Re: [patch] nto-procfs.c: Add to_xfer_partial

[Aleksandar Ristovski <aristovski@qnx.com>]

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Pedro Alves wrote:
> On Monday 27 July 2009 20:44:51, Aleksandar Ristovski wrote:
>> Pedro Alves wrote:
>>> (( Note: It isn't correct to defer to the target beneath for
>>> TARGET_OBJECT_MEMORY (and similars) objects, but, I see that nto-procfs.c
>>> is still implementing deprecated_xfer_memory.  ))
>> Did you want me to make changes here?
> 
> Nope, consider it an FYI.
> 
>>>> +  /* For 32-bit architecture, size of auxv_t is 8 bytes.  */
>>>> +  const unsigned int sizeof_auxv_t = 8;
>>> NTO doesn't support any 64-bit architecture?
>> No, not yet.
> 
> Okay.
> 
>>>> +  enum bfd_endian byte_order;
>>>> +
>>>> +  /* Skip over argc, argv and envp... (see comment in ldd.c)  */
>>>> +  if (target_read_memory (initial_stack + data_ofs, targ32, sizeof (targ32))
>>>> +      != 0)
>>>> +    return 0;
>>> Can you paste here that ldd.c comment too?  You had pasted it in the
>>> equivalent gdbserver bit.
>> Done.
> 
> Thanks!
> 
> On Monday 27 July 2009 20:44:51, Aleksandar Ristovski wrote:
>> +static LONGEST
>> +procfs_xfer_partial (struct target_ops *ops, enum target_object object,
>> +                    const char *annex, gdb_byte *readbuf,
>> +                    const gdb_byte *writebuf, ULONGEST offset, LONGEST len)
>> +{
>> +  if (object == TARGET_OBJECT_AUXV
>> +      && readbuf)
>> +    {
>> +      int err;
>> +      CORE_ADDR initial_stack;
>> +      debug_process_t procinfo;
>> +
>> +      if (offset > 0)
>> +       return 0;
> 
> This offset > 0 check isn't really correct.  Would it be hard to
> make this work with partial transfers?
> 

Implemented.

-- 
Aleksandar Ristovski
QNX Software Systems


ChangeLog:


* nto-procfs.c (procfs_xfer_partial): New function.
(init_procfs_ops): Register to_xfer_partial.
* nto-tdep.c (nto_read_auxv_from_initial_stack): Define.
* nto-tdep.h (nto_read_auxv_from_initial_stack): Declare.


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Index: gdb/nto-procfs.c
===================================================================
RCS file: /cvs/src/src/gdb/nto-procfs.c,v
retrieving revision 1.48
diff -u -p -r1.48 nto-procfs.c
--- gdb/nto-procfs.c	28 Jul 2009 13:20:26 -0000	1.48
+++ gdb/nto-procfs.c	28 Jul 2009 20:16:21 -0000
@@ -872,6 +872,56 @@ procfs_xfer_memory (CORE_ADDR memaddr, g
   return (nbytes);
 }
 
+static LONGEST
+procfs_xfer_partial (struct target_ops *ops, enum target_object object,
+		     const char *annex, gdb_byte *readbuf,
+		     const gdb_byte *writebuf, ULONGEST offset, LONGEST len)
+{
+  if (object == TARGET_OBJECT_MEMORY)
+    {
+      int nbytes = 0;
+
+      if (readbuf)
+	return (*ops->deprecated_xfer_memory) (offset, readbuf,
+					       len, 0, NULL, ops);
+      else if (writebuf)
+	return (*ops->deprecated_xfer_memory) (offset, (gdb_byte*) writebuf,
+					       len, 1, NULL, ops);
+      else
+	return 0;
+    }
+  else if (object == TARGET_OBJECT_AUXV && readbuf)
+    {
+      int err;
+      CORE_ADDR initial_stack;
+      debug_process_t procinfo;
+      /* For 32-bit architecture, size of auxv_t is 8 bytes.  */
+      const unsigned int sizeof_auxv_t = 8;
+      const unsigned int sizeof_tempbuf = 20 * sizeof_auxv_t;
+      int tempread;
+      gdb_byte *tempbuf = alloca (sizeof_tempbuf);
+
+      if (!tempbuf)
+	return -1;
+
+      err = devctl (ctl_fd, DCMD_PROC_INFO, &procinfo, sizeof procinfo, 0);
+      if (err != EOK)
+	return 0;
+
+      /* Similar as in the case of a core file, we read auxv from
+         initial_stack.  */
+      initial_stack = procinfo.initial_stack;
+
+      /* procfs is always 'self-hosted', no byte-order manipulation. */
+      tempread = nto_read_auxv_from_initial_stack (initial_stack, tempbuf,
+						   sizeof_tempbuf);
+      tempread = min (tempread, len) - offset;
+      memcpy (readbuf, tempbuf + offset, tempread);
+      return tempread;
+    }
+  return -1;
+}
+
 /* Take a program previously attached to and detaches it.
    The program resumes execution and will no longer stop
    on signals, etc.  We'd better not have left any breakpoints
@@ -1405,6 +1455,7 @@ init_procfs_ops (void)
   procfs_ops.to_store_registers = procfs_store_registers;
   procfs_ops.to_prepare_to_store = procfs_prepare_to_store;
   procfs_ops.deprecated_xfer_memory = procfs_xfer_memory;
+  procfs_ops.to_xfer_partial = procfs_xfer_partial;
   procfs_ops.to_files_info = procfs_files_info;
   procfs_ops.to_insert_breakpoint = procfs_insert_breakpoint;
   procfs_ops.to_remove_breakpoint = procfs_remove_breakpoint;
Index: gdb/nto-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/nto-tdep.c,v
retrieving revision 1.35
diff -u -p -r1.35 nto-tdep.c
--- gdb/nto-tdep.c	28 Jul 2009 13:20:26 -0000	1.35
+++ gdb/nto-tdep.c	28 Jul 2009 20:16:22 -0000
@@ -398,6 +398,84 @@ nto_initialize_signals (void)
 #endif
 }
 
+LONGEST
+nto_read_auxv_from_initial_stack (CORE_ADDR initial_stack, gdb_byte *readbuf,
+				  LONGEST len)
+{
+  gdb_byte targ32[4]; /* For 32 bit target values.  */
+  CORE_ADDR data_ofs = 0;
+  ULONGEST anint;
+  LONGEST len_read = 0;
+  gdb_byte *buff;
+  /* For 32-bit architecture, size of auxv_t is 8 bytes.  */
+  const unsigned int sizeof_auxv_t = 8;
+  enum bfd_endian byte_order;
+
+  /* Skip over argc, argv and envp... Comment from ldd.c:
+
+     The startup frame is set-up so that we have:
+     auxv
+     NULL
+     ...
+     envp2
+     envp1 <----- void *frame + (argc + 2) * sizeof(char *)
+     NULL
+     ...
+     argv2
+     argv1
+     argc  <------ void * frame
+
+     On entry to ldd, frame gives the address of argc on the stack.  */
+  if (target_read_memory (initial_stack + data_ofs, targ32, sizeof (targ32))
+      != 0)
+    return 0;
+
+  byte_order = gdbarch_byte_order (target_gdbarch);
+
+  anint = extract_unsigned_integer (targ32, sizeof (targ32), byte_order);
+
+  /* Size of pointer is assumed to be 4 bytes (32 bit arch.) */
+  data_ofs += (anint + 2) * sizeof (targ32); /* + 2 comes from argc itself and
+						NULL terminating pointer in
+						argv.  */
+
+  /* Now loop over env table:  */
+  while (target_read_memory (initial_stack + data_ofs, targ32, sizeof (targ32))
+	 == 0)
+    {
+      anint = extract_unsigned_integer (targ32, sizeof (targ32), byte_order);
+      data_ofs += sizeof (targ32);
+      if (anint == 0)
+	break;
+    }
+  initial_stack += data_ofs;
+
+  memset (readbuf, 0, len);
+  buff = readbuf;
+  while (len_read <= len-sizeof_auxv_t)
+    {
+      /* Search backwards until we have read AT_PHDR (num. 3),
+	 AT_PHENT (num 4), AT_PHNUM (num 5)  */
+      if (target_read_memory (initial_stack, buff, sizeof_auxv_t)
+	  == 0)
+	{
+	  ULONGEST a_type = extract_unsigned_integer (buff, sizeof (targ32),
+						      byte_order);
+	  if (a_type != AT_NULL)
+	    {
+	      buff += sizeof_auxv_t;
+	      len_read += sizeof_auxv_t;
+	    }
+	  if (a_type == AT_PHNUM) /* That's all we need.  */
+	    break;
+	  initial_stack += sizeof_auxv_t;
+	}
+      else
+	break;
+    }
+  return len_read;
+}
+
 /* Provide a prototype to silence -Wmissing-prototypes.  */
 extern initialize_file_ftype _initialize_nto_tdep;
 
Index: gdb/nto-tdep.h
===================================================================
RCS file: /cvs/src/src/gdb/nto-tdep.h,v
retrieving revision 1.17
diff -u -p -r1.17 nto-tdep.h
--- gdb/nto-tdep.h	28 Jul 2009 13:20:26 -0000	1.17
+++ gdb/nto-tdep.h	28 Jul 2009 20:16:22 -0000
@@ -173,4 +173,8 @@ int nto_in_dynsym_resolve_code (CORE_ADD
 
 char *nto_extra_thread_info (struct thread_info *);
 
+LONGEST nto_read_auxv_from_initial_stack (CORE_ADDR inital_stack,
+					  gdb_byte *readbuf,
+					  LONGEST len);
+
 #endif