@@ -5,7 +5,7 @@ CFLAGS-backtrace.c += -funwind-tables
endif
ifeq ($(subdir),elf)
-sysdep-dl-routines += tlsdesc dl-tlsdesc
+sysdep-dl-routines += tlsdesc dl-tlsdesc tcb-version
gen-as-const-headers += dl-link.sym
endif
@@ -3,3 +3,11 @@ libc {
_mcount;
}
}
+
+ld {
+ GLIBC_2.26 {
+ # Symbol used to version control the private GLIBC TCB split-stack
+ # field.
+ __libc_tcb_private_ss;
+ }
+}
@@ -3,4 +3,4 @@
PTHREAD_MULTIPLE_THREADS_OFFSET offsetof (struct pthread, header.multiple_threads)
PTHREAD_TID_OFFSET offsetof (struct pthread, tid)
-PTHREAD_SIZEOF sizeof (struct pthread)
+PTHREAD_PRE_TCB_SIZE TLS_PRE_TCB_SIZE
@@ -26,6 +26,7 @@
# include <stddef.h>
# include <stdint.h>
# include <dl-dtv.h>
+# include <libc-internal.h>
#else /* __ASSEMBLER__ */
# include <tcb-offsets.h>
@@ -49,6 +50,12 @@ typedef struct
void *private;
} tcbhead_t;
+typedef struct
+{
+ /* GCC split stack support. */
+ void *__private_ss;
+} tcbprehead_t;
+
/* This is the size of the initial TCB. */
# define TLS_INIT_TCB_SIZE sizeof (tcbhead_t)
@@ -58,8 +65,14 @@ typedef struct
/* 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)
+/* This is the size we need before TCB. Check if there is room for
+ tcbprehead_t in struct pthread's final padding and if not add it on
+ required pre-tcb size. */
+# define TLS_PRE_TCB_SIZE \
+ (sizeof (struct pthread) \
+ + (PTHREAD_STRUCT_END_PADDING < sizeof (tcbprehead_t) \
+ ? ALIGN_UP (sizeof (tcbprehead_t), __alignof__ (struct pthread)) \
+ : 0))
/* Alignment requirements for the TCB. */
# define TLS_TCB_ALIGN __alignof__ (struct pthread)
@@ -84,7 +97,8 @@ typedef struct
({ __asm __volatile ("msr tpidr_el0, %0" : : "r" (tcbp)); NULL; })
/* Value passed to 'clone' for initialization of the thread register. */
-# define TLS_DEFINE_INIT_TP(tp, pd) void *tp = (pd) + 1
+# define TLS_DEFINE_INIT_TP(tp, pd) \
+ void *tp = (void*)((uintptr_t) (pd) + TLS_PRE_TCB_SIZE)
/* Return the address of the dtv for the current thread. */
# define THREAD_DTV() \
@@ -92,11 +106,12 @@ typedef struct
/* Return the thread descriptor for the current thread. */
# define THREAD_SELF \
- ((struct pthread *)__builtin_thread_pointer () - 1)
+ ((struct pthread *)((uintptr_t) __builtin_thread_pointer () \
+ - TLS_PRE_TCB_SIZE))
/* Magic for libthread_db to know how to do THREAD_SELF. */
# define DB_THREAD_SELF \
- CONST_THREAD_AREA (64, sizeof (struct pthread))
+ CONST_THREAD_AREA (64, TLS_PRE_TCB_SIZE)
/* Access to data in the thread descriptor is easy. */
# define THREAD_GETMEM(descr, member) \
new file mode 100644
@@ -0,0 +1,23 @@
+/* TCB field abi advertise symbols.
+ Copyright (C) 2017 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/>. */
+
+#include <libc-internal.h>
+
+/* Symbol used to version control the private GLIBC TCB split-stack
+ field. */
+long int attribute_relro __libc_tcb_private_ss;
@@ -8,3 +8,5 @@ GLIBC_2.17 calloc F
GLIBC_2.17 free F
GLIBC_2.17 malloc F
GLIBC_2.17 realloc F
+GLIBC_2.26 GLIBC_2.26 A
+GLIBC_2.26 __libc_tcb_private_ss D 0x8
@@ -114,7 +114,7 @@ extern int __local_multiple_threads attribute_hidden;
# else
# define SINGLE_THREAD_P(R) \
mrs x##R, tpidr_el0; \
- sub x##R, x##R, PTHREAD_SIZEOF; \
+ sub x##R, x##R, PTHREAD_PRE_TCB_SIZE; \
ldr w##R, [x##R, PTHREAD_MULTIPLE_THREADS_OFFSET]
# endif
# endif
Changes from previous version [1] - Change the symbol exported by loader from a function to a data symbol (__libc_tcb_private_ss). This allows binaries to fail at loading time instead of runtime on older glibc. - Fixed struct pthread alignment on TLS_PRE_TCB_SIZE. -- This patch adds split-stack support pointer guard on glibc for aarch64. Different from other architectures (powerpc, s390) where the memory is placed on TCB, aarch64 one is placed bofore thread pointer initial position. It has an advantage over extending TCB because for aarch64 TLS variable placement take in consideration tcbhead_t size and by changing its value would require to also update the static linker (and it would also add incompatibility with glibc and older linkers). For aarch64 tcb direct access is fastest for thread local variable on all mode and related TLS access. It requires just a direct load with displacement of -8 (since thread pointer points to tcbhead_t). It also adds a loader symbol (__tcb_private_ss) to signal de existence of the split stack guard area. Checked on aarch64-linux-gnu. * sysdeps/aarch64/Makefile [$(subdir) = elf] (sysdeps-dl-routines): Add tcb-version. * sysdeps/aarch64/Versions [ld] (GLIBC_2.26): Add __libc_tcb_private_ss. * sysdeps/aarch64/nptl/tls.h (tcbprehead_t): New struct. (TLS_PRE_TCB_SIZE): Take tcbprehead_t in consideration. (TLS_DEFINE_INIT_TP): Likewise. (THREAD_SELF): Likewise. (DB_THREAD_SELF): Likewise. * sysdeps/aarch64/tcb-version.c: New file. * sysdeps/unix/sysv/linux/aarch64/ld.abilist (GLIBC_2.26): Add. (__libc_tcb_private_ss): Likewise. * sysdeps/aarch64/nptl/tcb-offsets.sym (PTHREAD_SIZEOF): Rename to PTHREAD_PRE_TCB_SIZE. * sysdeps/unix/sysv/linux/aarch64/sysdep-cancel.h [!IS_IN (libprthread) && !IS_IN (libc) (SINGLE_THREAD_P): Use PTHREAD_PRE_TCB_SIZE instead of PTHREAD_SIZEOF. --- ChangeLog | 20 ++++++++++++++++++++ sysdeps/aarch64/Makefile | 2 +- sysdeps/aarch64/Versions | 8 ++++++++ sysdeps/aarch64/nptl/tcb-offsets.sym | 2 +- sysdeps/aarch64/nptl/tls.h | 25 ++++++++++++++++++++----- sysdeps/aarch64/tcb-version.c | 23 +++++++++++++++++++++++ sysdeps/unix/sysv/linux/aarch64/ld.abilist | 2 ++ sysdeps/unix/sysv/linux/aarch64/sysdep-cancel.h | 2 +- 8 files changed, 76 insertions(+), 8 deletions(-) create mode 100644 sysdeps/aarch64/tcb-version.c