From a703aed9ec0380d8a08e42792ff6c87294d3760b Mon Sep 17 00:00:00 2001 From: johannst Date: Wed, 17 Feb 2021 22:45:32 +0000 Subject: deploy: f2a7581c71fe5863a527850e4c0e2906f02e4d2d --- tools/gdb.html | 103 +++++++++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 93 insertions(+), 10 deletions(-) (limited to 'tools') diff --git a/tools/gdb.html b/tools/gdb.html index 90e9568..2fb175d 100644 --- a/tools/gdb.html +++ b/tools/gdb.html @@ -160,25 +160,49 @@ --tty <tty> set I/O tty for debugee

Interactive usage

+

Misc

  tty <tty>
           Set <tty> as tty for debugee.
           Make sure nobody reads from target tty, easiest is to spawn a shell
           and run following in target tty:
           > while true; do sleep 1024; done
 
-  set follow-fork-mode <child | parent>
-          Specify which process to follow when debuggee makes a fork(2)
-          syscall.
-
   sharedlibrary [<regex>]
           Load symbols of shared libs loaded by debugee. Optionally use <regex>
           to filter libs for symbol loading.
 
-  break [-qualified] <sym> thread <tnum>
+  display [/FMT] <expr>
+          Print <expr> every time debugee stops. Eg print next instr, see
+          examples below.
+
+  undisplay [<num>]
+          Delete display expressions either all or one referenced by <num>.
+
+  info display
+          List display expressions.
+
+

Breakpoints

+
  break [-qualified] <sym> thread <tnum>
           Set a breakpoint only for a specific thread.
-          -qualified: Tred <sym> as fully qualified symbol (quiet handy to set
+          -qualified: Treat <sym> as fully qualified symbol (quiet handy to set
           breakpoints on C symbols in C++ contexts)
 
+  break <sym> if <cond>
+          Set conditional breakpoint (see examples below).
+
+  delete [<num>]
+          Delete breakpoint either all or one referenced by <num>.
+
+  info break
+          List breakpoints.
+
+  cond <bp> <cond>
+          Make existing breakpoint <bp> conditional with <cond>.
+
+  tbreak
+          Set temporary breakpoint, will be deleted when hit.
+          Same syntax as `break`.
+
   rbreak <regex>
           Set breakpoints matching <regex>, where matching internally is done
           on: .*<regex>.*
@@ -190,16 +214,18 @@
 
           <bp_list>: Space separates list, eg 'command 2 5-8' to run command
           for breakpoints: 2,5,6,7,8.
-
-  info functions [<regex>]
+
+

Inspection

+
  info functions [<regex>]
           List functions matching <regex>. List all functions if no <regex>
           provided.
 
   info variables [<regex>]
           List variables matching <regex>. List all variables if no <regex>
           provided.
-
-  info handle [<signal>]
+
+

Signal handling

+
  info handle [<signal>]
           Print how to handle <signal>. If no <signal> specified print for all
           signals.
 
@@ -213,6 +239,45 @@
   catch signal <signal>
           Create a catchpoint for <signal>.
+

Source file locations

+
  dir <path>
+          Add <path> to the beginning of the searh path for source files.
+
+  show dir
+          Show current search path.
+
+  set substitute-path <from> <to>
+          Add substitution rule checked during source file lookup.
+
+  show substitute-path
+          Show current substitution rules.
+
+

Configuration

+
  set follow-fork-mode <child | parent>
+          Specify which process to follow when debuggee makes a fork(2)
+          syscall.
+
+  set pagination <on | off>
+          Turn on/off gdb's pagination.
+
+  set breakpoint pending <on | off | auto>
+          on: always set pending breakpoints.
+          off: error when trying to set pending breakpoints.
+          auto: interatively query user to set breakpoint.
+
+  set print pretty <on | off>
+          Turn on/off pertty printing of structures.
+
+  set logging <on | off>
+          Enable output logging to file (default gdb.txt).
+
+  set logging file <fname>
+          Change output log file to <fname>
+
+  set logging redirect <on/off>
+          on: only log to file.
+          off: log to file and tty.
+

User commands (macros)

Gdb allows to create & document user commands as follows:

  define <cmd>
@@ -242,6 +307,24 @@
   end

Examples

+

Automatically print next instr

+

When ever the debugee stops automatically print the memory at the current +instruction pointer ($rip x86) and format as instruction /i.

+
  # rip - x86
+  display /i $rip
+
+  # step instruction, after the step the next instruction is automatically printed
+  si
+
+

Conditional breakpoints

+

Create conditional breakpoints for a function void foo(int i) in the debugee.

+
  # Create conditional breakpoint
+  b foo if i == 42
+
+  b foo     # would create bp 2
+  # Make existing breakpoint conditional
+  cond 2 if i == 7
+

Catch SIGSEGV and execute commands

This creates a catchpoint for the SIGSEGV signal and attached the command to it.

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