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glibc/sysdeps/csky/dl-machine.h
Fangrui Song 490e6c62aa elf: Avoid nested functions in the loader [BZ #27220] 
dynamic-link.h is included more than once in some elf/ files (rtld.c,
dl-conflict.c, dl-reloc.c, dl-reloc-static-pie.c) and uses GCC nested
functions. This harms readability and the nested functions usage
is the biggest obstacle prevents Clang build (Clang doesn't support GCC
nested functions).

The key idea for unnesting is to add extra parameters (struct link_map
*and struct r_scope_elm *[]) to RESOLVE_MAP,
ELF_MACHINE_BEFORE_RTLD_RELOC, ELF_DYNAMIC_RELOCATE, elf_machine_rel[a],
elf_machine_lazy_rel, and elf_machine_runtime_setup. (This is inspired
by Stan Shebs' ppc64/x86-64 implementation in the
google/grte/v5-2.27/master which uses mixed extra parameters and static
variables.)

Future simplification:
* If mips elf_machine_runtime_setup no longer needs RESOLVE_GOTSYM,
  elf_machine_runtime_setup can drop the `scope` parameter.
* If TLSDESC no longer need to be in elf_machine_lazy_rel,
  elf_machine_lazy_rel can drop the `scope` parameter.

Tested on aarch64, i386, x86-64, powerpc64le, powerpc64, powerpc32,
sparc64, sparcv9, s390x, s390, hppa, ia64, armhf, alpha, and mips64.
In addition, tested build-many-glibcs.py with {arc,csky,microblaze,nios2}-linux-gnu
and riscv64-linux-gnu-rv64imafdc-lp64d.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2021-10-07 11:55:02 -07:00

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/* Machine-dependent ELF dynamic relocation inline functions. C-SKY version.
Copyright (C) 2018-2021 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 "csky"
#include <sys/param.h>
#include <sysdep.h>
#include <dl-tls.h>
/* Return nonzero if ELF header is compatible with the running host. */
static inline int
elf_machine_matches_host (const Elf32_Ehdr *ehdr)
{
return ehdr->e_machine == EM_CSKY;
}
/* Return the link-time address of _DYNAMIC.
This must be inlined in a function which uses global data. */
static inline Elf32_Addr
elf_machine_dynamic (void)
{
register Elf32_Addr *got __asm__ ("gb");
return *got;
}
/* Return the run-time load address ,of the shared object. */
static inline Elf32_Addr
elf_machine_load_address (void)
{
extern Elf32_Addr __dl_start (void *) asm ("_dl_start");
Elf32_Addr got_addr = (Elf32_Addr) &__dl_start;
Elf32_Addr pcrel_addr;
asm ("grs %0,_dl_start\n" : "=r" (pcrel_addr));
return pcrel_addr - got_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, struct r_scope_elem *scope[],
int lazy, int profile)
{
Elf32_Addr *got;
extern void _dl_runtime_resolve (Elf32_Word);
if (l->l_info[DT_JMPREL] && lazy)
{
/* The GOT entries for functions in the PLT have not yet been
filled in. Their initial contents will arrange when called
to push an offset into the .rela.plt section, push
_GLOBAL_OFFSET_TABLE_[1], and then jump to
_GLOBAL_OFFSET_TABLE_[2]. */
got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
if (got[1])
l->l_mach.plt = got[1] + l->l_addr;
got[1] = (Elf32_Addr) l; /* Identify this shared object. */
/* The got[2] entry contains the address of a function which gets
called to get the address of a so far unresolved function and
jump to it. The profiling extension of the dynamic linker allows
to intercept the calls to collect information. In this case we
don't store the address in the GOT so that all future calls also
end in this function. */
got[2] = (Elf32_Addr) &_dl_runtime_resolve;
}
return lazy;
}
/* Mask identifying addresses reserved for the user program,
where the dynamic linker should not map anything. */
#define ELF_MACHINE_USER_ADDRESS_MASK 0x80000000UL
/* 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 ("\
.text\n\
.globl _start\n\
.type _start, @function\n\
.globl _dl_start_user\n\
.type _dl_start_user, @function\n\
_start:\n\
grs gb, .Lgetpc1\n\
.Lgetpc1:\n\
lrw t0, .Lgetpc1@GOTPC\n\
addu gb, t0\n\
mov a0, sp\n\
lrw t1, _dl_start@GOTOFF\n\
addu t1, gb\n\
jsr t1\n\
_dl_start_user:\n\
/* get _dl_skip_args */ \n\
lrw r11, _dl_skip_args@GOTOFF\n\
addu r11, gb\n\
ldw r11, (r11, 0)\n\
/* store program entry address in r11 */ \n\
mov r10, a0\n\
/* Get argc */\n\
ldw a1, (sp, 0)\n\
/* Get **argv */\n\
mov a2, sp\n\
addi a2, 4\n\
cmpnei r11, 0\n\
bt .L_fixup_stack\n\
.L_done_fixup:\n\
mov a3, a1\n\
lsli a3, 2\n\
add a3, a2\n\
addi a3, 4\n\
lrw a0, _rtld_local@GOTOFF\n\
addu a0, gb\n\
ldw a0, (a0, 0)\n\
lrw t1, _dl_init@PLT\n\
addu t1, gb\n\
ldw t1, (t1)\n\
jsr t1\n\
lrw a0, _dl_fini@GOTOFF\n\
addu a0, gb\n\
jmp r10\n\
.L_fixup_stack:\n\
subu a1, r11\n\
lsli r11, 2\n\
addu sp, r11\n\
stw a1, (sp, 0)\n\
mov a2, sp\n\
addi a2, 4\n\
lrw a3, _dl_argv@GOTOFF\n\
addu a3, gb\n\
stw a2, (a3, 0)\n\
br .L_done_fixup\n\
");
/* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
TLS variable, 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. */
#ifndef RTLD_BOOTSTRAP
# define elf_machine_type_class(type) \
((((type) == R_CKCORE_JUMP_SLOT || (type) == R_CKCORE_TLS_DTPMOD32 \
|| (type) == R_CKCORE_TLS_DTPOFF32 || (type) == R_CKCORE_TLS_TPOFF32) \
* ELF_RTYPE_CLASS_PLT) \
| (((type) == R_CKCORE_COPY) * ELF_RTYPE_CLASS_COPY))
#else
# define elf_machine_type_class(type) \
((((type) == R_CKCORE_JUMP_SLOT \
| (((type) == R_CKCORE_COPY) * ELF_RTYPE_CLASS_COPY))
#endif
/* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
#define ELF_MACHINE_JMP_SLOT R_CKCORE_JUMP_SLOT
/* C-SKY never uses Elf32_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;
}
static inline Elf32_Addr
elf_machine_fixup_plt (struct link_map *map, lookup_t t,
const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
const Elf32_Rela *reloc,
Elf32_Addr *reloc_addr, Elf32_Addr value)
{
return *reloc_addr = value;
}
/* Return the final value of a plt relocation. On the csky the JMP_SLOT
relocation ignores the addend. */
static inline Elf32_Addr
elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
Elf32_Addr value)
{
return value;
}
/* Names of the architecture-specific auditing callback functions. */
#define ARCH_LA_PLTENTER csky_gnu_pltenter
#define ARCH_LA_PLTEXIT csky_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. */
static inline void __attribute__ ((unused, always_inline))
elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
const Elf32_Rela *reloc, const Elf32_Sym *sym,
const struct r_found_version *version,
void *const reloc_addr_arg, int skip_ifunc)
{
Elf32_Addr *const reloc_addr = reloc_addr_arg;
const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
unsigned short __attribute__ ((unused)) *opcode16_addr;
Elf32_Addr __attribute__ ((unused)) insn_opcode = 0x0;
if (__builtin_expect (r_type == R_CKCORE_RELATIVE, 0))
*reloc_addr = map->l_addr + reloc->r_addend;
else
{
const Elf32_Sym *const refsym = sym;
struct link_map *sym_map = RESOLVE_MAP (map, scope, &sym, version,
r_type);
ElfW(Addr) value = SYMBOL_ADDRESS (sym_map, sym, true);
opcode16_addr = (unsigned short *)reloc_addr;
switch (r_type)
{
case R_CKCORE_COPY:
if (sym == NULL)
/* This can happen in trace mode if an object could not be
found. */
break;
if (sym->st_size > refsym->st_size
|| (sym->st_size < refsym->st_size && GLRO(dl_verbose)))
{
const char *strtab;
strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
_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,
MIN (sym->st_size, refsym->st_size));
break;
case R_CKCORE_GLOB_DAT:
case R_CKCORE_JUMP_SLOT:
*reloc_addr = value;
break;
case R_CKCORE_ADDR32:
*reloc_addr = value + reloc->r_addend;
break;
case R_CKCORE_PCREL32:
*reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
break;
#if defined(__CK810__) || defined(__CK807__)
case R_CKCORE_ADDR_HI16:
insn_opcode = (*opcode16_addr << 16) | (*(opcode16_addr + 1));
insn_opcode = (insn_opcode & 0xffff0000)
| (((value + reloc->r_addend) >> 16) & 0xffff);
*(opcode16_addr++) = (unsigned short)(insn_opcode >> 16);
*opcode16_addr = (unsigned short)(insn_opcode & 0xffff);
break;
case R_CKCORE_ADDR_LO16:
insn_opcode = (*opcode16_addr << 16) | (*(opcode16_addr + 1));
insn_opcode = (insn_opcode & 0xffff0000)
| ((value + reloc->r_addend) & 0xffff);
*(opcode16_addr++) = (unsigned short)(insn_opcode >> 16);
*opcode16_addr = (unsigned short)(insn_opcode & 0xffff);
break;
case R_CKCORE_PCREL_IMM26BY2:
{
unsigned int offset = ((value + reloc->r_addend
- (unsigned int)reloc_addr) >> 1);
insn_opcode = (*opcode16_addr << 16) | (*(opcode16_addr + 1));
if (offset > 0x3ffffff){
const char *strtab;
strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
_dl_error_printf ("\
%s:The reloc R_CKCORE_PCREL_IMM26BY2 cannot reach the symbol '%s'.\n",
rtld_progname ?: "<program name unknown>",
strtab + refsym->st_name);
break;
}
insn_opcode = (insn_opcode & ~0x3ffffff) | offset;
*(opcode16_addr++) = (unsigned short)(insn_opcode >> 16);
*opcode16_addr = (unsigned short)(insn_opcode & 0xffff);
break;
}
case R_CKCORE_PCREL_JSR_IMM26BY2:
break;
#endif
#ifndef RTLD_BOOTSTRAP
case R_CKCORE_TLS_DTPMOD32:
/* Get the information from the link map returned by the
resolv function. */
if (sym_map != NULL)
*reloc_addr = sym_map->l_tls_modid;
break;
case R_CKCORE_TLS_DTPOFF32:
if (sym != NULL)
*reloc_addr =(sym == NULL ? 0 : sym->st_value) + reloc->r_addend;
break;
case R_CKCORE_TLS_TPOFF32:
if (sym != NULL)
{
CHECK_STATIC_TLS (map, sym_map);
*reloc_addr = (sym->st_value + sym_map->l_tls_offset
+ reloc->r_addend);
}
break;
#endif /* !RTLD_BOOTSTRAP */
case R_CKCORE_NONE:
break;
default:
break;
}
}
}
static inline void __attribute__ ((unused, always_inline))
elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
void *const reloc_addr_arg)
{
Elf32_Addr *const reloc_addr = reloc_addr_arg;
*reloc_addr = l_addr + reloc->r_addend;
}
static inline void __attribute__ ((unused, always_inline))
elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
Elf32_Addr l_addr, const Elf32_Rela *reloc,
int skip_ifunc)
{
Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
if (ELF32_R_TYPE (reloc->r_info) == R_CKCORE_JUMP_SLOT)
{
/* Check for unexpected PLT reloc type. */
if (__builtin_expect (r_type == R_CKCORE_JUMP_SLOT, 1))
{
if (__builtin_expect (map->l_mach.plt, 0) == 0)
*reloc_addr = l_addr + reloc->r_addend;
else
*reloc_addr = map->l_mach.plt;
}
}
}
#endif /* RESOLVE_MAP */
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