On 17.05.2018 16:03, alamaral wrote:
> The problem is that most system library code is built
> without -g, so gdb doesn't have whatever information is necessary to
> unwind the stack properly.
this is wrong. every package is built with -g, however the debug symbols are
split out into separate -dbg or dbgsym packages.
> It seems that gcc, with the -g option, adds .cfi directives into the
> assembler code, and gdb needs that info. Remove the .cfi directives and
> you get the "Backtrace stopped: previous frame identical to this frame
> (corrupt stack?)" error.
>
> Even a very simple program with subroutine calls (similar to below) will
> exhibit this problem:
>
> void foo(int i)
> {
> if (i < 100) foo(i+1);
> printf("i=%d\n", i);
> }
>
> main()
> {
> foo(0);
> }
>
> When compiled without -g each time the program calls foo the stack looks
> to gdb like it's corrupted, and only the topmost level is shown, along
> with the error. Compile with -g and everything works, at least until
> you step into printf, which wasn't compiled with -g.
>
> Once you step out of printf you'll get your stack back.
>
> This feels like a compiler bug to me, i.e. gcc __SHOULD__ generate at
> least the minimal set of .cfi directives that are needed for gdb to
> generate a backtrace, regardless of whether -g is specified or not.
is gdb using the split out debug symbols for your use case?
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https://bugs.launchpad.net/bugs/1325503
Title:
gdb reports 'corrupt stack' on armhf without symbols
Status in Linaro GDB:
New
Status in gdb package in Ubuntu:
Triaged
Bug description:
[Test Case]
sleep 120 &
kill -SEGV %1
Observe a corrupt stack in the generated crash file.
Original Report
---------------
On armhf crash files fail to retrace and gdb reports 'corrupt stack' errors
For example bug 1323241
Thread 1 (Thread 0xb0b3b450 (LWP 2243)):
#0 0x00000030 in ?? ()
No symbol table info available.
#1 0xa9990cbe in ?? () from
/usr/lib/arm-linux-gnueabihf/unity8/qml/Unity/Launcher/libUnityLauncher-qml.so
No symbol table info available.
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
I also tried directly on the device to run an unstripped and stripped
build of cat and gdb fails to unwind the stack when the binary is
stripped. The result of this test is:
== unstripped ==
Reading symbols from ./cat...done.
(gdb) run
Starting program: /home/phablet/tmp/coreutils-8.21/src/cat
^C
Program received signal SIGINT, Interrupt.
0xb6f6e914 in read () from /lib/arm-linux-gnueabihf/libc.so.6
(gdb) bt
#0 0xb6f6e914 in read () from /lib/arm-linux-gnueabihf/libc.so.6
#1 0x0000b648 in read (__nbytes=65536, __buf=0x19000, __fd=0) at
/usr/include/arm-linux-gnueabihf/bits/unistd.h:44
#2 safe_read (fd=0, buf=buf@entry=0x19000, count=count@entry=65536) at
lib/safe-read.c:66
#3 0x00009ace in simple_cat (bufsize=65536, buf=0x19000 "") at src/cat.c:168
#4 main (argc=1, argv=<optimized out>) at src/cat.c:730
(gdb) quit
== stripped ==
Reading symbols from ./cat...(no debugging symbols found)...done.
(gdb) run
Starting program: /home/phablet/tmp/coreutils-8.21/src/cat
^C
Program received signal SIGINT, Interrupt.
0xb6f6e914 in read () from /lib/arm-linux-gnueabihf/libc.so.6
(gdb) bt
#0 0xb6f6e914 in read () from /lib/arm-linux-gnueabihf/libc.so.6
#1 0x0000b648 in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
I'd expect the same number of frames and addresses when the binary is
stripped or not with '??' instead of names when it is stripped.
ProblemType: BugDistroRelease: Ubuntu 14.10
Package: gdb (not installed)
Uname: Linux 3.4.0-5-mako armv7l
ApportVersion: 2.14.3-0ubuntu1
Architecture: armhf
Date: Mon Jun 2 11:07:07 2014
InstallationDate: Installed on 2014-06-02 (0 days ago)
InstallationMedia: Ubuntu Utopic Unicorn (development branch) - armhf
(20140602)SourcePackage: gdb
UpgradeStatus: No upgrade log present (probably fresh install)
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