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Diffstat (limited to 'include/aout/sun4.h')
| -rw-r--r-- | include/aout/sun4.h | 219 |
1 files changed, 219 insertions, 0 deletions
diff --git a/include/aout/sun4.h b/include/aout/sun4.h new file mode 100644 index 0000000..f42a0dd --- /dev/null +++ b/include/aout/sun4.h @@ -0,0 +1,219 @@ +/* SPARC-specific values for a.out files */ + +/* 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. */ + +/* 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]; +}; |