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

Aleksandar Ristovski
2009-07-27T19:45:20Z

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Hello Pedro,

Thanks for reviewing.

Pedro Alves wrote:
> On Tuesday 07 July 2009 17:22:39, Aleksandar Ristovski wrote:
>
>> Index: gdb/nto-procfs.c
>> ===================================================================
>> RCS file: /cvs/src/src/gdb/nto-procfs.c,v
>> retrieving revision 1.47
>> diff -u -p -r1.47 nto-procfs.c
>> --- gdb/nto-procfs.c 2 Jul 2009 17:12:25 -0000 1.47
>> +++ gdb/nto-procfs.c 7 Jul 2009 16:16:23 -0000
>> @@ -774,6 +774,39 @@ 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 (ops->beneath && ops->beneath->to_xfer_partial)
>> + return ops->beneath->to_xfer_partial (ops, object, annex, readbuf,
>> + writebuf, offset, len);
>
> (( 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?

>> + /* 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.

>
>> + 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.

>
> Otherwise, looks fine to me.
>

Thanks,

--
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 1.47
diff -u -p -r1.47 nto-procfs.c
--- gdb/nto-procfs.c 2 Jul 2009 17:12:25 -0000 1.47
+++ gdb/nto-procfs.c 27 Jul 2009 19:39:36 -0000
@@ -774,6 +774,39 @@ 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_AUXV
+ && readbuf)
+ {
+ int err;
+ CORE_ADDR initial_stack;
+ debug_process_t procinfo;
+
+ if (offset > 0)
+ return 0;
+
+ err = devctl (ctl_fd, DCMD_PROC_INFO, &procinfo, sizeof procinfo, 0);
+ if (err != EOK)
+ return -1;
+
+ /* 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. */
+ return nto_read_auxv_from_initial_stack (initial_stack, readbuf, len);
+ }
+
+ if (ops->beneath && ops->beneath->to_xfer_partial)
+ return ops->beneath->to_xfer_partial (ops, object, annex, readbuf,
+ writebuf, offset, len);
+ 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
@@ -1307,6 +1340,7 @@ 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 1.34
diff -u -p -r1.34 nto-tdep.c
--- gdb/nto-tdep.c 12 Jun 2009 02:32:10 -0000 1.34
+++ gdb/nto-tdep.c 27 Jul 2009 19:39:37 -0000
@@ -364,6 +364,84 @@ 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 1.16
diff -u -p -r1.16 nto-tdep.h
--- gdb/nto-tdep.h 12 Jun 2009 02:32:10 -0000 1.16
+++ gdb/nto-tdep.h 27 Jul 2009 19:39:37 -0000
@@ -162,4 +162,8 @@ void nto_dummy_supply_regset (struct reg

int nto_in_dynsym_resolve_code (CORE_ADDR pc);

+LONGEST nto_read_auxv_from_initial_stack (CORE_ADDR inital_stack,
+ gdb_byte *readbuf,
+ LONGEST len);
+
#endif