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

Aleksandar Ristovski
2009-07-28T20:20:22Z

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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