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This patch implements support for exec events on extended-remote Linux targets. Follow-exec-mode and rerun behave as expected. Catchpoints and test updates are implemented in subsequent patches. This patch was derived from a patch posted last October: https://sourceware.org/ml/gdb-patches/2014-10/msg00877.html. It was originally based on some work done by Luis Machado in 2013. IMPLEMENTATION ---------------- Exec events are enabled via ptrace options. When an exec event is detected by gdbserver, the existing process data, along with all its associated lwp and thread data, is deleted and replaced by data for a new single-threaded process. The new process data is initialized with the appropriate parts of the state of the execing process. This approach takes care of several potential pitfalls, including: * deleting the data for an execing non-leader thread before any wait/sigsuspend occurs * correctly initializing the architecture of the execed process We then report the exec event using a new RSP stop reason, "exec". When GDB receives an "exec" event, it saves the status in the event structure's target_waitstatus field, like what is done for remote fork events. Because the original and execed programs may have different architectures, we skip parsing the section of the stop reply packet that contains register data. The register data will be retrieved later after the inferior's architecture has been set up by infrun.c:follow_exec. At that point the exec event is handled by the existing event handling in GDB. However, a few changes were necessary so that infrun.c:follow_exec could accommodate the remote target. * Where follow-exec-mode "new" is handled, we now call add_inferior_with_spaces instead of add_inferior with separate calls to set up the program and address spaces. The motivation for this is that add_inferior_with_spaces also sets up the initial architecture for the inferior, which is needed later by target_find_description when it calls target_gdbarch. * We call a new target function, target_follow_exec. This function allows us to store the execd_pathname in the inferior, instead of using the static string remote_exec_file from remote.c. The static string didn't work for follow-exec-mode "new", since once you switched to the execed program, the original remote exec-file was lost. The execd_pathname is now stored in the inferior's program space as a REGISTRY field. All of the requisite mechanisms for this are defined in remote.c. gdb/gdbserver/ChangeLog: * linux-low.c (linux_mourn): Static declaration. (linux_arch_setup): Move in front of handle_extended_wait. (linux_arch_setup_thread): New function. (handle_extended_wait): Handle exec events. Call linux_arch_setup_thread. Make event_lwp argument a pointer-to-a-pointer. (check_zombie_leaders): Do not check stopped threads. (linux_low_ptrace_options): Add PTRACE_O_TRACEEXEC. (linux_low_filter_event): Add lwp and thread for exec'ing non-leader thread if leader thread has been deleted. Refactor code into linux_arch_setup_thread and call it. Pass child lwp pointer by reference to handle_extended_wait. (linux_wait_for_event_filtered): Update comment. (linux_wait_1): Prevent clobbering exec event status. (linux_supports_exec_events): New function. (linux_target_ops) <supports_exec_events>: Initialize new member. * lynx-low.c (lynx_target_ops) <supports_exec_events>: Initialize new member. * remote-utils.c (prepare_resume_reply): New stop reason 'exec'. * server.c (report_exec_events): New global variable. (handle_query): Handle qSupported query for exec-events feature. (captured_main): Initialize report_exec_events. * server.h (report_exec_events): Declare new global variable. * target.h (struct target_ops) <supports_exec_events>: New member. (target_supports_exec_events): New macro. * win32-low.c (win32_target_ops) <supports_exec_events>: Initialize new member. gdb/ChangeLog: * infrun.c (follow_exec): Use process-style ptid for exec message. Call add_inferior_with_spaces and target_follow_exec. * nat/linux-ptrace.c (linux_supports_traceexec): New function. * nat/linux-ptrace.h (linux_supports_traceexec): Declare. * remote.c (remote_pspace_data): New static variable. (remote_pspace_data_cleanup): New function. (get_remote_exec_file): New function. (set_remote_exec_file_1): New function. (set_remote_exec_file): New function. (show_remote_exec_file): New function. (remote_exec_file): Delete static variable. (anonymous enum) <PACKET_exec_event_feature> New enumeration constant. (remote_protocol_features): Add entry for exec-events feature. (remote_query_supported): Add client side of qSupported query for exec-events feature. (remote_follow_exec): New function. (remote_parse_stop_reply): Handle 'exec' stop reason. (extended_remote_run, extended_remote_create_inferior): Call get_remote_exec_file and set_remote_exec_file_1. (init_extended_remote_ops) <to_follow_exec>: Initialize new member. (_initialize_remote): Call register_program_space_data_with_cleanup. Call add_packet_config_cmd for remote exec-events feature. Modify call to add_setshow_string_noescape_cmd for exec-file to use new functions set_remote_exec_file and show_remote_exec_file. * target-debug.h, target-delegates.c: Regenerated. * target.c (target_follow_exec): New function. * target.h (struct target_ops) <to_follow_exec>: New member. (target_follow_exec): Declare new function.
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