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ARC: startup and dynamic linking code

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Code for C runtime startup and dynamic loading including PLT layout.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Vineet Gupta 2018-10-23 12:36:32 -07:00
parent 0e7d930c4c
commit dd2e6ef179
7 changed files with 591 additions and 0 deletions
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52
sysdeps/arc/bits/link.h Normal file
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/* Machine-specific declarations for dynamic linker interface, ARC version.
Copyright (C) 2020 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 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
<https://www.gnu.org/licenses/>. */
#ifndef _LINK_H
# error "Never include <bits/link.h> directly; use <link.h> instead."
#endif
/* Registers for entry into PLT on ARC. */
typedef struct La_arc_regs
{
uint32_t lr_reg[8]; /* r0 through r7 (upto 8 args). */
} La_arc_regs;
/* Return values for calls from PLT on ARC. */
typedef struct La_arc_retval
{
/* For ARCv2, a 64-bit integer return value can use 2 regs. */
uint32_t lrv_reg[2];
} La_arc_retval;
__BEGIN_DECLS
extern ElfW(Addr) la_arc_gnu_pltenter (ElfW(Sym) *__sym, unsigned int __ndx,
uintptr_t *__refcook,
uintptr_t *__defcook,
La_arc_regs *__regs,
unsigned int *__flags,
const char *__symname,
long int *__framesizep);
extern unsigned int la_arc_gnu_pltexit (ElfW(Sym) *__sym, unsigned int __ndx,
uintptr_t *__refcook,
uintptr_t *__defcook,
const La_arc_regs *__inregs,
La_arc_retval *__outregs,
const char *symname);
__END_DECLS

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sysdeps/arc/dl-machine.h Normal file
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/* Machine-dependent ELF dynamic relocation inline functions. ARC version.
Copyright (C) 2020 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 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
<https://www.gnu.org/licenses/>. */
#ifndef dl_machine_h
#define dl_machine_h
#define ELF_MACHINE_NAME "arc"
#include <entry.h>
#ifndef ENTRY_POINT
# error ENTRY_POINT needs to be defined for ARC
#endif
#include <string.h>
#include <link.h>
#include <dl-tls.h>
/* Dynamic Linking ABI for ARCv2 ISA.
PLT
-------------------------------- <---- DT_PLTGOT
| ld r11, [pcl, off-to-GOT[1] | 0
| | 4
plt0 | ld r10, [pcl, off-to-GOT[2] | 8
| | 12
| j [r10] | 16
--------------------------------
| Base address of GOT | 20
--------------------------------
| ld r12, [pcl, off-to-GOT[3] | 24
plt1 | |
| j.d [r12] | 32
| mov r12, pcl | 36
--------------------------------
| | 40
~ ~
~ ~
| |
--------------------------------
.got
--------------
| [0] |
| ... | Runtime address for data symbols
| [n] |
--------------
.got.plt
--------------
| [0] | Build address of .dynamic
--------------
| [1] | Module info - setup by ld.so
--------------
| [2] | resolver entry point
--------------
| [3] |
| ... | Runtime address for function symbols
| [f] |
--------------
For ARCompact, the PLT is 12 bytes due to short instructions
--------------------------------
| ld r12, [pcl, off-to-GOT[3] | 24 (12 bytes each)
plt1 | |
| j_s.d [r12] | 32
| mov_s r12, pcl | 34
--------------------------------
| | 36 */
/* Return nonzero iff ELF header is compatible with the running host. */
static inline int
elf_machine_matches_host (const Elf32_Ehdr *ehdr)
{
return (ehdr->e_machine == EM_ARCV2 /* ARC HS. */
|| ehdr->e_machine == EM_ARC_COMPACT); /* ARC 700. */
}
/* Get build time address of .dynamic as setup in GOT[0]
This is called very early in _dl_start so it has not been relocated to
runtime value. */
static inline ElfW(Addr)
elf_machine_dynamic (void)
{
extern const ElfW(Addr) _GLOBAL_OFFSET_TABLE_[] attribute_hidden;
return _GLOBAL_OFFSET_TABLE_[0];
}
/* Return the run-time load address of the shared object. */
static inline ElfW(Addr)
elf_machine_load_address (void)
{
ElfW(Addr) build_addr, run_addr;
/* For build address, below generates
ld r0, [pcl, _GLOBAL_OFFSET_TABLE_@pcl]. */
build_addr = elf_machine_dynamic ();
__asm__ ("add %0, pcl, _DYNAMIC@pcl \n" : "=r" (run_addr));
return run_addr - build_addr;
}
/* 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
__attribute__ ((always_inline))
elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
{
extern void _dl_runtime_resolve (Elf32_Word);
if (l->l_info[DT_JMPREL] && lazy)
{
/* On ARC DT_PLTGOT point to .plt whose 5th word (after the PLT header)
contains the address of .got. */
ElfW(Addr) *plt_base = (ElfW(Addr) *) D_PTR (l, l_info[DT_PLTGOT]);
ElfW(Addr) *got = (ElfW(Addr) *) (plt_base[5] + l->l_addr);
got[1] = (ElfW(Addr)) l; /* Identify this shared object. */
/* This function will get called to fix up the GOT entry indicated by
the offset on the stack, and then jump to the resolved address. */
got[2] = (ElfW(Addr)) &_dl_runtime_resolve;
}
return lazy;
}
/* What this code does:
-ldso starts execution here when kernel returns from execve
-calls into generic ldso entry point _dl_start
-optionally adjusts argc for executable if exec passed as cmd
-calls into app main with address of finaliser. */
#define RTLD_START asm ("\
.text \n\
.globl __start \n\
.type __start, @function \n\
__start: \n\
/* (1). bootstrap ld.so. */ \n\
bl.d _dl_start \n\
mov_s r0, sp /* pass ptr to aux vector tbl. */ \n\
mov r13, r0 /* safekeep app elf entry point. */ \n\
\n\
/* (2). If ldso ran with executable as arg. */ \n\
/* skip the extra args calc by dl_start. */ \n\
ld_s r1, [sp] /* orig argc. */ \n\
ld r12, [pcl, _dl_skip_args@pcl] \n\
breq r12, 0, 1f \n\
\n\
add2 sp, sp, r12 /* discard argv entries from stack. */ \n\
sub_s r1, r1, r12 /* adjusted argc on stack. */ \n\
st_s r1, [sp] \n\
add r2, sp, 4 \n\
/* intermediate LD for ST emcoding limitations. */ \n\
ld r3, [pcl, _dl_argv@gotpc] \n\
st r2, [r3] \n\
1: \n\
/* (3). call preinit stuff. */ \n\
ld r0, [pcl, _rtld_local@pcl] \n\
add r2, sp, 4 ; argv \n\
add2 r3, r2, r1 \n\
add r3, r3, 4 ; env \n\
bl _dl_init@plt \n\
\n\
/* (4) call app elf entry point. */ \n\
add r0, pcl, _dl_fini@pcl \n\
j [r13] \n\
\n\
.size __start,.-__start \n\
.previous \n\
");
/* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry, so
PLT entries 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. */
#define elf_machine_type_class(type) \
((((type) == R_ARC_JUMP_SLOT \
|| (type) == R_ARC_TLS_DTPMOD \
|| (type) == R_ARC_TLS_DTPOFF \
|| (type) == R_ARC_TLS_TPOFF) * ELF_RTYPE_CLASS_PLT) \
| (((type) == R_ARC_COPY) * ELF_RTYPE_CLASS_COPY))
/* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
#define ELF_MACHINE_JMP_SLOT R_ARC_JUMP_SLOT
/* ARC uses Elf32_Rela relocations. */
#define ELF_MACHINE_NO_REL 1
#define ELF_MACHINE_NO_RELA 0
/* Fixup a PLT entry to bounce directly to the function at VALUE. */
static inline ElfW(Addr)
elf_machine_fixup_plt (struct link_map *map, lookup_t t,
const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
const Elf32_Rela *reloc,
ElfW(Addr) *reloc_addr, ElfW(Addr) value)
{
return *reloc_addr = value;
}
/* Return the final value of a plt relocation. */
static inline ElfW(Addr)
elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
ElfW(Addr) value)
{
return value;
}
/* Names of the architecture-specific auditing callback functions. */
#define ARCH_LA_PLTENTER arc_gnu_pltenter
#define ARCH_LA_PLTEXIT arc_gnu_pltexit
#endif /* dl_machine_h */
#ifdef RESOLVE_MAP
inline void
__attribute__ ((always_inline))
elf_machine_rela (struct link_map *map, const ElfW(Rela) *reloc,
const ElfW(Sym) *sym, const struct r_found_version *version,
void *const reloc_addr_arg, int skip_ifunc)
{
ElfW(Addr) *const reloc_addr = reloc_addr_arg;
const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
if (__glibc_unlikely (r_type == R_ARC_RELATIVE))
*reloc_addr += map->l_addr;
else if (__glibc_unlikely (r_type == R_ARC_NONE))
return;
else
{
const ElfW(Sym) *const refsym = sym;
struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
ElfW(Addr) value = SYMBOL_ADDRESS (sym_map, sym, true);
switch (r_type)
{
case R_ARC_COPY:
if (__glibc_unlikely (sym == NULL))
/* This can happen in trace mode if an object could not be
found. */
break;
size_t size = sym->st_size;
if (__glibc_unlikely (size != refsym->st_size))
{
const char *strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
if (sym->st_size > refsym->st_size)
size = refsym->st_size;
if (sym->st_size > refsym->st_size || GLRO(dl_verbose))
_dl_error_printf ("\
%s: Symbol `%s' has different size in shared object, consider re-linking\n",
rtld_progname ?: "<program name unknown>",
strtab + refsym->st_name);
}
memcpy (reloc_addr_arg, (void *) value, size);
break;
case R_ARC_GLOB_DAT:
case R_ARC_JUMP_SLOT:
*reloc_addr = value;
break;
case R_ARC_TLS_DTPMOD:
if (sym_map != NULL)
/* Get the information from the link map returned by the
resolv function. */
*reloc_addr = sym_map->l_tls_modid;
break;
case R_ARC_TLS_DTPOFF:
if (sym != NULL)
/* Offset set by the linker in the GOT entry would be overwritten
by dynamic loader instead of added to the symbol location.
Other target have the same approach on DTPOFF relocs. */
*reloc_addr += sym->st_value;
break;
case R_ARC_TLS_TPOFF:
if (sym != NULL)
{
CHECK_STATIC_TLS (map, sym_map);
*reloc_addr = sym_map->l_tls_offset + sym->st_value + reloc->r_addend;
}
break;
case R_ARC_32:
*reloc_addr += value + reloc->r_addend;
break;
case R_ARC_PC32:
*reloc_addr += value + reloc->r_addend - (unsigned long int) reloc_addr;
break;
default:
_dl_reloc_bad_type (map, r_type, 0);
break;
}
}
}
inline void
__attribute__ ((always_inline))
elf_machine_rela_relative (ElfW(Addr) l_addr, const ElfW(Rela) *reloc,
void *const reloc_addr_arg)
{
ElfW(Addr) *const reloc_addr = reloc_addr_arg;
*reloc_addr += l_addr;
}
inline void
__attribute__ ((always_inline))
elf_machine_lazy_rel (struct link_map *map, ElfW(Addr) l_addr,
const ElfW(Rela) *reloc, int skip_ifunc)
{
ElfW(Addr) *const reloc_addr = (void *) (l_addr + reloc->r_offset);
if (ELF32_R_TYPE (reloc->r_info) == R_ARC_JUMP_SLOT)
*reloc_addr += l_addr;
else
_dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 1);
}
#endif /* RESOLVE_MAP */

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sysdeps/arc/entry.h Normal file
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#ifndef __ASSEMBLY__
extern void __start (void) attribute_hidden;
#endif
#define ENTRY_POINT __start

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sysdeps/arc/ldsodefs.h Normal file
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/* Run-time dynamic linker data structures for loaded ELF shared objects.
Copyright (C) 2020 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 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
<https://www.gnu.org/licenses/>. */
#ifndef _ARC_LDSODEFS_H
#define _ARC_LDSODEFS_H 1
#include <elf.h>
struct La_arc_regs;
struct La_arc_retval;
#define ARCH_PLTENTER_MEMBERS \
ElfW(Addr) (*arc_gnu_pltenter) (ElfW(Sym) *, unsigned int, \
uintptr_t *, uintptr_t *, \
const struct La_arc_regs *, \
unsigned int *, const char *, \
long int *);
#define ARCH_PLTEXIT_MEMBERS \
unsigned int (*arc_gnu_pltexit) (ElfW(Sym) *, unsigned int, \
uintptr_t *, uintptr_t *, \
const struct La_arc_regs *, \
struct La_arc_retval *, \
const char *);
#include_next <ldsodefs.h>
#endif

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sysdeps/arc/sotruss-lib.c Normal file
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/* Override generic sotruss-lib.c to define actual functions for ARC.
Copyright (C) 2020 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 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
<https://www.gnu.org/licenses/>. */
#define HAVE_ARCH_PLTENTER
#define HAVE_ARCH_PLTEXIT
#include <elf/sotruss-lib.c>
ElfW(Addr)
la_arc_gnu_pltenter (ElfW(Sym) *sym __attribute__ ((unused)),
unsigned int ndx __attribute__ ((unused)),
uintptr_t *refcook, uintptr_t *defcook,
La_arc_regs *regs, unsigned int *flags,
const char *symname, long int *framesizep)
{
print_enter (refcook, defcook, symname,
regs->lr_reg[0], regs->lr_reg[1], regs->lr_reg[2],
*flags);
/* No need to copy anything, we will not need the parameters in any case. */
*framesizep = 0;
return sym->st_value;
}
unsigned int
la_arc_gnu_pltexit (ElfW(Sym) *sym, unsigned int ndx, uintptr_t *refcook,
uintptr_t *defcook,
const struct La_arc_regs *inregs,
struct La_arc_retval *outregs, const char *symname)
{
print_exit (refcook, defcook, symname, outregs->lrv_reg[0]);
return 0;
}

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sysdeps/arc/start.S Normal file
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/* Startup code for ARC.
Copyright (C) 2020 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 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
<https://www.gnu.org/licenses/>. */
#define __ASSEMBLY__ 1
#include <entry.h>
#include <sysdep.h>
#ifndef ENTRY_POINT
# error ENTRY_POINT needs to be defined for ARC
#endif
/* When we enter this piece of code, the program stack looks like this:
argc argument counter (integer)
argv[0] program name (pointer)
argv[1...N] program args (pointers)
argv[argc-1] end of args (integer)
NULL
env[0...N] environment variables (pointers)
NULL. */
ENTRY (ENTRY_POINT)
/* Needed to make gdb backtraces stop here. */
.cfi_label .Ldummy
cfi_undefined (blink)
mov fp, 0
ld_s r1, [sp] /* argc. */
mov_s r5, r0 /* rltd_fini. */
add_s r2, sp, 4 /* argv. */
and sp, sp, -8
mov r6, sp
/* __libc_start_main (main, argc, argv, init, fini, rtld_fini, stack_end). */
#ifdef SHARED
ld r0, [pcl, @main@gotpc]
ld r3, [pcl, @__libc_csu_init@gotpc]
ld r4, [pcl, @__libc_csu_fini@gotpc]
bl __libc_start_main@plt
#else
mov_s r0, main
mov_s r3, __libc_csu_init
mov r4, __libc_csu_fini
bl __libc_start_main
#endif
/* Should never get here. */
flag 1
END (ENTRY_POINT)
/* Define a symbol for the first piece of initialized data. */
.data
.globl __data_start
__data_start:
.long 0
.weak data_start
data_start = __data_start

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sysdeps/arc/tst-audit.h Normal file
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/* Definitions for testing PLT entry/exit auditing. ARC version.
Copyright (C) 2020 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 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
<https://www.gnu.org/licenses/>. */
#define pltenter la_arc_gnu_pltenter
#define pltexit la_arc_gnu_pltexit
#define La_regs La_arc_regs
#define La_retval La_arc_retval
#define int_retval lrv_reg[0]