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/* Definition for thread-local data handling. nptl/x86_64 version.
Copyright (C) 2002-2022 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 _TLS_H
#define _TLS_H 1
#ifndef __ASSEMBLER__
# include <asm/prctl.h> /* For ARCH_SET_FS. */
# include <stdbool.h>
# include <stddef.h>
# include <stdint.h>
# include <stdlib.h>
# include <sysdep.h>
# include <libc-pointer-arith.h> /* For cast_to_integer. */
# include <kernel-features.h>
# include <dl-dtv.h>
/* Replacement type for __m128 since this file is included by ld.so,
which is compiled with -mno-sse. It must not change the alignment
of rtld_savespace_sse. */
typedef struct
{
int i[4];
} __128bits;
typedef struct
{
void *tcb; /* Pointer to the TCB. Not necessarily the
thread descriptor used by libpthread. */
dtv_t *dtv;
void *self; /* Pointer to the thread descriptor. */
int multiple_threads;
int gscope_flag;
uintptr_t sysinfo;
uintptr_t stack_guard;
uintptr_t pointer_guard;
unsigned long int unused_vgetcpu_cache[2];
/* Bit 0: X86_FEATURE_1_IBT.
Bit 1: X86_FEATURE_1_SHSTK.
*/
unsigned int feature_1;
int __glibc_unused1;
/* Reservation of some values for the TM ABI. */
void *__private_tm[4];
/* GCC split stack support. */
void *__private_ss;
/* The lowest address of shadow stack, */
unsigned long long int ssp_base;
/* Must be kept even if it is no longer used by glibc since programs,
like AddressSanitizer, depend on the size of tcbhead_t. */
__128bits __glibc_unused2[8][4] __attribute__ ((aligned (32)));
void *__padding[8];
} tcbhead_t;
# ifdef __ILP32__
/* morestack.S in libgcc uses offset 0x40 to access __private_ss, */
_Static_assert (offsetof (tcbhead_t, __private_ss) == 0x40,
"offset of __private_ss != 0x40");
/* NB: ssp_base used to be "long int __glibc_reserved2", which was
changed from 32 bits to 64 bits. Make sure that the offset of the
next field, __glibc_unused2, is unchanged. */
_Static_assert (offsetof (tcbhead_t, __glibc_unused2) == 0x60,
"offset of __glibc_unused2 != 0x60");
# else
/* morestack.S in libgcc uses offset 0x70 to access __private_ss, */
_Static_assert (offsetof (tcbhead_t, __private_ss) == 0x70,
"offset of __private_ss != 0x70");
_Static_assert (offsetof (tcbhead_t, __glibc_unused2) == 0x80,
"offset of __glibc_unused2 != 0x80");
# endif
#else /* __ASSEMBLER__ */
# include <tcb-offsets.h>
#endif
/* Alignment requirement for the stack. */
#define STACK_ALIGN 16
#ifndef __ASSEMBLER__
/* Get system call information. */
# include <sysdep.h>
#define LOCK_PREFIX "lock;"
/* This is the size of the initial TCB. Can't be just sizeof (tcbhead_t),
because NPTL getpid, __libc_alloca_cutoff etc. need (almost) the whole
struct pthread even when not linked with -lpthread. */
# define TLS_INIT_TCB_SIZE sizeof (struct pthread)
/* This is the size of the TCB. */
# define TLS_TCB_SIZE sizeof (struct pthread)
/* The TCB can have any size and the memory following the address the
thread pointer points to is unspecified. Allocate the TCB there. */
# define TLS_TCB_AT_TP 1
# define TLS_DTV_AT_TP 0
/* Get the thread descriptor definition. */
# include <nptl/descr.h>
/* Install the dtv pointer. The pointer passed is to the element with
index -1 which contain the length. */
# define INSTALL_DTV(descr, dtvp) \
((tcbhead_t *) (descr))->dtv = (dtvp) + 1
/* Install new dtv for current thread. */
# define INSTALL_NEW_DTV(dtvp) \
({ struct pthread *__pd; \
THREAD_SETMEM (__pd, header.dtv, (dtvp)); })
/* Return dtv of given thread descriptor. */
# define GET_DTV(descr) \
(((tcbhead_t *) (descr))->dtv)
/* Code to initially initialize the thread pointer. This might need
special attention since 'errno' is not yet available and if the
operation can cause a failure 'errno' must not be touched.
We have to make the syscall for both uses of the macro since the
address might be (and probably is) different. */
# define TLS_INIT_TP(thrdescr) \
({ void *_thrdescr = (thrdescr); \
tcbhead_t *_head = _thrdescr; \
int _result; \
\
_head->tcb = _thrdescr; \
/* For now the thread descriptor is at the same address. */ \
_head->self = _thrdescr; \
\
/* It is a simple syscall to set the %fs value for the thread. */ \
asm volatile ("syscall" \
: "=a" (_result) \
: "0" ((unsigned long int) __NR_arch_prctl), \
"D" ((unsigned long int) ARCH_SET_FS), \
"S" (_thrdescr) \
: "memory", "cc", "r11", "cx"); \
\
_result ? "cannot set %fs base address for thread-local storage" : 0; \
})
# define TLS_DEFINE_INIT_TP(tp, pd) void *tp = (pd)
/* Return the address of the dtv for the current thread. */
# define THREAD_DTV() \
({ struct pthread *__pd; \
THREAD_GETMEM (__pd, header.dtv); })
/* Return the thread descriptor for the current thread.
The contained asm must *not* be marked volatile since otherwise
assignments like
pthread_descr self = thread_self();
do not get optimized away. */
# if __GNUC_PREREQ (6, 0)
# define THREAD_SELF \
(*(struct pthread *__seg_fs *) offsetof (struct pthread, header.self))
# else
# define THREAD_SELF \
({ struct pthread *__self; \
asm ("mov %%fs:%c1,%0" : "=r" (__self) \
: "i" (offsetof (struct pthread, header.self))); \
__self;})
# endif
/* Magic for libthread_db to know how to do THREAD_SELF. */
# define DB_THREAD_SELF_INCLUDE <sys/reg.h> /* For the FS constant. */
# define DB_THREAD_SELF CONST_THREAD_AREA (64, FS)
# include <tcb-access.h>
/* Set the stack guard field in TCB head. */
# define THREAD_SET_STACK_GUARD(value) \
THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)
# define THREAD_COPY_STACK_GUARD(descr) \
((descr)->header.stack_guard \
= THREAD_GETMEM (THREAD_SELF, header.stack_guard))
/* Set the pointer guard field in the TCB head. */
# define THREAD_SET_POINTER_GUARD(value) \
THREAD_SETMEM (THREAD_SELF, header.pointer_guard, value)
# define THREAD_COPY_POINTER_GUARD(descr) \
((descr)->header.pointer_guard \
= THREAD_GETMEM (THREAD_SELF, header.pointer_guard))
/* Get and set the global scope generation counter in the TCB head. */
# define THREAD_GSCOPE_FLAG_UNUSED 0
# define THREAD_GSCOPE_FLAG_USED 1
# define THREAD_GSCOPE_FLAG_WAIT 2
# define THREAD_GSCOPE_RESET_FLAG() \
do \
{ int __res; \
asm volatile ("xchgl %0, %%fs:%P1" \
: "=r" (__res) \
: "i" (offsetof (struct pthread, header.gscope_flag)), \
"0" (THREAD_GSCOPE_FLAG_UNUSED)); \
if (__res == THREAD_GSCOPE_FLAG_WAIT) \
lll_futex_wake (&THREAD_SELF->header.gscope_flag, 1, LLL_PRIVATE); \
} \
while (0)
# define THREAD_GSCOPE_SET_FLAG() \
THREAD_SETMEM (THREAD_SELF, header.gscope_flag, THREAD_GSCOPE_FLAG_USED)
#endif /* __ASSEMBLER__ */
#endif /* tls.h */
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