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Diffstat (limited to 'sysdeps/powerpc/dl-machine.h')
| -rw-r--r-- | sysdeps/powerpc/dl-machine.h | 529 |
1 files changed, 529 insertions, 0 deletions
diff --git a/sysdeps/powerpc/dl-machine.h b/sysdeps/powerpc/dl-machine.h new file mode 100644 index 0000000000..a60a29723d --- /dev/null +++ b/sysdeps/powerpc/dl-machine.h @@ -0,0 +1,529 @@ +/* Machine-dependent ELF dynamic relocation inline functions. PowerPC version. + Copyright (C) 1995, 1996, 1997 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Library General Public License as + published by the Free Software Foundation; either version 2 of the + License, or (at your option) any later version. + + The GNU C Library 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 + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#define ELF_MACHINE_NAME "powerpc" + +#include <assert.h> +#include <string.h> +#include <link.h> + +/* stuff for the PLT */ +#define PLT_INITIAL_ENTRY_WORDS 18 +#define PLT_LONGBRANCH_ENTRY_WORDS 10 +#define OPCODE_ADDI(rd,ra,simm) \ + (0x38000000 | (rd) << 21 | (ra) << 16 | (simm) & 0xffff) +#define OPCODE_ADDIS(rd,ra,simm) \ + (0x3c000000 | (rd) << 21 | (ra) << 16 | (simm) & 0xffff) +#define OPCODE_ADD(rd,ra,rb) \ + (0x7c000214 | (rd) << 21 | (ra) << 16 | (rb) << 11) +#define OPCODE_B(target) (0x48000000 | (target) & 0x03fffffc) +#define OPCODE_BA(target) (0x48000002 | (target) & 0x03fffffc) +#define OPCODE_BCTR() 0x4e800420 +#define OPCODE_LWZ(rd,d,ra) \ + (0x80000000 | (rd) << 21 | (ra) << 16 | (d) & 0xffff) +#define OPCODE_MTCTR(rd) (0x7C0903A6 | (rd) << 21) +#define OPCODE_RLWINM(ra,rs,sh,mb,me) \ + (0x54000000 | (rs) << 21 | (ra) << 16 | (sh) << 11 | (mb) << 6 | (me) << 1) + +#define OPCODE_LI(rd,simm) OPCODE_ADDI(rd,0,simm) +#define OPCODE_SLWI(ra,rs,sh) OPCODE_RLWINM(ra,rs,sh,0,31-sh) + + +/* Return nonzero iff E_MACHINE is compatible with the running host. */ +static inline int +elf_machine_matches_host (Elf32_Half e_machine) +{ + return e_machine == EM_PPC; +} + + +/* Return the link-time address of _DYNAMIC, the first value in the GOT. */ +static inline Elf32_Addr +elf_machine_dynamic (void) +{ + Elf32_Addr *got; + asm (" bl _GLOBAL_OFFSET_TABLE_-4@local" + : "=l"(got)); + return *got; +} + +/* Return the run-time load address of the shared object. */ +static inline Elf32_Addr +elf_machine_load_address (void) +{ + unsigned *got; + unsigned *branchaddr; + + /* This is much harder than you'd expect. Possibly I'm missing something. + The 'obvious' way: + + Apparently, "bcl 20,31,$+4" is what should be used to load LR + with the address of the next instruction. + I think this is so that machines that do bl/blr pairing don't + get confused. + + asm ("bcl 20,31,0f ;" + "0: mflr 0 ;" + "lis %0,0b@ha;" + "addi %0,%0,0b@l;" + "subf %0,%0,0" + : "=b" (addr) : : "r0", "lr"); + + doesn't work, because the linker doesn't have to (and in fact doesn't) + update the @ha and @l references; the loader (which runs after this + code) will do that. + + Instead, we use the following trick: + + The linker puts the _link-time_ address of _DYNAMIC at the first + word in the GOT. We could branch to that address, if we wanted, + by using an @local reloc; the linker works this out, so it's safe + to use now. We can't, of course, actually branch there, because + we'd cause an illegal instruction exception; so we need to compute + the address ourselves. That gives us the following code: */ + + /* Get address of the 'b _DYNAMIC@local'... */ + asm ("bl 0f ;" + "b _DYNAMIC@local;" + "0:" + : "=l"(branchaddr)); + + /* ... and the address of the GOT. */ + asm (" bl _GLOBAL_OFFSET_TABLE_-4@local" + : "=l"(got)); + + /* So now work out the difference between where the branch actually points, + and the offset of that location in memory from the start of the file. */ + return (Elf32_Addr)branchaddr - *got + + (*branchaddr & 0x3fffffc | + (int)(*branchaddr << 6 & 0x80000000) >> 6); +} + +#define ELF_MACHINE_BEFORE_RTLD_RELOC(dynamic_info) /* nothing */ + +/* Perform the relocation specified by RELOC and SYM (which is fully resolved). + LOADADDR is the load address of the object; INFO is an array indexed + by DT_* of the .dynamic section info. */ + +#ifdef RESOLVE + +static inline void +elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc, + const Elf32_Sym *sym, const struct r_found_version *version) +{ + Elf32_Addr *const reloc_addr = (Elf32_Addr *)(map->l_addr + reloc->r_offset); + Elf32_Word loadbase, finaladdr; + const int rinfo = ELF32_R_TYPE (reloc->r_info); + + if (rinfo == R_PPC_NONE) + return; + + if (sym && ELF32_ST_TYPE (sym->st_info) == STT_SECTION || + rinfo == R_PPC_RELATIVE) + { + /* Has already been relocated. */ + loadbase = map->l_addr; + finaladdr = loadbase + reloc->r_addend; + } + else + { + assert (sym != NULL); + if (rinfo == R_PPC_JMP_SLOT) + loadbase = (Elf32_Word) (char *) RESOLVE (&sym, + version, DL_LOOKUP_NOPLT); + else + loadbase = (Elf32_Word) (char *) RESOLVE (&sym, version, 0); + if (sym == NULL) + { + /* Weak symbol that wasn't actually defined anywhere. */ + assert (loadbase == 0); + finaladdr = reloc->r_addend; + } + else + finaladdr = (loadbase + (Elf32_Word)(char *)sym->st_value + + reloc->r_addend); + } + + switch (rinfo) + { + case R_PPC_UADDR16: + case R_PPC_ADDR16_LO: + case R_PPC_ADDR16: + *(Elf32_Half*) reloc_addr = finaladdr; + break; + + case R_PPC_ADDR16_HI: + *(Elf32_Half*) reloc_addr = finaladdr >> 16; + break; + + case R_PPC_ADDR16_HA: + *(Elf32_Half*) reloc_addr = finaladdr + 0x8000 >> 16; + break; + + case R_PPC_REL24: + { + Elf32_Sword delta = finaladdr - (Elf32_Word) (char *) reloc_addr; + assert (delta << 6 >> 6 == delta); + *reloc_addr = *reloc_addr & 0xfc000003 | delta & 0x3fffffc; + } + break; + + case R_PPC_UADDR32: + case R_PPC_GLOB_DAT: + case R_PPC_ADDR32: + case R_PPC_RELATIVE: + *reloc_addr = finaladdr; + break; + + case R_PPC_ADDR24: + *reloc_addr = *reloc_addr & 0xfc000003 | finaladdr & 0x3fffffc; + break; + + case R_PPC_REL14_BRTAKEN: + case R_PPC_REL14_BRNTAKEN: + case R_PPC_REL14: + { + Elf32_Sword delta = finaladdr - (Elf32_Word) (char *) reloc_addr; + *reloc_addr = *reloc_addr & 0xffdf0003 | delta & 0xfffc; + if (rinfo == R_PPC_REL14_BRTAKEN && delta >= 0 || + rinfo == R_PPC_REL14_BRNTAKEN && delta < 0) + *reloc_addr |= 0x00200000; + } + break; + + case R_PPC_COPY: + { + /* Can't use memcpy (because we can't call any functions here). */ + int i; + for (i = 0; i < sym->st_size; ++i) + ((unsigned char *) reloc_addr)[i] = + ((unsigned char *)finaladdr)[i]; + } + break; + + case R_PPC_REL32: + *reloc_addr = finaladdr - (Elf32_Word) (char *) reloc_addr; + break; + + case R_PPC_JMP_SLOT: + if (finaladdr <= 0x01fffffc || finaladdr >= 0xfe000000) + *reloc_addr = OPCODE_BA (finaladdr); + else + { + Elf32_Sword delta = finaladdr - (Elf32_Word) (char *) reloc_addr; + if (delta <= 0x01fffffc && delta >= 0xfe000000) + *reloc_addr = OPCODE_B (delta); + else + { + Elf32_Word *plt = + (Elf32_Word *) ((char *) map->l_addr + + map->l_info[DT_PLTGOT]->d_un.d_val); + Elf32_Word index =((reloc_addr - plt - PLT_INITIAL_ENTRY_WORDS) + / 2); + int num_plt_entries = (map->l_info[DT_PLTRELSZ]->d_un.d_val + / sizeof (Elf32_Rela)); + int rel_offset_words = (PLT_INITIAL_ENTRY_WORDS + + num_plt_entries * 2); + + if (index >= (1 << 13)) + { + /* Indexes greater than or equal to 2^13 have 4 + words available instead of two. */ + plt[index * 2 + PLT_INITIAL_ENTRY_WORDS] = + OPCODE_LI (11, finaladdr); + plt[index * 2 + 1 + PLT_INITIAL_ENTRY_WORDS] = + OPCODE_ADDIS (11, 11, finaladdr + 0x8000 >> 16); + plt[index * 2 + 2 + PLT_INITIAL_ENTRY_WORDS] = + OPCODE_MTCTR (11); + plt[index * 2 + 2 + PLT_INITIAL_ENTRY_WORDS] = + OPCODE_BCTR (); + } + else + { + plt[index * 2 + PLT_INITIAL_ENTRY_WORDS] = + OPCODE_LI (11, index * 4); + plt[index * 2 + 1 + PLT_INITIAL_ENTRY_WORDS] = + OPCODE_B(-(4 * (index * 2 + 1 + PLT_INITIAL_ENTRY_WORDS + + PLT_LONGBRANCH_ENTRY_WORDS))); + plt[index + rel_offset_words] = finaladdr; + } + } + } + break; + + default: + assert (! "unexpected dynamic reloc type"); + } +} + +#define ELF_MACHINE_NO_REL 1 + +#endif + +/* Nonzero iff TYPE describes relocation of a PLT entry, so + PLT entries should not be allowed to define the value. */ +#define elf_machine_pltrel_p(type) ((type) == R_PPC_JMP_SLOT) + +/* Set up the loaded object described by L so its unrelocated PLT + entries will jump to the on-demand fixup code in dl-runtime.c. */ + +/* This code does not presently work if there are more than 2^13 PLT + entries. */ +static inline void +elf_machine_runtime_setup (struct link_map *map, int lazy) +{ + Elf32_Word *plt; + int i; + Elf32_Word num_plt_entries; + Elf32_Word rel_offset_words; + extern void _dl_runtime_resolve (void); + + if (map->l_info[DT_JMPREL]) + { + /* Fill in the PLT. Its initial contents are directed to a + function earlier in the PLT which arranges for the dynamic + linker to be called back. */ + plt = (Elf32_Word *) ((char *) map->l_addr + + map->l_info[DT_PLTGOT]->d_un.d_val); + num_plt_entries = (map->l_info[DT_PLTRELSZ]->d_un.d_val + / sizeof (Elf32_Rela)); + rel_offset_words = PLT_INITIAL_ENTRY_WORDS + num_plt_entries * 2; + + if (lazy) + for (i = 0; i < num_plt_entries; i++) + if (i >= (1 << 13)) + { + plt[i * 2 + (i - (1 << 13)) * 2 + PLT_INITIAL_ENTRY_WORDS] = + OPCODE_LI (11, i * 4); + plt[i * 2 + (i - (1 << 13)) * 2 + 1 + PLT_INITIAL_ENTRY_WORDS] = + OPCODE_ADDIS (11, 11, i * 4 + 0x8000 >> 16); + plt[i * 2 + (i - (1 << 13)) * 2 + 2 + PLT_INITIAL_ENTRY_WORDS] = + OPCODE_B (-(4 * ( i * 2 + 1 + PLT_INITIAL_ENTRY_WORDS))); + } + else + { + plt[i * 2 + PLT_INITIAL_ENTRY_WORDS] = OPCODE_LI (11, i * 4); + plt[i * 2 + 1 + PLT_INITIAL_ENTRY_WORDS] = + OPCODE_B (-(4 * (i * 2 + 1 + PLT_INITIAL_ENTRY_WORDS))); + } + + /* Multiply index of entry, by 0xC. */ + plt[0] = OPCODE_SLWI (12, 11, 1); + plt[1] = OPCODE_ADD (11, 12, 11); + if ((Elf32_Word) (char *) _dl_runtime_resolve <= 0x01fffffc || + (Elf32_Word) (char *) _dl_runtime_resolve >= 0xfe000000) + { + plt[2] = OPCODE_LI (12, (Elf32_Word) (char *) map); + plt[3] = OPCODE_ADDIS (12, 12, + (Elf32_Word) (char *) map + 0x8000 >> 16); + plt[4] = OPCODE_BA ((Elf32_Word) (char *) _dl_runtime_resolve); + } + else + { + plt[2] = OPCODE_LI (12, (Elf32_Word) (char *) _dl_runtime_resolve); + plt[3] = OPCODE_ADDIS (12, 12, 0x8000 + + ((Elf32_Word) (char *) _dl_runtime_resolve + >> 16)); + plt[4] = OPCODE_MTCTR (12); + plt[5] = OPCODE_LI (12, (Elf32_Word) (char *) map); + plt[6] = OPCODE_ADDIS (12, 12, ((Elf32_Word) (char *) map + + 0x8000 >> 16)); + plt[7] = OPCODE_BCTR (); + } + plt[PLT_LONGBRANCH_ENTRY_WORDS] = + OPCODE_ADDIS (11, 11, ((Elf32_Word) (char*) (plt+rel_offset_words) + + 0x8000 >> 16)); + plt[PLT_LONGBRANCH_ENTRY_WORDS+1] = + OPCODE_LWZ (11, (Elf32_Word) (char*) (plt + rel_offset_words), 11); + plt[PLT_LONGBRANCH_ENTRY_WORDS+2] = OPCODE_MTCTR (11); + plt[PLT_LONGBRANCH_ENTRY_WORDS+3] = OPCODE_BCTR (); + } +} + +static inline void +elf_machine_lazy_rel (struct link_map *map, const Elf32_Rela *reloc) +{ + if (ELF32_R_TYPE (reloc->r_info) != R_PPC_JMP_SLOT) + assert (! "unexpected PLT reloc type"); + + /* elf_machine_runtime_setup handles this. */ +} + +/* The PLT uses Elf32_Rela relocs. */ +#define elf_machine_relplt elf_machine_rela + + /* This code is used in dl-runtime.c to call the `fixup' function + and then redirect to the address it returns. */ +#define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\ + .section \".text\" + .globl _dl_runtime_resolve +_dl_runtime_resolve: + stwu 1,-48(1) + mflr 0 + stw 3,16(1) + stw 4,20(1) + stw 0,52(1) + stw 5,24(1) + mfcr 0 + stw 6,28(1) + stw 7,32(1) + stw 8,36(1) + stw 9,40(1) + stw 10,44(1) + stw 0,12(1) + mr 3,12 + mr 4,11 + bl fixup + mtctr 3 + lwz 0,52(1) + lwz 10,44(1) + lwz 9,40(1) + mtlr 0 + lwz 0,12(1) + lwz 8,36(1) + lwz 7,32(1) + lwz 6,28(1) + mtcrf 0xFF,0 + lwz 5,24(1) + lwz 4,20(1) + lwz 3,16(1) + addi 1,1,48 + bctr +"); + +/* Initial entry point code for the dynamic linker. + The C function `_dl_start' is the real entry point; + its return value is the user program's entry point. */ + +/* FIXME! We don't make provision for calling _dl_fini, + because Linux/PPC is somewhat broken. */ +#define RTLD_START \ +asm ("\ + .text + .align 2 + .globl _start + .type _start,@function +_start: + # We start with the following on the stack, from top: + # argc (4 bytes) + # arguments for program (terminated by NULL) + # environment variables (terminated by NULL) + # arguments for the program loader + + # Call _dl_start with one parameter pointing at argc + mr 3,1 + # (we have to frob the stack pointer a bit to allow room for + # _dl_start to save the link register) + li 4,0 + addi 1,1,-16 + stw 4,0(1) + bl _dl_start@local + + # Now, we do our main work of calling initialisation procedures. + # The ELF ABI doesn't say anything about parameters for these, + # so we just pass argc, argv, and the environment. + # Changing these is strongly discouraged (not least because argc is + # passed by value!). + + # put our GOT pointer in r31 + bl _GLOBAL_OFFSET_TABLE_-4@local + mflr 31 + # the address of _start in r30 + mr 30,3 + # &_dl_argc in 29, &_dl_argv in 27, and _dl_default_scope in 28 + lwz 28,_dl_default_scope@got(31) + lwz 29,_dl_argc@got(31) + lwz 27,_dl_argv@got(31) +0: + # call initfunc = _dl_init_next(_dl_default_scope[2]) + lwz 3,8(28) + bl _dl_init_next@plt + # if initfunc is NULL, we exit the loop + mr. 0,3 + beq 1f + # call initfunc(_dl_argc, _dl_argv, _dl_argv+_dl_argc+1) + mtlr 0 + lwz 3,0(29) + lwz 4,0(27) + slwi 5,3,2 + add 5,4,5 + addi 5,5,4 + blrl + # and loop. + b 0b +1: + # Now, to conform to the ELF ABI, we have to: + # pass argv (actually _dl_argv) in r4 + lwz 4,0(27) + # pass argc (actually _dl_argc) in r3 + lwz 3,0(29) + # pass envp (actually _dl_argv+_dl_argc+1) in r5 + slwi 5,3,2 + add 5,4,5 + addi 5,5,4 + # pass the auxilary vector in r6. This is passed just after _envp. + addi 6,5,-4 +2: lwzu 0,4(6) + cmpwi 1,0,0 + bne 2b + addi 6,6,4 + # pass a termination function pointer (in this case _dl_fini) in r7 + lwz 7,_dl_fini@got(31) + # now, call the start function in r30... + mtctr 30 + # pass the stack pointer in r1 (so far so good), pointing to a NULL value + # (this lets our startup code distinguish between a program linked statically, + # which linux will call with argc on top of the stack which will hopefully + # never be zero, and a dynamically linked program which will always have + # a NULL on the top of the stack). + # Take the opportunity to clear LR, so anyone who accidentally returns + # from _start gets SEGV. + li 0,0 + stw 0,0(1) + mtlr 0 + # and also clear _dl_starting_up + lwz 26,_dl_starting_up@got(31) + stw 0,0(3) + # go do it! + bctr +"); + +#define ELF_PREFERRED_ADDRESS_DATA static ElfW(Addr) _dl_preferred_address = 0; +#define ELF_PREFERRED_ADDRESS(loader, maplength, mapstartpref) \ +( { \ + ElfW(Addr) prefd; \ + if (mapstartpref != 0 && _dl_preferred_address == 0) \ + _dl_preferred_address = mapstartpref; \ + if (mapstartpref != 0) \ + prefd = mapstartpref; \ + else if (_dl_preferred_address < maplength + 0x50000) \ + prefd = 0; \ + else \ + prefd = _dl_preferred_address = \ + (_dl_preferred_address - maplength - 0x10000) & \ + ~(_dl_pagesize - 1); \ + prefd; \ +} ) +#define ELF_FIXED_ADDRESS(loader, mapstart) \ +( { \ + if (mapstart != 0 && _dl_preferred_address == 0) \ + _dl_preferred_address = mapstart; \ +} ) + +#define ELF_FIXUP_RETURNS_ADDRESS 1 |