| /* Machine-dependent ELF dynamic relocation inline functions. Alpha version. |
| Copyright (C) 1996-2018 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 !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 $7, __GI__dl_argv($gp) !gprelhigh \n\ |
| ldq $2, 0($sp) \n\ |
| ldq $5, __GI__dl_argv($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, __GI__dl_argv($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_COPY 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 |
| #define ELF_MACHINE_NO_RELA 0 |
| |
| /* 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 ElfW(Sym) *refsym, const ElfW(Sym) *sym, |
| 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, 0, 0, reloc, reloc_addr, sym_value); |
| } |
| #else |
| else if (r_type == R_ALPHA_JMP_SLOT) |
| elf_machine_fixup_plt (map, 0, 0, 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 */ |