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627f5ede70
TLS_INIT_TCB_ALIGN is not actually used. TLS_TCB_ALIGN was likely
introduced to support a configuration where the thread pointer
has not the same alignment as THREAD_SELF. Only ia64 seems to use
that, but for the stack/pointer guard, not for storing tcbhead_t.
Some ports use TLS_TCB_OFFSET and TLS_PRE_TCB_SIZE to shift
the thread pointer, potentially landing in a different residue class
modulo the alignment, but the changes should not impact that.
In general, given that TLS variables have their own alignment
requirements, having different alignment for the (unshifted) thread
pointer and struct pthread would potentially result in dynamic
offsets, leading to more complexity.
hppa had different values before: __alignof__ (tcbhead_t), which
seems to be 4, and __alignof__ (struct pthread), which was 8
(old default) and is now 32. However, it defines THREAD_SELF as:
/* Return the thread descriptor for the current thread. */
# define THREAD_SELF \
({ struct pthread *__self; \
__self = __get_cr27(); \
__self - 1; \
})
So the thread pointer points after struct pthread (hence __self - 1),
and they have to have the same alignment on hppa as well.
Similarly, on ia64, the definitions were different. We have:
# define TLS_PRE_TCB_SIZE \
(sizeof (struct pthread) \
+ (PTHREAD_STRUCT_END_PADDING < 2 * sizeof (uintptr_t) \
? ((2 * sizeof (uintptr_t) + __alignof__ (struct pthread) - 1) \
& ~(__alignof__ (struct pthread) - 1)) \
: 0))
# define THREAD_SELF \
((struct pthread *) ((char *) __thread_self - TLS_PRE_TCB_SIZE))
And TLS_PRE_TCB_SIZE is a multiple of the struct pthread alignment
(confirmed by the new _Static_assert in sysdeps/ia64/libc-tls.c).
On m68k, we have a larger gap between tcbhead_t and struct pthread.
But as far as I can tell, the port is fine with that. The definition
of TCB_OFFSET is sufficient to handle the shifted TCB scenario.
This fixes commit 23c77f60181eb549f11ec2f913b4270af29eee38
("nptl: Increase default TCB alignment to 32").
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
145 lines
4.6 KiB
C
145 lines
4.6 KiB
C
/* Definition for thread-local data handling. NPTL/m68k version.
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Copyright (C) 2010-2021 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 <dl-dtv.h>
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#else /* __ASSEMBLER__ */
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# include <tcb-offsets.h>
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#endif /* __ASSEMBLER__ */
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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 TP points to the start of the thread blocks. */
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# define TLS_DTV_AT_TP 1
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# define TLS_TCB_AT_TP 0
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/* Get the thread descriptor definition. */
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# include <nptl/descr.h>
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typedef struct
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{
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dtv_t *dtv;
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void *private;
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} tcbhead_t;
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/* This is the size of the initial TCB. Because our TCB is before the thread
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pointer, we don't need this. */
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# define TLS_INIT_TCB_SIZE 0
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/* This is the size of the TCB. Because our TCB is before the thread
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pointer, we don't need this. */
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# define TLS_TCB_SIZE 0
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/* This is the size we need before TCB - actually, it includes the TCB. */
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# define TLS_PRE_TCB_SIZE \
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(sizeof (struct pthread) \
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+ ((sizeof (tcbhead_t) + __alignof (struct pthread) - 1) \
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& ~(__alignof (struct pthread) - 1)))
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/* The thread pointer (TP) points to the end of the
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TCB + 0x7000, as for PowerPC and MIPS. This implies that TCB address is
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TP - 0x7000. As we define TLS_DTV_AT_TP we can
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assume that the pthread struct is allocated immediately ahead of the
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TCB. This implies that the pthread_descr address is
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TP - (TLS_PRE_TCB_SIZE + 0x7000). */
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# define TLS_TCB_OFFSET 0x7000
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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(tcbp, dtvp) \
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((tcbhead_t *) (tcbp))[-1].dtv = dtvp + 1
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/* Install new dtv for current thread. */
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# define INSTALL_NEW_DTV(dtv) \
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(THREAD_DTV () = (dtv))
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/* Return dtv of given thread descriptor. */
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# define GET_DTV(tcbp) \
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(((tcbhead_t *) (tcbp))[-1].dtv)
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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(tcbp) \
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({ \
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int _sys_result; \
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\
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_sys_result = INTERNAL_SYSCALL_CALL (set_thread_area, \
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((void *) (tcbp)) + TLS_TCB_OFFSET); \
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INTERNAL_SYSCALL_ERROR_P (_sys_result) ? "unknown error" : NULL; })
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# define TLS_DEFINE_INIT_TP(tp, pd) \
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void *tp = (void *) (pd) + TLS_TCB_OFFSET + TLS_PRE_TCB_SIZE
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extern void * __m68k_read_tp (void);
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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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(((tcbhead_t *) (__m68k_read_tp () - TLS_TCB_OFFSET))[-1].dtv)
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/* Return the thread descriptor for the current thread. */
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# define THREAD_SELF \
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((struct pthread *) (__m68k_read_tp () - TLS_TCB_OFFSET - TLS_PRE_TCB_SIZE))
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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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CONST_THREAD_AREA (32, TLS_TCB_OFFSET + TLS_PRE_TCB_SIZE)
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# include <tcb-access.h>
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/* l_tls_offset == 0 is perfectly valid on M68K, so we have to use some
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different value to mean unset l_tls_offset. */
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# define NO_TLS_OFFSET -1
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/* Get and set the global scope generation counter in struct pthread. */
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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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= atomic_exchange_rel (&THREAD_SELF->header.gscope_flag, \
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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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do \
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{ \
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THREAD_SELF->header.gscope_flag = THREAD_GSCOPE_FLAG_USED; \
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atomic_write_barrier (); \
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} \
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while (0)
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#endif /* __ASSEMBLER__ */
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#endif /* tls.h */
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