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Remove TLS_TCB_ALIGN and TLS_INIT_TCB_ALIGN

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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 23c77f6018
("nptl: Increase default TCB alignment to 32").

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
This commit is contained in:
Florian Weimer 2021-12-09 17:57:11 +01:00
parent a41c8e9235
commit 627f5ede70
23 changed files with 23 additions and 134 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
csu/libc-tls.c
View File

@ -24,6 +24,7 @@
#include <stdio.h>
#include <sys/param.h>
#include <array_length.h>
#include <pthreadP.h>
#ifdef SHARED
#error makefile bug, this file is for static only
@ -89,7 +90,7 @@ init_static_tls (size_t memsz, size_t align)
{
/* That is the size of the TLS memory for this object. */
GL(dl_tls_static_size) = roundup (memsz + GLRO(dl_tls_static_surplus),
TLS_TCB_ALIGN);
TCB_ALIGNMENT);
#if TLS_TCB_AT_TP
GL(dl_tls_static_size) += TLS_TCB_SIZE;
#endif
@ -214,5 +215,5 @@ __libc_setup_tls (void)
memsz += tcb_offset;
#endif
init_static_tls (memsz, MAX (TLS_TCB_ALIGN, max_align));
init_static_tls (memsz, MAX (TCB_ALIGNMENT, max_align));
}

4
elf/dl-tls.c
View File

@ -219,7 +219,7 @@ _dl_count_modids (void)
void
_dl_determine_tlsoffset (void)
{
size_t max_align = TLS_TCB_ALIGN;
size_t max_align = TCB_ALIGNMENT;
size_t freetop = 0;
size_t freebottom = 0;
@ -350,7 +350,7 @@ _dl_determine_tlsoffset (void)
GL(dl_tls_static_used) = offset;
GLRO (dl_tls_static_size) = roundup (offset + GLRO(dl_tls_static_surplus),
TLS_TCB_ALIGN);
TCB_ALIGNMENT);
#else
# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
#endif

6
sysdeps/aarch64/nptl/tls.h
View File

@ -52,18 +52,12 @@ typedef struct
/* This is the size of the initial TCB. */
# define TLS_INIT_TCB_SIZE sizeof (tcbhead_t)
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size of the TCB. */
# define TLS_TCB_SIZE sizeof (tcbhead_t)
/* This is the size we need before TCB. */
# define TLS_PRE_TCB_SIZE sizeof (struct pthread)
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN __alignof__ (struct pthread)
/* Install the dtv pointer. The pointer passed is to the element with
index -1 which contain the length. */
# define INSTALL_DTV(tcbp, dtvp) \

6
sysdeps/alpha/nptl/tls.h
View File

@ -46,18 +46,12 @@ typedef struct
/* This is the size of the initial TCB. */
# define TLS_INIT_TCB_SIZE sizeof (tcbhead_t)
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN 16
/* This is the size of the TCB. */
# define TLS_TCB_SIZE sizeof (tcbhead_t)
/* This is the size we need before TCB. */
# define TLS_PRE_TCB_SIZE sizeof (struct pthread)
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN 16
/* Install the dtv pointer. The pointer passed is to the element with
index -1 which contain the length. */
# define INSTALL_DTV(tcbp, dtvp) \

6
sysdeps/arc/nptl/tls.h
View File

@ -48,17 +48,11 @@ typedef struct
/* This is the size of the initial TCB. */
# define TLS_INIT_TCB_SIZE sizeof (tcbhead_t)
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size of the TCB. */
#ifndef TLS_TCB_SIZE
# define TLS_TCB_SIZE sizeof (tcbhead_t)
#endif
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size we need before TCB. */
# define TLS_PRE_TCB_SIZE sizeof (struct pthread)

6
sysdeps/arm/nptl/tls.h
View File

@ -50,18 +50,12 @@ typedef struct
/* This is the size of the initial TCB. */
# define TLS_INIT_TCB_SIZE sizeof (tcbhead_t)
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN 16
/* This is the size of the TCB. */
# define TLS_TCB_SIZE sizeof (tcbhead_t)
/* This is the size we need before TCB. */
# define TLS_PRE_TCB_SIZE sizeof (struct pthread)
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN 16
/* Install the dtv pointer. The pointer passed is to the element with
index -1 which contain the length. */
# define INSTALL_DTV(tcbp, dtvp) \

6
sysdeps/csky/nptl/tls.h
View File

@ -61,15 +61,9 @@ typedef struct
/* This is the size of the initial TCB. */
# define TLS_INIT_TCB_SIZE sizeof (tcbhead_t)
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN 8
/* This is the size of the TCB. */
# define TLS_TCB_SIZE sizeof (tcbhead_t)
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN 8
/* This is the size we need before TCB. */
# define TLS_PRE_TCB_SIZE sizeof (struct pthread)

14
sysdeps/generic/tls.h
View File

@ -19,6 +19,11 @@
/* An architecture-specific version of this file has to defined a
number of symbols:
TCB_ALIGNMENT
Alignment of THREAD_SELF (struct pthread *) and the thread
pointer.
TLS_TCB_AT_TP or TLS_DTV_AT_TP
The presence of one of these symbols signals which variant of
@ -43,15 +48,6 @@
dynamic linker itself. There are no threads in use at that time.
TLS_TCB_ALIGN
Alignment requirements for the TCB structure.
TLS_INIT_TCB_ALIGN
Similarly, but for the structure used at startup time.
INSTALL_DTV(tcb, init_dtv)
This macro must install the given initial DTV into the thread control

6
sysdeps/hppa/nptl/tls.h
View File

@ -52,15 +52,9 @@ typedef struct
/* This is the size of the initial TCB. */
# define TLS_INIT_TCB_SIZE sizeof (tcbhead_t)
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN __alignof__ (tcbhead_t)
/* This is the size of the TCB. */
# define TLS_TCB_SIZE sizeof (tcbhead_t)
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size we need before TCB */
# define TLS_PRE_TCB_SIZE sizeof (struct pthread)

6
sysdeps/i386/nptl/tls.h
View File

@ -102,15 +102,9 @@ union user_desc_init
struct pthread even when not linked with -lpthread. */
# define TLS_INIT_TCB_SIZE sizeof (struct pthread)
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size of the TCB. */
# define TLS_TCB_SIZE sizeof (struct pthread)
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN __alignof__ (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

3
sysdeps/ia64/libc-tls.c
View File

@ -18,6 +18,9 @@
#include <csu/libc-tls.c>
_Static_assert (TLS_PRE_TCB_SIZE % __alignof (struct pthread) == 0,
"__thread_self and THREAD_SELF have same alignment");
/* On IA-64, as it lacks linker optimizations, __tls_get_addr can be
called even in statically linked binaries.
In this case module must be always 1 and PT_TLS segment

6
sysdeps/ia64/nptl/tls.h
View File

@ -53,9 +53,6 @@ register struct pthread *__thread_self __asm__("r13");
/* This is the size of the initial TCB. */
# define TLS_INIT_TCB_SIZE sizeof (tcbhead_t)
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN __alignof__ (tcbhead_t)
/* This is the size of the TCB. */
# define TLS_TCB_SIZE sizeof (tcbhead_t)
@ -70,9 +67,6 @@ register struct pthread *__thread_self __asm__("r13");
& ~(__alignof__ (struct pthread) - 1)) \
: 0))
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN __alignof__ (struct pthread)
/* The DTV is allocated at the TP; the TCB is placed elsewhere. */
# define TLS_DTV_AT_TP 1
# define TLS_TCB_AT_TP 0

9
sysdeps/m68k/nptl/tls.h
View File

@ -53,20 +53,15 @@ typedef struct
pointer, we don't need this. */
# define TLS_INIT_TCB_SIZE 0
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size of the TCB. Because our TCB is before the thread
pointer, we don't need this. */
# define TLS_TCB_SIZE 0
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size we need before TCB - actually, it includes the TCB. */
# define TLS_PRE_TCB_SIZE \
(sizeof (struct pthread) \
+ ((sizeof (tcbhead_t) + TLS_TCB_ALIGN - 1) & ~(TLS_TCB_ALIGN - 1)))
+ ((sizeof (tcbhead_t) + __alignof (struct pthread) - 1) \
& ~(__alignof (struct pthread) - 1)))
/* The thread pointer (TP) points to the end of the
TCB + 0x7000, as for PowerPC and MIPS. This implies that TCB address is

8
sysdeps/mach/hurd/tls.h
View File

@ -29,20 +29,12 @@
# include <mach.h>
# include <atomic.h>
/* This is the size of the initial TCB. */
# define TLS_INIT_TCB_SIZE sizeof (tcbhead_t)
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN __alignof__ (tcbhead_t)
/* This is the size of the TCB. */
# define TLS_TCB_SIZE TLS_INIT_TCB_SIZE /* XXX */
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN TLS_INIT_TCB_ALIGN /* XXX */
/* Install the dtv pointer. The pointer passed is to the element with
index -1 which contain the length. */
# define INSTALL_DTV(descr, dtvp) \

6
sysdeps/microblaze/nptl/tls.h
View File

@ -56,18 +56,12 @@ typedef struct
/* This is the size of the initial TCB. */
# define TLS_INIT_TCB_SIZE sizeof (tcbhead_t)
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN __alignof__ (tcbhead_t)
/* This is the size of the TCB. */
# define TLS_TCB_SIZE sizeof (tcbhead_t)
/* This is the size we need before TCB. */
# define TLS_PRE_TCB_SIZE sizeof (struct pthread)
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN __alignof__ (struct pthread)
/* Install the dtv pointer. The pointer passed is to the element with
index -1 which contain the length. */
# define INSTALL_DTV(tcbp, dtvp) \

9
sysdeps/mips/nptl/tls.h
View File

@ -83,20 +83,15 @@ typedef struct
pointer, we don't need this. */
# define TLS_INIT_TCB_SIZE 0
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size of the TCB. Because our TCB is before the thread
pointer, we don't need this. */
# define TLS_TCB_SIZE 0
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size we need before TCB - actually, it includes the TCB. */
# define TLS_PRE_TCB_SIZE \
(sizeof (struct pthread) \
+ ((sizeof (tcbhead_t) + TLS_TCB_ALIGN - 1) & ~(TLS_TCB_ALIGN - 1)))
+ ((sizeof (tcbhead_t) + __alignof (struct pthread) - 1) \
& ~(__alignof (struct pthread) - 1)))
/* The thread pointer (in hardware register $29) points to the end of
the TCB + 0x7000, as for PowerPC. The pthread_descr structure is

9
sysdeps/nios2/nptl/tls.h
View File

@ -59,20 +59,15 @@ register struct pthread *__thread_self __asm__("r23");
pointer, we don't need this. */
# define TLS_INIT_TCB_SIZE 0
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size of the TCB. Because our TCB is before the thread
pointer, we don't need this. */
# define TLS_TCB_SIZE 0
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size we need before TCB - actually, it includes the TCB. */
# define TLS_PRE_TCB_SIZE \
(sizeof (struct pthread) \
+ ((sizeof (tcbhead_t) + TLS_TCB_ALIGN - 1) & ~(TLS_TCB_ALIGN - 1)))
+ ((sizeof (tcbhead_t) + __alignof (struct pthread) - 1) \
& ~(__alignof (struct pthread) - 1)))
/* The thread pointer (in hardware register r23) points to the end of
the TCB + 0x7000, as for PowerPC and MIPS. */

9
sysdeps/powerpc/nptl/tls.h
View File

@ -108,19 +108,14 @@ typedef struct
/* This is the size of the initial TCB. */
# define TLS_INIT_TCB_SIZE 0
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size of the TCB. */
# define TLS_TCB_SIZE 0
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size we need before TCB. */
# define TLS_PRE_TCB_SIZE \
(sizeof (struct pthread) \
+ ((sizeof (tcbhead_t) + TLS_TCB_ALIGN - 1) & ~(TLS_TCB_ALIGN - 1)))
+ ((sizeof (tcbhead_t) + __alignof (struct pthread) - 1) \
& ~(__alignof (struct pthread) - 1)))
/* The following assumes that TP (R2 or R13) points to the end of the
TCB + 0x7000 (per the ABI). This implies that TCB address is

9
sysdeps/riscv/nptl/tls.h
View File

@ -50,20 +50,15 @@ typedef struct
pointer, we don't need this. */
# define TLS_INIT_TCB_SIZE 0
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size of the TCB. Because our TCB is before the thread
pointer, we don't need this. */
# define TLS_TCB_SIZE 0
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size we need before TCB - actually, it includes the TCB. */
# define TLS_PRE_TCB_SIZE \
(sizeof (struct pthread) \
+ ((sizeof (tcbhead_t) + TLS_TCB_ALIGN - 1) & ~(TLS_TCB_ALIGN - 1)))
+ ((sizeof (tcbhead_t) + __alignof (struct pthread) - 1) \
& ~(__alignof (struct pthread) - 1)))
/* The thread pointer tp points to the end of the TCB.
The pthread_descr structure is immediately in front of the TCB. */

6
sysdeps/s390/nptl/tls.h
View File

@ -66,15 +66,9 @@ typedef struct
struct pthread even when not linked with -lpthread. */
# define TLS_INIT_TCB_SIZE sizeof (struct pthread)
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size of the TCB. */
# define TLS_TCB_SIZE sizeof (struct pthread)
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN __alignof__ (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

6
sysdeps/sh/nptl/tls.h
View File

@ -51,18 +51,12 @@ typedef struct
/* This is the size of the initial TCB. */
# define TLS_INIT_TCB_SIZE sizeof (tcbhead_t)
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN __alignof__ (tcbhead_t)
/* This is the size of the TCB. */
# define TLS_TCB_SIZE sizeof (tcbhead_t)
/* This is the size we need before TCB. */
# define TLS_PRE_TCB_SIZE sizeof (struct pthread)
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN __alignof__ (struct pthread)
/* The TLS blocks start right after the TCB. */
# define TLS_DTV_AT_TP 1
# define TLS_TCB_AT_TP 0

6
sysdeps/sparc/nptl/tls.h
View File

@ -63,15 +63,9 @@ register struct pthread *__thread_self __asm__("%g7");
struct pthread even when not linked with -lpthread. */
# define TLS_INIT_TCB_SIZE sizeof (struct pthread)
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size of the TCB. */
# define TLS_TCB_SIZE sizeof (struct pthread)
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN __alignof__ (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

6
sysdeps/x86_64/nptl/tls.h
View File

@ -106,15 +106,9 @@ _Static_assert (offsetof (tcbhead_t, __glibc_unused2) == 0x80,
struct pthread even when not linked with -lpthread. */
# define TLS_INIT_TCB_SIZE sizeof (struct pthread)
/* Alignment requirements for the initial TCB. */
# define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
/* This is the size of the TCB. */
# define TLS_TCB_SIZE sizeof (struct pthread)
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN __alignof__ (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