240 lines
9.8 KiB
C
240 lines
9.8 KiB
C
/* SPARC-specific values for a.out files
|
|
|
|
Copyright (C) 2001-2014 Free Software Foundation, Inc.
|
|
|
|
This program is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program; if not, write to the Free Software
|
|
Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
|
|
MA 02110-1301, USA. */
|
|
|
|
/* Some systems, e.g., AIX, may have defined this in header files already
|
|
included. */
|
|
#undef TARGET_PAGE_SIZE
|
|
#define TARGET_PAGE_SIZE 0x2000 /* 8K. aka NBPG in <sys/param.h> */
|
|
/* Note that some SPARCs have 4K pages, some 8K, some others. */
|
|
|
|
#define SEG_SIZE_SPARC TARGET_PAGE_SIZE
|
|
#define SEG_SIZE_SUN3 0x20000 /* Resolution of r/w protection hw */
|
|
|
|
#define TEXT_START_ADDR TARGET_PAGE_SIZE /* Location 0 is not accessible */
|
|
#define N_HEADER_IN_TEXT(x) 1
|
|
|
|
/* Non-default definitions of the accessor macros... */
|
|
|
|
/* Segment size varies on Sun-3 versus Sun-4. */
|
|
|
|
#define N_SEGSIZE(x) (N_MACHTYPE(x) == M_SPARC? SEG_SIZE_SPARC: \
|
|
N_MACHTYPE(x) == M_68020? SEG_SIZE_SUN3: \
|
|
/* Guess? */ TARGET_PAGE_SIZE)
|
|
|
|
/* Virtual Address of text segment from the a.out file. For OMAGIC,
|
|
(almost always "unlinked .o's" these days), should be zero.
|
|
Sun added a kludge so that shared libraries linked ZMAGIC get
|
|
an address of zero if a_entry (!!!) is lower than the otherwise
|
|
expected text address. These kludges have gotta go!
|
|
For linked files, should reflect reality if we know it. */
|
|
|
|
#define N_SHARED_LIB(x) ((x).a_entry < TEXT_START_ADDR \
|
|
&& (x).a_text >= EXEC_BYTES_SIZE)
|
|
|
|
/* This differs from the version in aout64.h (which we override by defining
|
|
it here) only for NMAGIC (we return TEXT_START_ADDR+EXEC_BYTES_SIZE;
|
|
they return 0). */
|
|
|
|
#define N_TXTADDR(x) \
|
|
(N_MAGIC(x)==OMAGIC? 0 \
|
|
: (N_MAGIC(x) == ZMAGIC && (x).a_entry < TEXT_START_ADDR)? 0 \
|
|
: TEXT_START_ADDR+EXEC_BYTES_SIZE)
|
|
|
|
/* When a file is linked against a shared library on SunOS 4, the
|
|
dynamic bit in the exec header is set, and the first symbol in the
|
|
symbol table is __DYNAMIC. Its value is the address of the
|
|
following structure. */
|
|
|
|
struct external_sun4_dynamic
|
|
{
|
|
/* The version number of the structure. SunOS 4.1.x creates files
|
|
with version number 3, which is what this structure is based on.
|
|
According to gdb, version 2 is similar. I believe that version 2
|
|
used a different type of procedure linkage table, and there may
|
|
have been other differences. */
|
|
bfd_byte ld_version[4];
|
|
/* The virtual address of a 28 byte structure used in debugging.
|
|
The contents are filled in at run time by ld.so. */
|
|
bfd_byte ldd[4];
|
|
/* The virtual address of another structure with information about
|
|
how to relocate the executable at run time. */
|
|
bfd_byte ld[4];
|
|
};
|
|
|
|
/* The size of the debugging structure pointed to by the debugger
|
|
field of __DYNAMIC. */
|
|
#define EXTERNAL_SUN4_DYNAMIC_DEBUGGER_SIZE (24)
|
|
|
|
/* The structure pointed to by the linker field of __DYNAMIC. As far
|
|
as I can tell, most of the addresses in this structure are offsets
|
|
within the file, but some are actually virtual addresses. */
|
|
|
|
struct internal_sun4_dynamic_link
|
|
{
|
|
/* Linked list of loaded objects. This is filled in at runtime by
|
|
ld.so and probably by dlopen. */
|
|
unsigned long ld_loaded;
|
|
|
|
/* The address of the list of names of shared objects which must be
|
|
included at runtime. Each entry in the list is 16 bytes: the 4
|
|
byte address of the string naming the object (e.g., for -lc this
|
|
is "c"); 4 bytes of flags--the high bit is whether to search for
|
|
the object using the library path; the 2 byte major version
|
|
number; the 2 byte minor version number; the 4 byte address of
|
|
the next entry in the list (zero if this is the last entry). The
|
|
version numbers seem to only be non-zero when doing library
|
|
searching. */
|
|
unsigned long ld_need;
|
|
|
|
/* The address of the path to search for the shared objects which
|
|
must be included. This points to a string in PATH format which
|
|
is generated from the -L arguments to the linker. According to
|
|
the man page, ld.so implicitly adds ${LD_LIBRARY_PATH} to the
|
|
beginning of this string and /lib:/usr/lib:/usr/local/lib to the
|
|
end. The string is terminated by a null byte. This field is
|
|
zero if there is no additional path. */
|
|
unsigned long ld_rules;
|
|
|
|
/* The address of the global offset table. This appears to be a
|
|
virtual address, not a file offset. The first entry in the
|
|
global offset table seems to be the virtual address of the
|
|
sun4_dynamic structure (the same value as the __DYNAMIC symbol).
|
|
The global offset table is used for PIC code to hold the
|
|
addresses of variables. A dynamically linked file which does not
|
|
itself contain PIC code has a four byte global offset table. */
|
|
unsigned long ld_got;
|
|
|
|
/* The address of the procedure linkage table. This appears to be a
|
|
virtual address, not a file offset.
|
|
|
|
On a SPARC, the table is composed of 12 byte entries, each of
|
|
which consists of three instructions. The first entry is
|
|
sethi %hi(0),%g1
|
|
jmp %g1
|
|
nop
|
|
These instructions are changed by ld.so into a jump directly into
|
|
ld.so itself. Each subsequent entry is
|
|
save %sp, -96, %sp
|
|
call <address of first entry in procedure linkage table>
|
|
<reloc_number | 0x01000000>
|
|
The reloc_number is the number of the reloc to use to resolve
|
|
this entry. The reloc will be a JMP_SLOT reloc against some
|
|
symbol that is not defined in this object file but should be
|
|
defined in a shared object (if it is not, ld.so will report a
|
|
runtime error and exit). The constant 0x010000000 turns the
|
|
reloc number into a sethi of %g0, which does nothing since %g0 is
|
|
hardwired to zero.
|
|
|
|
When one of these entries is executed, it winds up calling into
|
|
ld.so. ld.so looks at the reloc number, available via the return
|
|
address, to determine which entry this is. It then looks at the
|
|
reloc and patches up the entry in the table into a sethi and jmp
|
|
to the real address followed by a nop. This means that the reloc
|
|
lookup only has to happen once, and it also means that the
|
|
relocation only needs to be done if the function is actually
|
|
called. The relocation is expensive because ld.so must look up
|
|
the symbol by name.
|
|
|
|
The size of the procedure linkage table is given by the ld_plt_sz
|
|
field. */
|
|
unsigned long ld_plt;
|
|
|
|
/* The address of the relocs. These are in the same format as
|
|
ordinary relocs. Symbol index numbers refer to the symbols
|
|
pointed to by ld_stab. I think the only way to determine the
|
|
number of relocs is to assume that all the bytes from ld_rel to
|
|
ld_hash contain reloc entries. */
|
|
unsigned long ld_rel;
|
|
|
|
/* The address of a hash table of symbols. The hash table has
|
|
roughly the same number of entries as there are dynamic symbols;
|
|
I think the only way to get the exact size is to assume that
|
|
every byte from ld_hash to ld_stab is devoted to the hash table.
|
|
|
|
Each entry in the hash table is eight bytes. The first four
|
|
bytes are a symbol index into the dynamic symbols. The second
|
|
four bytes are the index of the next hash table entry in the
|
|
bucket. The ld_buckets field gives the number of buckets, say B.
|
|
The first B entries in the hash table each start a bucket which
|
|
is chained through the second four bytes of each entry. A value
|
|
of zero ends the chain.
|
|
|
|
The hash function is simply
|
|
h = 0;
|
|
while (*string != '\0')
|
|
h = (h << 1) + *string++;
|
|
h &= 0x7fffffff;
|
|
|
|
To look up a symbol, compute the hash value of the name. Take
|
|
the modulos of hash value and the number of buckets. Start at
|
|
that entry in the hash table. See if the symbol (from the first
|
|
four bytes of the hash table entry) has the name you are looking
|
|
for. If not, use the chain field (the second four bytes of the
|
|
hash table entry) to move on to the next entry in this bucket.
|
|
If the chain field is zero you have reached the end of the
|
|
bucket, and the symbol is not in the hash table. */
|
|
unsigned long ld_hash;
|
|
|
|
/* The address of the symbol table. This is a list of
|
|
external_nlist structures. The string indices are relative to
|
|
the ld_symbols field. I think the only way to determine the
|
|
number of symbols is to assume that all the bytes between ld_stab
|
|
and ld_symbols are external_nlist structures. */
|
|
unsigned long ld_stab;
|
|
|
|
/* I don't know what this is for. It seems to always be zero. */
|
|
unsigned long ld_stab_hash;
|
|
|
|
/* The number of buckets in the hash table. */
|
|
unsigned long ld_buckets;
|
|
|
|
/* The address of the symbol string table. The first string in this
|
|
string table need not be the empty string. */
|
|
unsigned long ld_symbols;
|
|
|
|
/* The size in bytes of the symbol string table. */
|
|
unsigned long ld_symb_size;
|
|
|
|
/* The size in bytes of the text segment. */
|
|
unsigned long ld_text;
|
|
|
|
/* The size in bytes of the procedure linkage table. */
|
|
unsigned long ld_plt_sz;
|
|
};
|
|
|
|
/* The external form of the structure. */
|
|
|
|
struct external_sun4_dynamic_link
|
|
{
|
|
bfd_byte ld_loaded[4];
|
|
bfd_byte ld_need[4];
|
|
bfd_byte ld_rules[4];
|
|
bfd_byte ld_got[4];
|
|
bfd_byte ld_plt[4];
|
|
bfd_byte ld_rel[4];
|
|
bfd_byte ld_hash[4];
|
|
bfd_byte ld_stab[4];
|
|
bfd_byte ld_stab_hash[4];
|
|
bfd_byte ld_buckets[4];
|
|
bfd_byte ld_symbols[4];
|
|
bfd_byte ld_symb_size[4];
|
|
bfd_byte ld_text[4];
|
|
bfd_byte ld_plt_sz[4];
|
|
};
|