** Description changed:
- GDB 12.1 had a regression where it will break program execution when the
- program contains mixed ARM code and THUMB code.
+ [ Impact ]
+
+ * GDB 12.1 introduced a regression where it will break program execution
when the program contains mixed ARM code and THUMB code.
+ * Upstream stated they tested the changes on Ubuntu 20.04 and it went okay.
+
+ [ Test Plan ]
Considering the following C program:
```
__attribute__((target("arm"), noinline))
int thumb_func() {
- return 42;
+ return 42;
}
__attribute__((target("thumb")))
int main() { return thumb_func(); }
```
If you build it using `gcc repro.c -ggdb3 -Og -o repro` and run the GDB
- using the following commands:
+ using the following commands ...
```
b 3
r
c
```
- (you can save it to a file and run GDB using `gdb -x script ./repro`)
+ (you can save the contents above to a file and run GDB using `gdb -x
+ script ./repro`)
- You will notice GDB broke the program and threw SIGILL.
+ ... you will notice GDB broke the program and threw SIGILL.
If you run the program without GDB, the program exits normally.
- This bug has been fixed in GDB 13, but the fix was never backported to
- GDB 12. You can find the upstream bug in the remote bug watch.
+ [ Where problems could occur ]
+
+ * GDB is a complex software. As the patch suggests, it may break other use
cases (like single-stepping) entirely.
+ * Since this is an ARM-only patch, it's unlikely to affect other CPU
architectures. However, it is possible that this fix may break ARM64 execution.
+
+ [ Other Info ]
+
+ * This bug has been fixed in GDB 13, but the fix was never backported to GDB
12. You can find the upstream bug in the remote bug watch.
--
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Touch seeded packages, which is subscribed to gdb in Ubuntu.
https://bugs.launchpad.net/bugs/2041396
Title:
gdb 12.1 generates SIGILL on armhf
Status in gdb:
Unknown
Status in gdb package in Ubuntu:
New
Bug description:
[ Impact ]
* GDB 12.1 introduced a regression where it will break program execution
when the program contains mixed ARM code and THUMB code.
* Upstream stated they tested the changes on Ubuntu 20.04 and it went okay.
[ Test Plan ]
Considering the following C program:
```
__attribute__((target("arm"), noinline))
int thumb_func() {
return 42;
}
__attribute__((target("thumb")))
int main() { return thumb_func(); }
```
If you build it using `gcc repro.c -ggdb3 -Og -o repro` and run the
GDB using the following commands ...
```
b 3
r
c
```
(you can save the contents above to a file and run GDB using `gdb -x
script ./repro`)
... you will notice GDB broke the program and threw SIGILL.
If you run the program without GDB, the program exits normally.
[ Where problems could occur ]
* GDB is a complex software. As the patch suggests, it may break other use
cases (like single-stepping) entirely.
* Since this is an ARM-only patch, it's unlikely to affect other CPU
architectures. However, it is possible that this fix may break ARM64 execution.
[ Other Info ]
* This bug has been fixed in GDB 13, but the fix was never backported to GDB
12. You can find the upstream bug in the remote bug watch.
To manage notifications about this bug go to:
https://bugs.launchpad.net/gdb/+bug/2041396/+subscriptions
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