From 523d4f80c32f43a6b009645947b94f87df35f79f Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Wed, 8 Apr 2020 14:33:35 -0600 Subject: [PATCH 1/1] Implement stopped_by_sw_breakpoint for Windows gdbserver This changes the Windows gdbserver port to implement the stopped_by_sw_breakpoint target method. This is needed to support pending stops. This is a separate patch now, because Pedro suggested splitting it out for simpler bisecting, in the case that it introduces a bug. gdbserver/ChangeLog 2020-04-08 Tom Tromey * win32-low.h (win32_process_target::stopped_by_sw_breakpoint) (win32_process_target::supports_stopped_by_sw_breakpoint): Declare. * win32-low.c (win32_supports_z_point_type): Always handle Z_PACKET_SW_BP. (win32_insert_point): Call insert_memory_breakpoint when needed. (win32_remove_point): Call remove_memory_breakpoint when needed. (win32_process_target::stopped_by_sw_breakpoint) (win32_process_target::supports_stopped_by_sw_breakpoint): New methods. (win32_target_ops): Update. (maybe_adjust_pc): New function. (win32_wait): Call maybe_adjust_pc. --- gdbserver/ChangeLog | 16 ++++++++++ gdbserver/win32-low.cc | 67 ++++++++++++++++++++++++++++++++++-------- gdbserver/win32-low.h | 4 +++ 3 files changed, 75 insertions(+), 12 deletions(-) diff --git a/gdbserver/ChangeLog b/gdbserver/ChangeLog index 24c42e28d0..36d6f29e42 100644 --- a/gdbserver/ChangeLog +++ b/gdbserver/ChangeLog @@ -1,3 +1,19 @@ +2020-04-08 Tom Tromey + + * win32-low.h (win32_process_target::stopped_by_sw_breakpoint) + (win32_process_target::supports_stopped_by_sw_breakpoint): + Declare. + * win32-low.c (win32_supports_z_point_type): Always handle + Z_PACKET_SW_BP. + (win32_insert_point): Call insert_memory_breakpoint when needed. + (win32_remove_point): Call remove_memory_breakpoint when needed. + (win32_process_target::stopped_by_sw_breakpoint) + (win32_process_target::supports_stopped_by_sw_breakpoint): New + methods. + (win32_target_ops): Update. + (maybe_adjust_pc): New function. + (win32_wait): Call maybe_adjust_pc. + 2020-04-08 Tom Tromey * win32-low.h (struct win32_target_ops) : New diff --git a/gdbserver/win32-low.cc b/gdbserver/win32-low.cc index 131eacb13c..4312bb3ab7 100644 --- a/gdbserver/win32-low.cc +++ b/gdbserver/win32-low.cc @@ -236,15 +236,18 @@ child_delete_thread (DWORD pid, DWORD tid) bool win32_process_target::supports_z_point_type (char z_type) { - return (the_low_target.supports_z_point_type != NULL - && the_low_target.supports_z_point_type (z_type)); + return (z_type == Z_PACKET_SW_BP + || (the_low_target.supports_z_point_type != NULL + && the_low_target.supports_z_point_type (z_type))); } int win32_process_target::insert_point (enum raw_bkpt_type type, CORE_ADDR addr, int size, raw_breakpoint *bp) { - if (the_low_target.insert_point != NULL) + if (type == raw_bkpt_type_sw) + return insert_memory_breakpoint (bp); + else if (the_low_target.insert_point != NULL) return the_low_target.insert_point (type, addr, size, bp); else /* Unsupported (see target.h). */ @@ -255,7 +258,9 @@ int win32_process_target::remove_point (enum raw_bkpt_type type, CORE_ADDR addr, int size, raw_breakpoint *bp) { - if (the_low_target.remove_point != NULL) + if (type == raw_bkpt_type_sw) + return remove_memory_breakpoint (bp); + else if (the_low_target.remove_point != NULL) return the_low_target.remove_point (type, addr, size, bp); else /* Unsupported (see target.h). */ @@ -1189,6 +1194,32 @@ windows_nat::handle_ms_vc_exception (const EXCEPTION_RECORD *rec) return false; } +/* A helper function that will, if needed, set + 'stopped_at_software_breakpoint' on the thread and adjust the + PC. */ + +static void +maybe_adjust_pc () +{ + struct regcache *regcache = get_thread_regcache (current_thread, 1); + child_fetch_inferior_registers (regcache, -1); + + windows_thread_info *th = thread_rec (current_thread_ptid (), + DONT_INVALIDATE_CONTEXT); + th->stopped_at_software_breakpoint = false; + + if (current_event.dwDebugEventCode == EXCEPTION_DEBUG_EVENT + && (current_event.u.Exception.ExceptionRecord.ExceptionCode + == EXCEPTION_BREAKPOINT) + && child_initialization_done) + { + th->stopped_at_software_breakpoint = true; + CORE_ADDR pc = regcache_read_pc (regcache); + CORE_ADDR sw_breakpoint_pc = pc - the_low_target.decr_pc_after_break; + regcache_write_pc (regcache, sw_breakpoint_pc); + } +} + /* Get the next event from the child. */ static int @@ -1417,8 +1448,6 @@ ptid_t win32_process_target::wait (ptid_t ptid, target_waitstatus *ourstatus, int options) { - struct regcache *regcache; - if (cached_status.kind != TARGET_WAITKIND_IGNORE) { /* The core always does a wait after creating the inferior, and @@ -1446,12 +1475,12 @@ win32_process_target::wait (ptid_t ptid, target_waitstatus *ourstatus, case TARGET_WAITKIND_STOPPED: case TARGET_WAITKIND_SIGNALLED: case TARGET_WAITKIND_LOADED: - OUTMSG2 (("Child Stopped with signal = %d \n", - ourstatus->value.sig)); - - regcache = get_thread_regcache (current_thread, 1); - child_fetch_inferior_registers (regcache, -1); - return debug_event_ptid (¤t_event); + { + OUTMSG2 (("Child Stopped with signal = %d \n", + ourstatus->value.sig)); + maybe_adjust_pc (); + return debug_event_ptid (¤t_event); + } default: OUTMSG (("Ignoring unknown internal event, %d\n", ourstatus->kind)); /* fall-through */ @@ -1659,6 +1688,20 @@ win32_process_target::sw_breakpoint_from_kind (int kind, int *size) return the_low_target.breakpoint; } +bool +win32_process_target::stopped_by_sw_breakpoint () +{ + windows_thread_info *th = thread_rec (current_thread_ptid (), + DONT_INVALIDATE_CONTEXT); + return th == nullptr ? false : th->stopped_at_software_breakpoint; +} + +bool +win32_process_target::supports_stopped_by_sw_breakpoint () +{ + return true; +} + CORE_ADDR win32_process_target::read_pc (struct regcache *regcache) { diff --git a/gdbserver/win32-low.h b/gdbserver/win32-low.h index d2b39a46fd..b3fa392dd3 100644 --- a/gdbserver/win32-low.h +++ b/gdbserver/win32-low.h @@ -155,6 +155,10 @@ public: CORE_ADDR read_pc (regcache *regcache) override; void write_pc (regcache *regcache, CORE_ADDR pc) override; + + bool stopped_by_sw_breakpoint () override; + + bool supports_stopped_by_sw_breakpoint () override; }; /* Retrieve the context for this thread, if not already retrieved. */ -- 2.34.1