From c969310c992a12459ed4025c1cd8b22f29c763b5 Mon Sep 17 00:00:00 2001 From: Dmitry Chagin Date: Thu, 29 Jun 2023 19:34:39 +0300 Subject: [PATCH] csu: Implement _start using as to satisfy unwinders on x86_64 The right unwinding stop indicator should be CFI-undefined PC. https://dwarfstd.org/doc/Dwarf3.pdf - page 118: If a Return Address register is defined in the virtual unwind table, and its rule is undefined (for example, by DW_CFA_undefined), then there is no return address and no call address, and the virtual unwind of stack activations is complete. This requires the crt code be built with unwind tables, for that remove -fno-asynchronous-unwind-tables to enable unwind tables generation. PR: 241562, 246322, 246537 Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D40780 --- lib/csu/Makefile.inc | 22 ++++++----- lib/csu/amd64/Makefile | 3 ++ lib/csu/amd64/crt1_c.c | 22 ----------- lib/csu/amd64/crt1_s.S | 88 ++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 103 insertions(+), 32 deletions(-) create mode 100644 lib/csu/amd64/crt1_s.S diff --git a/lib/csu/Makefile.inc b/lib/csu/Makefile.inc index 1633fa3dc3e..ee60c3968b8 100644 --- a/lib/csu/Makefile.inc +++ b/lib/csu/Makefile.inc @@ -20,7 +20,6 @@ CRT1OBJS+= crtbrand.o feature_note.o ignore_init_note.o ACFLAGS+= -DLOCORE CFLAGS+= -DSTRIP_FBSDID -CFLAGS+= -fno-asynchronous-unwind-tables CFLAGS+= -fno-omit-frame-pointer CFLAGS+= -I${.CURDIR:H}/common \ -I${SRCTOP}/lib/libc/include @@ -35,25 +34,28 @@ FILESDIR= ${LIBDIR} # These FILES qualify as libraries for the purpose of LIBRARIES_ONLY. .undef LIBRARIES_ONLY -CLEANFILES+= ${OBJS} ${CRT1OBJS} crt1_c.o gcrt1_c.o Scrt1_c.o -CLEANFILES+= crti_s.o +CRT1SRC?= crt1_c.c +CRT1OBJ?= -crt1.o: crt1_c.o ${CRT1OBJS} +CLEANFILES+= ${OBJS} ${CRT1OBJS} crt1_c.o gcrt1_c.o Scrt1_c.o +CLEANFILES+= crti_s.o ${CRT1SRC:C/.[S|c]$/.o/} + +crt1.o: ${CRT1SRC:C/.[S|c]$/.o/} ${CRT1OBJS} ${CRT1OBJ} ${LD} ${_LDFLAGS} -o ${.TARGET} -r ${.ALLSRC:M*.o} .if ${MACHINE_ARCH} == "i386" ${OBJCOPY} --localize-symbol _start1 ${.TARGET} .endif -gcrt1_c.o: crt1_c.c - ${CC} ${CFLAGS} -DGCRT -c -o ${.TARGET} ${.CURDIR}/crt1_c.c +gcrt1_c.o: ${CRT1SRC} + ${CC} ${CFLAGS} -DGCRT -c -o ${.TARGET} ${.CURDIR}/${CRT1SRC} -gcrt1.o: gcrt1_c.o ${CRT1OBJS} +gcrt1.o: gcrt1_c.o ${CRT1OBJS} ${CRT1OBJ} ${LD} ${_LDFLAGS} -o ${.TARGET} -r ${.ALLSRC:M*.o} -Scrt1_c.o: crt1_c.c - ${CC} ${CFLAGS} -fPIC -DPIC -c -o ${.TARGET} ${.CURDIR}/crt1_c.c +Scrt1_c.o: ${CRT1SRC} + ${CC} ${CFLAGS} -fPIC -DPIC -c -o ${.TARGET} ${.CURDIR}/${CRT1SRC} -Scrt1.o: Scrt1_c.o ${CRT1OBJS} +Scrt1.o: Scrt1_c.o ${CRT1OBJS} ${CRT1OBJ} ${LD} ${_LDFLAGS} -o ${.TARGET} -r ${.ALLSRC:M*.o} .if ${MACHINE_ARCH} == "i386" ${OBJCOPY} --localize-symbol _start1 ${.TARGET} diff --git a/lib/csu/amd64/Makefile b/lib/csu/amd64/Makefile index 9f3afb4cc1a..370d206259d 100644 --- a/lib/csu/amd64/Makefile +++ b/lib/csu/amd64/Makefile @@ -5,4 +5,7 @@ CFLAGS+= -I${.CURDIR} CFLAGS+= -fno-omit-frame-pointer +CRT1SRC= crt1_s.S +CRT1OBJ= crt1_c.o + .include diff --git a/lib/csu/amd64/crt1_c.c b/lib/csu/amd64/crt1_c.c index 9fe227f2e43..8c57e36becf 100644 --- a/lib/csu/amd64/crt1_c.c +++ b/lib/csu/amd64/crt1_c.c @@ -29,26 +29,4 @@ #include __FBSDID("$FreeBSD$"); -#include "libc_private.h" #include "csu_common.h" - -void _start(char **, void (*)(void)) __dead2; - -/* The entry function. */ -void -_start(char **ap, void (*cleanup)(void)) -{ - int argc; - char **argv; - char **env; - - argc = *(long *)(void *)ap; - argv = ap + 1; - env = ap + 2 + argc; -#ifdef GCRT - __libc_start1_gcrt(argc, argv, env, cleanup, main, &eprol, &etext); -__asm__("eprol:"); -#else - __libc_start1(argc, argv, env, cleanup, main); -#endif -} diff --git a/lib/csu/amd64/crt1_s.S b/lib/csu/amd64/crt1_s.S new file mode 100644 index 00000000000..0c1c3b960bd --- /dev/null +++ b/lib/csu/amd64/crt1_s.S @@ -0,0 +1,88 @@ +/*- + * SPDX-License-Identifier: BSD-2-Clause + * + * Copyright (C) 2023 Dmitry Chagin + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include + + + .text + .align 8 + + /* + * The program entry point + * %rdi %rsi + * void _start(char **ap, void (*cleanup)(void)) __dead2 + */ + .globl _start + .type _start, @function +_start: + .cfi_startproc + .cfi_undefined %rip /* Terminate call chain. */ + pushq %rbp /* Align stack, terminate call chain. */ + .cfi_def_cfa_offset 8 + movq %rsp, %rbp + .cfi_offset %rbp, -16 + .cfi_def_cfa_register %rbp +#ifdef GCRT + subq $16, %rsp +#endif + movq %rsi, %rcx + movq %rdi, %rsi /* argv = ap */ + addq $8, %rsi /* argv += 1 */ + movq %rdi, %rdx /* env = ap */ + addq $16, %rdx /* env += 2 */ + movslq (%rdi), %rax + movl %eax, %edi /* argc = *(long *)(void *)ap */ + shlq $3, %rax + addq %rax, %rdx /* env += argc */ +#ifdef PIC + /* + * XXX. %rip relative addressing does not intended to use in the + * large memory model due to offset from %rip is limited to 32 bits. + */ + leaq main(%rip), %r8 +#else + movabsq $main, %r8 +#endif +#ifdef GCRT + movabsq $eprol, %r9 + movabsq $etext, %rax + movq %rax, (%rsp) + /* + * %edi %rsi %rdx %rcx %r8 %r9 (%rsp) + * __libc_start1_gcrt(argc, argv, env, cleanup, main, &eprol, &etext) + */ + callq __libc_start1_gcrt +eprol: +#else + /* __libc_start1(argc, argv, env, cleanup, main) */ + callq __libc_start1 +#endif + int3 + .cfi_endproc + .size _start, . - _start + + .section .note.GNU-stack,"",%progbits