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285 lines
9.4 KiB
C
285 lines
9.4 KiB
C
/* Definition for thread-local data handling. nptl/i386 version.
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Copyright (C) 2002-2024 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _TLS_H
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#define _TLS_H 1
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#include <dl-sysdep.h>
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#ifndef __ASSEMBLER__
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# include <stdbool.h>
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# include <stddef.h>
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# include <stdint.h>
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# include <stdlib.h>
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# include <sysdep.h>
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# include <libc-pointer-arith.h> /* For cast_to_integer. */
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# include <kernel-features.h>
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# include <dl-dtv.h>
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typedef struct
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{
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void *tcb; /* Pointer to the TCB. Not necessarily the
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thread descriptor used by libpthread. */
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dtv_t *dtv;
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void *self; /* Pointer to the thread descriptor. */
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int multiple_threads;
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uintptr_t sysinfo;
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uintptr_t stack_guard;
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uintptr_t pointer_guard;
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int gscope_flag;
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/* Bit 0: X86_FEATURE_1_IBT.
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Bit 1: X86_FEATURE_1_SHSTK.
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*/
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unsigned int feature_1;
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/* Reservation of some values for the TM ABI. */
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void *__private_tm[3];
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/* GCC split stack support. */
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void *__private_ss;
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/* The lowest address of shadow stack, */
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unsigned long ssp_base;
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} tcbhead_t;
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/* morestack.S in libgcc uses offset 0x30 to access __private_ss, */
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_Static_assert (offsetof (tcbhead_t, __private_ss) == 0x30,
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"offset of __private_ss != 0x30");
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# define TLS_MULTIPLE_THREADS_IN_TCB 1
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#else /* __ASSEMBLER__ */
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# include <tcb-offsets.h>
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#endif
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/* Alignment requirement for the stack. For IA-32 this is governed by
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the SSE memory functions. */
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#define STACK_ALIGN 16
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#ifndef __ASSEMBLER__
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/* Get system call information. */
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# include <sysdep.h>
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/* The old way: using LDT. */
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/* Structure passed to `modify_ldt', 'set_thread_area', and 'clone' calls. */
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struct user_desc
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{
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unsigned int entry_number;
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unsigned long int base_addr;
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unsigned int limit;
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unsigned int seg_32bit:1;
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unsigned int contents:2;
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unsigned int read_exec_only:1;
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unsigned int limit_in_pages:1;
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unsigned int seg_not_present:1;
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unsigned int useable:1;
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unsigned int empty:25;
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};
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/* Initializing bit fields is slow. We speed it up by using a union. */
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union user_desc_init
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{
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struct user_desc desc;
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unsigned int vals[4];
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};
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/* This is the size of the initial TCB. Can't be just sizeof (tcbhead_t),
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because NPTL getpid, __libc_alloca_cutoff etc. need (almost) the whole
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struct pthread even when not linked with -lpthread. */
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# define TLS_INIT_TCB_SIZE sizeof (struct pthread)
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/* This is the size of the TCB. */
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# define TLS_TCB_SIZE sizeof (struct pthread)
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/* The TCB can have any size and the memory following the address the
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thread pointer points to is unspecified. Allocate the TCB there. */
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# define TLS_TCB_AT_TP 1
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# define TLS_DTV_AT_TP 0
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/* Get the thread descriptor definition. */
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# include <nptl/descr.h>
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/* Install the dtv pointer. The pointer passed is to the element with
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index -1 which contain the length. */
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# define INSTALL_DTV(descr, dtvp) \
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((tcbhead_t *) (descr))->dtv = (dtvp) + 1
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/* Install new dtv for current thread. */
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# define INSTALL_NEW_DTV(dtvp) \
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({ struct pthread *__pd; \
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THREAD_SETMEM (__pd, header.dtv, (dtvp)); })
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/* Return dtv of given thread descriptor. */
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# define GET_DTV(descr) \
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(((tcbhead_t *) (descr))->dtv)
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/* Macros to load from and store into segment registers. */
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# ifndef TLS_GET_GS
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# define TLS_GET_GS() \
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({ int __seg; __asm ("movw %%gs, %w0" : "=q" (__seg)); __seg & 0xffff; })
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# endif
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# ifndef TLS_SET_GS
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# define TLS_SET_GS(val) \
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__asm ("movw %w0, %%gs" :: "q" (val))
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# endif
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#ifdef NEED_DL_SYSINFO
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# define INIT_SYSINFO \
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_head->sysinfo = GLRO(dl_sysinfo)
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# define SETUP_THREAD_SYSINFO(pd) \
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((pd)->header.sysinfo = THREAD_GETMEM (THREAD_SELF, header.sysinfo))
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# define CHECK_THREAD_SYSINFO(pd) \
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assert ((pd)->header.sysinfo == THREAD_GETMEM (THREAD_SELF, header.sysinfo))
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#else
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# define INIT_SYSINFO
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#endif
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#define LOCK_PREFIX "lock;"
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static inline void __attribute__ ((unused, always_inline))
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tls_fill_user_desc (union user_desc_init *desc,
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unsigned int entry_number,
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void *pd)
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{
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desc->vals[0] = entry_number;
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/* The 'base_addr' field. Pointer to the TCB. */
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desc->vals[1] = (unsigned long int) pd;
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/* The 'limit' field. We use 4GB which is 0xfffff pages. */
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desc->vals[2] = 0xfffff;
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/* Collapsed value of the bitfield:
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.seg_32bit = 1
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.contents = 0
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.read_exec_only = 0
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.limit_in_pages = 1
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.seg_not_present = 0
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.useable = 1 */
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desc->vals[3] = 0x51;
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}
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/* Code to initially initialize the thread pointer. This might need
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special attention since 'errno' is not yet available and if the
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operation can cause a failure 'errno' must not be touched. */
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# define TLS_INIT_TP(thrdescr) \
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({ void *_thrdescr = (thrdescr); \
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tcbhead_t *_head = _thrdescr; \
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union user_desc_init _segdescr; \
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int _result; \
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\
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_head->tcb = _thrdescr; \
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/* For now the thread descriptor is at the same address. */ \
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_head->self = _thrdescr; \
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/* New syscall handling support. */ \
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INIT_SYSINFO; \
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\
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/* Let the kernel pick a value for the 'entry_number' field. */ \
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tls_fill_user_desc (&_segdescr, -1, _thrdescr); \
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\
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/* Install the TLS. */ \
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_result = INTERNAL_SYSCALL_CALL (set_thread_area, &_segdescr.desc); \
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\
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if (_result == 0) \
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/* We know the index in the GDT, now load the segment register. \
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The use of the GDT is described by the value 3 in the lower \
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three bits of the segment descriptor value. \
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\
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Note that we have to do this even if the numeric value of \
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the descriptor does not change. Loading the segment register \
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causes the segment information from the GDT to be loaded \
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which is necessary since we have changed it. */ \
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TLS_SET_GS (_segdescr.desc.entry_number * 8 + 3); \
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\
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_result == 0; })
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# define TLS_DEFINE_INIT_TP(tp, pd) \
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union user_desc_init _segdescr; \
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/* Find the 'entry_number' field that the kernel selected in TLS_INIT_TP. \
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The first three bits of the segment register value select the GDT, \
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ignore them. We get the index from the value of the %gs register in \
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the current thread. */ \
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tls_fill_user_desc (&_segdescr, TLS_GET_GS () >> 3, pd); \
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const struct user_desc *tp = &_segdescr.desc
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/* Return the address of the dtv for the current thread. */
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# define THREAD_DTV() \
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({ struct pthread *__pd; \
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THREAD_GETMEM (__pd, header.dtv); })
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/* Return the thread descriptor for the current thread.
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The contained asm must *not* be marked volatile since otherwise
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assignments like
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pthread_descr self = thread_self();
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do not get optimized away. */
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# if __GNUC_PREREQ (6, 0)
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# define THREAD_SELF \
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(*(struct pthread *__seg_gs *) offsetof (struct pthread, header.self))
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# else
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# define THREAD_SELF \
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({ struct pthread *__self; \
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asm ("movl %%gs:%c1,%0" : "=r" (__self) \
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: "i" (offsetof (struct pthread, header.self))); \
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__self;})
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# endif
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/* Magic for libthread_db to know how to do THREAD_SELF. */
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# define DB_THREAD_SELF \
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REGISTER_THREAD_AREA (32, offsetof (struct user_regs_struct, xgs), 3) \
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REGISTER_THREAD_AREA (64, 26 * 8, 3) /* x86-64's user_regs_struct->gs */
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# include <tcb-access.h>
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/* Set the stack guard field in TCB head. */
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#define THREAD_SET_STACK_GUARD(value) \
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THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)
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#define THREAD_COPY_STACK_GUARD(descr) \
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((descr)->header.stack_guard \
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= THREAD_GETMEM (THREAD_SELF, header.stack_guard))
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/* Set the pointer guard field in the TCB head. */
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#define THREAD_SET_POINTER_GUARD(value) \
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THREAD_SETMEM (THREAD_SELF, header.pointer_guard, value)
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#define THREAD_COPY_POINTER_GUARD(descr) \
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((descr)->header.pointer_guard \
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= THREAD_GETMEM (THREAD_SELF, header.pointer_guard))
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/* Get and set the global scope generation counter in the TCB head. */
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#define THREAD_GSCOPE_FLAG_UNUSED 0
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#define THREAD_GSCOPE_FLAG_USED 1
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#define THREAD_GSCOPE_FLAG_WAIT 2
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#define THREAD_GSCOPE_RESET_FLAG() \
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do \
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{ int __res; \
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asm volatile ("xchgl %0, %%gs:%P1" \
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: "=r" (__res) \
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: "i" (offsetof (struct pthread, header.gscope_flag)), \
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"0" (THREAD_GSCOPE_FLAG_UNUSED)); \
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if (__res == THREAD_GSCOPE_FLAG_WAIT) \
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lll_futex_wake (&THREAD_SELF->header.gscope_flag, 1, LLL_PRIVATE); \
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} \
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while (0)
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#define THREAD_GSCOPE_SET_FLAG() \
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THREAD_SETMEM (THREAD_SELF, header.gscope_flag, THREAD_GSCOPE_FLAG_USED)
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#endif /* __ASSEMBLER__ */
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#endif /* tls.h */
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