架构x86_64
在使用OpenWrt SDK编译gcc package的时候，报如下错误：
i486-openwrt-linux-gnu-gcc -g -O2 -g -Os -O2 -g -O2 -g -Os -DIN_GCC -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition -isystem ./include -fpic -mlong-double-80 -g -DIN_LIBGCC2 -fbuilding-libgcc -fno-stack-protector -fpic -mlong-double-80 -I. -I. -I../../host-i486-openwrt-linux-gnu/gcc -I../.././libgcc -I../.././libgcc/. -I../.././libgcc/../gcc -I../.././libgcc/../include -DHAVE_CC_TLS -DUSE_TLS -o unwind-dw2.o -MT unwind-dw2.o -MD -MP -MF unwind-dw2.dep -fexceptions -c ../.././libgcc/unwind-dw2.c -fvisibility=hidden -DHIDE_EXPORTS cc1: note: someone does not honour COPTS correctly, passed 0 times In file included from ../.././libgcc/unwind-dw2.c:401:0: ./md-unwind-support.h: In function 'x86_fallback_frame_state': ./md-unwind-support.h:141:18: error: field 'uc' has incomplete type struct ucontext uc; ^~ ../.././libgcc/shared-object.mk:14: recipe for target 'unwind-dw2.o' failed make[5]: *** [unwind-dw2.o] Error 1 make[5]: Leaving directory '/home/wang/Desktop/openwrt-x86/build_dir/target-i386_pentium4_glibc/gcc-5.4.0/i486-openwrt-linux-gnu/libgcc' Makefile:12262: recipe for target 'all-target-libgcc' failed make[4]: *** [all-target-libgcc] Error 2 make[4]: Leaving directory '/home/wang/Desktop/openwrt-x86/build_dir/target-i386_pentium4_glibc/gcc-5.4.0' Makefile:879: recipe for target 'all' failed make[3]: *** [all] Error 2 make[3]: Leaving directory '/home/wang/Desktop/openwrt-x86/build_dir/target-i386_pentium4_glibc/gcc-5.4.0' Makefile:176: recipe for target '/home/wang/Desktop/openwrt-x86/build_dir/target-i386_pentium4_glibc/gcc-5.4.0/.built' failed make[2]: *** [/home/wang/Desktop/openwrt-x86/build_dir/target-i386_pentium4_glibc/gcc-5.4.0/.built] Error 2 make[2]: Leaving directory '/home/wang/Desktop/openwrt-x86/feeds/packages/devel/gcc' Command exited with non-zero status 2 time: package/feeds/packages/gcc/compile#1.49#1.08#19.61 package/Makefile:107: recipe for target 'package/feeds/packages/gcc/compile' failed make[1]: *** [package/feeds/packages/gcc/compile] Error 2 make[1]: Leaving directory '/home/wang/Desktop/openwrt-x86' /home/wang/Desktop/openwrt-x86/include/toplevel.mk:216: recipe for target 'package/gcc/compile' failed make: *** [package/gcc/compile] Error 2 wang@wang-VirtualBox:~/Desktop/openwrt-x86$在这里找到灵感：https://github.com/voidlinux/void-packages/issues/7284
解决方案：
修改{openwrt-ROOT}/build_dir/target-x86_64-glibc/gcc-5.4.0/x86_64-openwrt-linux-gnu/libgcc/md-unwind-support.h中的俩处：
Fix1:@line 61: if (*(unsigned char *)(pc+0) == 0x48 && *(unsigned long long *)(pc+1) == RT_SIGRETURN_SYSCALL) { // struct ucontext *uc_ = context->cfa; ucontext_t *uc_ = context->cfa; / The void * cast is necessary to avoid an aliasing warning. The aliasing warning is correct, but should not be a problem because it does not alias anything. */ sc = (struct sigcontext *) (void *) &uc_->uc_mcontext; } Fix2:@line144 { struct rt_sigframe { int sig; siginfo_t *pinfo; void *puc; siginfo_t info; // struct ucontext uc; ucontext_t uc; } *rt_ = context->cfa;
最终效果：
/* DWARF2 EH unwinding support for AMD x86-64 and x86. Copyright (C) 2004-2015 Free Software Foundation, Inc. This file is part of GCC. GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version. GCC 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 General Public License for more details. Under Section 7 of GPL version 3, you are granted additional permissions described in the GCC Runtime Library Exception, version 3.1, as published by the Free Software Foundation. You should have received a copy of the GNU General Public License and a copy of the GCC Runtime Library Exception along with this program; see the files COPYING3 and COPYING.RUNTIME respectively. If not, see <http://www.gnu.org/licenses/>. */ /* Do code reading to identify a signal frame, and set the frame state data appropriately. See unwind-dw2.c for the structs. Don't use this at all if inhibit_libc is used. */ #ifndef inhibit_libc /* There's no sys/ucontext.h for glibc 2.0, so no signal-turned-exceptions for them. There's also no configure-run for the target, so we can't check on (e.g.) HAVE_SYS_UCONTEXT_H. Using the target libc version macro should be enough. */ #if defined __GLIBC__ && !(__GLIBC__ == 2 && __GLIBC_MINOR__ == 0) #include <signal.h> #include <sys/ucontext.h> #ifdef __x86_64__ #define MD_FALLBACK_FRAME_STATE_FOR x86_64_fallback_frame_state static _Unwind_Reason_Code x86_64_fallback_frame_state (struct _Unwind_Context *context, _Unwind_FrameState *fs) { unsigned char *pc = context->ra; struct sigcontext *sc; long new_cfa; /* movq $__NR_rt_sigreturn, %rax ; syscall. */ #ifdef __LP64__ #define RT_SIGRETURN_SYSCALL 0x050f0000000fc0c7ULL #else #define RT_SIGRETURN_SYSCALL 0x050f40000201c0c7ULL #endif if (*(unsigned char *)(pc+0) == 0x48 && *(unsigned long long *)(pc+1) == RT_SIGRETURN_SYSCALL) { // struct ucontext *uc_ = context->cfa; ucontext_t *uc_ = context->cfa; /* The void * cast is necessary to avoid an aliasing warning. The aliasing warning is correct, but should not be a problem because it does not alias anything. */ sc = (struct sigcontext *) (void *) &uc_->uc_mcontext; } else return _URC_END_OF_STACK; new_cfa = sc->rsp; fs->regs.cfa_how = CFA_REG_OFFSET; /* Register 7 is rsp */ fs->regs.cfa_reg = 7; fs->regs.cfa_offset = new_cfa - (long) context->cfa; /* The SVR4 register numbering macros aren't usable in libgcc. */ fs->regs.reg[0].how = REG_SAVED_OFFSET; fs->regs.reg[0].loc.offset = (long)&sc->rax - new_cfa; fs->regs.reg[1].how = REG_SAVED_OFFSET; fs->regs.reg[1].loc.offset = (long)&sc->rdx - new_cfa; fs->regs.reg[2].how = REG_SAVED_OFFSET; fs->regs.reg[2].loc.offset = (long)&sc->rcx - new_cfa; fs->regs.reg[3].how = REG_SAVED_OFFSET; fs->regs.reg[3].loc.offset = (long)&sc->rbx - new_cfa; fs->regs.reg[4].how = REG_SAVED_OFFSET; fs->regs.reg[4].loc.offset = (long)&sc->rsi - new_cfa; fs->regs.reg[5].how = REG_SAVED_OFFSET; fs->regs.reg[5].loc.offset = (long)&sc->rdi - new_cfa; fs->regs.reg[6].how = REG_SAVED_OFFSET; fs->regs.reg[6].loc.offset = (long)&sc->rbp - new_cfa; fs->regs.reg[8].how = REG_SAVED_OFFSET; fs->regs.reg[8].loc.offset = (long)&sc->r8 - new_cfa; fs->regs.reg[9].how = REG_SAVED_OFFSET; fs->regs.reg[9].loc.offset = (long)&sc->r9 - new_cfa; fs->regs.reg[10].how = REG_SAVED_OFFSET; fs->regs.reg[10].loc.offset = (long)&sc->r10 - new_cfa; fs->regs.reg[11].how = REG_SAVED_OFFSET; fs->regs.reg[11].loc.offset = (long)&sc->r11 - new_cfa; fs->regs.reg[12].how = REG_SAVED_OFFSET; fs->regs.reg[12].loc.offset = (long)&sc->r12 - new_cfa; fs->regs.reg[13].how = REG_SAVED_OFFSET; fs->regs.reg[13].loc.offset = (long)&sc->r13 - new_cfa; fs->regs.reg[14].how = REG_SAVED_OFFSET; fs->regs.reg[14].loc.offset = (long)&sc->r14 - new_cfa; fs->regs.reg[15].how = REG_SAVED_OFFSET; fs->regs.reg[15].loc.offset = (long)&sc->r15 - new_cfa; fs->regs.reg[16].how = REG_SAVED_OFFSET; fs->regs.reg[16].loc.offset = (long)&sc->rip - new_cfa; fs->retaddr_column = 16; fs->signal_frame = 1; return _URC_NO_REASON; } #else /* ifdef __x86_64__ */ #define MD_FALLBACK_FRAME_STATE_FOR x86_fallback_frame_state static _Unwind_Reason_Code x86_fallback_frame_state (struct _Unwind_Context *context, _Unwind_FrameState *fs) { unsigned char *pc = context->ra; struct sigcontext *sc; long new_cfa; /* popl %eax ; movl $__NR_sigreturn,%eax ; int $0x80 */ if (*(unsigned short *)(pc+0) == 0xb858 && *(unsigned int *)(pc+2) == 119 && *(unsigned short *)(pc+6) == 0x80cd) sc = context->cfa + 4; /* movl $__NR_rt_sigreturn,%eax ; int $0x80 */ else if (*(unsigned char *)(pc+0) == 0xb8 && *(unsigned int *)(pc+1) == 173 && *(unsigned short *)(pc+5) == 0x80cd) { struct rt_sigframe { int sig; siginfo_t *pinfo; void *puc; siginfo_t info; // struct ucontext uc; ucontext_t uc; } *rt_ = context->cfa; /* The void * cast is necessary to avoid an aliasing warning. The aliasing warning is correct, but should not be a problem because it does not alias anything. */ sc = (struct sigcontext *) (void *) &rt_->uc.uc_mcontext; } else return _URC_END_OF_STACK; new_cfa = sc->esp; fs->regs.cfa_how = CFA_REG_OFFSET; fs->regs.cfa_reg = 4; fs->regs.cfa_offset = new_cfa - (long) context->cfa; /* The SVR4 register numbering macros aren't usable in libgcc. */ fs->regs.reg[0].how = REG_SAVED_OFFSET; fs->regs.reg[0].loc.offset = (long)&sc->eax - new_cfa; fs->regs.reg[3].how = REG_SAVED_OFFSET; fs->regs.reg[3].loc.offset = (long)&sc->ebx - new_cfa; fs->regs.reg[1].how = REG_SAVED_OFFSET; fs->regs.reg[1].loc.offset = (long)&sc->ecx - new_cfa; fs->regs.reg[2].how = REG_SAVED_OFFSET; fs->regs.reg[2].loc.offset = (long)&sc->edx - new_cfa; fs->regs.reg[6].how = REG_SAVED_OFFSET; fs->regs.reg[6].loc.offset = (long)&sc->esi - new_cfa; fs->regs.reg[7].how = REG_SAVED_OFFSET; fs->regs.reg[7].loc.offset = (long)&sc->edi - new_cfa; fs->regs.reg[5].how = REG_SAVED_OFFSET; fs->regs.reg[5].loc.offset = (long)&sc->ebp - new_cfa; fs->regs.reg[8].how = REG_SAVED_OFFSET; fs->regs.reg[8].loc.offset = (long)&sc->eip - new_cfa; fs->retaddr_column = 8; fs->signal_frame = 1; return _URC_NO_REASON; } #define MD_FROB_UPDATE_CONTEXT x86_frob_update_context /* Fix up for kernels that have vDSO, but don't have S flag in it. */ static void x86_frob_update_context (struct _Unwind_Context *context, _Unwind_FrameState *fs ATTRIBUTE_UNUSED) { unsigned char *pc = context->ra; /* movl $__NR_rt_sigreturn,%eax ; {int $0x80 | syscall} */ if (*(unsigned char *)(pc+0) == 0xb8 && *(unsigned int *)(pc+1) == 173 && (*(unsigned short *)(pc+5) == 0x80cd || *(unsigned short *)(pc+5) == 0x050f)) _Unwind_SetSignalFrame (context, 1); } #endif /* ifdef __x86_64__ */ #endif /* not glibc 2.0 */ #endif /* ifdef inhibit_libc */重新编译即可。
原理：glibc2.25+移除了struct ucontext 取而代之的是一个新类型：ucontext_t，目前来看该类型与以前的结构相兼容，可以通过修改源文件的方法通过编译。编译后的二进制经过测试，看起来没有问题。
后注：次解决方案丑陋无比，除非万不得已，还是打patch的好！！！
