valgrind是一个很好的内存检测工具，可以让程序员避免用“瞪眼法”去定位内存泄露问题。下面记录一下本人在arm64上使用valgrind的过程。
1.下载最新版本的valgrind源码
https://sourceware.org/ftp/valgrind/
2.解压
tar -xjf valgrind-3.23.0.tar.bz2
3.编译
(1)valgrind早已经准备了不同平台的编译说明，进入目录找到对应平台的readme
README
README.aarch64
README.android
README.android_emulator
README_DEVELOPERS
README_DEVELOPERS_processes
README.freebsd
README.mips
README_MISSING_SYSCALL_OR_IOCTL
README_PACKAGERS
README.s390
README.solaris
(2)我的是aarch64，参考README.aarch64，为了方便把编译命令写入脚本
#$ vim build.sh
#!/bin/bash
export CC=aarch64-gnu-linux-gcc
export CXX=aarch64-gnu-linux-g++
export AR=aarch64-gnu-linux-ar
export RANLIB=aarch64-gnu-linux-ranlib
export STRIP=aarch64-gnu-linux-strip
export LD=aarch64-gnu-linux-ld
export NM=aarch64-gnu-linux-nm
export AS=aarch64-gnu-linux-as
export CFLAGS="--sysroot=/path/to/toolchain/sysroots/aarch64-gnu-linux -g"$CFLAGS
export CXXFLAGS="--sysroot=/path/to/toolchain/sysroots/aarch64-gnu-linux -g"$CXXFLAGS
export LDFLAGS="--sysroot=/path/to/toolchain/sysroots/aarch64-gnu-linux "$LDFLAGS
./autogen.sh
./configure --prefix=/tmp/ins --host=aarch64-gnu-linux \
--enable-only64bit
make -j4
make -j4 install
在执行这个脚本之前,需要切换到交叉编译环境,不同的平台有不同的方法。
source env-setup-aarch64-gnu-linux
执行脚本：
chmod 777 build.sh
./build.sh
从脚本中可以看到，比README多了一些东西，其中AR、RANLIB等，是编译其他工程时的参数，直接复制过来的，在这用不到。
CFLAGS里的--sysroot指定了目标平台系统的头文件和库文件的搜索路径，如果编译不成功，不妨加上这个参数试试。
4.打包
在上一步中--prefix指定的是/tmp/ins，所以
cd /tmp/
tar -zcvf ins.tar.gz ins/
传到自己的开发板上
scp ins.tar.gz root@192.168.1.33:/tmp/
注意，最好把包解压到和prefix指定的相同的路径里。
4.运行
export VALGRIND_LIB=/tmp/ins/libexec/valgrind
/tmp/ins/bin/valgrind --tool=memcheck --leak-check=yes --log-file=valgrind_output.txt ./mydemo ${ARG1} "${ARG2}"
--leak-check表示检测内存泄露
--log-file是将结果输出到文件
mydemo是自己写的demo程序
${ARG1}、${ARG2}是mydemo的参数
5.报错及解决方法
1."valgrind: failed to start tool 'memcheck' for platform 'arm64-linux': No such file or directory"
解决方法：需要执行之前指定VALGRIND_LIB的路径，记住是libexec的路径：
export VALGRIND_LIB=/tmp/ins/libexec/valgrind
2.执行时被退出
valgrind: Fatal error at startup: a function redirection
valgrind: which is mandatory for this platform-tool combination
valgrind: cannot be set up. Details of the redirection are:
valgrind:
valgrind: A must-be-redirected function
valgrind: whose name matches the pattern: strlen
valgrind: in an object with soname matching: ld-linux-aarch64.so.1
valgrind: was not found whilst processing
valgrind: symbols from the object with soname: ld-linux-aarch64.so.1
valgrind:
valgrind: Possible fixes: (1, short term): install glibc's debuginfo
valgrind: package on this machine. (2, longer term): ask the packagers
valgrind: for your Linux distribution to please in future ship a non-
valgrind: stripped ld.so (or whatever the dynamic linker .so is called)
valgrind: that exports the above-named function using the standard
valgrind: calling conventions for this platform. The package you need
valgrind: to install for fix (1) is called
valgrind:
valgrind: On Debian, Ubuntu: libc6-dbg
valgrind: On SuSE, openSuSE, Fedora, RHEL: glibc-debuginfo
valgrind:
valgrind: Note that if you are debugging a 32 bit process on a
valgrind: 64 bit system, you will need a corresponding 32 bit debuginfo
valgrind: package (e.g. libc6-dbg:i386).
valgrind:
valgrind: Cannot continue -- exiting now. Sorry.
解决方法：
sudo apt-get install libc6-dbg
可惜，苦命的打工人在调试的时候，用的板子哪会有yum、apt-get、dplg那些东西？
还有人说自己编译glibc，不知道你成没成功，反正我交叉编译glibc没能成功。就算成功了，把libc库直接换到你的系统里，如果最后弄得ssh都用不了，哭都来不及。
更何况，我已经给mydemo编译的时候加了-g选项，还要我再安装libc6-dbg，你不觉的有些过分么？大不了我不看libc里的堆栈内容就行了，何必强人所难？
最终找到了解决方法:修改valgrind源码，把报错地方的VG_(exit)注释掉，重新编译valgrind，世界终于清净了。
963 "%sCannot continue -- exiting now. Sorry.\n", v);
964 VG_(printf)("\n");
965 //VG_(exit)(1);
神挡杀神，佛挡杀佛，如果还有别处报错也注释掉。
1914 VG_(printf)(
1915 "%sCannot continue -- exiting now.\n", v);
1916 VG_(printf)("\n");
1917 //VG_(exit)(1);
最后运行出来的结果是这样的，那些本来也不用去看的第三方库文件显示"？"完全可以接受。
==3219788== 4,096 bytes in 2 blocks are possibly lost in loss record 12,024 of 12,306
==3219788== at 0x74F66B8: malloc (vg_replace_malloc.c:446)
==3219788== by 0x85A71AB: PL_ArenaAllocate (in /usr/lib/libplds4.so)
==3219788== by 0x7AA0F43: ??? (in /usr/lib/libnss3.so)
==3219788== by 0x7AA1157: ??? (in /usr/lib/libnss3.so)
==3219788== by 0x7A5457F: ??? (in /usr/lib/libnss3.so)
==3219788== by 0x7A9AE27: ??? (in /usr/lib/libnss3.so)
==3219788== by 0x7A9AF93: ??? (in /usr/lib/libnss3.so)
==3219788== by 0x7A41D1F: ??? (in /usr/lib/libnss3.so)
==3219788== by 0x7A42413: NSS_InitReadWrite (in /usr/lib/libnss3.so)
==3219788== by 0x26C6E73: crypto::(anonymous namespace)::NSSInitSingleton::NSSInitSingleton() (in mydemo)
==3219788== by 0x26C756B: crypto::EnsureNSSInit() (in mydemo)
==3219788== by 0x25C5963: net::CertDatabase::GetInstance() (in mydemo)
