From 12279366d71627bfbdd74d1a6675dca825d8feca Mon Sep 17 00:00:00 2001 From: John Baldwin Date: Sat, 3 Mar 2018 21:25:33 -0800 Subject: [PATCH] Implement "to_stopped_by_hw_breakpoint" for x86 debug registers. Report that a thread is stopped by a hardware breakpoint if a non-data watchpoint is set in DR6. This change should be a no-op since a target still needs to implement the "to_supports_stopped_by_hw_breakpoint" method before this function is used. gdb/ChangeLog: * nat/x86-dregs.c (x86_dr_stopped_by_hw_breakpoint): New function. * nat/x86-dregs.h (x86_dr_stopped_by_hw_breakpoint): New prototype. * x86-nat.c (x86_stopped_by_hw_breakpoint): New function. (x86_use_watchpoints): Set "stopped_by_hw_breakpoint" target method. --- gdb/ChangeLog | 9 +++++++++ gdb/nat/x86-dregs.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ gdb/nat/x86-dregs.h | 4 ++++ gdb/x86-nat.c | 17 +++++++++++++++++ 4 files changed, 75 insertions(+) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 074bf08cd2c..f5484617676 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,12 @@ +2018-03-04 John Baldwin + + * nat/x86-dregs.c (x86_dr_stopped_by_hw_breakpoint): New function. + * nat/x86-dregs.h (x86_dr_stopped_by_hw_breakpoint): New + prototype. + * x86-nat.c (x86_stopped_by_hw_breakpoint): New function. + (x86_use_watchpoints): Set "stopped_by_hw_breakpoint" target + method. + 2018-03-02 Simon Marchi * common/gdb_vecs.c (free_char_ptr_vec): Remove. diff --git a/gdb/nat/x86-dregs.c b/gdb/nat/x86-dregs.c index c816473628f..f11a708e27a 100644 --- a/gdb/nat/x86-dregs.c +++ b/gdb/nat/x86-dregs.c @@ -649,3 +649,48 @@ x86_dr_stopped_by_watchpoint (struct x86_debug_reg_state *state) CORE_ADDR addr = 0; return x86_dr_stopped_data_address (state, &addr); } + +/* Return non-zero if the inferior has some hardware breakpoint that + triggered. Otherwise return zero. */ + +int +x86_dr_stopped_by_hw_breakpoint (struct x86_debug_reg_state *state) +{ + CORE_ADDR addr = 0; + int i; + int rc = 0; + /* The current thread's DR_STATUS. We always need to read this to + check whether some watchpoint caused the trap. */ + unsigned status; + /* We need DR_CONTROL as well, but only iff DR_STATUS indicates a + breakpoint trap. Only fetch it when necessary, to avoid an + unnecessary extra syscall when no watchpoint triggered. */ + int control_p = 0; + unsigned control = 0; + + /* As above, always read the current thread's debug registers rather + than trusting dr_mirror. */ + status = x86_dr_low_get_status (); + + ALL_DEBUG_ADDRESS_REGISTERS (i) + { + if (!X86_DR_WATCH_HIT (status, i)) + continue; + + if (!control_p) + { + control = x86_dr_low_get_control (); + control_p = 1; + } + + if (X86_DR_GET_RW_LEN (control, i) == 0) + { + addr = x86_dr_low_get_addr (i); + rc = 1; + if (show_debug_regs) + x86_show_dr (state, "watchpoint_hit", addr, -1, hw_execute); + } + } + + return rc; +} diff --git a/gdb/nat/x86-dregs.h b/gdb/nat/x86-dregs.h index dd6242eda95..e86e83aea0c 100644 --- a/gdb/nat/x86-dregs.h +++ b/gdb/nat/x86-dregs.h @@ -128,4 +128,8 @@ extern int x86_dr_stopped_data_address (struct x86_debug_reg_state *state, Otherwise return false. */ extern int x86_dr_stopped_by_watchpoint (struct x86_debug_reg_state *state); +/* Return true if the inferior has some hardware breakpoint that + triggered. Otherwise return false. */ +extern int x86_dr_stopped_by_hw_breakpoint (struct x86_debug_reg_state *state); + #endif /* X86_DREGS_H */ diff --git a/gdb/x86-nat.c b/gdb/x86-nat.c index b126c47c943..bec51373a66 100644 --- a/gdb/x86-nat.c +++ b/gdb/x86-nat.c @@ -260,6 +260,18 @@ x86_can_use_hw_breakpoint (struct target_ops *self, return 1; } +/* Return non-zero if the inferior has some breakpoint that triggered. + Otherwise return zero. */ + +static int +x86_stopped_by_hw_breakpoint (struct target_ops *ops) +{ + struct x86_debug_reg_state *state + = x86_debug_reg_state (ptid_get_pid (inferior_ptid)); + + return x86_dr_stopped_by_hw_breakpoint (state); +} + static void add_show_debug_regs_command (void) { @@ -297,6 +309,11 @@ x86_use_watchpoints (struct target_ops *t) t->to_remove_watchpoint = x86_remove_watchpoint; t->to_insert_hw_breakpoint = x86_insert_hw_breakpoint; t->to_remove_hw_breakpoint = x86_remove_hw_breakpoint; + + /* A target must provide an implementation of the + "to_supports_stopped_by_hw_breakpoint" target method before this + callback will be used. */ + t->to_stopped_by_hw_breakpoint = x86_stopped_by_hw_breakpoint; } void -- 2.30.2