All, I've posted the initial archive containing my modifications to the mailing list in October. Alas, no response to that post. I did however, take the time to sync out the development tree and put my modifications in there. This all compiles now and the diffs are attached to this email (svn diff)
Can anyone take a look and see if there is anything else they'd like me to do in order for this patch to be taken into the downstream uclibc versions? This patch is currently working for arm, and i386. You will need to compile your sources with the option -mapcs using gcc if you rely on this feature. If there is any interest, I can keep plugging away on implementing the backtrace_sym.c and backtrace_symfd.c BTW, awesome build system :) - Eivind
Index: include/execinfo.h =================================================================== --- include/execinfo.h (revision 0) +++ include/execinfo.h (revision 0) @@ -0,0 +1,44 @@ +/* Copyright (C) 1998, 1999, 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 _EXECINFO_H +#define _EXECINFO_H 1 + +#include <features.h> + +__BEGIN_DECLS + +/* Store up to SIZE return address of the current program state in + ARRAY and return the exact number of values stored. */ +extern int backtrace (void **__array, int __size) __nonnull ((1)); + + +/* Return names of functions from the backtrace list in ARRAY in a newly + malloc()ed memory block. */ +extern char **backtrace_symbols (void *__const *__array, int __size) + __THROW __nonnull ((1)); + + +/* This function is similar to backtrace_symbols() but it writes the result + immediately to a file. */ +extern void backtrace_symbols_fd (void *__const *__array, int __size, int __fd) + __THROW __nonnull ((1)); + +__END_DECLS + +#endif /* execinfo.h */ Index: Rules.mak =================================================================== --- Rules.mak (revision 20450) +++ Rules.mak (working copy) @@ -199,7 +199,7 @@ CPU_LDFLAGS-$(ARCH_BIG_ENDIAN)+=-Wl,-EB CPU_CFLAGS-$(ARCH_LITTLE_ENDIAN)+=-mlittle-endian CPU_CFLAGS-$(ARCH_BIG_ENDIAN)+=-mbig-endian - CPU_CFLAGS-$(CONFIG_GENERIC_ARM)+= + CPU_CFLAGS-$(CONFIG_GENERIC_ARM)+=-mapcs CPU_CFLAGS-$(CONFIG_ARM610)+=-mtune=arm610 -march=armv3 CPU_CFLAGS-$(CONFIG_ARM710)+=-mtune=arm710 -march=armv3 CPU_CFLAGS-$(CONFIG_ARM7TDMI)+=-mtune=arm7tdmi -march=armv4t Index: libc/sysdeps/linux/arm/frame.h =================================================================== --- libc/sysdeps/linux/arm/frame.h (revision 0) +++ libc/sysdeps/linux/arm/frame.h (revision 0) @@ -0,0 +1,56 @@ +/* frame.h for generating stack traces on an ARM architecture. + * + * Copyright (C) 2007 Eivind Naess <[EMAIL PROTECTED]>, + * Watchguard Technologies, Inc. http://www.watchguard.com + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU Library General Public License as published by + * the Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + * + * This program 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 Library General Public License + * for more details. + * + * You should have received a copy of the GNU Library General Public License + * along with this program; if not, write to the Free Software Foundation, + * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +/* + * There are 4 registers pushed onto the stack if the APCS (ARM Procedure Calling Standard) compatible + * frames are enabled, FP (Frame Pointer), SP (Stack Pointer), LR (Link Register), and + * PC (Program Counter). + * + * LR contains the abosulute return address to where the current frame was called from, the PC holds the + * address of the function this frame was called from. The SP holds the previous top of stack. The FP holds + * the address of the previous frame. + * + * If you use optimization then, you will need to enable -mapcs or -mapcs-frame which ensures that + * each function have a function prologue that pushes FP, SP, IP, and PC onto the stack. Please consult + * your toolchain options and processor handbook. + * + * This was tested on a Intel IXP425 platform with an Big-Endian ARM (XScale) processor). Configured for + * CONFIG_GENERIC_ARM=y. + */ + +struct layout { + + struct layout *next; /*! This is the FP pointing to the previous frame */ + void *sp; /*! This is the SP pointing to the top of previous frame */ + void *return_address; /*! This is the RA pointing to the location to return */ + void *pc; /*! This is the PC pointing to the caller function */ +}; + + +#define FIRST_FRAME_POINTER (__builtin_frame_address(0) - 12) + +#define ADVANCE_STACK_FRAME(next) (struct layout *) ((int)next - 12) + +#define DEBUG_PRINT_FRAME(frame) \ + printf("FP: 0x%08lx, IP: 0x%08lx, LR: 0x%08lx, PC: 0x%08lx\n", frame->next, \ + frame->sp, frame->return_address, frame->pc) + + + Index: libc/sysdeps/linux/arm/backtrace.c =================================================================== --- libc/sysdeps/linux/arm/backtrace.c (revision 0) +++ libc/sysdeps/linux/arm/backtrace.c (revision 0) @@ -0,0 +1,142 @@ +/* backtrace.c for the generic platform. + * + * Copyright (C) 2007 Eivind Naess <[EMAIL PROTECTED]>, + * Watchguard Technologies, Inc. http://www.watchguard.com + * + * The original file was a part of the GNU C Library licensed under the LGPL + * Copyright (C) 1998, 2000, 2002, 2004 Free Software Foundation, Inc. + * Contributed by Ulrich Drepper <[EMAIL PROTECTED]>, 1998. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU Library General Public License as published by + * the Free Software Foundation; either version 2.1 of the License, or (at your + * option) any later version. + * + * This program 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 Library General Public License + * for more details. + * + * You should have received a copy of the GNU Library General Public License + * along with this program; if not, write to the Free Software Foundation, + * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include <execinfo.h> +#include "frame.h" + +/* + * Secretly exported by uClibc or glibc. + */ +extern void *__libc_stack_end; + + +/* + * Get some notion of the current stack. Need not be exactly the top + * of the stack, just something somewhere in the current frame. + */ +#ifndef CURRENT_STACK_FRAME +#define CURRENT_STACK_FRAME ({ char __csf; &__csf; }) +#endif + + +/* + * By default we assume that the stack grows downward. + */ +#ifndef INNER_THAN +#define INNER_THAN < +#endif + + +/* + * By default assume the `next' pointer in struct layout points to the + * next struct layout. + */ +#ifndef ADVANCE_STACK_FRAME +#define ADVANCE_STACK_FRAME(next) (struct layout *) ( next ) +#endif + + +/* + * By default, the frame pointer is just what we get from gcc. + */ +#ifndef FIRST_FRAME_POINTER +#define FIRST_FRAME_POINTER __builtin_frame_address (0) +#endif + +#ifndef DEBUG_PRINT_FRAME +#define DEBUG_PRINT_FRAME(frame) {} +#endif + +/* + * This implementation of backtrace walks the stack-frames, reads the return address and + * frame pointer of next frame. + * + * There is arguably a better way of getting around this by using GCC's __Unwind_Backtrace, + * but my preliminary investigation found that it returned after calling the provided + * function callback only once. For those of you who are interested in this, there is an + * excellent library called libunwind (www.hpl.hp.com/research/linux/libunwind/) that gets + * you a stacktrace the same way (stripped < ~40K). + * + * Do not compile with -fomit-frame-pointer, this will cause the compiler to possibly + * remove the stack frames we are walking. + */ + +int __backtrace (void **array, int size) +{ + struct layout *current = (struct layout*)0; + struct layout *next = (struct layout*)0; + + void *top_frame; + void *top_stack; + + int cnt = 0; + top_frame = FIRST_FRAME_POINTER; + top_stack = CURRENT_STACK_FRAME; + + current = (struct layout*) top_frame; + +#ifdef DEBUG + printf("top_frame: 0x%08lx, top_stack: 0x%08lx\n", top_frame, top_stack); + DEBUG_PRINT_FRAME(current); +#endif + + /* + * We skip the call to this function, it makes no sense to record it. + */ + while ( cnt < size ) { + + /* Make sure we don't cross the upper bound */ + if (!current || (void *) current INNER_THAN top_stack || + !((void *) current INNER_THAN __libc_stack_end)) { + + break; + } + + next = ADVANCE_STACK_FRAME(current->next); + + /* Make sure next is valid and we are not in a loop */ + if ( !next || next == current ) + break; + + /* Make sure we are moving in the right direction */ + if ( next INNER_THAN current ) + break; + + /* Don't record (NULL) addresses */ + if ( !current->return_address ) + break; + +#ifdef DEBUG + DEBUG_PRINT_FRAME(current); +#endif + array[cnt++] = current->return_address; + current = next; + } + + return cnt; +} + +weak_alias(__backtrace, backtrace) + + Index: libc/sysdeps/linux/common/backtrace.c =================================================================== --- libc/sysdeps/linux/common/backtrace.c (revision 0) +++ libc/sysdeps/linux/common/backtrace.c (revision 0) @@ -0,0 +1,38 @@ +/* backtrace.c for the generic platform. + * + * Copyright (C) 2007 Eivind Naess <[EMAIL PROTECTED]>, + * Watchguard Technologies, Inc. http://www.watchguard.com + * + * The original file was a part of the GNU C Library licensed under the LGPL + * Copyright (C) 1998, 2000, 2002, 2004 Free Software Foundation, Inc. + * Contributed by Ulrich Drepper <[EMAIL PROTECTED]>, 1998. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU Library General Public License as published by + * the Free Software Foundation; either version 2.1 of the License, or (at your + * option) any later version. + * + * This program 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 Library General Public License + * for more details. + * + * You should have received a copy of the GNU Library General Public License + * along with this program; if not, write to the Free Software Foundation, + * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include <execinfo.h> + +int __backtrace (void **array, int size) +{ + /* + * Not implemented for common, architecture specific. + */ + return -1; +} + +link_warning(__backtrace, "the `backtrace()' function is a stub. Do you really need it?") +weak_alias(__backtrace, backtrace) + + Index: libc/sysdeps/linux/common/backtrace_symsfd.c =================================================================== --- libc/sysdeps/linux/common/backtrace_symsfd.c (revision 0) +++ libc/sysdeps/linux/common/backtrace_symsfd.c (revision 0) @@ -0,0 +1,30 @@ +/* backtrace.c for the generic platform. + * + * Copyright (C) 2007 Eivind Naess <[EMAIL PROTECTED]>, + * Watchguard Technologies, Inc. http://www.watchguard.com + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU Library General Public License as published by + * the Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + * + * This program 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 Library General Public License + * for more details. + * + * You should have received a copy of the GNU Library General Public License + * along with this program; if not, write to the Free Software Foundation, + * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include <execinfo.h> + +void __backtrace_symbols_fd (void *__const *__array, int __size, int __fd) +{ + return; +} + +link_warning(__backtrace_symbols_fd, "the `backtrace_symbols_fd()' function is a stub. Do you really need it?") +weak_alias(__backtrace_symbols_fd, backtrace_symbols_fd) + Index: libc/sysdeps/linux/common/backtrace_syms.c =================================================================== --- libc/sysdeps/linux/common/backtrace_syms.c (revision 0) +++ libc/sysdeps/linux/common/backtrace_syms.c (revision 0) @@ -0,0 +1,33 @@ +/* backtrace.c for the generic platform. + * + * Copyright (C) 2007 Eivind Naess <[EMAIL PROTECTED]>, + * Watchguard Technologies, Inc. http://www.watchguard.com + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU Library General Public License as published by + * the Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + * + * This program 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 Library General Public License + * for more details. + * + * You should have received a copy of the GNU Library General Public License + * along with this program; if not, write to the Free Software Foundation, + * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include <execinfo.h> + + +char **__backtrace_symbols( void *__const *__array, int __size ) +{ + return (char**)0; +} + +link_warning(__backtrace_symbols, "the `backtrace_symbols()' function is a stub. Do you really need it?") +weak_alias(__backtrace_symbols, backtrace_symbols) + + + Index: libc/sysdeps/linux/i386/frame.h =================================================================== --- libc/sysdeps/linux/i386/frame.h (revision 0) +++ libc/sysdeps/linux/i386/frame.h (revision 0) @@ -0,0 +1,43 @@ +/* frame.h for generating stack traces on a i386/i686 architecture. + * + * Copyright (C) 2007 Eivind Naess <[EMAIL PROTECTED]>, + * Watchguard Technologies, Inc. http://www.watchguard.com + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU Library General Public License as published by + * the Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + * + * This program 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 Library General Public License + * for more details. + * + * You should have received a copy of the GNU Library General Public License + * along with this program; if not, write to the Free Software Foundation, + * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +/* + * The Stack Frames on an i686/i386 consists of two values, EBP (Frame Pointer) and EIP (Instruction + * Pointer). The latter is the return address. + * + * +-----------------+ +-----------------+ + * %ebp -> | %ebp last frame-|------> | %ebp last frame-|->... + * | | | | + * | return address | | return address | + * +-----------------+ +-----------------+ + */ +struct layout { + + struct layout *next; /*! Holds the previous value of EBP (Frame Pointer) */ + void *return_address; /*! Holds the previous value of EIP (Return Address) */ +}; + +#define FIRST_FRAME_POINTER (__builtin_frame_address(0)) + +#define ADVANCE_STACK_FRAME(next) (struct layout *)((int)next) + +#define DEBUG_PRINT_FRAME(frame) \ + printf("EBP: 0x%08lx, EIP: 0x%08lx\n", frame->next, frame->return_address) + Index: libc/sysdeps/linux/i386/backtrace.c =================================================================== --- libc/sysdeps/linux/i386/backtrace.c (revision 0) +++ libc/sysdeps/linux/i386/backtrace.c (revision 0) @@ -0,0 +1,142 @@ +/* backtrace.c for the generic platform. + * + * Copyright (C) 2007 Eivind Naess <[EMAIL PROTECTED]>, + * Watchguard Technologies, Inc. http://www.watchguard.com + * + * The original file was a part of the GNU C Library licensed under the LGPL + * Copyright (C) 1998, 2000, 2002, 2004 Free Software Foundation, Inc. + * Contributed by Ulrich Drepper <[EMAIL PROTECTED]>, 1998. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU Library General Public License as published by + * the Free Software Foundation; either version 2.1 of the License, or (at your + * option) any later version. + * + * This program 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 Library General Public License + * for more details. + * + * You should have received a copy of the GNU Library General Public License + * along with this program; if not, write to the Free Software Foundation, + * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include <execinfo.h> +#include "frame.h" + +/* + * Secretly exported by uClibc or glibc. + */ +extern void *__libc_stack_end; + + +/* + * Get some notion of the current stack. Need not be exactly the top + * of the stack, just something somewhere in the current frame. + */ +#ifndef CURRENT_STACK_FRAME +#define CURRENT_STACK_FRAME ({ char __csf; &__csf; }) +#endif + + +/* + * By default we assume that the stack grows downward. + */ +#ifndef INNER_THAN +#define INNER_THAN < +#endif + + +/* + * By default assume the `next' pointer in struct layout points to the + * next struct layout. + */ +#ifndef ADVANCE_STACK_FRAME +#define ADVANCE_STACK_FRAME(next) (struct layout *) ( next ) +#endif + + +/* + * By default, the frame pointer is just what we get from gcc. + */ +#ifndef FIRST_FRAME_POINTER +#define FIRST_FRAME_POINTER __builtin_frame_address (0) +#endif + +#ifndef DEBUG_PRINT_FRAME +#define DEBUG_PRINT_FRAME(frame) {} +#endif + +/* + * This implementation of backtrace walks the stack-frames, reads the return address and + * frame pointer of next frame. + * + * There is arguably a better way of getting around this by using GCC's __Unwind_Backtrace, + * but my preliminary investigation found that it returned after calling the provided + * function callback only once. For those of you who are interested in this, there is an + * excellent library called libunwind (www.hpl.hp.com/research/linux/libunwind/) that gets + * you a stacktrace the same way (stripped < ~40K). + * + * Do not compile with -fomit-frame-pointer, this will cause the compiler to possibly + * remove the stack frames we are walking. + */ + +int __backtrace (void **array, int size) +{ + struct layout *current = (struct layout*)0; + struct layout *next = (struct layout*)0; + + void *top_frame; + void *top_stack; + + int cnt = 0; + top_frame = FIRST_FRAME_POINTER; + top_stack = CURRENT_STACK_FRAME; + + current = (struct layout*) top_frame; + +#ifdef DEBUG + printf("top_frame: 0x%08lx, top_stack: 0x%08lx\n", top_frame, top_stack); + DEBUG_PRINT_FRAME(current); +#endif + + /* + * We skip the call to this function, it makes no sense to record it. + */ + while ( cnt < size ) { + + /* Make sure we don't cross the upper bound */ + if (!current || (void *) current INNER_THAN top_stack || + !((void *) current INNER_THAN __libc_stack_end)) { + + break; + } + + next = ADVANCE_STACK_FRAME(current->next); + + /* Make sure next is valid and we are not in a loop */ + if ( !next || next == current ) + break; + + /* Make sure we are moving in the right direction */ + if ( next INNER_THAN current ) + break; + + /* Don't record (NULL) addresses */ + if ( !current->return_address ) + break; + +#ifdef DEBUG + DEBUG_PRINT_FRAME(current); +#endif + array[cnt++] = current->return_address; + current = next; + } + + return cnt; +} + +weak_alias(__backtrace, backtrace) + +
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