ARM: link register and frame pointer
ARM Stack Frame Layout
ARM GCC generated functions prolog
ARM Procedure Call Standard (APCS)
Procedure Call Standard for the ARM Architecture (AAPCS)
On the AAPCS, with an application to efficient parameter passing
ARM to C calling convention, registers to save
General
Der Stack Frame
Deep Wizardry: Stack Unwinding
What is exactly the base pointer and stack pointer? To what do they point?
What is stack unwinding?
Stack Unwinding in C++
github.com/evgeny-panasyuk/stack_unwinding, The stack_unwinding is a small header only C++ library which supplies primitive(class unwinding_indicator) to determining when object destructor is called due to stack-unwinding or due to normal scope leaving.
backtrace
libc Backtraces
How to automatically generate a stacktrace when my gcc C++ program crashes
Backtrace on ARM has repeating entries
libunwind / Call chain
- allows you to easily walk the stack frames
- access to the callee-saved registers contents
- support for resuming execution at a certain frame
The libunwind project
KenWerner/Sandbox/libunwind – Linaro Wiki
Stack frame unwinding on ARM (2011)
#define UNW_LOCAL_ONLY
#include <libunwind.h>
void show_backtrace (void) {
unw_cursor_t cursor; unw_context_t uc;
unw_word_t ip, sp;
unw_getcontext(&uc);
unw_init_local(&cursor, &uc);
while (unw_step(&cursor) > 0) {
unw_get_reg(&cursor, UNW_REG_IP, &ip);
unw_get_reg(&cursor, UNW_REG_SP, &sp);
printf ("ip = %lx, sp = %lx\n", (long) ip, (long) sp);
}
}
libbacktrace
github.com/ianlancetaylor/libbacktrace, A C library that may be linked into a C/C++ program to produce symbolic backtraces (2018)
Android
Before Android 8.0, crashes were handled by the debuggerd and debuggerd64 daemons. In Android O and later, crash_dump32 and crash_dump64 are spawned as needed.
Debugging Native Android Platform Code
android / platform / system / core / libbacktrace
android / platform / system / core / include / backtrace / backtrace.h/a>
android / platform / system / libbacktrace / Backtrace.cpp
android-aosp-sdcard debuggerd backtrace.c, Rewrite libbacktrace using C++
am 98f87d92: Merge “Rewrite libbacktrace using C++.”
backtrace_create_context() dump_backtrace_to_log()
Breakpoint 1, main () at /home/andreas/src/DermoInspectMiniServer/src/tcp_server.cpp:79
79 A();
(gdb) info register pc lr sp fp
pc 0x142824 0x142824 <main()+72>
lr 0x76d7b208 1993847304
sp 0x7efff568 0x7efff568
fp 0x7efff5fc 0x7efff5fc
(gdb) s
A () at /home/andreas/src/DermoInspectMiniServer/src/tcp_server.cpp:72
72 B();
(gdb) info register pc lr sp fp
pc 0x1427d0 0x1427d0 <A()+8>
lr 0x142828 1321000
sp 0x7efff560 0x7efff560
fp 0x7efff564 0x7efff564
(gdb) s
B () at /home/andreas/src/DermoInspectMiniServer/src/tcp_server.cpp:67
67 C();
(gdb) info register pc lr sp fp
pc 0x1427bc 0x1427bc <B()+8>
lr 0x1427d4 1320916
sp 0x7efff558 0x7efff558
fp 0x7efff55c 0x7efff55c
(gdb) s
C () at /home/andreas/src/DermoInspectMiniServer/src/tcp_server.cpp:62
62 MyBacktrace();
(gdb) info register pc lr sp fp
pc 0x1427a8 0x1427a8 <C()+8>
lr 0x1427c0 1320896
sp 0x7efff550 0x7efff550
fp 0x7efff554 0x7efff554
(gdb) s
100 frame = (struct frame*) ctx.uc_mcontext.arm_lr;
(gdb)
102 for (int i = 0; frame && frame->fr_savfp; i++) {
(gdb) info register pc lr sp fp
pc 0x170a74 0x170a74 <MyBacktrace()+32>
lr 0x170a6c 1509996
sp 0x7efff238 0x7efff238
fp 0x7efff54c 0x7efff54c