* [pushed 1/2] [gdb/testsuite] Make gdb.base/longjmp.exp FAIL more stable across archs
@ 2022-12-06 11:02 Tom de Vries
2022-12-06 11:02 ` [pushed 2/2] [gdb/testsuite] Fix test names in gdb.base/longjmp.exp Tom de Vries
0 siblings, 1 reply; 2+ messages in thread
From: Tom de Vries @ 2022-12-06 11:02 UTC (permalink / raw)
To: gdb-patches
When running test-case gdb.base/longjmp.exp on x86_64-linux, the master
longjmp breakpoint is set using probes and the test-case passes:
...
(gdb) PASS: gdb.base/longjmp.exp: next to longjmp (1)
next^M
0x00000000004005cc 49 if (setjmp (env) == 0) /* patt1 */^M
(gdb) PASS: gdb.base/longjmp.exp: next over longjmp(1)
next^M
56 resumes++;^M
(gdb) PASS: gdb.base/longjmp.exp: next into else block (1)
...
However, if I disable
create_longjmp_master_breakpoint_probe, we have instead:
...
(gdb) PASS: gdb.base/longjmp.exp: next to longjmp (1)
next^M
56 resumes++;^M
(gdb) FAIL: gdb.base/longjmp.exp: next over longjmp(1)
...
At first glance, the failure mode doesn't look too bad: we stop
a few insns later than the passing scenario.
For contrast, if we do the same on powerpc64le, the failure mode is:
...
(gdb) PASS: gdb.base/longjmp.exp: next to longjmp (1)
next^M
^M
Breakpoint 3, main () at longjmp.c:59^M
59 i = 1; /* miss_step_1 */^M
(gdb) FAIL: gdb.base/longjmp.exp: next over longjmp(1)
...
Here we only stop because of running into the safety net breakpoint at
miss_step_1.
So, how does this happen on x86_64? Let's look at the code:
...
4005c7: e8 94 fe ff ff call 400460 <_setjmp@plt>
4005cc: 85 c0 test %eax,%eax
4005ce: 75 1e jne 4005ee <main+0x3b>
4005d0: 8b 05 8e 0a 20 00 mov 0x200a8e(%rip),%eax # 601064 <longjmps>
4005d6: 83 c0 01 add $0x1,%eax
4005d9: 89 05 85 0a 20 00 mov %eax,0x200a85(%rip) # 601064 <longjmps>
4005df: be 01 00 00 00 mov $0x1,%esi
4005e4: bf 80 10 60 00 mov $0x601080,%edi
4005e9: e8 82 fe ff ff call 400470 <longjmp@plt>
4005ee: 8b 05 74 0a 20 00 mov 0x200a74(%rip),%eax # 601068 <resumes>
...
The next over the longjmp call at 4005e9 is supposed to stop at the longjmp
target at 4005cc, but instead we stop at 4005ee, where we have the step-resume
breakpoint inserted by the next. In other words, we accidentally "return"
from the longjmp call to the insn immediately after it (even though
a longjmp is a noreturn function).
Try to avoid this accident and make the failure mode on x86_64 the same as on
powerpc64le, by switching the then and else branch.
Tested on x86_64-linux.
---
gdb/testsuite/gdb.base/longjmp.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/gdb/testsuite/gdb.base/longjmp.c b/gdb/testsuite/gdb.base/longjmp.c
index 4139e49e6f1..ce6990ca99a 100644
--- a/gdb/testsuite/gdb.base/longjmp.c
+++ b/gdb/testsuite/gdb.base/longjmp.c
@@ -46,14 +46,14 @@ main ()
volatile int i = 0;
/* Pattern 1 - simple longjmp. */
- if (setjmp (env) == 0) /* patt1 */
+ if (setjmp (env) != 0) /* patt1 */
{
- longjmps++;
- longjmp (env, 1);
+ resumes++;
}
else
{
- resumes++;
+ longjmps++;
+ longjmp (env, 1);
}
i = 1; /* miss_step_1 */
base-commit: c8ea5e409b02cf7fa848e44af74b2e8246ad03f1
--
2.35.3
^ permalink raw reply [flat|nested] 2+ messages in thread
* [pushed 2/2] [gdb/testsuite] Fix test names in gdb.base/longjmp.exp
2022-12-06 11:02 [pushed 1/2] [gdb/testsuite] Make gdb.base/longjmp.exp FAIL more stable across archs Tom de Vries
@ 2022-12-06 11:02 ` Tom de Vries
0 siblings, 0 replies; 2+ messages in thread
From: Tom de Vries @ 2022-12-06 11:02 UTC (permalink / raw)
To: gdb-patches
When running test-case gdb.base/longjmp.exp, we have:
...
PASS: gdb.base/longjmp.exp: next over setjmp (1)
...
PASS: gdb.base/longjmp.exp: next over setjmp (2)
...
The trailing " (1)" and " (2)" are interpreted as comments rather than parts
of the test name, and therefore this is a duplicate, which is currently not
detected by our duplicate detection mechanism (PR testsuite/29772).
Fix the duplicate by using with_test_prefix.
Tested on x86_64-linux.
---
gdb/testsuite/gdb.base/longjmp.exp | 111 ++++++++++++++++-------------
1 file changed, 63 insertions(+), 48 deletions(-)
diff --git a/gdb/testsuite/gdb.base/longjmp.exp b/gdb/testsuite/gdb.base/longjmp.exp
index bd2fc21a442..10e440bfca8 100644
--- a/gdb/testsuite/gdb.base/longjmp.exp
+++ b/gdb/testsuite/gdb.base/longjmp.exp
@@ -42,30 +42,35 @@ set bp_start_test_3 [gdb_get_line_number "patt3"]
# Pattern 1 - simple longjmp.
#
-delete_breakpoints
-
-gdb_test "break $bp_start_test_1" \
- "Breakpoint.*at.* file .*$srcfile, line.*$bp_start_test_1.*" \
- "breakpoint at pattern 1 start"
-gdb_test "continue" "patt1.*" "continue to breakpoint at pattern 1 start"
-
-# set safe-net break
-gdb_test "break $bp_miss_step_1" \
- "Breakpoint.*at.* file .*$srcfile, line.*$bp_miss_step_1.*" \
- "breakpoint at miss_step_1"
-
-gdb_test "next" "longjmps\\+\\+;.*" "next over setjmp (1)"
-gdb_test "next" "longjmp \\(env, 1\\);.*" "next to longjmp (1)"
-
-set msg "next over longjmp(1)"
-gdb_test_multiple "next" $msg {
- -re ".*patt1.*$gdb_prompt $" {
- pass $msg
- gdb_test "next" "resumes\\+\\+.*" "next into else block (1)"
- gdb_test "next" "miss_step_1.*" "next into safety net (1)"
+with_test_prefix "pattern 1" {
+
+ with_test_prefix setup {
+ delete_breakpoints
+
+ gdb_test "break $bp_start_test_1" \
+ "Breakpoint.*at.* file .*$srcfile, line.*$bp_start_test_1.*" \
+ "breakpoint at pattern start"
+ gdb_test "continue" "patt1.*" "continue to breakpoint at pattern start"
+
+ # set safe-net break
+ gdb_test "break $bp_miss_step_1" \
+ "Breakpoint.*at.* file .*$srcfile, line.*$bp_miss_step_1.*" \
+ "breakpoint at safety net"
}
- -re "miss_step_1.*$gdb_prompt $" {
- fail $msg
+
+ gdb_test "next" "longjmps\\+\\+;.*" "next over setjmp"
+ gdb_test "next" "longjmp \\(env, 1\\);.*" "next to longjmp"
+
+ set msg "next over longjmp"
+ gdb_test_multiple "next" $msg {
+ -re ".*patt1.*$gdb_prompt $" {
+ pass $msg
+ gdb_test "next" "resumes\\+\\+.*" "next into else block"
+ gdb_test "next" "miss_step_1.*" "next into safety net"
+ }
+ -re "miss_step_1.*$gdb_prompt $" {
+ fail $msg
+ }
}
}
@@ -73,30 +78,35 @@ gdb_test_multiple "next" $msg {
# Pattern 2 - longjmp from an inner function.
#
-delete_breakpoints
+with_test_prefix "pattern 2" {
+
+ with_test_prefix setup {
+ delete_breakpoints
-gdb_test "break $bp_start_test_2" \
- "Breakpoint.*at.* file .*$srcfile, line.*$bp_start_test_2.*" \
- "breakpoint at pattern 2 start"
-gdb_test "continue" "patt2.*" "continue to breakpoint at pattern 2 start"
+ gdb_test "break $bp_start_test_2" \
+ "Breakpoint.*at.* file .*$srcfile, line.*$bp_start_test_2.*" \
+ "breakpoint at pattern start"
+ gdb_test "continue" "patt2.*" "continue to breakpoint at pattern start"
-# set safe-net break
-gdb_test "break $bp_miss_step_2" \
- "Breakpoint.*at.* file .*$srcfile, line.*$bp_miss_step_2.*" \
- "breakpoint at miss_step_2"
+ # set safe-net break
+ gdb_test "break $bp_miss_step_2" \
+ "Breakpoint.*at.* file .*$srcfile, line.*$bp_miss_step_2.*" \
+ "breakpoint at safety net"
+ }
-gdb_test "next" "call_longjmp.*" "next over setjmp (2)"
+ gdb_test "next" "call_longjmp.*" "next over setjmp"
-set msg "next over call_longjmp (2)"
-gdb_test_multiple "next" $msg {
- -re ".*patt2.*$gdb_prompt $" {
- pass $msg
+ set msg "next over call_longjmp"
+ gdb_test_multiple "next" $msg {
+ -re ".*patt2.*$gdb_prompt $" {
+ pass $msg
- gdb_test "next" "resumes\\+\\+.*" "next into else block (2)"
- gdb_test "next" "miss_step_2.*" "next into safety net (2)"
- }
- -re "miss_step_2.*$gdb_prompt $" {
- fail $msg
+ gdb_test "next" "resumes\\+\\+.*" "next into else block"
+ gdb_test "next" "miss_step_2.*" "next into safety net"
+ }
+ -re "miss_step_2.*$gdb_prompt $" {
+ fail $msg
+ }
}
}
@@ -104,11 +114,16 @@ gdb_test_multiple "next" $msg {
# Pattern 3 - setjmp/longjmp inside stepped-over function.
#
-delete_breakpoints
+with_test_prefix "pattern 3" {
-gdb_test "break $bp_start_test_3" \
- "Breakpoint.*at.* file .*$srcfile, line.*$bp_start_test_3.*" \
- "breakpoint at pattern 3 start"
-gdb_test "continue" "patt3.*" "continue to breakpoint at pattern 3 start"
+ with_test_prefix setup {
+ delete_breakpoints
-gdb_test "next" "longjmp caught.*" "next over patt3"
+ gdb_test "break $bp_start_test_3" \
+ "Breakpoint.*at.* file .*$srcfile, line.*$bp_start_test_3.*" \
+ "breakpoint at pattern start"
+ gdb_test "continue" "patt3.*" "continue to breakpoint at pattern start"
+ }
+
+ gdb_test "next" "longjmp caught.*" "next over pattern"
+}
--
2.35.3
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