On x86_64-freebsd, with test-case gdb.arch/amd64-disp-step-self-call.exp, I
run into:
...
(gdb) continue
Continuing.
Program received signal SIGBUS, Bus error.
Object-specific hardware error.
0x000000080051492c in alarm () from /lib/libc.so.7
(gdb) FAIL: $exp: continue to breakpoint: test_call
...
The behaviour is not specific to gdb, it can be reproduced by running the
test-case executable:
...
$ ./outputs/gdb.arch/amd64-disp-step-self-call/amd64-disp-step-self-call
Bus error (core dumped)
$
...
The bus error happens when executing this instruction in alarm:
...
0000000000093910 <alarm>:
...
9392c: 0f 29 45 d0 movaps %xmm0, -0x30(%rbp)
...
because $rbp is not 16-byte aligned.
This can be fixed by adding the missing frame setup instructions at the start
of main in amd64-disp-step-self-call.S:
...
main:
+ pushq %rbp
+ movq %rsp, %rbp
...
Instead, fix this by moving main from the assembly file to the c file, which
has the same effect.
Also remove the done label, which looks like a copy-past left-over. Instead,
add an unreachable function and use it where appropriate.
Do the same for i386 case (which makes the source files identical for the
amd64 and i386 case, but I decided to leave it like that).
Tested on x86_64-freebsd and x86_64-linux.
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <unistd.h>
+#include <stdlib.h>
+
+extern void test_call (void);
+
+void
+unreachable (void)
+{
+ abort ();
+}
void
setup_alarm (void)
{
alarm (300);
}
+
+int
+main ()
+{
+ setup_alarm ();
+ test_call ();
+ unreachable ();
+ return 0;
+}
handling. */
.text
-
- .global main
-main:
- nop
-
- callq setup_alarm
-
- nop
-
-/***********************************************/
-
-/* test call/ret */
-
.global test_call
test_call:
call test_call
- nop
+ call unreachable
.global test_ret_end
test_ret_end:
nop
-/***********************************************/
-
-/* all done */
-
-done:
- mov $0,%rdi
- call exit
- hlt
.section .note.GNU-stack,"",@progbits
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <unistd.h>
+#include <stdlib.h>
+
+extern void test_call (void);
+
+void
+unreachable (void)
+{
+ abort ();
+}
void
setup_alarm (void)
{
alarm (300);
}
+
+int
+main ()
+{
+ setup_alarm ();
+ test_call ();
+ unreachable ();
+ return 0;
+}
handling. */
.text
-
- .global main
-main:
- nop
-
- call setup_alarm
-
- nop
-
-/***********************************************/
-
-/* test call/ret */
-
.global test_call
test_call:
call test_call
- nop
+ call unreachable
.global test_ret_end
test_ret_end:
nop
-/***********************************************/
-
-/* all done */
-
-done:
- pushl $0
- call exit
- hlt
.section .note.GNU-stack,"",@progbits