/* Definitions for thread-local data handling. Hurd/i386 version. Copyright (C) 2003-2020 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 . */ #ifndef _I386_TLS_H #define _I386_TLS_H /* Some things really need not be machine-dependent. */ #include #ifndef __ASSEMBLER__ # include /* Type of the TCB. */ typedef struct { void *tcb; /* Points to this structure. */ dtv_t *dtv; /* Vector of pointers to TLS data. */ thread_t self; /* This thread's control port. */ int multiple_threads; uintptr_t sysinfo; uintptr_t stack_guard; uintptr_t pointer_guard; int gscope_flag; int private_futex; /* Reservation of some values for the TM ABI. */ void *__private_tm[4]; /* GCC split stack support. */ void *__private_ss; /* Keep this field last, so fields above can continue being compatible with the Linux version. */ mach_port_t reply_port; /* This thread's reply port. */ struct hurd_sigstate *_hurd_sigstate; } tcbhead_t; #endif /* Return tcbhead_t from a TLS segment descriptor. */ # define HURD_DESC_TLS(desc) \ ({ \ (tcbhead_t *) ( (desc->low_word >> 16) \ | ((desc->high_word & 0xff) << 16) \ | (desc->high_word & 0xff000000)); \ }) /* Return 1 if TLS is not initialized yet. */ #define __LIBC_NO_TLS() \ ({ unsigned short ds, gs; \ asm ("movw %%ds,%w0; movw %%gs,%w1" : "=q" (ds), "=q" (gs)); \ __builtin_expect (ds == gs, 0); }) /* 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 /* Alignment requirement for TCB. Some processors such as Intel Atom pay a big penalty on every access using a segment override if that segment's base is not aligned to the size of a cache line. (See Intel 64 and IA-32 Architectures Optimization Reference Manual, section 13.3.3.3, "Segment Base".) On such machines, a cache line is 64 bytes. */ #define TCB_ALIGNMENT 64 #ifndef __ASSEMBLER__ /* Use i386-specific RPCs to arrange that %gs segment register prefix addresses the TCB in each thread. */ # include # ifndef HAVE_I386_SET_GDT # define __i386_set_gdt(thr, sel, desc) ((void) (thr), (void) (sel), (void) (desc), MIG_BAD_ID) # endif # include # include # define HURD_TLS_DESC_DECL(desc, tcb) \ struct descriptor desc = \ { /* low word: */ \ 0xffff /* limit 0..15 */ \ | (((unsigned int) (tcb)) << 16) /* base 0..15 */ \ , /* high word: */ \ ((((unsigned int) (tcb)) >> 16) & 0xff) /* base 16..23 */ \ | ((0x12 | 0x60 | 0x80) << 8) /* access = ACC_DATA_W|ACC_PL_U|ACC_P */ \ | (0xf << 16) /* limit 16..19 */ \ | ((4 | 8) << 20) /* granularity = SZ_32|SZ_G */ \ | (((unsigned int) (tcb)) & 0xff000000) /* base 24..31 */ \ } # define HURD_SEL_LDT(sel) (__builtin_expect ((sel) & 4, 0)) static inline const char * __attribute__ ((unused)) _hurd_tls_init (tcbhead_t *tcb) { HURD_TLS_DESC_DECL (desc, tcb); thread_t self = __mach_thread_self (); const char *msg = NULL; /* This field is used by TLS accesses to get our "thread pointer" from the TLS point of view. */ tcb->tcb = tcb; /* We always at least start the sigthread anyway. */ tcb->multiple_threads = 1; /* Get the first available selector. */ int sel = -1; error_t err = __i386_set_gdt (self, &sel, desc); if (err == MIG_BAD_ID) { /* Old kernel, use a per-thread LDT. */ sel = 0x27; err = __i386_set_ldt (self, sel, &desc, 1); assert_perror (err); if (err) { msg = "i386_set_ldt failed"; goto out; } } else if (err) { assert_perror (err); /* Separate from above with different line #. */ msg = "i386_set_gdt failed"; goto out; } /* Now install the new selector. */ asm volatile ("mov %w0, %%gs" :: "q" (sel)); out: __mach_port_deallocate (__mach_task_self (), self); return msg; } /* 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. */ # define TLS_INIT_TP(descr) \ _hurd_tls_init ((tcbhead_t *) (descr)) /* Return the TCB address of the current thread. */ # define THREAD_SELF \ ({ tcbhead_t *__tcb; \ __asm__ ("movl %%gs:%c1,%0" : "=r" (__tcb) \ : "i" (offsetof (tcbhead_t, tcb))); \ __tcb;}) /* Return the TCB address of a thread given its state. Note: this is expensive. */ # define THREAD_TCB(thread, thread_state) \ ({ int __sel = (thread_state)->basic.gs; \ struct descriptor __desc, *___desc = &__desc; \ unsigned int __count = 1; \ kern_return_t __err; \ if (HURD_SEL_LDT (__sel)) \ __err = __i386_get_ldt ((thread), __sel, 1, &___desc, &__count); \ else \ __err = __i386_get_gdt ((thread), __sel, &__desc); \ assert_perror (__err); \ assert (__count == 1); \ HURD_DESC_TLS (___desc);}) /* Install new dtv for current thread. */ # define INSTALL_NEW_DTV(dtvp) \ ({ asm volatile ("movl %0,%%gs:%P1" \ : : "ir" (dtvp), "i" (offsetof (tcbhead_t, dtv))); }) /* Return the address of the dtv for the current thread. */ # define THREAD_DTV() \ ({ dtv_t *_dtv; \ asm ("movl %%gs:%P1,%0" : "=q" (_dtv) : "i" (offsetof (tcbhead_t, dtv)));\ _dtv; }) # include /* Set up TLS in the new thread of a fork child, copying from the original. */ static inline kern_return_t __attribute__ ((unused)) _hurd_tls_fork (thread_t child, thread_t orig, struct i386_thread_state *state) { /* Fetch the selector set by _hurd_tls_init. */ int sel; asm ("mov %%gs, %w0" : "=q" (sel) : "0" (0)); if (sel == state->ds) /* _hurd_tls_init was never called. */ return 0; struct descriptor desc, *_desc = &desc; error_t err; unsigned int count = 1; if (HURD_SEL_LDT (sel)) err = __i386_get_ldt (orig, sel, 1, &_desc, &count); else err = __i386_get_gdt (orig, sel, &desc); assert_perror (err); if (err) return err; if (HURD_SEL_LDT (sel)) err = __i386_set_ldt (child, sel, &desc, 1); else err = __i386_set_gdt (child, &sel, desc); state->gs = sel; return err; } static inline kern_return_t __attribute__ ((unused)) _hurd_tls_new (thread_t child, struct i386_thread_state *state, tcbhead_t *tcb) { /* Fetch the selector set by _hurd_tls_init. */ int sel; asm ("mov %%gs, %w0" : "=q" (sel) : "0" (0)); if (sel == state->ds) /* _hurd_tls_init was never called. */ return 0; HURD_TLS_DESC_DECL (desc, tcb); error_t err; tcb->tcb = tcb; tcb->self = child; if (HURD_SEL_LDT (sel)) err = __i386_set_ldt (child, sel, &desc, 1); else err = __i386_set_gdt (child, &sel, desc); state->gs = sel; return err; } #endif /* !__ASSEMBLER__ */ #endif /* i386/tls.h */