcache::supply_regset): Likewise.
+       (regcache_collect_regset): Likewise.
+       (regcache::collect_regset): Likewise.
+       * regcache.h (reg_buffer::raw_collect_part): New declaration.
+       (reg_buffer::raw_supply_part): Likewise.
+       (regcache::transfer_regset_register): Likewise.
+       (regcache::transfer_regset): Use gdb_byte*.
+
 2018-06-22  Alan Hayward  <alan.hayward@arm.com>
 
        * nat/aarch64-sve-linux-ptrace.h (HAS_SVE_STATE): Use &.

diff --git a/gdb/regcache.c b/gdb/regcache.c
index 1bc4f0de8801f586b742d1448eacdb0bf66c247a..1e241de281a18d3f17183a5a4512f277ad809bb0 100644 (file)
--- a/gdb/regcache.c
+++ b/gdb/regcache.c
@@ -801,7 +801,8 @@ readable_regcache::read_part (int regnum, int offset, int len,
   int reg_size = register_size (arch (), regnum);
 
   gdb_assert (out != NULL);
-  gdb_assert (offset >= 0 && len >= 0 && offset + len <= reg_size);
+  gdb_assert (offset >= 0 && offset <= reg_size);
+  gdb_assert (len >= 0 && offset + len <= reg_size);
 
   if (offset == 0 && len == 0)
     {
@@ -830,6 +831,36 @@ readable_regcache::read_part (int regnum, int offset, int len,
 
 /* See regcache.h.  */
 
+void
+reg_buffer::raw_collect_part (int regnum, int offset, int len,
+                             gdb_byte *out) const
+{
+  int reg_size = register_size (arch (), regnum);
+
+  gdb_assert (out != nullptr);
+  gdb_assert (offset >= 0 && offset <= reg_size);
+  gdb_assert (len >= 0 && offset + len <= reg_size);
+
+  if (offset == 0 && len == 0)
+    {
+      /* Nothing to do.  */
+      return;
+    }
+
+  if (offset == 0 && len == reg_size)
+    {
+      /* Collect the full register.  */
+      return raw_collect (regnum, out);
+    }
+
+  /* Read to buffer, then write out.  */
+  gdb_byte *reg = (gdb_byte *) alloca (reg_size);
+  raw_collect (regnum, reg);
+  memcpy (out, reg + offset, len);
+}
+
+/* See regcache.h.  */
+
 enum register_status
 regcache::write_part (int regnum, int offset, int len,
                      const gdb_byte *in, bool is_raw)
@@ -837,7 +868,8 @@ regcache::write_part (int regnum, int offset, int len,
   int reg_size = register_size (arch (), regnum);
 
   gdb_assert (in != NULL);
-  gdb_assert (offset >= 0 && len >= 0 && offset + len <= reg_size);
+  gdb_assert (offset >= 0 && offset <= reg_size);
+  gdb_assert (len >= 0 && offset + len <= reg_size);
 
   if (offset == 0 && len == 0)
     {
@@ -868,6 +900,38 @@ regcache::write_part (int regnum, int offset, int len,
 
 /* See regcache.h.  */
 
+void
+reg_buffer::raw_supply_part (int regnum, int offset, int len,
+                            const gdb_byte *in)
+{
+  int reg_size = register_size (arch (), regnum);
+
+  gdb_assert (in != nullptr);
+  gdb_assert (offset >= 0 && offset <= reg_size);
+  gdb_assert (len >= 0 && offset + len <= reg_size);
+
+  if (offset == 0 && len == 0)
+    {
+      /* Nothing to do.  */
+      return;
+    }
+
+  if (offset == 0 && len == reg_size)
+    {
+      /* Supply the full register.  */
+      return raw_supply (regnum, in);
+    }
+
+  gdb_byte *reg = (gdb_byte *) alloca (reg_size);
+
+  /* Read existing value to buffer.  */
+  raw_collect (regnum, reg);
+
+  /* Write to buffer, then write out.  */
+  memcpy (reg + offset, in, len);
+  raw_supply (regnum, reg);
+}
+
 enum register_status
 readable_regcache::raw_read_part (int regnum, int offset, int len,
                                  gdb_byte *buf)
@@ -1006,15 +1070,43 @@ reg_buffer::raw_collect_integer (int regnum, gdb_byte *addr, int addr_len,
                        byte_order);
 }
 
-/* Transfer a single or all registers belonging to a certain register
-   set to or from a buffer.  This is the main worker function for
-   regcache_supply_regset and regcache_collect_regset.  */
+/* See regcache.h.  */
+
+void
+regcache::transfer_regset_register (struct regcache *out_regcache, int regnum,
+                                   const gdb_byte *in_buf, gdb_byte *out_buf,
+                                   int slot_size, int offs) const
+{
+  struct gdbarch *gdbarch = arch ();
+  int reg_size = std::min (register_size (gdbarch, regnum), slot_size);
+
+  /* Use part versions and reg_size to prevent possible buffer overflows when
+     accessing the regcache.  */
+
+  if (out_buf != nullptr)
+    {
+      raw_collect_part (regnum, 0, reg_size, out_buf + offs);
+
+      /* Ensure any additional space is cleared.  */
+      if (slot_size > reg_size)
+       memset (out_buf + offs + reg_size, 0, slot_size - reg_size);
+    }
+  else if (in_buf != nullptr)
+    out_regcache->raw_supply_part (regnum, 0, reg_size, in_buf + offs);
+  else
+    {
+      /* Invalidate the register.  */
+      out_regcache->raw_supply (regnum, nullptr);
+    }
+}
+
+/* See regcache.h.  */
 
 void
 regcache::transfer_regset (const struct regset *regset,
                           struct regcache *out_regcache,
-                          int regnum, const void *in_buf,
-                          void *out_buf, size_t size) const
+                          int regnum, const gdb_byte *in_buf,
+                          gdb_byte *out_buf, size_t size) const
 {
   const struct regcache_map_entry *map;
   int offs = 0, count;
@@ -1040,12 +1132,8 @@ regcache::transfer_regset (const struct regset *regset,
            if (offs + slot_size > size)
              break;
 
-           if (out_buf)
-             raw_collect (regno, (gdb_byte *) out_buf + offs);
-           else
-             out_regcache->raw_supply (regno, in_buf
-                                       ? (const gdb_byte *) in_buf + offs
-                                       : NULL);
+           transfer_regset_register (out_regcache, regno, in_buf, out_buf,
+                                     slot_size, offs);
          }
       else
        {
@@ -1054,12 +1142,8 @@ regcache::transfer_regset (const struct regset *regset,
          if (offs + slot_size > size)
            return;
 
-         if (out_buf)
-           raw_collect (regnum, (gdb_byte *) out_buf + offs);
-         else
-           out_regcache->raw_supply (regnum, in_buf
-                                     ? (const gdb_byte *) in_buf + offs
-                                     : NULL);
+         transfer_regset_register (out_regcache, regnum, in_buf, out_buf,
+                                   slot_size, offs);
          return;
        }
     }
@@ -1074,14 +1158,14 @@ regcache_supply_regset (const struct regset *regset,
                        struct regcache *regcache,
                        int regnum, const void *buf, size_t size)
 {
-  regcache->supply_regset (regset, regnum, buf, size);
+  regcache->supply_regset (regset, regnum, (const gdb_byte *) buf, size);
 }
 
 void
 regcache::supply_regset (const struct regset *regset,
                         int regnum, const void *buf, size_t size)
 {
-  transfer_regset (regset, this, regnum, buf, NULL, size);
+  transfer_regset (regset, this, regnum, (const gdb_byte *) buf, nullptr, size);
 }
 
 /* Collect register REGNUM from REGCACHE to BUF, using the register
@@ -1093,14 +1177,14 @@ regcache_collect_regset (const struct regset *regset,
                         const struct regcache *regcache,
                         int regnum, void *buf, size_t size)
 {
-  regcache->collect_regset (regset, regnum, buf, size);
+  regcache->collect_regset (regset, regnum, (gdb_byte *) buf, size);
 }
 
 void
 regcache::collect_regset (const struct regset *regset,
                         int regnum, void *buf, size_t size) const
 {
-  transfer_regset (regset, NULL, regnum, NULL, buf, size);
+  transfer_regset (regset, nullptr, regnum, nullptr, (gdb_byte *) buf, size);
 }
 
 /* See common/common-regcache.h.  */

diff --git a/gdb/regcache.h b/gdb/regcache.h
index 983137f6addaa2248271d59f99fbcac8ad81c4bc..ea692f38b83ac070ccad228ea6dabff0f276d28c 100644 (file)
--- a/gdb/regcache.h
+++ b/gdb/regcache.h
@@ -166,6 +166,10 @@ public:
   void raw_collect_integer (int regnum, gdb_byte *addr, int addr_len,
                            bool is_signed) const;
 
+  /* Collect register REGNUM from REGCACHE, starting at OFFSET in register,
+     reading only LEN.  */
+  void raw_collect_part (int regnum, int offset, int len, gdb_byte *out) const;
+
   /* See common/common-regcache.h.  */
   void raw_supply (int regnum, const void *buf) override;
 
@@ -187,6 +191,10 @@ public:
      unavailable).  */
   void raw_supply_zeroed (int regnum);
 
+  /* Supply register REGNUM to REGCACHE, starting at OFFSET in register, writing
+     only LEN, without editing the rest of the register.  */
+  void raw_supply_part (int regnum, int offset, int len, const gdb_byte *in);
+
   void invalidate (int regnum);
 
   virtual ~reg_buffer () = default;
@@ -358,10 +366,18 @@ protected:
 
 private:
 
+  /* Helper function for transfer_regset.  Copies across a single register.  */
+  void transfer_regset_register (struct regcache *out_regcache, int regnum,
+                                const gdb_byte *in_buf, gdb_byte *out_buf,
+                                int slot_size, int offs) const;
+
+  /* Transfer a single or all registers belonging to a certain register
+     set to or from a buffer.  This is the main worker function for
+     regcache_supply_regset and regcache_collect_regset.  */
   void transfer_regset (const struct regset *regset,
                        struct regcache *out_regcache,
-                       int regnum, const void *in_buf,
-                       void *out_buf, size_t size) const;
+                       int regnum, const gdb_byte *in_buf,
+                       gdb_byte *out_buf, size_t size) const;
 
   /* Perform a partial register transfer using a read, modify, write
      operation.  */