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9570bc53fc
glibc/sysdeps/i386/nptl/tls.h
Mark Wielaard 9570bc53fc i386 TLS_INIT_TP might produce bogus asm changing stack pointer [BZ #17319] 
TLS_INIT_TP in sysdeps/i386/nptl/tls.h uses some hand written asm to
generate a set_thread_area that might result in exchanging ebx and esp
around the syscall causing introspection tools like valgrind to loose
track of the user stack. Just use INTERNAL_SYSCALL which makes sure
esp isn't changed arbitrarily.

Before the patch the code would generate:

mov    $0xf3,%eax
movl   $0xfffff,0x8(%esp)
movl   $0x51,0xc(%esp)
xchg   %esp,%ebx
int    $0x80
xchg   %esp,%ebx

Using INTERNAL_SYSCALL instead will generate:

movl   $0xfffff,0x8(%esp)
movl   $0x51,0xc(%esp)
xchg   %ecx,%ebx
mov    $0xf3,%eax
int    $0x80
xchg   %ecx,%ebx

Thanks to Florian Weimer for analysing why the original code generated
the bogus esp usage:

  _segdescr.desc happens to be at the top of the stack, so its address
  is in %esp.  The asm statement says that %3 is an input, so its value
  will not change, and GCC can use %esp as the input register for the
  expression &_segdescr.desc.  But the constraints do not fully describe
  the asm statement because the %3 register is actually modified, albeit
  only temporarily.

	[BZ #17319]
	* sysdeps/i386/nptl/tls.h (TLS_INIT_TP): Use INTERNAL_SYSCALL
	to call set_thread_area instead of hand written asm.
	(__NR_set_thread_area): Removed define.
	(TLS_FLAG_WRITABLE): Likewise.
	(__ASSUME_SET_THREAD_AREA): Remove check.
	(TLS_EBX_ARG): Remove define.
	(TLS_LOAD_EBX): Likewise.
2014-08-28 09:53:08 +02:00

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/* Definition for thread-local data handling. nptl/i386 version.
Copyright (C) 2002-2014 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
<http://www.gnu.org/licenses/>. */
#ifndef _TLS_H
#define _TLS_H 1
#include <dl-sysdep.h>
#ifndef __ASSEMBLER__
# include <stdbool.h>
# include <stddef.h>
# include <stdint.h>
# include <stdlib.h>
# include <sysdep.h>
# include <libc-internal.h>
# include <kernel-features.h>
/* Type for the dtv. */
typedef union dtv
{
size_t counter;
struct
{
void *val;
bool is_static;
} pointer;
} dtv_t;
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;
#ifndef __ASSUME_PRIVATE_FUTEX
int private_futex;
#else
int __glibc_reserved1;
#endif
/* Reservation of some values for the TM ABI. */
void *__private_tm[4];
/* GCC split stack support. */
void *__private_ss;
} tcbhead_t;
# define TLS_MULTIPLE_THREADS_IN_TCB 1
#else /* __ASSEMBLER__ */
# include <tcb-offsets.h>
#endif
/* Alignment requirement for the stack. For IA-32 this is governed by
the SSE memory functions. */
#define STACK_ALIGN 16
#ifndef __ASSEMBLER__
/* Get system call information. */
# include <sysdep.h>
/* The old way: using LDT. */
/* Structure passed to `modify_ldt', 'set_thread_area', and 'clone' calls. */
struct user_desc
{
unsigned int entry_number;
unsigned long int base_addr;
unsigned int limit;
unsigned int seg_32bit:1;
unsigned int contents:2;
unsigned int read_exec_only:1;
unsigned int limit_in_pages:1;
unsigned int seg_not_present:1;
unsigned int useable:1;
unsigned int empty:25;
};
/* Initializing bit fields is slow. We speed it up by using a union. */
union user_desc_init
{
struct user_desc desc;
unsigned int vals[4];
};
/* This is the size of the initial TCB. Can't be just sizeof (tcbhead_t),
because NPTL getpid, __libc_alloca_cutoff etc. need (almost) the whole
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
# define TLS_DTV_AT_TP 0
/* Get the thread descriptor definition. */
# include <nptl/descr.h>
/* Install the dtv pointer. The pointer passed is to the element with
index -1 which contain the length. */
# define INSTALL_DTV(descr, dtvp) \
((tcbhead_t *) (descr))->dtv = (dtvp) + 1
/* Install new dtv for current thread. */
# define INSTALL_NEW_DTV(dtvp) \
({ struct pthread *__pd; \
THREAD_SETMEM (__pd, header.dtv, (dtvp)); })
/* Return dtv of given thread descriptor. */
# define GET_DTV(descr) \
(((tcbhead_t *) (descr))->dtv)
#define THREAD_SELF_SYSINFO THREAD_GETMEM (THREAD_SELF, header.sysinfo)
#define THREAD_SYSINFO(pd) ((pd)->header.sysinfo)
/* Macros to load from and store into segment registers. */
# ifndef TLS_GET_GS
# define TLS_GET_GS() \
({ int __seg; __asm ("movw %%gs, %w0" : "=q" (__seg)); __seg & 0xffff; })
# endif
# ifndef TLS_SET_GS
# define TLS_SET_GS(val) \
__asm ("movw %w0, %%gs" :: "q" (val))
# endif
#if defined NEED_DL_SYSINFO
# define INIT_SYSINFO \
_head->sysinfo = GLRO(dl_sysinfo)
#else
# define INIT_SYSINFO
#endif
#ifndef LOCK_PREFIX
# ifdef UP
# define LOCK_PREFIX /* nothing */
# else
# define LOCK_PREFIX "lock;"
# endif
#endif
static inline void __attribute__ ((unused, always_inline))
tls_fill_user_desc (union user_desc_init *desc,
unsigned int entry_number,
void *pd)
{
desc->vals[0] = entry_number;
/* The 'base_addr' field. Pointer to the TCB. */
desc->vals[1] = (unsigned long int) pd;
/* The 'limit' field. We use 4GB which is 0xfffff pages. */
desc->vals[2] = 0xfffff;
/* Collapsed value of the bitfield:
.seg_32bit = 1
.contents = 0
.read_exec_only = 0
.limit_in_pages = 1
.seg_not_present = 0
.useable = 1 */
desc->vals[3] = 0x51;
}
/* 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(thrdescr) \
({ void *_thrdescr = (thrdescr); \
tcbhead_t *_head = _thrdescr; \
union user_desc_init _segdescr; \
int _result; \
\
_head->tcb = _thrdescr; \
/* For now the thread descriptor is at the same address. */ \
_head->self = _thrdescr; \
/* New syscall handling support. */ \
INIT_SYSINFO; \
\
/* Let the kernel pick a value for the 'entry_number' field. */ \
tls_fill_user_desc (&_segdescr, -1, _thrdescr); \
\
/* Install the TLS. */ \
INTERNAL_SYSCALL_DECL (err); \
_result = INTERNAL_SYSCALL (set_thread_area, err, 1, &_segdescr.desc); \
\
if (_result == 0) \
/* We know the index in the GDT, now load the segment register. \
The use of the GDT is described by the value 3 in the lower \
three bits of the segment descriptor value. \
\
Note that we have to do this even if the numeric value of \
the descriptor does not change. Loading the segment register \
causes the segment information from the GDT to be loaded \
which is necessary since we have changed it. */ \
TLS_SET_GS (_segdescr.desc.entry_number * 8 + 3); \
\
_result == 0 ? NULL \
: "set_thread_area failed when setting up thread-local storage\n"; })
# define TLS_DEFINE_INIT_TP(tp, pd) \
union user_desc_init _segdescr; \
/* Find the 'entry_number' field that the kernel selected in TLS_INIT_TP. \
The first three bits of the segment register value select the GDT, \
ignore them. We get the index from the value of the %gs register in \
the current thread. */ \
tls_fill_user_desc (&_segdescr, TLS_GET_GS () >> 3, pd); \
const struct user_desc *tp = &_segdescr.desc
/* Return the address of the dtv for the current thread. */
# define THREAD_DTV() \
({ struct pthread *__pd; \
THREAD_GETMEM (__pd, header.dtv); })
/* Return the thread descriptor for the current thread.
The contained asm must *not* be marked volatile since otherwise
assignments like
pthread_descr self = thread_self();
do not get optimized away. */
# define THREAD_SELF \
({ struct pthread *__self; \
asm ("movl %%gs:%c1,%0" : "=r" (__self) \
: "i" (offsetof (struct pthread, header.self))); \
__self;})
/* Magic for libthread_db to know how to do THREAD_SELF. */
# define DB_THREAD_SELF \
REGISTER_THREAD_AREA (32, offsetof (struct user_regs_struct, xgs), 3) \
REGISTER_THREAD_AREA (64, 26 * 8, 3) /* x86-64's user_regs_struct->gs */
/* Read member of the thread descriptor directly. */
# define THREAD_GETMEM(descr, member) \
({ __typeof (descr->member) __value; \
if (sizeof (__value) == 1) \
asm volatile ("movb %%gs:%P2,%b0" \
: "=q" (__value) \
: "0" (0), "i" (offsetof (struct pthread, member))); \
else if (sizeof (__value) == 4) \
asm volatile ("movl %%gs:%P1,%0" \
: "=r" (__value) \
: "i" (offsetof (struct pthread, member))); \
else \
{ \
if (sizeof (__value) != 8) \
/* There should not be any value with a size other than 1, \
4 or 8. */ \
abort (); \
\
asm volatile ("movl %%gs:%P1,%%eax\n\t" \
"movl %%gs:%P2,%%edx" \
: "=A" (__value) \
: "i" (offsetof (struct pthread, member)), \
"i" (offsetof (struct pthread, member) + 4)); \
} \
__value; })
/* Same as THREAD_GETMEM, but the member offset can be non-constant. */
# define THREAD_GETMEM_NC(descr, member, idx) \
({ __typeof (descr->member[0]) __value; \
if (sizeof (__value) == 1) \
asm volatile ("movb %%gs:%P2(%3),%b0" \
: "=q" (__value) \
: "0" (0), "i" (offsetof (struct pthread, member[0])), \
"r" (idx)); \
else if (sizeof (__value) == 4) \
asm volatile ("movl %%gs:%P1(,%2,4),%0" \
: "=r" (__value) \
: "i" (offsetof (struct pthread, member[0])), \
"r" (idx)); \
else \
{ \
if (sizeof (__value) != 8) \
/* There should not be any value with a size other than 1, \
4 or 8. */ \
abort (); \
\
asm volatile ("movl %%gs:%P1(,%2,8),%%eax\n\t" \
"movl %%gs:4+%P1(,%2,8),%%edx" \
: "=&A" (__value) \
: "i" (offsetof (struct pthread, member[0])), \
"r" (idx)); \
} \
__value; })
/* Same as THREAD_SETMEM, but the member offset can be non-constant. */
# define THREAD_SETMEM(descr, member, value) \
({ if (sizeof (descr->member) == 1) \
asm volatile ("movb %b0,%%gs:%P1" : \
: "iq" (value), \
"i" (offsetof (struct pthread, member))); \
else if (sizeof (descr->member) == 4) \
asm volatile ("movl %0,%%gs:%P1" : \
: "ir" (value), \
"i" (offsetof (struct pthread, member))); \
else \
{ \
if (sizeof (descr->member) != 8) \
/* There should not be any value with a size other than 1, \
4 or 8. */ \
abort (); \
\
asm volatile ("movl %%eax,%%gs:%P1\n\t" \
"movl %%edx,%%gs:%P2" : \
: "A" ((uint64_t) cast_to_integer (value)), \
"i" (offsetof (struct pthread, member)), \
"i" (offsetof (struct pthread, member) + 4)); \
}})
/* Set member of the thread descriptor directly. */
# define THREAD_SETMEM_NC(descr, member, idx, value) \
({ if (sizeof (descr->member[0]) == 1) \
asm volatile ("movb %b0,%%gs:%P1(%2)" : \
: "iq" (value), \
"i" (offsetof (struct pthread, member)), \
"r" (idx)); \
else if (sizeof (descr->member[0]) == 4) \
asm volatile ("movl %0,%%gs:%P1(,%2,4)" : \
: "ir" (value), \
"i" (offsetof (struct pthread, member)), \
"r" (idx)); \
else \
{ \
if (sizeof (descr->member[0]) != 8) \
/* There should not be any value with a size other than 1, \
4 or 8. */ \
abort (); \
\
asm volatile ("movl %%eax,%%gs:%P1(,%2,8)\n\t" \
"movl %%edx,%%gs:4+%P1(,%2,8)" : \
: "A" ((uint64_t) cast_to_integer (value)), \
"i" (offsetof (struct pthread, member)), \
"r" (idx)); \
}})
/* Atomic compare and exchange on TLS, returning old value. */
#define THREAD_ATOMIC_CMPXCHG_VAL(descr, member, newval, oldval) \
({ __typeof (descr->member) __ret; \
__typeof (oldval) __old = (oldval); \
if (sizeof (descr->member) == 4) \
asm volatile (LOCK_PREFIX "cmpxchgl %2, %%gs:%P3" \
: "=a" (__ret) \
: "0" (__old), "r" (newval), \
"i" (offsetof (struct pthread, member))); \
else \
/* Not necessary for other sizes in the moment. */ \
abort (); \
__ret; })
/* Atomic logical and. */
#define THREAD_ATOMIC_AND(descr, member, val) \
(void) ({ if (sizeof ((descr)->member) == 4) \
asm volatile (LOCK_PREFIX "andl %1, %%gs:%P0" \
:: "i" (offsetof (struct pthread, member)), \
"ir" (val)); \
else \
/* Not necessary for other sizes in the moment. */ \
abort (); })
/* Atomic set bit. */
#define THREAD_ATOMIC_BIT_SET(descr, member, bit) \
(void) ({ if (sizeof ((descr)->member) == 4) \
asm volatile (LOCK_PREFIX "orl %1, %%gs:%P0" \
:: "i" (offsetof (struct pthread, member)), \
"ir" (1 << (bit))); \
else \
/* Not necessary for other sizes in the moment. */ \
abort (); })
/* Call the user-provided thread function. */
#define CALL_THREAD_FCT(descr) \
({ void *__res; \
int __ignore1, __ignore2; \
asm volatile ("pushl %%eax\n\t" \
"pushl %%eax\n\t" \
"pushl %%eax\n\t" \
"pushl %%gs:%P4\n\t" \
"call *%%gs:%P3\n\t" \
"addl $16, %%esp" \
: "=a" (__res), "=c" (__ignore1), "=d" (__ignore2) \
: "i" (offsetof (struct pthread, start_routine)), \
"i" (offsetof (struct pthread, arg))); \
__res; })
/* Set the stack guard field in TCB head. */
#define THREAD_SET_STACK_GUARD(value) \
THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)
#define THREAD_COPY_STACK_GUARD(descr) \
((descr)->header.stack_guard \
= THREAD_GETMEM (THREAD_SELF, header.stack_guard))
/* Set the pointer guard field in the TCB head. */
#define THREAD_SET_POINTER_GUARD(value) \
THREAD_SETMEM (THREAD_SELF, header.pointer_guard, value)
#define THREAD_COPY_POINTER_GUARD(descr) \
((descr)->header.pointer_guard \
= THREAD_GETMEM (THREAD_SELF, header.pointer_guard))
/* Get and set the global scope generation counter in the TCB head. */
#define THREAD_GSCOPE_FLAG_UNUSED 0
#define THREAD_GSCOPE_FLAG_USED 1
#define THREAD_GSCOPE_FLAG_WAIT 2
#define THREAD_GSCOPE_RESET_FLAG() \
do \
{ int __res; \
asm volatile ("xchgl %0, %%gs:%P1" \
: "=r" (__res) \
: "i" (offsetof (struct pthread, header.gscope_flag)), \
"0" (THREAD_GSCOPE_FLAG_UNUSED)); \
if (__res == THREAD_GSCOPE_FLAG_WAIT) \
lll_futex_wake (&THREAD_SELF->header.gscope_flag, 1, LLL_PRIVATE); \
} \
while (0)
#define THREAD_GSCOPE_SET_FLAG() \
THREAD_SETMEM (THREAD_SELF, header.gscope_flag, THREAD_GSCOPE_FLAG_USED)
#define THREAD_GSCOPE_WAIT() \
GL(dl_wait_lookup_done) ()
#endif /* __ASSEMBLER__ */
#endif /* tls.h */
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