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ARM EABI support - changes to existing ARM code
- From: Daniel Jacobowitz <drow at false dot org>
- To: libc-alpha at sources dot redhat dot com
- Cc: Phil Blundell <pb at reciva dot com>
- Date: Tue, 22 Mar 2005 11:08:19 -0500
- Subject: ARM EABI support - changes to existing ARM code
This patch updates the common ARM files for EABI support. The changes are:
- Old ARM ABI targets always use FPA (mixed-endian) byte ordering. EABI
targets always use VFP byte ordering for doubles, which is standard
ieee754 layout. Removing the arm-specific ieee754.h doesn't break FPA;
it was a specialized version of the common header, which handles FPA
but also handles VFP.
- The stack needs to be aligned to eight bytes instead of just four,
including in mmap2 and when shifting _dl_argv.
- We need some markers around _start to indicate end-of-stack for the
unwinder - ARM EABI does not use either SJLJ exceptions or DWARF-2
exceptions. It uses a table based format which seems to be not
quite completely unlike DWARF-2.
Do these changes look OK?
--
Daniel Jacobowitz
CodeSourcery, LLC
2005-03-22 Daniel Jacobowitz <dan@codesourcery.com>
* sysdeps/arm/bits/endian.h (__FLOAT_WORD_ORDER): Handle VFP.
* sysdeps/arm/gmp-mparam.h (IEEE_DOUBLE_BIG_ENDIAN,
IEEE_DOUBLE_MIXED_ENDIAN): Handle big-endian and VFP.
* sysdeps/arm/ieee754.h: Remove.
* sysdeps/arm/dl-machine.h (_dl_start_user): Align the stack to eight
bytes even when shifting arguments.
* sysdeps/arm/dl-sysdep.h: New file.
* sysdeps/arm/elf/start.S (_start): If not using SJLJ exceptions, include
EABI unwind markers to terminate unwinding.
* sysdeps/unix/sysv/linux/arm/mmap64.S: Handle big-endian byte ordering
and EABI stack layout.
Index: glibc/sysdeps/arm/bits/endian.h
===================================================================
--- glibc.orig/sysdeps/arm/bits/endian.h 2005-03-22 10:26:27.092978200 -0500
+++ glibc/sysdeps/arm/bits/endian.h 2005-03-22 10:27:39.457490903 -0500
@@ -9,4 +9,9 @@
#else
#define __BYTE_ORDER __LITTLE_ENDIAN
#endif
+
+#ifdef __VFP_FP__
+#define __FLOAT_WORD_ORDER __BYTE_ORDER
+#else
#define __FLOAT_WORD_ORDER __BIG_ENDIAN
+#endif
Index: glibc/sysdeps/arm/dl-machine.h
===================================================================
--- glibc.orig/sysdeps/arm/dl-machine.h 2005-03-22 10:26:27.092978200 -0500
+++ glibc/sysdeps/arm/dl-machine.h 2005-03-22 10:27:39.457490903 -0500
@@ -156,22 +156,19 @@ _dl_start_user:\n\
add sl, pc, sl\n\
.L_GOT_GOT:\n\
ldr r4, [sl, r4]\n\
- @ get the original arg count\n\
- ldr r1, [sp]\n\
@ save the entry point in another register\n\
mov r6, r0\n\
- @ adjust the stack pointer to skip the extra args\n\
- add sp, sp, r4, lsl #2\n\
- @ subtract _dl_skip_args from original arg count\n\
- sub r1, r1, r4\n\
+ @ get the original arg count\n\
+ ldr r1, [sp]\n\
@ get the argv address\n\
add r2, sp, #4\n\
- @ store the new argc in the new stack location\n\
- str r1, [sp]\n\
+ @ Fix up the stack if necessary.\n\
+ cmp r4, #0\n\
+ bne .L_fixup_stack\n\
+.L_done_fixup:\n\
@ compute envp\n\
add r3, r2, r1, lsl #2\n\
add r3, r3, #4\n\
-\n\
@ now we call _dl_init\n\
ldr r0, .L_LOADED\n\
ldr r0, [sl, r0]\n\
@@ -182,12 +179,45 @@ _dl_start_user:\n\
add r0, sl, r0\n\
@ jump to the user_s entry point\n\
" BX(r6) "\n\
+\n\
+ @ iWMMXt and EABI targets require the stack to be eight byte\n\
+ @ aligned - shuffle arguments etc.\n\
+.L_fixup_stack:\n\
+ @ subtract _dl_skip_args from original arg count\n\
+ sub r1, r1, r4\n\
+ @ store the new argc in the new stack location\n\
+ str r1, [sp]\n\
+ @ find the first unskipped argument\n\
+ mov r3, r2\n\
+ add r4, r2, r4, lsl #2\n\
+ @ shuffle argv down\n\
+1: ldr r5, [r4], #4\n\
+ str r5, [r3], #4\n\
+ cmp r5, #0\n\
+ bne 1b\n\
+ @ shuffle envp down\n\
+1: ldr r5, [r4], #4\n\
+ str r5, [r3], #4\n\
+ cmp r5, #0\n\
+ bne 1b\n\
+ @ shuffle auxv down\n\
+1: ldmia r4!, {r0, r5}\n\
+ stmia r3!, {r0, r5}\n\
+ cmp r0, #0\n\
+ bne 1b\n\
+ @ Update _dl_argv\n\
+ ldr r3, .L_ARGV\n\
+ str r2, [sl, r3]\n\
+ b .L_done_fixup\n\
+\n\
.L_GET_GOT:\n\
.word _GLOBAL_OFFSET_TABLE_ - .L_GOT_GOT - 4\n\
.L_SKIP_ARGS:\n\
.word _dl_skip_args(GOTOFF)\n\
.L_FINI_PROC:\n\
.word _dl_fini(GOTOFF)\n\
+.L_ARGV:\n\
+ .word _dl_argv(GOTOFF)\n\
.L_LOADED:\n\
.word _rtld_local(GOTOFF)\n\
.previous\n\
Index: glibc/sysdeps/arm/dl-sysdep.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ glibc/sysdeps/arm/dl-sysdep.h 2005-03-22 10:27:39.458490675 -0500
@@ -0,0 +1,41 @@
+/* System-specific settings for dynamic linker code. ARM version.
+ Copyright (C) 2004, 2005 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. */
+
+#ifndef _DL_SYSDEP_H
+#define _DL_SYSDEP_H 1
+
+/* This macro must be defined to either 0 or 1.
+
+ If 1, then an errno global variable hidden in ld.so will work right with
+ all the errno-using libc code compiled for ld.so, and there is never a
+ need to share the errno location with libc. This is appropriate only if
+ all the libc functions that ld.so uses are called without PLT and always
+ get the versions linked into ld.so rather than the libc ones. */
+
+#ifdef IS_IN_rtld
+# define RTLD_PRIVATE_ERRNO 1
+#else
+# define RTLD_PRIVATE_ERRNO 0
+#endif
+
+/* _dl_argv cannot be attribute_relro, because _dl_start_user
+ might write into it after _dl_start returns. */
+#define DL_ARGV_NOT_RELRO 1
+
+#endif /* dl-sysdep.h */
Index: glibc/sysdeps/arm/elf/start.S
===================================================================
--- glibc.orig/sysdeps/arm/elf/start.S 2005-03-22 10:26:27.096977288 -0500
+++ glibc/sysdeps/arm/elf/start.S 2005-03-22 11:00:35.178522707 -0500
@@ -1,5 +1,6 @@
/* Startup code for ARM & ELF
- Copyright (C) 1995, 1996, 1997, 1998, 2001, 2002 Free Software Foundation, Inc.
+ Copyright (C) 1995, 1996, 1997, 1998, 2001, 2002, 2005
+ 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
@@ -62,6 +63,10 @@
.globl _start
.type _start,#function
_start:
+#if !defined(__USING_SJLJ_EXCEPTIONS__)
+ /* Protect against unhandled exceptions. */
+ .fnstart
+#endif
/* Fetch address of fini */
ldr ip, =__libc_csu_fini
@@ -93,6 +98,11 @@ _start:
/* should never get here....*/
bl abort
+#if !defined(__USING_SJLJ_EXCEPTIONS__)
+ .cantunwind
+ .fnend
+#endif
+
/* Define a symbol for the first piece of initialized data. */
.data
.globl __data_start
Index: glibc/sysdeps/arm/gmp-mparam.h
===================================================================
--- glibc.orig/sysdeps/arm/gmp-mparam.h 2005-03-22 10:26:27.092978200 -0500
+++ glibc/sysdeps/arm/gmp-mparam.h 2005-03-22 11:00:42.795683773 -0500
@@ -1,6 +1,6 @@
/* gmp-mparam.h -- Compiler/machine parameter header file.
-Copyright (C) 1991, 1993, 1994, 1995 Free Software Foundation, Inc.
+Copyright (C) 1991, 1993, 1994, 1995, 2005 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
@@ -26,5 +26,13 @@ MA 02111-1307, USA. */
#define BITS_PER_SHORTINT 16
#define BITS_PER_CHAR 8
-#define IEEE_DOUBLE_BIG_ENDIAN 0
-#define IEEE_DOUBLE_MIXED_ENDIAN 1
+#if defined(__ARMEB__)
+# define IEEE_DOUBLE_MIXED_ENDIAN 0
+# define IEEE_DOUBLE_BIG_ENDIAN 1
+#elif defined(__VFP_FP__)
+# define IEEE_DOUBLE_MIXED_ENDIAN 0
+# define IEEE_DOUBLE_BIG_ENDIAN 0
+#else
+# define IEEE_DOUBLE_BIG_ENDIAN 0
+# define IEEE_DOUBLE_MIXED_ENDIAN 1
+#endif
Index: glibc/sysdeps/arm/ieee754.h
===================================================================
--- glibc.orig/sysdeps/arm/ieee754.h 2005-03-22 10:26:27.092978200 -0500
+++ /dev/null 1970-01-01 00:00:00.000000000 +0000
@@ -1,115 +0,0 @@
-/* Copyright (C) 1992, 1995, 1996, 1998 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. */
-
-#ifndef _IEEE754_H
-
-#define _IEEE754_H 1
-#include <features.h>
-
-#include <endian.h>
-
-__BEGIN_DECLS
-
-union ieee754_float
- {
- float f;
-
- /* This is the IEEE 754 single-precision format. */
- struct
- {
- unsigned int mantissa:23;
- unsigned int exponent:8;
- unsigned int negative:1;
- } ieee;
-
- /* This format makes it easier to see if a NaN is a signalling NaN. */
- struct
- {
- unsigned int mantissa:22;
- unsigned int quiet_nan:1;
- unsigned int exponent:8;
- unsigned int negative:1;
- } ieee_nan;
- };
-
-#define IEEE754_FLOAT_BIAS 0x7f /* Added to exponent. */
-
-
-union ieee754_double
- {
- double d;
-
- /* This is the IEEE 754 double-precision format. */
- struct
- {
- unsigned int mantissa0:20;
- unsigned int exponent:11;
- unsigned int negative:1;
- unsigned int mantissa1:32;
- } ieee;
-
- /* This format makes it easier to see if a NaN is a signalling NaN. */
- struct
- {
- unsigned int mantissa0:19;
- unsigned int quiet_nan:1;
- unsigned int exponent:11;
- unsigned int negative:1;
- unsigned int mantissa1:32;
- } ieee_nan;
- };
-
-#define IEEE754_DOUBLE_BIAS 0x3ff /* Added to exponent. */
-
-
-/* The following two structures are correct for `new' floating point systems but
- wrong for the old FPPC. The only solution seems to be to avoid their use on
- old hardware. */
-
-union ieee854_long_double
- {
- long double d;
-
- /* This is the IEEE 854 double-extended-precision format. */
- struct
- {
- unsigned int exponent:15;
- unsigned int empty:16;
- unsigned int negative:1;
- unsigned int mantissa1:32;
- unsigned int mantissa0:32;
- } ieee;
-
- /* This is for NaNs in the IEEE 854 double-extended-precision format. */
- struct
- {
- unsigned int exponent:15;
- unsigned int empty:16;
- unsigned int negative:1;
- unsigned int mantissa1:32;
- unsigned int mantissa0:30;
- unsigned int quiet_nan:1;
- unsigned int one:1;
- } ieee_nan;
- };
-
-#define IEEE854_LONG_DOUBLE_BIAS 0x3fff
-
-__END_DECLS
-
-#endif /* ieee754.h */
Index: glibc/sysdeps/unix/sysv/linux/arm/mmap64.S
===================================================================
--- glibc.orig/sysdeps/unix/sysv/linux/arm/mmap64.S 2005-03-22 10:26:27.097977060 -0500
+++ glibc/sysdeps/unix/sysv/linux/arm/mmap64.S 2005-03-22 11:00:53.051209928 -0500
@@ -1,4 +1,4 @@
-/* Copyright (C) 2000, 2003 Free Software Foundation, Inc.
+/* Copyright (C) 2000, 2003, 2005 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
@@ -23,13 +23,28 @@
#include "kernel-features.h"
+#ifdef __ARM_EABI__
+# define INITIAL_OFFSET 8
+#else
+# define INITIAL_OFFSET 4
+#endif
+
+#ifdef __ARMEB__
+# define LOW_OFFSET INITIAL_OFFSET + 4
+/* The initial + 4 is for the stack postdecrement. */
+# define HIGH_OFFSET 4 + INITIAL_OFFSET + 0
+#else
+# define LOW_OFFSET INITIAL_OFFSET + 0
+# define HIGH_OFFSET 4 + INITIAL_OFFSET + 4
+#endif
+
/* The mmap2 system call takes six arguments, all in registers. */
.text
ENTRY (__mmap64)
#ifdef __NR_mmap2
- ldr ip, [sp, $4] @ offset low part
+ ldr ip, [sp, $LOW_OFFSET] @ offset low part
str r5, [sp, #-4]!
- ldr r5, [sp, $12] @ offset high part
+ ldr r5, [sp, $HIGH_OFFSET] @ offset high part
str r4, [sp, #-4]!
movs r4, ip, lsl $20 @ check that offset is page-aligned
mov ip, ip, lsr $12