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i386: Change offset of __private_ss to 0x30 [BZ #23250]

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sysdeps/i386/nptl/tls.h has

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;
  uintptr_t sysinfo;
  uintptr_t stack_guard;
  uintptr_t pointer_guard;
  int gscope_flag;
  int __glibc_reserved1;
  /* Reservation of some values for the TM ABI.  */
  void *__private_tm[4];
  /* GCC split stack support.  */
  void *__private_ss;
} tcbhead_t;

The offset of __private_ss is 0x34.  But GCC defines

/* We steal the last transactional memory word.  */
 #define TARGET_THREAD_SPLIT_STACK_OFFSET 0x30

and libgcc/config/i386/morestack.S has

	cmpl	%gs:0x30,%eax		# See if we have enough space.
	movl	%eax,%gs:0x30		# Save the new stack boundary.
	movl	%eax,%gs:0x30		# Save the new stack boundary.
	movl	%ecx,%gs:0x30		# Save new stack boundary.
	movl	%eax,%gs:0x30
	movl	%gs:0x30,%eax
	movl	%eax,%gs:0x30

Since update TARGET_THREAD_SPLIT_STACK_OFFSET changes split stack ABI,
this patch updates tcbhead_t to match GCC.

	[BZ #23250]
	[BZ #10686]
	* sysdeps/i386/nptl/tls.h (tcbhead_t): Change __private_tm[4]
	to _private_tm[3] and add __glibc_reserved2.
	Add _Static_assert of offset of __private_ss == 0x30.
	* sysdeps/x86_64/nptl/tls.h: Add _Static_assert of offset of
	__private_ss == 0x40 for ILP32 and == 0x70 for LP64.
This commit is contained in:
H.J. Lu 2018-06-12 06:23:28 -07:00
parent e826574c98
commit 0221ce2a90
3 changed files with 26 additions and 1 deletions
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10
ChangeLog
View File

@ -1,3 +1,13 @@
2018-06-12 H.J. Lu <hongjiu.lu@intel.com>
[BZ #23250]
[BZ #10686]
* sysdeps/i386/nptl/tls.h (tcbhead_t): Change __private_tm[4]
to _private_tm[3] and add __glibc_reserved2.
Add _Static_assert of offset of __private_ss == 0x30.
* sysdeps/x86_64/nptl/tls.h: Add _Static_assert of offset of
__private_ss == 0x40 for ILP32 and == 0x70 for LP64.
2018-06-12 Florian Weimer <fweimer@redhat.com>
x86: Make strncmp usable from rtld.

7
sysdeps/i386/nptl/tls.h
View File

@ -43,11 +43,16 @@ typedef struct
int gscope_flag;
int __glibc_reserved1;
/* Reservation of some values for the TM ABI. */
void *__private_tm[4];
void *__private_tm[3];
/* GCC split stack support. */
void *__private_ss;
void *__glibc_reserved2;
} tcbhead_t;
/* morestack.S in libgcc uses offset 0x30 to access __private_ss, */
_Static_assert (offsetof (tcbhead_t, __private_ss) == 0x30,
"offset of __private_ss != 0x30");
# define TLS_MULTIPLE_THREADS_IN_TCB 1
#else /* __ASSEMBLER__ */

10
sysdeps/x86_64/nptl/tls.h
View File

@ -65,6 +65,16 @@ typedef struct
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");
# 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");
# endif
#else /* __ASSEMBLER__ */
# include <tcb-offsets.h>
#endif