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glibc/sysdeps/x86_64/dl-machine.h
H.J. Lu 107e6a3c22 x86: Support usable check for all CPU features 
Support usable check for all CPU features with the following changes:

1. Change struct cpu_features to

struct cpuid_features
{
  struct cpuid_registers cpuid;
  struct cpuid_registers usable;
};

struct cpu_features
{
  struct cpu_features_basic basic;
  struct cpuid_features features[COMMON_CPUID_INDEX_MAX];
  unsigned int preferred[PREFERRED_FEATURE_INDEX_MAX];
...
};

so that there is a usable bit for each cpuid bit.
2. After the cpuid bits have been initialized, copy the known bits to the
usable bits.  EAX/EBX from INDEX_1 and EAX from INDEX_7 aren't used for
CPU feature detection.
3. Clear the usable bits which require OS support.
4. If the feature is supported by OS, copy its cpuid bit to its usable
bit.
5. Replace HAS_CPU_FEATURE and CPU_FEATURES_CPU_P with CPU_FEATURE_USABLE
and CPU_FEATURE_USABLE_P to check if a feature is usable.
6. Add DEPR_FPU_CS_DS for INDEX_7_EBX_13.
7. Unset MPX feature since it has been deprecated.

The results are

1. If the feature is known and doesn't requre OS support, its usable bit
is copied from the cpuid bit.
2. Otherwise, its usable bit is copied from the cpuid bit only if the
feature is known to supported by OS.
3. CPU_FEATURE_USABLE/CPU_FEATURE_USABLE_P are used to check if the
feature can be used.
4. HAS_CPU_FEATURE/CPU_FEATURE_CPU_P are used to check if CPU supports
the feature.
2020-07-13 06:05:16 -07:00

587 lines
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/* Machine-dependent ELF dynamic relocation inline functions. x86-64 version.
Copyright (C) 2001-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Andreas Jaeger <aj@suse.de>.
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 "x86_64"
#include <sys/param.h>
#include <sysdep.h>
#include <tls.h>
#include <dl-tlsdesc.h>
#include <cpu-features.c>
/* Return nonzero iff ELF header is compatible with the running host. */
static inline int __attribute__ ((unused))
elf_machine_matches_host (const ElfW(Ehdr) *ehdr)
{
return ehdr->e_machine == EM_X86_64;
}
/* Return the link-time address of _DYNAMIC. Conveniently, this is the
first element of the GOT. This must be inlined in a function which
uses global data. */
static inline ElfW(Addr) __attribute__ ((unused))
elf_machine_dynamic (void)
{
/* This produces an IP-relative reloc which is resolved at link time. */
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) __attribute__ ((unused))
elf_machine_load_address (void)
{
/* Compute the difference between the runtime address of _DYNAMIC as seen
by an IP-relative reference, and the link-time address found in the
special unrelocated first GOT entry. */
extern ElfW(Dyn) _DYNAMIC[] attribute_hidden;
return (ElfW(Addr)) &_DYNAMIC - elf_machine_dynamic ();
}
/* 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__ ((unused, always_inline))
elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
{
Elf64_Addr *got;
extern void _dl_runtime_resolve_fxsave (ElfW(Word)) attribute_hidden;
extern void _dl_runtime_resolve_xsave (ElfW(Word)) attribute_hidden;
extern void _dl_runtime_resolve_xsavec (ElfW(Word)) attribute_hidden;
extern void _dl_runtime_profile_sse (ElfW(Word)) attribute_hidden;
extern void _dl_runtime_profile_avx (ElfW(Word)) attribute_hidden;
extern void _dl_runtime_profile_avx512 (ElfW(Word)) attribute_hidden;
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 .rel.plt section, push _GLOBAL_OFFSET_TABLE_[1],
and then jump to _GLOBAL_OFFSET_TABLE_[2]. */
got = (Elf64_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
/* If a library is prelinked but we have to relocate anyway,
we have to be able to undo the prelinking of .got.plt.
The prelinker saved us here address of .plt + 0x16. */
if (got[1])
{
l->l_mach.plt = got[1] + l->l_addr;
l->l_mach.gotplt = (ElfW(Addr)) &got[3];
}
/* Identify this shared object. */
*(ElfW(Addr) *) (got + 1) = (ElfW(Addr)) l;
/* 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. */
if (__glibc_unlikely (profile))
{
if (CPU_FEATURE_USABLE (AVX512F))
*(ElfW(Addr) *) (got + 2) = (ElfW(Addr)) &_dl_runtime_profile_avx512;
else if (CPU_FEATURE_USABLE (AVX))
*(ElfW(Addr) *) (got + 2) = (ElfW(Addr)) &_dl_runtime_profile_avx;
else
*(ElfW(Addr) *) (got + 2) = (ElfW(Addr)) &_dl_runtime_profile_sse;
if (GLRO(dl_profile) != NULL
&& _dl_name_match_p (GLRO(dl_profile), l))
/* This is the object we are looking for. Say that we really
want profiling and the timers are started. */
GL(dl_profile_map) = l;
}
else
{
/* 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. */
if (GLRO(dl_x86_cpu_features).xsave_state_size != 0)
*(ElfW(Addr) *) (got + 2)
= (CPU_FEATURE_USABLE (XSAVEC)
? (ElfW(Addr)) &_dl_runtime_resolve_xsavec
: (ElfW(Addr)) &_dl_runtime_resolve_xsave);
else
*(ElfW(Addr) *) (got + 2)
= (ElfW(Addr)) &_dl_runtime_resolve_fxsave;
}
}
if (l->l_info[ADDRIDX (DT_TLSDESC_GOT)] && lazy)
*(ElfW(Addr)*)(D_PTR (l, l_info[ADDRIDX (DT_TLSDESC_GOT)]) + l->l_addr)
= (ElfW(Addr)) &_dl_tlsdesc_resolve_rela;
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 ("\n\
.text\n\
.align 16\n\
.globl _start\n\
.globl _dl_start_user\n\
_start:\n\
movq %rsp, %rdi\n\
call _dl_start\n\
_dl_start_user:\n\
# Save the user entry point address in %r12.\n\
movq %rax, %r12\n\
# See if we were run as a command with the executable file\n\
# name as an extra leading argument.\n\
movl _dl_skip_args(%rip), %eax\n\
# Pop the original argument count.\n\
popq %rdx\n\
# Adjust the stack pointer to skip _dl_skip_args words.\n\
leaq (%rsp,%rax,8), %rsp\n\
# Subtract _dl_skip_args from argc.\n\
subl %eax, %edx\n\
# Push argc back on the stack.\n\
pushq %rdx\n\
# Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
# argc -> rsi\n\
movq %rdx, %rsi\n\
# Save %rsp value in %r13.\n\
movq %rsp, %r13\n\
# And align stack for the _dl_init call. \n\
andq $-16, %rsp\n\
# _dl_loaded -> rdi\n\
movq _rtld_local(%rip), %rdi\n\
# env -> rcx\n\
leaq 16(%r13,%rdx,8), %rcx\n\
# argv -> rdx\n\
leaq 8(%r13), %rdx\n\
# Clear %rbp to mark outermost frame obviously even for constructors.\n\
xorl %ebp, %ebp\n\
# Call the function to run the initializers.\n\
call _dl_init\n\
# Pass our finalizer function to the user in %rdx, as per ELF ABI.\n\
leaq _dl_fini(%rip), %rdx\n\
# And make sure %rsp points to argc stored on the stack.\n\
movq %r13, %rsp\n\
# Jump to the user's entry point.\n\
jmp *%r12\n\
.previous\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_COPY iff TYPE should not be allowed to resolve to one
of the main executable's symbols, as for a COPY reloc.
ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA iff TYPE describes relocation may
against protected data whose address be external due to copy relocation.
*/
#define elf_machine_type_class(type) \
((((type) == R_X86_64_JUMP_SLOT \
|| (type) == R_X86_64_DTPMOD64 \
|| (type) == R_X86_64_DTPOFF64 \
|| (type) == R_X86_64_TPOFF64 \
|| (type) == R_X86_64_TLSDESC) \
* ELF_RTYPE_CLASS_PLT) \
| (((type) == R_X86_64_COPY) * ELF_RTYPE_CLASS_COPY) \
| (((type) == R_X86_64_GLOB_DAT) * ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA))
/* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
#define ELF_MACHINE_JMP_SLOT R_X86_64_JUMP_SLOT
/* The relative ifunc relocation. */
// XXX This is a work-around for a broken linker. Remove!
#define ELF_MACHINE_IRELATIVE R_X86_64_IRELATIVE
/* The x86-64 never uses Elf64_Rel/Elf32_Rel relocations. */
#define ELF_MACHINE_NO_REL 1
#define ELF_MACHINE_NO_RELA 0
/* We define an initialization function. 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 IS_IN (rtld)
/* init_cpu_features has been called early from __libc_start_main in
static executable. */
init_cpu_features (&GLRO(dl_x86_cpu_features));
#else
if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0')
/* Avoid an empty string which would disturb us. */
GLRO(dl_platform) = NULL;
#endif
}
static inline ElfW(Addr)
elf_machine_fixup_plt (struct link_map *map, lookup_t t,
const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
const ElfW(Rela) *reloc,
ElfW(Addr) *reloc_addr, ElfW(Addr) value)
{
return *reloc_addr = value;
}
/* Return the final value of a PLT relocation. On x86-64 the
JUMP_SLOT relocation ignores the addend. */
static inline ElfW(Addr)
elf_machine_plt_value (struct link_map *map, const ElfW(Rela) *reloc,
ElfW(Addr) value)
{
return value;
}
/* Names of the architecture-specific auditing callback functions. */
#define ARCH_LA_PLTENTER x86_64_gnu_pltenter
#define ARCH_LA_PLTEXIT x86_64_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 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 long int r_type = ELFW(R_TYPE) (reloc->r_info);
# if !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC
if (__glibc_unlikely (r_type == R_X86_64_RELATIVE))
{
# if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC
/* 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. */
# ifndef SHARED
weak_extern (GL(dl_rtld_map));
# endif
if (map != &GL(dl_rtld_map)) /* Already done in rtld itself. */
# endif
*reloc_addr = map->l_addr + reloc->r_addend;
}
else
# endif
# if !defined RTLD_BOOTSTRAP
/* l_addr + r_addend may be > 0xffffffff and R_X86_64_RELATIVE64
relocation updates the whole 64-bit entry. */
if (__glibc_unlikely (r_type == R_X86_64_RELATIVE64))
*(Elf64_Addr *) reloc_addr = (Elf64_Addr) map->l_addr + reloc->r_addend;
else
# endif
if (__glibc_unlikely (r_type == R_X86_64_NONE))
return;
else
{
# ifndef RTLD_BOOTSTRAP
const ElfW(Sym) *const refsym = sym;
# endif
struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
ElfW(Addr) value = SYMBOL_ADDRESS (sym_map, sym, true);
if (sym != NULL
&& __glibc_unlikely (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC)
&& __glibc_likely (sym->st_shndx != SHN_UNDEF)
&& __glibc_likely (!skip_ifunc))
{
# ifndef RTLD_BOOTSTRAP
if (sym_map != map
&& sym_map->l_type != lt_executable
&& !sym_map->l_relocated)
{
const char *strtab
= (const char *) D_PTR (map, l_info[DT_STRTAB]);
_dl_error_printf ("\
%s: Relink `%s' with `%s' for IFUNC symbol `%s'\n",
RTLD_PROGNAME, map->l_name,
sym_map->l_name,
strtab + refsym->st_name);
}
# endif
value = ((ElfW(Addr) (*) (void)) value) ();
}
switch (r_type)
{
# ifndef RTLD_BOOTSTRAP
# ifdef __ILP32__
case R_X86_64_SIZE64:
/* Set to symbol size plus addend. */
*(Elf64_Addr *) (uintptr_t) reloc_addr
= (Elf64_Addr) sym->st_size + reloc->r_addend;
break;
case R_X86_64_SIZE32:
# else
case R_X86_64_SIZE64:
# endif
/* Set to symbol size plus addend. */
value = sym->st_size;
# endif
/* Fall through. */
case R_X86_64_GLOB_DAT:
case R_X86_64_JUMP_SLOT:
*reloc_addr = value + reloc->r_addend;
break;
# ifndef RESOLVE_CONFLICT_FIND_MAP
case R_X86_64_DTPMOD64:
# ifdef RTLD_BOOTSTRAP
/* During startup the dynamic linker is always the module
with index 1.
XXX If this relocation is necessary move before RESOLVE
call. */
*reloc_addr = 1;
# else
/* Get the information from the link map returned by the
resolve function. */
if (sym_map != NULL)
*reloc_addr = sym_map->l_tls_modid;
# endif
break;
case R_X86_64_DTPOFF64:
# ifndef RTLD_BOOTSTRAP
/* During relocation all TLS symbols are defined and used.
Therefore the offset is already correct. */
if (sym != NULL)
{
value = sym->st_value + reloc->r_addend;
# ifdef __ILP32__
/* This relocation type computes a signed offset that is
usually negative. The symbol and addend values are 32
bits but the GOT entry is 64 bits wide and the whole
64-bit entry is used as a signed quantity, so we need
to sign-extend the computed value to 64 bits. */
*(Elf64_Sxword *) reloc_addr = (Elf64_Sxword) (Elf32_Sword) value;
# else
*reloc_addr = value;
# endif
}
# endif
break;
case R_X86_64_TLSDESC:
{
struct tlsdesc volatile *td =
(struct tlsdesc volatile *)reloc_addr;
# ifndef RTLD_BOOTSTRAP
if (! sym)
{
td->arg = (void*)reloc->r_addend;
td->entry = _dl_tlsdesc_undefweak;
}
else
# endif
{
# ifndef RTLD_BOOTSTRAP
# ifndef SHARED
CHECK_STATIC_TLS (map, sym_map);
# else
if (!TRY_STATIC_TLS (map, sym_map))
{
td->arg = _dl_make_tlsdesc_dynamic
(sym_map, sym->st_value + reloc->r_addend);
td->entry = _dl_tlsdesc_dynamic;
}
else
# endif
# endif
{
td->arg = (void*)(sym->st_value - sym_map->l_tls_offset
+ reloc->r_addend);
td->entry = _dl_tlsdesc_return;
}
}
break;
}
case R_X86_64_TPOFF64:
/* The offset is negative, forward from the thread pointer. */
# ifndef RTLD_BOOTSTRAP
if (sym != NULL)
# endif
{
# ifndef RTLD_BOOTSTRAP
CHECK_STATIC_TLS (map, sym_map);
# endif
/* We know the offset of the object the symbol is contained in.
It is a negative value which will be added to the
thread pointer. */
value = (sym->st_value + reloc->r_addend
- sym_map->l_tls_offset);
# ifdef __ILP32__
/* The symbol and addend values are 32 bits but the GOT
entry is 64 bits wide and the whole 64-bit entry is used
as a signed quantity, so we need to sign-extend the
computed value to 64 bits. */
*(Elf64_Sxword *) reloc_addr = (Elf64_Sxword) (Elf32_Sword) value;
# else
*reloc_addr = value;
# endif
}
break;
# endif
# ifndef RTLD_BOOTSTRAP
case R_X86_64_64:
/* value + r_addend may be > 0xffffffff and R_X86_64_64
relocation updates the whole 64-bit entry. */
*(Elf64_Addr *) reloc_addr = (Elf64_Addr) value + reloc->r_addend;
break;
# ifndef __ILP32__
case R_X86_64_SIZE32:
/* Set to symbol size plus addend. */
value = sym->st_size;
# endif
/* Fall through. */
case R_X86_64_32:
value += reloc->r_addend;
*(unsigned int *) reloc_addr = value;
const char *fmt;
if (__glibc_unlikely (value > UINT_MAX))
{
const char *strtab;
fmt = "\
%s: Symbol `%s' causes overflow in R_X86_64_32 relocation\n";
# ifndef RESOLVE_CONFLICT_FIND_MAP
print_err:
# endif
strtab = (const char *) D_PTR (map, l_info[DT_STRTAB]);
_dl_error_printf (fmt, RTLD_PROGNAME, strtab + refsym->st_name);
}
break;
# ifndef RESOLVE_CONFLICT_FIND_MAP
/* Not needed for dl-conflict.c. */
case R_X86_64_PC32:
value += reloc->r_addend - (ElfW(Addr)) reloc_addr;
*(unsigned int *) reloc_addr = value;
if (__glibc_unlikely (value != (int) value))
{
fmt = "\
%s: Symbol `%s' causes overflow in R_X86_64_PC32 relocation\n";
goto print_err;
}
break;
case R_X86_64_COPY:
if (sym == NULL)
/* This can happen in trace mode if an object could not be
found. */
break;
memcpy (reloc_addr_arg, (void *) value,
MIN (sym->st_size, refsym->st_size));
if (__glibc_unlikely (sym->st_size > refsym->st_size)
|| (__glibc_unlikely (sym->st_size < refsym->st_size)
&& GLRO(dl_verbose)))
{
fmt = "\
%s: Symbol `%s' has different size in shared object, consider re-linking\n";
goto print_err;
}
break;
# endif
case R_X86_64_IRELATIVE:
value = map->l_addr + reloc->r_addend;
if (__glibc_likely (!skip_ifunc))
value = ((ElfW(Addr) (*) (void)) value) ();
*reloc_addr = value;
break;
default:
_dl_reloc_bad_type (map, r_type, 0);
break;
# endif
}
}
}
auto 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;
#if !defined RTLD_BOOTSTRAP
/* l_addr + r_addend may be > 0xffffffff and R_X86_64_RELATIVE64
relocation updates the whole 64-bit entry. */
if (__glibc_unlikely (ELFW(R_TYPE) (reloc->r_info) == R_X86_64_RELATIVE64))
*(Elf64_Addr *) reloc_addr = (Elf64_Addr) l_addr + reloc->r_addend;
else
#endif
{
assert (ELFW(R_TYPE) (reloc->r_info) == R_X86_64_RELATIVE);
*reloc_addr = l_addr + reloc->r_addend;
}
}
auto 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);
const unsigned long int r_type = ELFW(R_TYPE) (reloc->r_info);
/* Check for unexpected PLT reloc type. */
if (__glibc_likely (r_type == R_X86_64_JUMP_SLOT))
{
/* Prelink has been deprecated. */
if (__glibc_likely (map->l_mach.plt == 0))
*reloc_addr += l_addr;
else
*reloc_addr =
map->l_mach.plt
+ (((ElfW(Addr)) reloc_addr) - map->l_mach.gotplt) * 2;
}
else if (__glibc_likely (r_type == R_X86_64_TLSDESC))
{
struct tlsdesc volatile * __attribute__((__unused__)) td =
(struct tlsdesc volatile *)reloc_addr;
td->arg = (void*)reloc;
td->entry = (void*)(D_PTR (map, l_info[ADDRIDX (DT_TLSDESC_PLT)])
+ map->l_addr);
}
else if (__glibc_unlikely (r_type == R_X86_64_IRELATIVE))
{
ElfW(Addr) value = map->l_addr + reloc->r_addend;
if (__glibc_likely (!skip_ifunc))
value = ((ElfW(Addr) (*) (void)) value) ();
*reloc_addr = value;
}
else
_dl_reloc_bad_type (map, r_type, 1);
}
#endif /* RESOLVE_MAP */
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