c – 关于MIPS的pthreads中的Segfault

我正在尝试在MIPS
Linux机器上运行我的代码(little-endian,没有硬件浮点数):

# cat /proc/cpuinfo | grep model
cpu model               : MIPS 24Kc V5.5

我的程序在x86和ARM系统上运行良好,但在MIPS上崩溃时出现分段错误,总是在(或接近)pthreads库函数调用中.我尝试了两个工具链(here的MTI GNU / Linux工具链MIPS32R2-MIPS32R5和here的Sourcery CodeBench Lite 2016.05-8) – 细节略有不同,但总是会出现段错误.

阅读邮件列表我发现MIPS平台上出现pthreads分段错误的两个原因:

>可能在MIPS版本的uClibc中错误地实现了pthread_unlock_mutex()和pthread_wait_cond().但我使用glibc(虽然设备上的操作系统是基于uClibc的);
> pthreads中的动态库加载问题;但我的程序是静态链接的.

我写了一个非常简单的程序:

#include <chrono>
#include <iostream>
#include <thread>

using namespace std;

void sayHello() {
    this_thread::sleep_for(chrono::seconds(2));
    cout << "Hello world!" << endl;
}

int main(int argc, char* argv[]) {
    thread t(sayHello);
    t.join();
    return 0;
}

它也在MIPS上崩溃了.在t.join()上有一个breakpoin的调试器中,我看到以下内容:

(gdb) c
Continuing.

Breakpoint 1, __start () at ../sysdeps/mips/start.S:84
84      in ../sysdeps/mips/start.S
(gdb) disassemble 
Dump of assembler code for function __start:
   0x004059b0 <+0>:     lui     gp,0x5b
   0x004059b4 <+4>:     addiu   gp,gp,-30464
=> 0x004059b8 <+8>:     move    ra,zero
   0x004059bc <+12>:    lui     a0,0x40
   0x004059c0 <+16>:    addiu   a0,a0,21584
   0x004059c4 <+20>:    lw      a1,0(sp)
   0x004059c8 <+24>:    addiu   a2,sp,4
   0x004059cc <+28>:    li      at,-8
   0x004059d0 <+32>:    and     sp,sp,at
   0x004059d4 <+36>:    addiu   sp,sp,-32
   0x004059d8 <+40>:    lui     a3,0x4d
   0x004059dc <+44>:    addiu   a3,a3,-208
   0x004059e0 <+48>:    lui     t0,0x4d
   0x004059e4 <+52>:    addiu   t0,t0,4
   0x004059e8 <+56>:    sw      t0,16(sp)
   0x004059ec <+60>:    sw      v0,20(sp)
   0x004059f0 <+64>:    jal     0x4cf8a0 <__libc_start_main>
   0x004059f4 <+68>:    sw      sp,24(sp)
End of assembler dump.
… (some boring "n"-s here) …
(gdb) n
109     in ../sysdeps/mips/start.S
(gdb) disassemble 
Dump of assembler code for function __start:
   0x004059b0 <+0>:     lui     gp,0x5b
   0x004059b4 <+4>:     addiu   gp,gp,-30464
   0x004059b8 <+8>:     move    ra,zero
   0x004059bc <+12>:    lui     a0,0x40
   0x004059c0 <+16>:    addiu   a0,a0,21584
   0x004059c4 <+20>:    lw      a1,0(sp)
   0x004059c8 <+24>:    addiu   a2,sp,4
   0x004059cc <+28>:    li      at,-8
   0x004059d0 <+32>:    and     sp,sp,at
   0x004059d4 <+36>:    addiu   sp,sp,-32
   0x004059d8 <+40>:    lui     a3,0x4d
   0x004059dc <+44>:    addiu   a3,a3,-208
   0x004059e0 <+48>:    lui     t0,0x4d
   0x004059e4 <+52>:    addiu   t0,t0,4
   0x004059e8 <+56>:    sw      t0,16(sp)
   0x004059ec <+60>:    sw      v0,20(sp)
=> 0x004059f0 <+64>:    jal     0x4cf8a0 <__libc_start_main>
   0x004059f4 <+68>:    sw      sp,24(sp)
End of assembler dump.
(gdb) n
[New Thread 29775]

Program received signal SIGSEGV, Segmentation fault.
0x00000000 in ?? ()
(gdb) info registers 
          zero       at       v0       v1       a0       a1       a2       a3
 R0   00000000 00000000 00000016 005af490 2bc7d310 00000000 2bc7d378 00000000 
            t0       t1       t2       t3       t4       t5       t6       t7
 R8   00000000 00000000 00000000 82ee2000 00000000 00000000 00000001 74697773 
            s0       s1       s2       s3       s4       s5       s6       s7
 R16  7fbbf194 004450c4 00464200 004641f0 00460000 2b929478 0045742c 00000001 
            t8       t9       k0       k1       gp       sp       s8       ra
 R24  00000000 00000000 2bc847a0 00000000 005a8900 7fbbf158 7f894280 0041bd54 
        status       lo       hi badvaddr    cause       pc
      0100ff13 3b9aca00 00000000 00000000 50800008 00000000 
          fcsr      fir      hi1      lo1      hi2      lo2      hi3      lo3
      00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 
        dspctl  restart
      00000000 00000000

没有线程的示例程序运行良好.

我现在能做什么?在MIPS上有任何类似的pthreads经验吗?

最佳答案 回答我自己的问题.

Erik Alapää是对的,使用uClibc构建解决了这个问题.我仍然无法理解为什么(程序静态链接).

顺便说一下:我使用了glibc,因为无法使用uClibc构建Boost.Asio – 使用我的工具链中的uClibc构建的pthreads库不包含pthread_condattr_setclock()函数.修复了Boost.Asio的以下补丁:

diff --git a/include/boost/asio/detail/impl/posix_event.ipp b/include/boost/asio/detail/impl/posix_event.ipp
index 4ff246f3..04f87a3a 100644
--- a/include/boost/asio/detail/impl/posix_event.ipp
+++ b/include/boost/asio/detail/impl/posix_event.ipp
@@ -33,10 +33,12 @@ posix_event::posix_event()
   : state_(0)
 {
 #if (defined(__MACH__) && defined(__APPLE__)) \
-      || (defined(__ANDROID__) && (__ANDROID_API__ < 21))
+      || (defined(__ANDROID__) && (__ANDROID_API__ < 21)) \
+      || (defined(__UCLIBC__))
   int error = ::pthread_cond_init(&cond_, 0);
 #else // (defined(__MACH__) && defined(__APPLE__))
       // || (defined(__ANDROID__) && (__ANDROID_API__ < 21))
+      // || (defined(__UCLIBC__))
   ::pthread_condattr_t attr;
   ::pthread_condattr_init(&attr);
   int error = ::pthread_condattr_setclock(&attr, CLOCK_MONOTONIC);
@@ -44,7 +46,7 @@ posix_event::posix_event()
     error = ::pthread_cond_init(&cond_, &attr);
 #endif // (defined(__MACH__) && defined(__APPLE__))
        // || (defined(__ANDROID__) && (__ANDROID_API__ < 21))
-
+       // || (defined(__UCLIBC__))
   boost::system::error_code ec(error,
       boost::asio::error::get_system_category());
   boost::asio::detail::throw_error(ec, "event");

嗯,这是一种kludge,但它的工作原理.

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