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Re: [PATCH/RFC] auxv entries
> Date: Mon, 15 Sep 2008 11:20:31 +0200 (CEST)
> From: Mark Kettenis <mark.kettenis@xs4all.nl>
>
> > From: Thiago Jung Bauermann <bauerman@br.ibm.com>
> > Date: Sun, 14 Sep 2008 21:33:04 -0300
> >
> > I have this in <elf.h> in ppc64-linux:
> >
> > typedef struct
> > {
> > uint64_t a_type; /* Entry type */
> > union
> > {
> > uint64_t a_val; /* Integer value */
> > /* We use to have pointer elements added here. We cannot do that,
> > though, since it does not work when using 32-bit definitions
> > on 64-bit platforms and vice versa. */
> > } a_un;
> > } Elf64_auxv_t;
> >
> > So default_auxv_parse seems right to me.
>
> Hmm, so it looks like Linux doesn't follow the 64-bit PowerPC ABI
> here. At least version 1.7 of that spec has the "standard" form of
> the struct with a_type being an int.
>
> OpenBSD and Solaris both use the "standard" form, so I'd argue that
> Linux is the odd one out here. I'll see if I can come up with a diff
> that overrides the standard layout for 64-bit PPC linux.
>
Here is the promised diff. Tested on Linux on amd64 (which doesn't
say a lot since it is little-endian).
ok?
Index: ChangeLog
from Mark Kettenis <kettenis@gnu.org>
* auxv.c (default_auxv_parse): Change code to reflect standard
auxv_t layout.
* linux-nat.c (linux_nat_auxv_parse): New function.
(linux_nat_add_target): Install linux_nat_auxv_parse.
Index: auxv.c
===================================================================
RCS file: /cvs/src/src/gdb/auxv.c,v
retrieving revision 1.14
diff -u -p -r1.14 auxv.c
--- auxv.c 11 Sep 2008 14:29:21 -0000 1.14
+++ auxv.c 15 Sep 2008 20:17:42 -0000
@@ -82,20 +82,22 @@ int
default_auxv_parse (struct target_ops *ops, gdb_byte **readptr,
gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp)
{
- const int sizeof_auxv_field = gdbarch_ptr_bit (target_gdbarch)
- / TARGET_CHAR_BIT;
+ struct type *builtin_int = builtin_type (target_gdbarch)->builtin_int;
+ struct type *builtin_long = builtin_type (target_gdbarch)->builtin_long;
+ const int sizeof_auxv_type = TYPE_LENGTH(builtin_int);
+ const int sizeof_auxv_val = TYPE_LENGTH(builtin_long);
gdb_byte *ptr = *readptr;
if (endptr == ptr)
return 0;
- if (endptr - ptr < sizeof_auxv_field * 2)
+ if (endptr - ptr < sizeof_auxv_val * 2)
return -1;
- *typep = extract_unsigned_integer (ptr, sizeof_auxv_field);
- ptr += sizeof_auxv_field;
- *valp = extract_unsigned_integer (ptr, sizeof_auxv_field);
- ptr += sizeof_auxv_field;
+ *typep = extract_unsigned_integer (ptr, sizeof_auxv_type);
+ ptr += sizeof_auxv_val; /* Alignment. */
+ *valp = extract_unsigned_integer (ptr, sizeof_auxv_val);
+ ptr += sizeof_auxv_val;
*readptr = ptr;
return 1;
Index: linux-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/linux-nat.c,v
retrieving revision 1.102
diff -u -p -r1.102 linux-nat.c
--- linux-nat.c 8 Sep 2008 21:51:18 -0000 1.102
+++ linux-nat.c 15 Sep 2008 20:17:44 -0000
@@ -4353,6 +4353,29 @@ send_sigint_callback (struct lwp_info *l
return 0;
}
+static int
+linux_nat_auxv_parse(struct target_ops *ops, gdb_byte **readptr,
+ gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp)
+{
+ struct type *builtin_long = builtin_type (target_gdbarch)->builtin_long;
+ const int sizeof_auxv_field = TYPE_LENGTH(builtin_long);
+ gdb_byte *ptr = *readptr;
+
+ if (endptr == ptr)
+ return 0;
+
+ if (endptr - ptr < sizeof_auxv_field * 2)
+ return -1;
+
+ *typep = extract_unsigned_integer (ptr, sizeof_auxv_field);
+ ptr += sizeof_auxv_field;
+ *valp = extract_unsigned_integer (ptr, sizeof_auxv_field);
+ ptr += sizeof_auxv_field;
+
+ *readptr = ptr;
+ return 1;
+}
+
static void
linux_nat_stop (ptid_t ptid)
{
@@ -4401,6 +4424,10 @@ linux_nat_add_target (struct target_ops
t->to_terminal_inferior = linux_nat_terminal_inferior;
t->to_terminal_ours = linux_nat_terminal_ours;
+ /* The Linux folks messed up and didn't follow the ELF ABI on
+ various 64-bit architectures. */
+ t->to_auxv_parse = linux_nat_auxv_parse;
+
/* Methods for non-stop support. */
t->to_stop = linux_nat_stop;