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Thumb-2 support patch
- From: "Joseph S. Myers" <joseph at codesourcery dot com>
- To: libc-ports at sourceware dot org
- Date: Thu, 5 Feb 2009 14:52:00 +0000 (UTC)
- Subject: Thumb-2 support patch
I have committed this patch adding Thumb-2 support to the ARM port of
glibc.
This means support for glibc to be compiled by GCC generating Thumb-2
code. Most of the assembly code in glibc will still be built in ARM mode
as the .S files do not contain any directives to switch to Thumb mode;
this works fine with interworking; however, inline asms need various fixes
(in this patch) to work for Thumb-2.
Note that this has only been tested for EABI. I see no reason why Thumb-2
should not work for old-ABI, but also no reason to use it with old-ABI
instead of EABI.
Index: ChangeLog.arm
===================================================================
RCS file: /cvs/glibc/ports/ChangeLog.arm,v
retrieving revision 1.90
retrieving revision 1.91
diff -u -r1.90 -r1.91
--- ChangeLog.arm 2 Feb 2009 15:35:22 -0000 1.90
+++ ChangeLog.arm 5 Feb 2009 14:46:41 -0000 1.91
@@ -1,3 +1,25 @@
+2009-02-05 Paul Brook <paul@codesourcery.com>
+ Joseph Myers <joseph@codesourcery.com>
+
+ * sysdeps/arm/dl-machine.h (elf_machine_dynamic): Ditto.
+ (elf_machine_load_address): Clear T bit of PLT entry contents.
+ (RTLD_START): Mark function symbols as such. Tweak pc-relative
+ addressing to avoid depending on pc read pipeline offset.
+ * sysdeps/arm/machine-gmon.h (MCOUNT): Add Thumb-2 implementation.
+ * sysdeps/arm/tls-macros.h: Add alignment for Thumb-2.
+ (ARM_PC_OFFSET): Define.
+ (TLS_IE): Define differently for Thumb-2.
+ (TLS_LE, TLS_LD, TLS_GD): Use ARM_PC_OFFSET.
+ * sysdeps/arm/elf/start.S: Switch to thumb mode for Thumb-2.
+ * sysdeps/unix/sysv/linux/arm/eabi/sysdep.h (INTERNAL_SYSCALL_RAW):
+ Add Thumb implementation.
+ * sysdeps/unix/sysv/linux/arm/eabi/nptl/aio_misc.h: New.
+ * sysdeps/unix/sysv/linux/arm/eabi/nptl/unwind-resume.c: Enforce
+ alignment for Thumb-2. Adjust offset from PC for Thumb-2.
+ * sysdeps/unix/sysv/linux/arm/eabi/nptl/unwind-forcedunwind.c: Ditto.
+ * sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h (atomic_full_barrier,
+ __arch_compare_and_exchange_val_32_acq): Add Thumb-2 implementation.
+
2009-02-02 Joseph Myers <joseph@codesourcery.com>
* sysdeps/unix/sysv/linux/arm/bits/shm.h (SHM_EXEC): Define.
Index: sysdeps/arm/dl-machine.h
===================================================================
RCS file: /cvs/glibc/ports/sysdeps/arm/dl-machine.h,v
retrieving revision 1.60
retrieving revision 1.61
diff -u -r1.60 -r1.61
--- sysdeps/arm/dl-machine.h 21 Sep 2006 18:21:19 -0000 1.60
+++ sysdeps/arm/dl-machine.h 5 Feb 2009 14:46:41 -0000 1.61
@@ -53,11 +53,22 @@
elf_machine_dynamic (void)
{
Elf32_Addr dynamic;
+#ifdef __thumb2__
+ long tmp;
+ asm ("ldr\t%0, 1f\n\t"
+ "adr\t%1, 1f\n\t"
+ "ldr\t%0, [%0, %1]\n\t"
+ "b 2f\n"
+ ".align 2\n"
+ "1: .word _GLOBAL_OFFSET_TABLE_ - 1b\n"
+ "2:" : "=r" (dynamic), "=r"(tmp));
+#else
asm ("ldr %0, 2f\n"
"1: ldr %0, [pc, %0]\n"
"b 3f\n"
"2: .word _GLOBAL_OFFSET_TABLE_ - (1b+8)\n"
"3:" : "=r" (dynamic));
+#endif
return dynamic;
}
@@ -69,6 +80,10 @@
extern void __dl_start asm ("_dl_start");
Elf32_Addr got_addr = (Elf32_Addr) &__dl_start;
Elf32_Addr pcrel_addr;
+#ifdef __thumb__
+ /* Clear the low bit of the funciton address. */
+ got_addr &= ~(Elf32_Addr) 1;
+#endif
asm ("adr %0, _dl_start" : "=r" (pcrel_addr));
return pcrel_addr - got_addr;
}
@@ -140,7 +155,9 @@
#define RTLD_START asm ("\
.text\n\
.globl _start\n\
+.type _start, %function\n\
.globl _dl_start_user\n\
+.type _dl_start_user, %function\n\
_start:\n\
@ we are PIC code, so get global offset table\n\
ldr sl, .L_GET_GOT\n\
@@ -152,8 +169,8 @@
bl _dl_start\n\
@ returns user entry point in r0\n\
_dl_start_user:\n\
- add sl, pc, sl\n\
-.L_GOT_GOT:\n\
+ adr r6, .L_GET_GOT\n\
+ add sl, sl, r6\n\
ldr r4, [sl, r4]\n\
@ save the entry point in another register\n\
mov r6, r0\n\
@@ -210,7 +227,7 @@
b .L_done_fixup\n\
\n\
.L_GET_GOT:\n\
- .word _GLOBAL_OFFSET_TABLE_ - .L_GOT_GOT - 4\n\
+ .word _GLOBAL_OFFSET_TABLE_ - .L_GET_GOT\n\
.L_SKIP_ARGS:\n\
.word _dl_skip_args(GOTOFF)\n\
.L_FINI_PROC:\n\
Index: sysdeps/arm/machine-gmon.h
===================================================================
RCS file: /cvs/glibc/ports/sysdeps/arm/machine-gmon.h,v
retrieving revision 1.7
retrieving revision 1.8
diff -u -r1.7 -r1.8
--- sysdeps/arm/machine-gmon.h 10 Oct 2005 15:09:14 -0000 1.7
+++ sysdeps/arm/machine-gmon.h 5 Feb 2009 14:46:41 -0000 1.8
@@ -50,6 +50,28 @@
}
*/
+#ifdef __thumb2__
+
+#define MCOUNT \
+void _mcount (void) \
+{ \
+ __asm__("push {r0, r1, r2, r3};" \
+ "movs fp, fp;" \
+ "it eq;" \
+ "moveq r1, #0;" \
+ "itttt ne;" \
+ "ldrne r1, [fp, $-4];" \
+ "ldrne r0, [fp, $-12];" \
+ "movnes r0, r0;" \
+ "ldrne r0, [r0, $-4];" \
+ "movs r0, r0;" \
+ "it ne;" \
+ "blne mcount_internal;" \
+ "pop {r0, r1, r2, r3}"); \
+}
+
+#else
+
#define MCOUNT \
void _mcount (void) \
{ \
@@ -65,3 +87,4 @@
"ldmia sp!, {r0, r1, r2, r3}"); \
}
+#endif
Index: sysdeps/arm/tls-macros.h
===================================================================
RCS file: /cvs/glibc/ports/sysdeps/arm/tls-macros.h,v
retrieving revision 1.1
retrieving revision 1.2
diff -u -r1.1 -r1.2
--- sysdeps/arm/tls-macros.h 5 Oct 2005 20:15:21 -0000 1.1
+++ sysdeps/arm/tls-macros.h 5 Feb 2009 14:46:41 -0000 1.2
@@ -1,14 +1,36 @@
+#ifdef __thumb2__
+#define ARM_PC_OFFSET "4"
+#else
+#define ARM_PC_OFFSET "8"
+#endif
+
#define TLS_LE(x) \
({ int *__result; \
void *tp = __builtin_thread_pointer (); \
asm ("ldr %0, 1f; " \
"add %0, %1, %0; " \
"b 2f; " \
+ ".align 2; " \
"1: .word " #x "(tpoff); " \
"2: " \
: "=&r" (__result) : "r" (tp)); \
__result; })
+#ifdef __thumb2__
+#define TLS_IE(x) \
+ ({ int *__result; \
+ void *tp = __builtin_thread_pointer (); \
+ asm ("ldr %0, 1f; " \
+ "3: add %0, pc, %0;" \
+ "ldr %0, [%0];" \
+ "add %0, %1, %0; " \
+ "b 2f; " \
+ ".align 2; " \
+ "1: .word " #x "(gottpoff) + (. - 3b - 4); " \
+ "2: " \
+ : "=&r" (__result) : "r" (tp)); \
+ __result; })
+#else
#define TLS_IE(x) \
({ int *__result; \
void *tp = __builtin_thread_pointer (); \
@@ -16,10 +38,12 @@
"3: ldr %0, [pc, %0];" \
"add %0, %1, %0; " \
"b 2f; " \
+ ".align 2; " \
"1: .word " #x "(gottpoff) + (. - 3b - 8); " \
"2: " \
: "=&r" (__result) : "r" (tp)); \
__result; })
+#endif
#define TLS_LD(x) \
({ char *__result; \
@@ -28,12 +52,14 @@
asm ("ldr %0, 2f; " \
"1: add %0, pc, %0; " \
"b 3f; " \
- "2: .word " #x "(tlsldm) + (. - 1b - 8); " \
+ ".align 2; " \
+ "2: .word " #x "(tlsldm) + (. - 1b - "ARM_PC_OFFSET"); " \
"3: " \
: "=r" (__result)); \
__result = (char *)__tls_get_addr (__result); \
asm ("ldr %0, 1f; " \
"b 2f; " \
+ ".align 2; " \
"1: .word " #x "(tlsldo); " \
"2: " \
: "=r" (__offset)); \
@@ -45,7 +71,8 @@
asm ("ldr %0, 2f; " \
"1: add %0, pc, %0; " \
"b 3f; " \
- "2: .word " #x "(tlsgd) + (. - 1b - 8); " \
+ ".align 2; " \
+ "2: .word " #x "(tlsgd) + (. - 1b - "ARM_PC_OFFSET"); " \
"3: " \
: "=r" (__result)); \
(int *)__tls_get_addr (__result); })
Index: sysdeps/arm/elf/start.S
===================================================================
RCS file: /cvs/glibc/ports/sysdeps/arm/elf/start.S,v
retrieving revision 1.10
retrieving revision 1.11
diff -u -r1.10 -r1.11
--- sysdeps/arm/elf/start.S 27 Jan 2009 16:01:19 -0000 1.10
+++ sysdeps/arm/elf/start.S 5 Feb 2009 14:46:42 -0000 1.11
@@ -58,6 +58,10 @@
...
NULL
*/
+#if defined(__thumb2__)
+ .thumb
+ .syntax unified
+#endif
.text
.globl _start
Index: sysdeps/unix/sysv/linux/arm/eabi/sysdep.h
===================================================================
RCS file: /cvs/glibc/ports/sysdeps/unix/sysv/linux/arm/eabi/sysdep.h,v
retrieving revision 1.4
retrieving revision 1.5
diff -u -r1.4 -r1.5
--- sysdeps/unix/sysv/linux/arm/eabi/sysdep.h 12 Sep 2007 12:57:25 -0000 1.4
+++ sysdeps/unix/sysv/linux/arm/eabi/sysdep.h 5 Feb 2009 14:46:42 -0000 1.5
@@ -44,6 +44,30 @@
argument; otherwise the (optional) compatibility code for APCS binaries
may be invoked. */
+#ifdef __thumb__
+/* Hide the use of r7 from the compiler, this would be a lot
+ easier but for the fact that the syscalls can exceed 255.
+ For the moment the LOAD_ARGS_7 is sacrificed.
+ We can't use push/pop inside the asm because that breaks
+ unwinding (ie. thread cancellation). */
+#undef LOAD_ARGS_7
+#undef INTERNAL_SYSCALL_RAW
+#define INTERNAL_SYSCALL_RAW(name, err, nr, args...) \
+ ({ \
+ int _sys_buf[2]; \
+ register int _a1 asm ("a1"); \
+ register int *_r6 asm ("r6") = _sys_buf; \
+ *_r6 = name; \
+ LOAD_ARGS_##nr (args) \
+ asm volatile ("str r7, [r6, #4]\n\t" \
+ "ldr r7, [r6]\n\t" \
+ "swi 0 @ syscall " #name "\n\t" \
+ "ldr r7, [r6, #4]" \
+ : "=r" (_a1) \
+ : "r" (_r6) ASM_ARGS_##nr \
+ : "memory"); \
+ _a1; })
+#else /* ARM */
#undef INTERNAL_SYSCALL_RAW
#define INTERNAL_SYSCALL_RAW(name, err, nr, args...) \
({ \
@@ -55,6 +79,7 @@
: "r" (_nr) ASM_ARGS_##nr \
: "memory"); \
_a1; })
+#endif
/* For EABI, non-constant syscalls are actually pretty easy... */
#undef INTERNAL_SYSCALL_NCS
Index: sysdeps/unix/sysv/linux/arm/eabi/nptl/aio_misc.h
===================================================================
RCS file: sysdeps/unix/sysv/linux/arm/eabi/nptl/aio_misc.h
diff -N sysdeps/unix/sysv/linux/arm/eabi/nptl/aio_misc.h
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ sysdeps/unix/sysv/linux/arm/eabi/nptl/aio_misc.h 5 Feb 2009 14:46:42 -0000 1.1
@@ -0,0 +1,52 @@
+/* Copyright (C) 2008 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include_next <aio_misc.h>
+
+#ifdef __thumb2__
+
+#include <errno.h>
+
+/* The Thumb-2 definition of INTERNAL_SYSCALL_RAW has to hide the use
+ of r7 from the compiler because it cannot handle asm clobbering the
+ hard frame pointer. In aio_suspend, GCC does not eliminate the
+ hard frame pointer because the function uses variable-length
+ arrays, so it generates unwind information using r7 as virtual
+ stack pointer. During system calls, when r7 has been saved on the
+ stack, this means the unwind information is invalid. Without extra
+ unwind directives, which would need to cause unwind information for
+ the asm to be generated separately from that for the parts of the
+ function before and after the asm (with three index table entries),
+ it is not possible to represent any temporary change to the virtual
+ stack pointer. Instead, we move the problematic system calls out
+ of line into a function that does not require a frame pointer. */
+
+static __attribute_noinline__ void
+aio_misc_wait (int *resultp,
+ volatile int *futexp,
+ const struct timespec *timeout,
+ int cancel)
+{
+ AIO_MISC_WAIT (*resultp, *futexp, timeout, cancel);
+}
+
+#undef AIO_MISC_WAIT
+#define AIO_MISC_WAIT(result, futex, timeout, cancel) \
+ aio_misc_wait (&result, &futex, timeout, cancel)
+
+#endif
Index: sysdeps/unix/sysv/linux/arm/eabi/nptl/unwind-forcedunwind.c
===================================================================
RCS file: /cvs/glibc/ports/sysdeps/unix/sysv/linux/arm/eabi/nptl/unwind-forcedunwind.c,v
retrieving revision 1.2
retrieving revision 1.3
diff -u -r1.2 -r1.3
--- sysdeps/unix/sysv/linux/arm/eabi/nptl/unwind-forcedunwind.c 10 Jul 2007 13:35:28 -0000 1.2
+++ sysdeps/unix/sysv/linux/arm/eabi/nptl/unwind-forcedunwind.c 5 Feb 2009 14:46:42 -0000 1.3
@@ -89,7 +89,12 @@
"4: bl pthread_cancel_init\n"
" ldr r3, [r4, r5]\n"
" b 5b\n"
+" .align 2\n"
+#ifdef __thumb2__
+"1: .word _GLOBAL_OFFSET_TABLE_ - 3b - 4\n"
+#else
"1: .word _GLOBAL_OFFSET_TABLE_ - 3b - 8\n"
+#endif
"2: .word libgcc_s_resume(GOTOFF)\n"
" .size _Unwind_Resume, .-_Unwind_Resume\n"
);
Index: sysdeps/unix/sysv/linux/arm/eabi/nptl/unwind-resume.c
===================================================================
RCS file: /cvs/glibc/ports/sysdeps/unix/sysv/linux/arm/eabi/nptl/unwind-resume.c,v
retrieving revision 1.1
retrieving revision 1.2
diff -u -r1.1 -r1.2
--- sysdeps/unix/sysv/linux/arm/eabi/nptl/unwind-resume.c 16 Nov 2005 19:03:42 -0000 1.1
+++ sysdeps/unix/sysv/linux/arm/eabi/nptl/unwind-resume.c 5 Feb 2009 14:46:42 -0000 1.2
@@ -66,7 +66,12 @@
"4: bl init\n"
" ldr r3, [r4, r5]\n"
" b 5b\n"
+" .align 2\n"
+#ifdef __thumb2__
+"1: .word _GLOBAL_OFFSET_TABLE_ - 3b - 4\n"
+#else
"1: .word _GLOBAL_OFFSET_TABLE_ - 3b - 8\n"
+#endif
"2: .word libgcc_s_resume(GOTOFF)\n"
" .size _Unwind_Resume, .-_Unwind_Resume\n"
);
Index: sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h
===================================================================
RCS file: /cvs/glibc/ports/sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h,v
retrieving revision 1.2
retrieving revision 1.3
diff -u -r1.2 -r1.3
--- sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h 2 Jun 2008 01:57:03 -0000 1.2
+++ sysdeps/unix/sysv/linux/arm/nptl/bits/atomic.h 5 Feb 2009 14:46:42 -0000 1.3
@@ -37,12 +37,21 @@
void __arm_link_error (void);
+#ifdef __thumb2__
+#define atomic_full_barrier() \
+ __asm__ __volatile__ \
+ ("movw\tip, #0x0fa0\n\t" \
+ "movt\tip, #0xffff\n\t" \
+ "blx\tip" \
+ : : : "ip", "lr", "cc", "memory");
+#else
#define atomic_full_barrier() \
__asm__ __volatile__ \
("mov\tip, #0xffff0fff\n\t" \
"mov\tlr, pc\n\t" \
"add\tpc, ip, #(0xffff0fa0 - 0xffff0fff)" \
: : : "ip", "lr", "cc", "memory");
+#endif
/* Atomic compare and exchange. This sequence relies on the kernel to
provide a compare and exchange operation which is atomic on the
@@ -59,6 +68,32 @@
specify one to work around GCC PR rtl-optimization/21223. Otherwise
it may cause a_oldval or a_tmp to be moved to a different register. */
+#ifdef __thumb2__
+/* Thumb-2 has ldrex/strex. However it does not have barrier instructions,
+ so we still need to use the kernel helper. */
+#define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval) \
+ ({ register __typeof (oldval) a_oldval asm ("r0"); \
+ register __typeof (oldval) a_newval asm ("r1") = (newval); \
+ register __typeof (mem) a_ptr asm ("r2") = (mem); \
+ register __typeof (oldval) a_tmp asm ("r3"); \
+ register __typeof (oldval) a_oldval2 asm ("r4") = (oldval); \
+ __asm__ __volatile__ \
+ ("0:\tldr\t%[tmp],[%[ptr]]\n\t" \
+ "cmp\t%[tmp], %[old2]\n\t" \
+ "bne\t1f\n\t" \
+ "mov\t%[old], %[old2]\n\t" \
+ "movw\t%[tmp], #0x0fc0\n\t" \
+ "movt\t%[tmp], #0xffff\n\t" \
+ "blx\t%[tmp]\n\t" \
+ "bcc\t0b\n\t" \
+ "mov\t%[tmp], %[old2]\n\t" \
+ "1:" \
+ : [old] "=&r" (a_oldval), [tmp] "=&r" (a_tmp) \
+ : [new] "r" (a_newval), [ptr] "r" (a_ptr), \
+ [old2] "r" (a_oldval2) \
+ : "ip", "lr", "cc", "memory"); \
+ a_tmp; })
+#else
#define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval) \
({ register __typeof (oldval) a_oldval asm ("r0"); \
register __typeof (oldval) a_newval asm ("r1") = (newval); \
@@ -81,6 +116,7 @@
[old2] "r" (a_oldval2) \
: "ip", "lr", "cc", "memory"); \
a_tmp; })
+#endif
#define __arch_compare_and_exchange_val_64_acq(mem, newval, oldval) \
({ __arm_link_error (); oldval; })
--
Joseph S. Myers
joseph@codesourcery.com