diff options
| -rw-r--r-- | gdb/ChangeLog | 7 | ||||
| -rw-r--r-- | gdb/gdbarch.h | 2 | ||||
| -rwxr-xr-x | gdb/gdbarch.sh | 2 | ||||
| -rw-r--r-- | gdb/target.h | 34 |
4 files changed, 45 insertions, 0 deletions
diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 30c0c6f..0b8ed31 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,5 +1,12 @@ 2018-08-31 Pedro Alves <palves@redhat.com> + * gdbarch.sh (have_nonsteppable_watchpoint): Add comment. + * target.h (Hardware watchpoint interfaces): Describe + continuable/steppable/non-steppable watchpoints. + * gdbarch.h, gdbarch.c: Regenerate. + +2018-08-31 Pedro Alves <palves@redhat.com> + * nto-procfs.c (nto_procfs_target::have_continuable_watchpoint): Delete. * s390-linux-nat.c diff --git a/gdb/gdbarch.h b/gdb/gdbarch.h index b563f8d..8340881 100644 --- a/gdb/gdbarch.h +++ b/gdb/gdbarch.h @@ -818,6 +818,8 @@ extern void set_gdbarch_adjust_dwarf2_line (struct gdbarch *gdbarch, gdbarch_adj extern int gdbarch_cannot_step_breakpoint (struct gdbarch *gdbarch); extern void set_gdbarch_cannot_step_breakpoint (struct gdbarch *gdbarch, int cannot_step_breakpoint); +/* See comment in target.h about continue, steppable and non-steppable watchpoints. */ + extern int gdbarch_have_nonsteppable_watchpoint (struct gdbarch *gdbarch); extern void set_gdbarch_have_nonsteppable_watchpoint (struct gdbarch *gdbarch, int have_nonsteppable_watchpoint); diff --git a/gdb/gdbarch.sh b/gdb/gdbarch.sh index 24a553b..670ac30 100755 --- a/gdb/gdbarch.sh +++ b/gdb/gdbarch.sh @@ -707,6 +707,8 @@ f;CORE_ADDR;adjust_dwarf2_addr;CORE_ADDR pc;pc;;default_adjust_dwarf2_addr;;0 # stop PC. f;CORE_ADDR;adjust_dwarf2_line;CORE_ADDR addr, int rel;addr, rel;;default_adjust_dwarf2_line;;0 v;int;cannot_step_breakpoint;;;0;0;;0 +# See comment in target.h about continuable, steppable and +# non-steppable watchpoints. v;int;have_nonsteppable_watchpoint;;;0;0;;0 F;int;address_class_type_flags;int byte_size, int dwarf2_addr_class;byte_size, dwarf2_addr_class M;const char *;address_class_type_flags_to_name;int type_flags;type_flags diff --git a/gdb/target.h b/gdb/target.h index b29d34b..229b5d0 100644 --- a/gdb/target.h +++ b/gdb/target.h @@ -1905,6 +1905,40 @@ extern struct thread_info *target_thread_handle_to_thread_info /* Hardware watchpoint interfaces. */ +/* GDB's current model is that there are three "kinds" of watchpoints, + with respect to when they trigger and how you can move past them. + + Those are: continuable, steppable, and non-steppable. + + Continuable watchpoints are like x86's -- those trigger after the + memory access's side effects are fully committed to memory. I.e., + they trap with the PC pointing at the next instruction already. + Continuing past such a watchpoint is doable by just normally + continuing, hence the name. + + Both steppable and non-steppable watchpoints trap before the memory + access. I.e, the PC points at the instruction that is accessing + the memory. So GDB needs to single-step once past the current + instruction in order to make the access effective and check whether + the instruction's side effects change the watched expression. + + Now, in order to step past that instruction, depending on + architecture and target, you can have two situations: + + - steppable watchpoints: you can single-step with the watchpoint + still armed, and the watchpoint won't trigger again. + + - non-steppable watchpoints: if you try to single-step with the + watchpoint still armed, you'd trap the watchpoint again and the + thread wouldn't make any progress. So GDB needs to temporarily + remove the watchpoint in order to step past it. + + If your target/architecture does not signal that it has either + steppable or non-steppable watchpoints via either + target_have_steppable_watchpoint or + gdbarch_have_nonsteppable_watchpoint, GDB assumes continuable + watchpoints. */ + /* Returns non-zero if we were stopped by a hardware watchpoint (memory read or write). Only the INFERIOR_PTID task is being queried. */ |