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138 lines
4.8 KiB
C++
138 lines
4.8 KiB
C++
/*
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# see: https://github.com/ossrs/srs/issues/190
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# see: https://github.com/ossrs/srs/wiki/v1_CN_SrsLinuxArm
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g++ -g -O0 -o jmp_sp jmp_sp.cpp
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arm-linux-gnueabi-g++ -g -o jmp_sp jmp_sp.cpp -static
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arm-linux-gnueabi-strip jmp_sp
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <setjmp.h>
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jmp_buf context;
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void do_longjmp()
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{
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/**
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the definition of jmp_buf:
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typedef struct __jmp_buf_tag jmp_buf[1];
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struct __jmp_buf_tag {
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__jmp_buf __jmpbuf;
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int __mask_was_saved;
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__sigset_t __saved_mask;
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};
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*/
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#if defined(__amd64__) || defined(__x86_64__)
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// http://ftp.gnu.org/gnu/glibc/glibc-2.12.2.tar.xz
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// http://ftp.gnu.org/gnu/glibc/glibc-2.12.1.tar.gz
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/*
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* Starting with glibc 2.4, JB_SP definitions are not public anymore.
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* They, however, can still be found in glibc source tree in
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* architecture-specific "jmpbuf-offsets.h" files.
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* Most importantly, the content of jmp_buf is mangled by setjmp to make
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* it completely opaque (the mangling can be disabled by setting the
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* LD_POINTER_GUARD environment variable before application execution).
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* Therefore we will use built-in _st_md_cxt_save/_st_md_cxt_restore
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* functions as a setjmp/longjmp replacement wherever they are available
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* unless USE_LIBC_SETJMP is defined.
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*/
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// for glibc 2.4+, it's not possible to get and set the sp in jmp_buf
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/**
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for example, the following is show the jmp_buf when setjmp:
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(gdb) x /64xb context[0].__jmpbuf
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0x600ca0 <context>: 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x600ca8 <context+8>: 0xf8 0xc1 0x71 0xe5 0xa8 0x88 0xb4 0x15
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0x600cb0 <context+16>: 0xa0 0x05 0x40 0x00 0x00 0x00 0x00 0x00
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0x600cb8 <context+24>: 0x90 0xe4 0xff 0xff 0xff 0x7f 0x00 0x00
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0x600cc0 <context+32>: 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x600cc8 <context+40>: 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
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0x600cd0 <context+48>: 0xf8 0xc1 0x51 0xe5 0xa8 0x88 0xb4 0x15
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0x600cd8 <context+56>: 0xf8 0xc1 0xd9 0x2f 0xd7 0x77 0x4b 0xea
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(gdb) p /x $sp
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$4 = 0x7fffffffe380
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we cannot finger the sp out.
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where the glibc is 2.12.
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*/
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register long int rsp0 asm("rsp");
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int ret = setjmp(context);
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printf("setjmp func0 ret=%d, rsp=%#lx\n", ret, rsp0);
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printf("after setjmp: ");
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for (int i = 0; i < 8; i++) {
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printf("env[%d]=%#x, ", i, (int)context[0].__jmpbuf[i]);
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}
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printf("\n");
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#endif
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#if defined(__arm__)
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/**
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/usr/arm-linux-gnueabi/include/bits/setjmp.h
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#ifndef _ASM
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The exact set of registers saved may depend on the particular core
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in use, as some coprocessor registers may need to be saved. The C
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Library ABI requires that the buffer be 8-byte aligned, and
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recommends that the buffer contain 64 words. The first 28 words
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are occupied by v1-v6, sl, fp, sp, pc, d8-d15, and fpscr. (Note
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that d8-15 require 17 words, due to the use of fstmx.)
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typedef int __jmp_buf[64] __attribute__((__aligned__ (8)));
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the layout of setjmp for arm:
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0-5: v1-v6
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6: sl
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7: fp
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8: sp
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9: pc
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10-26: d8-d15 17words
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27: fpscr
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*/
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/**
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For example, on raspberry-pi, armv6 cpu:
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(gdb) x /64xb (char*)context[0].__jmpbuf
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v1, 0: 0x00 0x00 0x00 0x00
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v2, 1: 0x00 0x00 0x00 0x00
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v3, 2: 0x2c 0x84 0x00 0x00
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v4, 3: 0x00 0x00 0x00 0x00
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v5, 4: 0x00 0x00 0x00 0x00
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v6, 5: 0x00 0x00 0x00 0x00
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sl, 6: 0x00 0xf0 0xff 0xb6
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fp, 7: 0x9c 0xfb 0xff 0xbe
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sp, 8: 0x88 0xfb 0xff 0xbe
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pc, 9: 0x08 0x85 0x00 0x00
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(gdb) p /x $sp
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$5 = 0xbefffb88
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(gdb) p /x $pc
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$4 = 0x850c
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*/
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int ret = setjmp(context);
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printf("setjmp func1 ret=%d\n", ret);
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printf("after setjmp: ");
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for (int i = 0; i < 64; i++) {
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printf("env[%d]=%#x, ", i, (int)context[0].__jmpbuf[i]);
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}
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printf("func0 terminated\n");
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#endif
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}
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int main(int argc, char** argv)
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{
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#if defined(__amd64__) || defined(__x86_64__)
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printf("x86_64 sizeof(long int)=%d, sizeof(long)=%d, "
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"sizeof(int)=%d, __WORDSIZE=%d, __GLIBC__=%d, __GLIBC_MINOR__=%d\n",
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(int)sizeof(long int), (int)sizeof(long), (int)sizeof(int),
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(int)__WORDSIZE, (int)__GLIBC__, (int)__GLIBC_MINOR__);
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#else
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printf("arm sizeof(long int)=%d, sizeof(long)=%d, "
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"sizeof(int)=%d, __GLIBC__=%d,__GLIBC_MINOR__=%d\n",
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(int)sizeof(long int), (int)sizeof(long), (int)sizeof(int),
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(int)__GLIBC__, (int)__GLIBC_MINOR__);
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#endif
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do_longjmp();
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printf("terminated\n");
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return 0;
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}
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