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authorJan Kratochvil <jan.kratochvil@redhat.com>2016-09-29 17:38:16 +0200
committerJan Kratochvil <jan.kratochvil@redhat.com>2016-09-29 17:39:39 +0200
commitbb805577d2b212411fb7b0a2d01644567fac4e8d (patch)
tree975c7465c2f346d1122bc64221db7ca2ed176c9c /gdb/infcmd.c
parent50751e18f3f2fc47959a577a5754f1a2d80baf18 (diff)
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PR gdb/20609 - attach of JIT-debug-enabled inf 7.11.1 regression
Regression: gdb --pid $(pidof qemu-system-x86_64) stopped working with gdb 7.11.1 https://sourceware.org/bugzilla/show_bug.cgi?id=20609 It was reported for qemu-system-x86_64 but it happens for any multithreaded inferior with a JIT debugging hook. 136613ef0c6850427317e57be1b644080ff6decb is the first bad commit Author: Pedro Alves <palves@redhat.com> Fix PR gdb/19828: gdb -p <process from a container>: internal error Message-ID: <cbdf2e04-4fa8-872a-2a23-08c9c1b26e00@redhat.com> https://sourceware.org/ml/gdb-patches/2016-05/msg00450.html jit_breakpoint_re_set() is specific by trying to insert a breakpoint into the main executable, not into a shared library. During attachment GDB thinks it needs to use 'breakpoint always-inserted' from breakpoints_should_be_inserted_now() as a newly attached thread is 'thread_info->executing' due to 'lwp_info->must_set_ptrace_flags' enabled and the task not yet stopped. This did not happen before the 'bad commit' above which adds tracking of such thread. GDB then fails to insert the breakpoints to invalid address as PIE executable gets properly relocated during later phase of attachment. One can see in the backtraces below: -> jit_breakpoint_re_set_internal() later: -> svr4_exec_displacement() One can suppress the initial breakpoint_re_set() call as there will be another breakpoint_re_set() done from the final post_create_inferior() call in setup_inferior(). BTW additionally 'threads_executing' cache bool is somehow stale (somewhere is missing update_threads_executing()). I was trying to deal with that in my first/second attempt below but in my final third attempt (attached) I have left it as it is. First attempt trying not to falsely require 'breakpoint always-inserted': https://people.redhat.com/jkratoch/rhbz1375553-fix1.patch Reduced first attempt: https://people.redhat.com/jkratoch/rhbz1375553-fix2.patch The third attempt suppresses breakpoint insertion until PIE executable gets relocated by svr4_exec_displacement(). Applied. gdb/ChangeLog 2016-09-29 Jan Kratochvil <jan.kratochvil@redhat.com> PR gdb/20609 - attach of JIT-debug-enabled inf 7.11.1 regression * exec.c (exec_file_locate_attach): Add parameter defer_bp_reset. Use it. * gdbcore.h (exec_file_locate_attach): Add parameter defer_bp_reset. * infcmd.c (setup_inferior): Update caller. * remote.c (remote_add_inferior): Likewise. gdb/testsuite/ChangeLog 2016-09-29 Jan Kratochvil <jan.kratochvil@redhat.com> PR gdb/20609 - attach of JIT-debug-enabled inf 7.11.1 regression * gdb.base/jit-attach-pie.c: New file. * gdb.base/jit-attach-pie.exp: New file.
Diffstat (limited to 'gdb/infcmd.c')
-rw-r--r--gdb/infcmd.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index 44a1fd1..8e34b7e 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -2660,7 +2660,7 @@ setup_inferior (int from_tty)
/* If no exec file is yet known, try to determine it from the
process itself. */
if (get_exec_file (0) == NULL)
- exec_file_locate_attach (ptid_get_pid (inferior_ptid), from_tty);
+ exec_file_locate_attach (ptid_get_pid (inferior_ptid), 1, from_tty);
else
{
reopen_exec_file ();