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Diffstat (limited to 'sysdeps/alpha/dl-machine.h')
| -rw-r--r-- | sysdeps/alpha/dl-machine.h | 528 |
1 files changed, 528 insertions, 0 deletions
diff --git a/sysdeps/alpha/dl-machine.h b/sysdeps/alpha/dl-machine.h new file mode 100644 index 0000000000..63db19c6cf --- /dev/null +++ b/sysdeps/alpha/dl-machine.h @@ -0,0 +1,528 @@ +/* Machine-dependent ELF dynamic relocation inline functions. Alpha version. + Copyright (C) 1996-2014 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Richard Henderson <rth@tamu.edu>. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library. If not, see + <http://www.gnu.org/licenses/>. */ + +/* This was written in the absence of an ABI -- don't expect + it to remain unchanged. */ + +#ifndef dl_machine_h +#define dl_machine_h 1 + +#define ELF_MACHINE_NAME "alpha" + +#include <string.h> + + +/* Mask identifying addresses reserved for the user program, + where the dynamic linker should not map anything. */ +#define ELF_MACHINE_USER_ADDRESS_MASK 0x120000000UL + +/* Translate a processor specific dynamic tag to the index in l_info array. */ +#define DT_ALPHA(x) (DT_ALPHA_##x - DT_LOPROC + DT_NUM) + +/* Return nonzero iff ELF header is compatible with the running host. */ +static inline int +elf_machine_matches_host (const Elf64_Ehdr *ehdr) +{ + return ehdr->e_machine == EM_ALPHA; +} + +/* Return the link-time address of _DYNAMIC. The multiple-got-capable + linker no longer allocates the first .got entry for this. But not to + worry, no special tricks are needed. */ +static inline Elf64_Addr +elf_machine_dynamic (void) +{ +#ifndef NO_AXP_MULTI_GOT_LD + return (Elf64_Addr) &_DYNAMIC; +#else + register Elf64_Addr *gp __asm__ ("$29"); + return gp[-4096]; +#endif +} + +/* Return the run-time load address of the shared object. */ + +static inline Elf64_Addr +elf_machine_load_address (void) +{ + /* This relies on the compiler using gp-relative addresses for static symbols. */ + static void *dot = ˙ + return (void *)&dot - dot; +} + +/* 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. */ + +static inline int +elf_machine_runtime_setup (struct link_map *map, int lazy, int profile) +{ + extern char _dl_runtime_resolve_new[] attribute_hidden; + extern char _dl_runtime_profile_new[] attribute_hidden; + extern char _dl_runtime_resolve_old[] attribute_hidden; + extern char _dl_runtime_profile_old[] attribute_hidden; + + struct pltgot { + char *resolve; + struct link_map *link; + }; + + struct pltgot *pg; + long secureplt; + char *resolve; + + if (map->l_info[DT_JMPREL] == 0 || !lazy) + return lazy; + + /* Check to see if we're using the read-only plt form. */ + secureplt = map->l_info[DT_ALPHA(PLTRO)] != 0; + + /* If the binary uses the read-only secure plt format, PG points to + the .got.plt section, which is the right place for ld.so to place + its hooks. Otherwise, PG is currently pointing at the start of + the plt; the hooks go at offset 16. */ + pg = (struct pltgot *) D_PTR (map, l_info[DT_PLTGOT]); + pg += !secureplt; + + /* This function will be called to perform the relocation. They're + not declared as functions to convince the compiler to use gp + relative relocations for them. */ + if (secureplt) + resolve = _dl_runtime_resolve_new; + else + resolve = _dl_runtime_resolve_old; + + if (__builtin_expect (profile, 0)) + { + if (secureplt) + resolve = _dl_runtime_profile_new; + else + resolve = _dl_runtime_profile_old; + + if (GLRO(dl_profile) && _dl_name_match_p (GLRO(dl_profile), map)) + { + /* This is the object we are looking for. Say that we really + want profiling and the timers are started. */ + GL(dl_profile_map) = map; + } + } + + pg->resolve = resolve; + pg->link = map; + + return lazy; +} + +/* 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. */ + +#define RTLD_START asm ("\ + .section .text \n\ + .set at \n\ + .globl _start \n\ + .ent _start \n\ +_start: \n\ + .frame $31,0,$31,0 \n\ + br $gp, 0f \n\ +0: ldgp $gp, 0($gp) \n\ + .prologue 0 \n\ + /* Pass pointer to argument block to _dl_start. */ \n\ + mov $sp, $16 \n\ + bsr $26, _dl_start !samegp \n\ + .end _start \n\ + /* FALLTHRU */ \n\ + .globl _dl_start_user \n\ + .ent _dl_start_user \n\ +_dl_start_user: \n\ + .frame $31,0,$31,0 \n\ + .prologue 0 \n\ + /* Save the user entry point address in s0. */ \n\ + mov $0, $9 \n\ + /* See if we were run as a command with the executable \n\ + file name as an extra leading argument. */ \n\ + ldah $1, _dl_skip_args($gp) !gprelhigh \n\ + ldl $1, _dl_skip_args($1) !gprellow \n\ + bne $1, $fixup_stack \n\ +$fixup_stack_ret: \n\ + /* The special initializer gets called with the stack \n\ + just as the application's entry point will see it; \n\ + it can switch stacks if it moves these contents \n\ + over. */ \n\ +" RTLD_START_SPECIAL_INIT " \n\ + /* Call _dl_init(_dl_loaded, argc, argv, envp) to run \n\ + initializers. */ \n\ + ldah $16, _rtld_local($gp) !gprelhigh \n\ + ldq $16, _rtld_local($16) !gprellow \n\ + ldq $17, 0($sp) \n\ + lda $18, 8($sp) \n\ + s8addq $17, 8, $19 \n\ + addq $19, $18, $19 \n\ + bsr $26, _dl_init_internal !samegp \n\ + /* Pass our finalizer function to the user in $0. */ \n\ + ldah $0, _dl_fini($gp) !gprelhigh \n\ + lda $0, _dl_fini($0) !gprellow \n\ + /* Jump to the user's entry point. */ \n\ + mov $9, $27 \n\ + jmp ($9) \n\ +$fixup_stack: \n\ + /* Adjust the stack pointer to skip _dl_skip_args words.\n\ + This involves copying everything down, since the \n\ + stack pointer must always be 16-byte aligned. */ \n\ + ldah $7, _dl_argv_internal($gp) !gprelhigh \n\ + ldq $2, 0($sp) \n\ + ldq $5, _dl_argv_internal($7) !gprellow \n\ + subq $31, $1, $6 \n\ + subq $2, $1, $2 \n\ + s8addq $6, $5, $5 \n\ + mov $sp, $4 \n\ + s8addq $1, $sp, $3 \n\ + stq $2, 0($sp) \n\ + stq $5, _dl_argv_internal($7) !gprellow \n\ + /* Copy down argv. */ \n\ +0: ldq $5, 8($3) \n\ + addq $4, 8, $4 \n\ + addq $3, 8, $3 \n\ + stq $5, 0($4) \n\ + bne $5, 0b \n\ + /* Copy down envp. */ \n\ +1: ldq $5, 8($3) \n\ + addq $4, 8, $4 \n\ + addq $3, 8, $3 \n\ + stq $5, 0($4) \n\ + bne $5, 1b \n\ + /* Copy down auxiliary table. */ \n\ +2: ldq $5, 8($3) \n\ + ldq $6, 16($3) \n\ + addq $4, 16, $4 \n\ + addq $3, 16, $3 \n\ + stq $5, -8($4) \n\ + stq $6, 0($4) \n\ + bne $5, 2b \n\ + br $fixup_stack_ret \n\ + .end _dl_start_user \n\ + .set noat \n\ +.previous"); + +#ifndef RTLD_START_SPECIAL_INIT +#define RTLD_START_SPECIAL_INIT /* nothing */ +#endif + +/* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry + or TLS variables, so undefined references should not be allowed + to define the value. + + ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve + to one of the main executable's symbols, as for a COPY reloc. + This is unused on Alpha. */ + +# define elf_machine_type_class(type) \ + (((type) == R_ALPHA_JMP_SLOT \ + || (type) == R_ALPHA_DTPMOD64 \ + || (type) == R_ALPHA_DTPREL64 \ + || (type) == R_ALPHA_TPREL64) * ELF_RTYPE_CLASS_PLT) + +/* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */ +#define ELF_MACHINE_JMP_SLOT R_ALPHA_JMP_SLOT + +/* The alpha never uses Elf64_Rel relocations. */ +#define ELF_MACHINE_NO_REL 1 + +/* We define an initialization functions. This is called very early in + * _dl_sysdep_start. */ +#define DL_PLATFORM_INIT dl_platform_init () + +static inline void __attribute__ ((unused)) +dl_platform_init (void) +{ + if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0') + /* Avoid an empty string which would disturb us. */ + GLRO(dl_platform) = NULL; +} + +/* Fix up the instructions of a PLT entry to invoke the function + rather than the dynamic linker. */ +static inline Elf64_Addr +elf_machine_fixup_plt (struct link_map *map, lookup_t t, + const Elf64_Rela *reloc, + Elf64_Addr *got_addr, Elf64_Addr value) +{ + const Elf64_Rela *rela_plt; + Elf64_Word *plte; + long int edisp; + + /* Store the value we are going to load. */ + *got_addr = value; + + /* If this binary uses the read-only secure plt format, we're done. */ + if (map->l_info[DT_ALPHA(PLTRO)]) + return value; + + /* Otherwise we have to modify the plt entry in place to do the branch. */ + + /* Recover the PLT entry address by calculating reloc's index into the + .rela.plt, and finding that entry in the .plt. */ + rela_plt = (const Elf64_Rela *) D_PTR (map, l_info[DT_JMPREL]); + plte = (Elf64_Word *) (D_PTR (map, l_info[DT_PLTGOT]) + 32); + plte += 3 * (reloc - rela_plt); + + /* Find the displacement from the plt entry to the function. */ + edisp = (long int) (value - (Elf64_Addr)&plte[3]) / 4; + + if (edisp >= -0x100000 && edisp < 0x100000) + { + /* If we are in range, use br to perfect branch prediction and + elide the dependency on the address load. This case happens, + e.g., when a shared library call is resolved to the same library. */ + + int hi, lo; + hi = value - (Elf64_Addr)&plte[0]; + lo = (short int) hi; + hi = (hi - lo) >> 16; + + /* Emit "lda $27,lo($27)" */ + plte[1] = 0x237b0000 | (lo & 0xffff); + + /* Emit "br $31,function" */ + plte[2] = 0xc3e00000 | (edisp & 0x1fffff); + + /* Think about thread-safety -- the previous instructions must be + committed to memory before the first is overwritten. */ + __asm__ __volatile__("wmb" : : : "memory"); + + /* Emit "ldah $27,hi($27)" */ + plte[0] = 0x277b0000 | (hi & 0xffff); + } + else + { + /* Don't bother with the hint since we already know the hint is + wrong. Eliding it prevents the wrong page from getting pulled + into the cache. */ + + int hi, lo; + hi = (Elf64_Addr)got_addr - (Elf64_Addr)&plte[0]; + lo = (short)hi; + hi = (hi - lo) >> 16; + + /* Emit "ldq $27,lo($27)" */ + plte[1] = 0xa77b0000 | (lo & 0xffff); + + /* Emit "jmp $31,($27)" */ + plte[2] = 0x6bfb0000; + + /* Think about thread-safety -- the previous instructions must be + committed to memory before the first is overwritten. */ + __asm__ __volatile__("wmb" : : : "memory"); + + /* Emit "ldah $27,hi($27)" */ + plte[0] = 0x277b0000 | (hi & 0xffff); + } + + /* At this point, if we've been doing runtime resolution, Icache is dirty. + This will be taken care of in _dl_runtime_resolve. If instead we are + doing this as part of non-lazy startup relocation, that bit of code + hasn't made it into Icache yet, so there's nothing to clean up. */ + + return value; +} + +/* Return the final value of a plt relocation. */ +static inline Elf64_Addr +elf_machine_plt_value (struct link_map *map, const Elf64_Rela *reloc, + Elf64_Addr value) +{ + return value + reloc->r_addend; +} + +/* Names of the architecture-specific auditing callback functions. */ +#define ARCH_LA_PLTENTER alpha_gnu_pltenter +#define ARCH_LA_PLTEXIT alpha_gnu_pltexit + +#endif /* !dl_machine_h */ + +#ifdef RESOLVE_MAP + +/* Perform the relocation specified by RELOC and SYM (which is fully resolved). + MAP is the object containing the reloc. */ +auto inline void +__attribute__ ((always_inline)) +elf_machine_rela (struct link_map *map, + const Elf64_Rela *reloc, + const Elf64_Sym *sym, + const struct r_found_version *version, + void *const reloc_addr_arg, + int skip_ifunc) +{ + Elf64_Addr *const reloc_addr = reloc_addr_arg; + unsigned long int const r_type = ELF64_R_TYPE (reloc->r_info); + +#if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC && !defined SHARED + /* This is defined in rtld.c, but nowhere in the static libc.a; make the + reference weak so static programs can still link. This declaration + cannot be done when compiling rtld.c (i.e. #ifdef RTLD_BOOTSTRAP) + because rtld.c contains the common defn for _dl_rtld_map, which is + incompatible with a weak decl in the same file. */ + weak_extern (_dl_rtld_map); +#endif + + /* We cannot use a switch here because we cannot locate the switch + jump table until we've self-relocated. */ + +#if !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC + if (__builtin_expect (r_type == R_ALPHA_RELATIVE, 0)) + { +# if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC + /* Already done in dynamic linker. */ + if (map != &GL(dl_rtld_map)) +# endif + { + /* XXX Make some timings. Maybe it's preferable to test for + unaligned access and only do it the complex way if necessary. */ + Elf64_Addr reloc_addr_val; + + /* Load value without causing unaligned trap. */ + memcpy (&reloc_addr_val, reloc_addr_arg, 8); + reloc_addr_val += map->l_addr; + + /* Store value without causing unaligned trap. */ + memcpy (reloc_addr_arg, &reloc_addr_val, 8); + } + } + else +#endif + if (__builtin_expect (r_type == R_ALPHA_NONE, 0)) + return; + else + { + struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type); + Elf64_Addr sym_value; + Elf64_Addr sym_raw_value; + + sym_raw_value = sym_value = reloc->r_addend; + if (sym_map) + { + sym_raw_value += sym->st_value; + sym_value = sym_raw_value + sym_map->l_addr; + } + + if (r_type == R_ALPHA_GLOB_DAT) + *reloc_addr = sym_value; +#ifdef RESOLVE_CONFLICT_FIND_MAP + /* In .gnu.conflict section, R_ALPHA_JMP_SLOT relocations have + R_ALPHA_JMP_SLOT in lower 8 bits and the remaining 24 bits + are .rela.plt index. */ + else if ((r_type & 0xff) == R_ALPHA_JMP_SLOT) + { + /* elf_machine_fixup_plt needs the map reloc_addr points into, + while in _dl_resolve_conflicts map is _dl_loaded. */ + RESOLVE_CONFLICT_FIND_MAP (map, reloc_addr); + reloc = ((const Elf64_Rela *) D_PTR (map, l_info[DT_JMPREL])) + + (r_type >> 8); + elf_machine_fixup_plt (map, 0, reloc, reloc_addr, sym_value); + } +#else + else if (r_type == R_ALPHA_JMP_SLOT) + elf_machine_fixup_plt (map, 0, reloc, reloc_addr, sym_value); +#endif +#ifndef RTLD_BOOTSTRAP + else if (r_type == R_ALPHA_REFQUAD) + { + /* Store value without causing unaligned trap. */ + memcpy (reloc_addr_arg, &sym_value, 8); + } +#endif + else if (r_type == R_ALPHA_DTPMOD64) + { +# ifdef RTLD_BOOTSTRAP + /* During startup the dynamic linker is always index 1. */ + *reloc_addr = 1; +# else + /* Get the information from the link map returned by the + resolv function. */ + if (sym_map != NULL) + *reloc_addr = sym_map->l_tls_modid; +# endif + } + else if (r_type == R_ALPHA_DTPREL64) + { +# ifndef RTLD_BOOTSTRAP + /* During relocation all TLS symbols are defined and used. + Therefore the offset is already correct. */ + *reloc_addr = sym_raw_value; +# endif + } + else if (r_type == R_ALPHA_TPREL64) + { +# ifdef RTLD_BOOTSTRAP + *reloc_addr = sym_raw_value + map->l_tls_offset; +# else + if (sym_map) + { + CHECK_STATIC_TLS (map, sym_map); + *reloc_addr = sym_raw_value + sym_map->l_tls_offset; + } +# endif + } + else + _dl_reloc_bad_type (map, r_type, 0); + } +} + +/* Let do-rel.h know that on Alpha if l_addr is 0, all RELATIVE relocs + can be skipped. */ +#define ELF_MACHINE_REL_RELATIVE 1 + +auto inline void +__attribute__ ((always_inline)) +elf_machine_rela_relative (Elf64_Addr l_addr, const Elf64_Rela *reloc, + void *const reloc_addr_arg) +{ + /* XXX Make some timings. Maybe it's preferable to test for + unaligned access and only do it the complex way if necessary. */ + Elf64_Addr reloc_addr_val; + + /* Load value without causing unaligned trap. */ + memcpy (&reloc_addr_val, reloc_addr_arg, 8); + reloc_addr_val += l_addr; + + /* Store value without causing unaligned trap. */ + memcpy (reloc_addr_arg, &reloc_addr_val, 8); +} + +auto inline void +__attribute__ ((always_inline)) +elf_machine_lazy_rel (struct link_map *map, + Elf64_Addr l_addr, const Elf64_Rela *reloc, + int skip_ifunc) +{ + Elf64_Addr * const reloc_addr = (void *)(l_addr + reloc->r_offset); + unsigned long int const r_type = ELF64_R_TYPE (reloc->r_info); + + if (r_type == R_ALPHA_JMP_SLOT) + { + /* Perform a RELATIVE reloc on the .got entry that transfers + to the .plt. */ + *reloc_addr += l_addr; + } + else if (r_type == R_ALPHA_NONE) + return; + else + _dl_reloc_bad_type (map, r_type, 1); +} + +#endif /* RESOLVE_MAP */ |