From 12ab52e9772a9170018feb44de3ef217e051cc60 Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Wed, 26 Feb 2014 14:22:33 +0000 Subject: [PATCH] Multiple Ada task-specific breakpoints at the same address. With the test changed as in the patch, against current mainline, we get: (gdb) PASS: gdb.ada/tasks.exp: info tasks before inserting breakpoint break break_me task 1 Breakpoint 2 at 0x4030b0: file /home/pedro/gdb/mygit/src/gdb/testsuite/gdb.ada/tasks/foo.adb, line 27. (gdb) PASS: gdb.ada/tasks.exp: break break_me task 1 break break_me task 3 Note: breakpoint 2 also set at pc 0x4030b0. Breakpoint 3 at 0x4030b0: file /home/pedro/gdb/mygit/src/gdb/testsuite/gdb.ada/tasks/foo.adb, line 27. (gdb) PASS: gdb.ada/tasks.exp: break break_me task 3 continue Continuing. [Switching to Thread 0x7ffff7dc7700 (LWP 27133)] Breakpoint 2, foo.break_me () at /home/pedro/gdb/mygit/src/gdb/testsuite/gdb.ada/tasks/foo.adb:27 27 null; (gdb) FAIL: gdb.ada/tasks.exp: continue to breakpoint info tasks ID TID P-ID Pri State Name 1 63b010 48 Waiting on RV with 3 main_task 2 63bd80 1 48 Accept or Select Term task_list(1) * 3 63f510 1 48 Accepting RV with 1 task_list(2) 4 642ca0 1 48 Accept or Select Term task_list(3) (gdb) PASS: gdb.ada/tasks.exp: info tasks after hitting breakpoint The breakpoint that caused a stop is breakpoint 3, but GDB end up reporting (and running breakpoint commands of) "Breakpoint 2" instead. The issue is that the bpstat_check_breakpoint_conditions logic of "wrong thread" is missing the "wrong task" check. This is usually harmless, because the thread hop code in infrun.c code that handles wrong-task-hitting-breakpoint does check for task-specific breakpoints (within breakpoint_thread_match): /* Check if a regular breakpoint has been hit before checking for a potential single step breakpoint. Otherwise, GDB will not see this breakpoint hit when stepping onto breakpoints. */ if (regular_breakpoint_inserted_here_p (aspace, stop_pc)) { if (!breakpoint_thread_match (aspace, stop_pc, ecs->ptid)) thread_hop_needed = 1; } IOW, usually, when one only has a task specific breakpoint at a given address, things work correctly. Put another task-specific or non-task-specific breakpoint there, and things break. A patch that eliminates the special thread hop code in infrun.c is what exposed this, as after that GDB solely relies on bpstat_check_breakpoint_conditions to know whether the right or wrong task hit a breakpoint. IOW, given the latent bug, Ada task-specific breakpoints become non-task-specific, and that is caught by the testsuite, as: break break_me task 3 Breakpoint 2 at 0x4030b0: file /home/pedro/gdb/mygit/src/gdb/testsuite/gdb.ada/tasks/foo.adb, line 27. (gdb) PASS: gdb.ada/tasks.exp: break break_me task 3 continue Continuing. [Switching to Thread 0x7ffff7fcb700 (LWP 17122)] Breakpoint 2, foo.break_me () at /home/pedro/gdb/mygit/src/gdb/testsuite/gdb.ada/tasks/foo.adb:27 27 null; (gdb) PASS: gdb.ada/tasks.exp: continue to breakpoint info tasks ID TID P-ID Pri State Name 1 63b010 48 Waiting on RV with 2 main_task * 2 63bd80 1 48 Accepting RV with 1 task_list(1) 3 63f510 1 48 Accept or Select Term task_list(2) 4 642ca0 1 48 Accept or Select Term task_list(3) (gdb) FAIL: gdb.ada/tasks.exp: info tasks after hitting breakpoint It was after seeing this that I thought of how to expose the bug with current mainline. Tested on x86_64 Fedora 17. gdb/ 2014-02-26 Pedro Alves * breakpoint.c (bpstat_check_breakpoint_conditions): Handle task-specific breakpoints. gdb/testsuite/ 2014-02-26 Pedro Alves * gdb.ada/tasks.exp: Set a task-specific breakpoint at break_me that won't ever trigger. Make sure that GDB reports the correct breakpoint that caused the stop. --- gdb/ChangeLog | 5 +++++ gdb/breakpoint.c | 10 ++++++---- gdb/testsuite/ChangeLog | 6 ++++++ gdb/testsuite/gdb.ada/tasks.exp | 28 ++++++++++++++++++++++++---- 4 files changed, 41 insertions(+), 8 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 16f4619180..3a02a49057 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,8 @@ +2014-02-26 Pedro Alves + + * breakpoint.c (bpstat_check_breakpoint_conditions): Handle + task-specific breakpoints. + 2014-02-25 Pedro Alves * ia64-linux-nat.c (ia64_linux_xfer_partial): Reimplement diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c index ef81443dfa..45c341752f 100644 --- a/gdb/breakpoint.c +++ b/gdb/breakpoint.c @@ -5159,7 +5159,6 @@ bpstat_check_watchpoint (bpstat bs) static void bpstat_check_breakpoint_conditions (bpstat bs, ptid_t ptid) { - int thread_id = pid_to_thread_id (ptid); const struct bp_location *bl; struct breakpoint *b; int value_is_zero = 0; @@ -5184,9 +5183,12 @@ bpstat_check_breakpoint_conditions (bpstat bs, ptid_t ptid) return; } - /* If this is a thread-specific breakpoint, don't waste cpu evaluating the - condition if this isn't the specified thread. */ - if (b->thread != -1 && b->thread != thread_id) + /* If this is a thread/task-specific breakpoint, don't waste cpu + evaluating the condition if this isn't the specified + thread/task. */ + if ((b->thread != -1 && b->thread != pid_to_thread_id (ptid)) + || (b->task != 0 && b->task != ada_get_task_number (ptid))) + { bs->stop = 0; return; diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index d54ed98b8f..09cc8a3228 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,9 @@ +2014-02-26 Pedro Alves + + * gdb.ada/tasks.exp: Set a task-specific breakpoint at break_me + that won't ever trigger. Make sure that GDB reports the correct + breakpoint that caused the stop. + 2014-02-25 Jan Kratochvil PR gdb/16626 diff --git a/gdb/testsuite/gdb.ada/tasks.exp b/gdb/testsuite/gdb.ada/tasks.exp index 710deb05e4..088be6d31e 100644 --- a/gdb/testsuite/gdb.ada/tasks.exp +++ b/gdb/testsuite/gdb.ada/tasks.exp @@ -37,15 +37,35 @@ gdb_test "info tasks" \ "\r\n"] \ "info tasks before inserting breakpoint" -# Now, insert a breakpoint that should stop only if task 3 stops. -gdb_test "break break_me task 3" "Breakpoint .* at .*" +# Insert a breakpoint that should stop only if task 1 stops. Since +# task 1 never calls break_me, this shouldn't actually ever trigger. +# The fact that this breakpoint is created _before_ the next one +# matters. GDB used to have a bug where it would report the first +# breakpoint in the list that matched the triggered-breakpoint's +# address, no matter which task it was specific to. +gdb_test "break break_me task 1" "Breakpoint .* at .*" + +# Now, insert a breakpoint that should stop only if task 3 stops, and +# extract its number. +set bp_number -1 +set test "break break_me task 3" +gdb_test_multiple $test $test { + -re "Breakpoint (.*) at .*$gdb_prompt $" { + set bp_number $expect_out(1,string) + pass $test + } +} + +if {$bp_number < 0} { + return +} # Continue to that breakpoint. Task 2 should hit it first, and GDB # is expected to ignore that hit and resume the execution. Only then # task 3 will hit our breakpoint, and GDB is expected to stop at that -# point. +# point. Also make sure that GDB reports the correct breakpoint number. gdb_test "continue" \ - ".*Breakpoint.*, foo.break_me \\(\\).*" \ + ".*Breakpoint $bp_number, foo.break_me \\(\\).*" \ "continue to breakpoint" # Check that it is indeed task 3 that hit the breakpoint by checking -- 2.34.1