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gdb [2015/11/06 14:08] – niziakgdb [2025/05/28 07:16] (current) – [stepping] niziak
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 +====== GDB ======
 +
 +====== Starting  ======
 +<code>
 +gdb <executable>
 +gdb --args <executable> arg1 arg2 arg3
 +gdb -x gdbcommands --init-commands=gdb-openocd.cfg
 +</code>
 +
 +====== Symbols and paths =====
 +
 +Add symbols:
 +<code>
 +symbol-file /mnt/nfs/binary-with-symbols.elf
 +dir /mnt/nfs/src
 +</code>
 +
 +====== Using ======
 +
 ==== getting info ==== ==== getting info ====
-  * p[rint] var+set print pretty on 
 +  * p[rint] <name> - print value 
 +    * p * <name> - print what is pointed by 
 +    * p/x <name> - print in hex format 
 +    * p <name> @<n> print <n> values starting at <name> 
 +    * p <chars> <TAB> - List all variables starting with <chars> 
 +    * p ((sturct dummy*)variable)[0] - Dump structure members 
 +  * ptype var
   * x /100bx m - eXamine memory located by variable m, print 100 bytes in hex format   * x /100bx m - eXamine memory located by variable m, print 100 bytes in hex format
   * bt (backtrace)   * bt (backtrace)
   * t (threads)   * t (threads)
  
 +==== call stack ====
 +  * bt (backtrace)
 +  * frame 4 - switch to frame #4
 +  * up
 +  * down
  
 ==== breakpoints ==== ==== breakpoints ====
-  * break malloc+  * b[reak] malloc 
 +  * b mall <TAB> - List all starting with mall
   * clear malloc   * clear malloc
 +  * info break
 +    * i[nfo] b
 +  * dis[able] 1 - disable brakpoint 1
 +  * en[able] 1
 +  * d[elete] 1
 +  * d 1 2
 +  * d - delete all breakpoints
 +  * cond[ition] 1 <expr> - stop at breakpoint 1 only if <expr> is true
 +  * cond 1 - Remove condition from breakpoint 1
 +
 +Add to C code to catch timing critical issues:
 +<code c>
 +if (p_queue->p_cb->locked) {
 +  __BKPT(8);
 +}
 +</code>
  
 ==== stepping ==== ==== stepping ====
-  * s[tep] + 
-  * c[ontinue] <num_to_ignore> +  * **s** [tep] - step to next **source** line 
-  * n[ext] - to next line +  * **c** [ontinue] <num_to_ignore> 
-  * fin[ish] - execute until stack frame returns +  * **n** [ext] - step (do not enter to subroutines) 
-  * u[ntil] <line number> - execute to line (to avoid loops)+  * **fin** [ish] - execute until stack frame returns 
 +  * **u** [ntil] <line number> - execute to line (to avoid loops) 
 +   
 +Skip current command: 
 +<code> 
 +tbreak +1 
 +jump +1 
 +</code> 
 +==== infos ==== 
 +  * show debug-file-directory 
 + 
 +==== threads ==== 
 +  * info threads - show info about threads 
 +  * thread 4 - switch to thread 4 
 +  * print mutex 
 +  * info line - print current code line 
 +  * frame - print current execution position and code 
 + 
 +==== OpenOCD ==== 
 +Disable Cortex M0 interrupts 
 +  * mon cortex_m maskisr on 
 + 
 +<code> 
 +set remote hardware-breakpoint-limit 4 
 +set remote hardware-watchpoint-limit 2 
 +define hook-step 
 +mon cortex_m maskisr on 
 +end 
 +define hookpost-step 
 +mon cortex_m maskisr off 
 +end 
 +</code> 
 + 
 +===== gdbcommands file ===== 
 +<file | gdbcommands> 
 +set verbose on 
 +set auto-load safe-path / 
 +set debug auto-load on 
 + 
 +set sysroot /home/user/prj/buildroot/output/target 
 + 
 +source ../../interactive/src 
 + 
 +set substitute-path /usr/sbin/app /apps/app/app 
 + 
 +add-symbol-file /home/user/prj/stm32/main/bootloader/build/bin/main.elf 0x08005000 
 + 
 +dir ../../out/build/app-undefined 
 +dir ../../out/build/app-undefined/apps/app 
 +dir ../../out/build/app-undefined/apps/app/app 
 + 
 +set substitute-path /usr/lib ../../out/target/usr/lib 
 + 
 +set args -m 0 -c /etc/conf.d/conf.xml 
 + 
 +#sharedlibrary 
 + 
 +#target extended-remote 192.168.1.62:12345 
 + 
 +break myFunction 
 +</file> 
 + 
 +<file | gdb-openocd.cfg> 
 +target extended-remote localhost:2331 
 +#monitor reset 
 +monitor halt 
 + 
 +# Setup GDB FOR FASTER DOWNLOADS 
 +#set remote memory-write-packet-size 1024 
 +#set remote memory-write-packet-size fixed 
 +</file> 
 + 
 +<file> 
 +# Add GDB access to mem range where VTOR is located 
 +mem 0xE0000000 0xE00FFFFF 
 + 
 +define bootapp 
 +  monitor reset halt 
 +  # Adjust VTOR (Vector table offset register) 
 +  set {int}0xE000ED08 = &exception_table 
 +  # Set SP/PC to the values from the actual vector table 
 +  set $sp = *(int*)&exception_table 
 +  set $pc = *((int*)(&exception_table)+1) 
 +end 
 +</file> 
 +==== symbols ==== 
 +  * set symbol-reloading on 
 +  * add-symbol-file ~/mymodule.o 0xd8be4000 
 +  * add-symbol-file ~/myanother.o 0x12341234 
 + 
 +  * set debug-file-directory <directory> - set directory contain symbol file 
 +  * show debug-file-directory
  
 ==== file paths and libraries ==== ==== file paths and libraries ====
Line 23: Line 162:
   * set sysroot /home/niziak/n/3/out/host/usr/arm-buildroot-linux-uclibcgnueabi/sysroot   * set sysroot /home/niziak/n/3/out/host/usr/arm-buildroot-linux-uclibcgnueabi/sysroot
  
-=== source paths ===+==== source paths ====
 Search paths (prefixes): Search paths (prefixes):
   * dir /path/to/src1   * dir /path/to/src1
Line 31: Line 170:
   * set substitute-path /usr/lib ../../out/target/usr/lib   * set substitute-path /usr/lib ../../out/target/usr/lib
  
-==== infos ==== + 
-  * show debug-file-directory+====== Kernel OOPS ====== 
 +=== Reading === 
 +<code> 
 +PC is at RTMPCheckEtherType+0x90/0x4d4 [mt7601Uapsta] 
 +LR is at RTMPCheckEtherType+0x34/0x4d4 [mt7601Uapsta] 
 + 
 +Code: e59f3418 e0256593 e2859d43 e289902c (e5d939ba) 
 +</code> 
 + 
 +Oops occurs at offset 0x90 from RTMPCheckEtherType. 0x4d4 is length. 
 +"Code" line shows last instruction. Instruction in bracket is problematic instruction (at RTMPCheckEtherType+0x90) 
 + 
 +=== Tracing === 
 +Disassembly kernel binary or module binary: 
 +objdump -dS vmlinux > /tmp/kernel.s 
 +and look into generated code. 
 + 
 +====== Python ====== 
 + 
 +<code bash>apt-get install gdb python2.7-dbg</code> 
 +<code bash>gdb python <pid></code> 
 + 
 + 
 +====== DRAFTS ====== 
 +call raise(kernel-thread-id, signo) or call pthread_kill(pthread-thread-id, signo). 
 +