| Message ID | 20191223173432.16955-1-luis.machado@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | [AArch64] Recognize more program breakpoint patterns | expand |
On 1/9/20 12:59 PM, Aktemur, Tankut Baris wrote: > On Monday, December 23, 2019 6:35 PM, Luis Machado wrote: >> diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c >> index 1d5fb2001d..c69361d4ea 100644 >> --- a/gdb/aarch64-tdep.c >> +++ b/gdb/aarch64-tdep.c >> @@ -1201,6 +1201,28 @@ aarch64_execute_dwarf_cfa_vendor_op (struct gdbarch *gdbarch, gdb_byte op, >> return false; >> } >> >> +#define BRK_INSN_MASK 0xd4200000 > > I have a general question here. Given that GDB is using C++11, would it > make more sense to have this as > > static constexpr uint32_t BRK_INSN_MASK = 0xd4200000; > > for more type-safety for the uses of this #define? > I guess so. I have no problem with it, so i went ahead and fixed it and the other nits. Thanks!
I failed to update the description... I'll send a new version. On 1/13/20 2:03 PM, Luis Machado wrote: > It was reported to me that program breakpoints (permanent ones inserted into > the code itself) other than the one GDB uses for AArch64 (0xd4200000) do not > generate visible stops when continuing, and GDB will continue spinning > infinitely. > > This happens because GDB, upon hitting one of those program breakpoints, thinks > the SIGTRAP came from a delayed breakpoint hit... > > (gdb) x/i $pc > => 0x4005c0 <problem_function>: brk #0x90f > (gdb) c > Continuing. > infrun: clear_proceed_status_thread (process 14198) > infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT) > infrun: proceed: resuming process 14198 > infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0 > infrun: infrun_async(1) > infrun: prepare_to_wait > infrun: target_wait (-1.0.0, status) = > infrun: 14198.14198.0 [process 14198], > infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP > infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP > infrun: stop_pc = 0x4005c0 > infrun: delayed software breakpoint trap, ignoring > infrun: no stepping, continue > infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0 > infrun: prepare_to_wait > infrun: target_wait (-1.0.0, status) = > infrun: 14198.14198.0 [process 14198], > infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP > infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP > infrun: stop_pc = 0x4005c0 > infrun: delayed software breakpoint trap, ignoring > infrun: no stepping, continue > infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0 > infrun: prepare_to_wait > infrun: target_wait (-1.0.0, status) = > infrun: 14198.14198.0 [process 14198], > infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP > infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP > infrun: stop_pc = 0x4005c0 > infrun: delayed software breakpoint trap, ignoring > infrun: no stepping, continue > infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0 > infrun: prepare_to_wait > infrun: target_wait (-1.0.0, status) = > infrun: 14198.14198.0 [process 14198], > infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP > infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP > infrun: stop_pc = 0x4005c0 > infrun: delayed software breakpoint trap, ignoring > infrun: no stepping, continue > infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0 > infrun: prepare_to_wait > infrun: target_wait (-1.0.0, status) = > infrun: 14198.14198.0 [process 14198], > infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP > ... > > ... which is not the case. > > If the program breakpoint is one GDB recognizes, then it will stop when it > hits it. > > (gdb) x/i $pc > => 0x4005c0 <problem_function>: brk #0x0 > (gdb) c > Continuing. > infrun: clear_proceed_status_thread (process 14193) > infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT) > infrun: proceed: resuming process 14193 > infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14193] at 0x4005c0 > infrun: infrun_async(1) > infrun: prepare_to_wait > infrun: target_wait (-1.0.0, status) = > infrun: 14193.14193.0 [process 14193], > infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP > infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP > infrun: stop_pc = 0x4005c0 > infrun: random signal (GDB_SIGNAL_TRAP) > infrun: stop_waiting > infrun: stop_all_threads > infrun: stop_all_threads, pass=0, iterations=0 > infrun: process 14193 not executing > infrun: stop_all_threads, pass=1, iterations=1 > infrun: process 14193 not executing > infrun: stop_all_threads done > > Program received signal SIGTRAP, Trace/breakpoint trap. > problem_function () at brk_0.c:7 > 7 asm("brk %0\n\t" ::"n"(0x0)); > infrun: infrun_async(0) > > Otherwise GDB will keep trying to resume the inferior and will keep > seeing the SIGTRAP's, without stopping. > > To the user it appears GDB has gone into an infinite loop, interruptible only > by Ctrl-C. > > Also, windbg seems to use a different variation of AArch64 breakpoint compared > to GDB. This causes problems when debugging Windows on ARM binaries, when > program breakpoints are being used. > > The proposed patch creates a new gdbarch method (gdbarch_insn_is_breakpoint) > that tells GDB whether the underlying instruction is a breakpoint instruction > or not. > > This is more general than only checking for the instruction GDB uses as > breakpoint. > > The existing logic is still preserved for targets that do not implement this > new gdbarch method. > > The end result is like so: > > (gdb) x/i $pc > => 0x4005c0 <problem_function>: brk #0x90f > (gdb) c > Continuing. > infrun: clear_proceed_status_thread (process 16417) > infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT) > infrun: proceed: resuming process 16417 > infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 16417] at 0x4005c0 > infrun: infrun_async(1) > infrun: prepare_to_wait > infrun: target_wait (-1.0.0, status) = > infrun: 16417.16417.0 [process 16417], > infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP > infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP > infrun: stop_pc = 0x4005c0 > infrun: random signal (GDB_SIGNAL_TRAP) > infrun: stop_waiting > infrun: stop_all_threads > infrun: stop_all_threads, pass=0, iterations=0 > infrun: process 16417 not executing > infrun: stop_all_threads, pass=1, iterations=1 > infrun: process 16417 not executing > infrun: stop_all_threads done > > Program received signal SIGTRAP, Trace/breakpoint trap. > problem_function () at brk.c:7 > 7 asm("brk %0\n\t" ::"n"(0x900 + 0xf)); > infrun: infrun_async(0) > > Does this change look ok? > > gdb/ChangeLog: > > 2020-01-13 Luis Machado <luis.machado@linaro.org> > > * aarch64-tdep.c (BRK_INSN_MASK): Define to 0xffe0001f. > (BRK_INSN_MASK): Define to 0xd4200000. > (aarch64_program_breakpoint_here_p): New function. > (aarch64_gdbarch_init): Set gdbarch_program_breakpoint_here_p hook. > * arch-utils.c (default_program_breakpoint_here_p): Moved from > breakpoint.c. > * arch-utils.h (default_program_breakpoint_here_p): Moved from > breakpoint.h > * breakpoint.c (bp_loc_is_permanent): Changed return type to bool and > call gdbarch_program_breakpoint_here_p. > (program_breakpoint_here): Moved to arch-utils.c, renamed to > default_program_breakpoint_here_p and changed return type to bool. > * breakpoint.h (program_breakpoint_here): Moved prototype to > arch-utils.h, renamed to default_program_breakpoint_here_p and changed > return type to bool. > * gdbarch.c: Regenerate. > * gdbarch.h: Regenerate. > * gdbarch.sh (program_breakpoint_here_p): New method. > * infrun.c (handle_signal_stop): Call > gdbarch_program_breakpoint_here_p. > > Change-Id: I96eb27151442f435560a58c87eac48b0f68432bc > > Using gdbarch_program_breakpoint_here_p > --- > gdb/aarch64-tdep.c | 39 +++++++++++++++++++++++++++++++++++++++ > gdb/arch-utils.c | 37 +++++++++++++++++++++++++++++++++++++ > gdb/arch-utils.h | 4 ++++ > gdb/breakpoint.c | 46 +++++++--------------------------------------- > gdb/breakpoint.h | 5 ----- > gdb/gdbarch.c | 23 +++++++++++++++++++++++ > gdb/gdbarch.h | 7 +++++++ > gdb/gdbarch.sh | 4 ++++ > gdb/infrun.c | 4 ++-- > 9 files changed, 123 insertions(+), 46 deletions(-) > > diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c > index da41e22130..6b0ef210b1 100644 > --- a/gdb/aarch64-tdep.c > +++ b/gdb/aarch64-tdep.c > @@ -1201,6 +1201,41 @@ aarch64_execute_dwarf_cfa_vendor_op (struct gdbarch *gdbarch, gdb_byte op, > return false; > } > > +/* Used for matching BRK instructions for AArch64. */ > +static constexpr uint32_t BRK_INSN_MASK = 0xffe0001f; > +static constexpr uint32_t BRK_INSN_BASE = 0xd4200000; > + > +/* Implementation of gdbarch_program_breakpoint_here_p for aarch64. */ > + > +static bool > +aarch64_program_breakpoint_here_p (gdbarch *gdbarch, CORE_ADDR address) > +{ > + const uint32_t insn_len = 4; > + gdb_byte *target_mem; > + > + target_mem = (gdb_byte *) alloca (insn_len); > + > + /* Enable the automatic memory restoration from breakpoints while > + we read the memory. Otherwise we may find temporary breakpoints, ones > + inserted by GDB, and flag them as permanent breakpoints. */ > + scoped_restore restore_memory > + = make_scoped_restore_show_memory_breakpoints (0); > + > + if (target_read_memory (address, target_mem, insn_len) == 0) > + { > + uint32_t insn = > + (uint32_t) extract_unsigned_integer (target_mem, insn_len, > + gdbarch_byte_order_for_code (gdbarch)); > + > + /* Check if INSN is a BRK instruction pattern. There are multiple choices > + of such instructions with different immediate values. Different OS' > + may use a different variation, but they have the same outcome. */ > + return ((insn & BRK_INSN_MASK) == BRK_INSN_BASE); > + } > + > + return false; > +} > + > /* When arguments must be pushed onto the stack, they go on in reverse > order. The code below implements a FILO (stack) to do this. */ > > @@ -3357,6 +3392,10 @@ aarch64_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches) > set_gdbarch_execute_dwarf_cfa_vendor_op (gdbarch, > aarch64_execute_dwarf_cfa_vendor_op); > > + /* Permanent/Program breakpoint handling. */ > + set_gdbarch_program_breakpoint_here_p (gdbarch, > + aarch64_program_breakpoint_here_p); > + > /* Add some default predicates. */ > frame_unwind_append_unwinder (gdbarch, &aarch64_stub_unwind); > dwarf2_append_unwinders (gdbarch); > diff --git a/gdb/arch-utils.c b/gdb/arch-utils.c > index 55b115c135..a7364531f9 100644 > --- a/gdb/arch-utils.c > +++ b/gdb/arch-utils.c > @@ -876,6 +876,43 @@ int default_insn_is_jump (struct gdbarch *gdbarch, CORE_ADDR addr) > return 0; > } > > +/* See arch-utils.h. */ > + > +bool > +default_program_breakpoint_here_p (struct gdbarch *gdbarch, > + CORE_ADDR address) > +{ > + int len; > + CORE_ADDR addr; > + const gdb_byte *bpoint; > + gdb_byte *target_mem; > + > + addr = address; > + bpoint = gdbarch_breakpoint_from_pc (gdbarch, &addr, &len); > + > + /* Software breakpoints unsupported? */ > + if (bpoint == NULL) > + return false; > + > + target_mem = (gdb_byte *) alloca (len); > + > + /* Enable the automatic memory restoration from breakpoints while > + we read the memory. Otherwise we may find temporary breakpoints, ones > + inserted by GDB, and flag them as permanent breakpoints. */ > + scoped_restore restore_memory > + = make_scoped_restore_show_memory_breakpoints (0); > + > + if (target_read_memory (address, target_mem, len) == 0) > + { > + /* Check if this is a breakpoint instruction for this architecture, > + including ones used by GDB. */ > + if (memcmp (target_mem, bpoint, len) == 0) > + return true; > + } > + > + return false; > +} > + > void > default_skip_permanent_breakpoint (struct regcache *regcache) > { > diff --git a/gdb/arch-utils.h b/gdb/arch-utils.h > index 3fb9ad317a..43d64b1f4f 100644 > --- a/gdb/arch-utils.h > +++ b/gdb/arch-utils.h > @@ -228,6 +228,10 @@ extern int default_insn_is_call (struct gdbarch *, CORE_ADDR); > extern int default_insn_is_ret (struct gdbarch *, CORE_ADDR); > extern int default_insn_is_jump (struct gdbarch *, CORE_ADDR); > > +/* Default implementation of gdbarch_program_breakpoint_here_p. */ > +extern bool default_program_breakpoint_here_p (struct gdbarch *gdbarch, > + CORE_ADDR addr); > + > /* Do-nothing version of vsyscall_range. Returns false. */ > > extern int default_vsyscall_range (struct gdbarch *gdbarch, struct mem_range *range); > diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c > index 5b734abf1c..b6ac1f1e98 100644 > --- a/gdb/breakpoint.c > +++ b/gdb/breakpoint.c > @@ -8515,7 +8515,7 @@ mention (struct breakpoint *b) > } > > > -static int bp_loc_is_permanent (struct bp_location *loc); > +static bool bp_loc_is_permanent (struct bp_location *loc); > > static struct bp_location * > add_location_to_breakpoint (struct breakpoint *b, > @@ -8581,42 +8581,10 @@ add_location_to_breakpoint (struct breakpoint *b, > } > > > -/* See breakpoint.h. */ > - > -int > -program_breakpoint_here_p (struct gdbarch *gdbarch, CORE_ADDR address) > -{ > - int len; > - CORE_ADDR addr; > - const gdb_byte *bpoint; > - gdb_byte *target_mem; > - > - addr = address; > - bpoint = gdbarch_breakpoint_from_pc (gdbarch, &addr, &len); > - > - /* Software breakpoints unsupported? */ > - if (bpoint == NULL) > - return 0; > - > - target_mem = (gdb_byte *) alloca (len); > - > - /* Enable the automatic memory restoration from breakpoints while > - we read the memory. Otherwise we could say about our temporary > - breakpoints they are permanent. */ > - scoped_restore restore_memory > - = make_scoped_restore_show_memory_breakpoints (0); > +/* Return true if LOC is pointing to a permanent breakpoint, > + return false otherwise. */ > > - if (target_read_memory (address, target_mem, len) == 0 > - && memcmp (target_mem, bpoint, len) == 0) > - return 1; > - > - return 0; > -} > - > -/* Return 1 if LOC is pointing to a permanent breakpoint, > - return 0 otherwise. */ > - > -static int > +static bool > bp_loc_is_permanent (struct bp_location *loc) > { > gdb_assert (loc != NULL); > @@ -8624,14 +8592,14 @@ bp_loc_is_permanent (struct bp_location *loc) > /* If we have a non-breakpoint-backed catchpoint or a software > watchpoint, just return 0. We should not attempt to read from > the addresses the locations of these breakpoint types point to. > - program_breakpoint_here_p, below, will attempt to read > + gdbarch_program_breakpoint_here_p, below, will attempt to read > memory. */ > if (!bl_address_is_meaningful (loc)) > - return 0; > + return false; > > scoped_restore_current_pspace_and_thread restore_pspace_thread; > switch_to_program_space_and_thread (loc->pspace); > - return program_breakpoint_here_p (loc->gdbarch, loc->address); > + return gdbarch_program_breakpoint_here_p (loc->gdbarch, loc->address); > } > > /* Build a command list for the dprintf corresponding to the current > diff --git a/gdb/breakpoint.h b/gdb/breakpoint.h > index 13d8102c17..347aeb75f3 100644 > --- a/gdb/breakpoint.h > +++ b/gdb/breakpoint.h > @@ -1194,11 +1194,6 @@ enum breakpoint_here > > /* Prototypes for breakpoint-related functions. */ > > -/* Return 1 if there's a program/permanent breakpoint planted in > - memory at ADDRESS, return 0 otherwise. */ > - > -extern int program_breakpoint_here_p (struct gdbarch *gdbarch, CORE_ADDR address); > - > extern enum breakpoint_here breakpoint_here_p (const address_space *, > CORE_ADDR); > > diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c > index ab9bf1f5f4..277cbf20df 100644 > --- a/gdb/gdbarch.c > +++ b/gdb/gdbarch.c > @@ -345,6 +345,7 @@ struct gdbarch > gdbarch_insn_is_call_ftype *insn_is_call; > gdbarch_insn_is_ret_ftype *insn_is_ret; > gdbarch_insn_is_jump_ftype *insn_is_jump; > + gdbarch_program_breakpoint_here_p_ftype *program_breakpoint_here_p; > gdbarch_auxv_parse_ftype *auxv_parse; > gdbarch_print_auxv_entry_ftype *print_auxv_entry; > gdbarch_vsyscall_range_ftype *vsyscall_range; > @@ -464,6 +465,7 @@ gdbarch_alloc (const struct gdbarch_info *info, > gdbarch->insn_is_call = default_insn_is_call; > gdbarch->insn_is_ret = default_insn_is_ret; > gdbarch->insn_is_jump = default_insn_is_jump; > + gdbarch->program_breakpoint_here_p = default_program_breakpoint_here_p; > gdbarch->print_auxv_entry = default_print_auxv_entry; > gdbarch->vsyscall_range = default_vsyscall_range; > gdbarch->infcall_mmap = default_infcall_mmap; > @@ -708,6 +710,7 @@ verify_gdbarch (struct gdbarch *gdbarch) > /* Skip verify of insn_is_call, invalid_p == 0 */ > /* Skip verify of insn_is_ret, invalid_p == 0 */ > /* Skip verify of insn_is_jump, invalid_p == 0 */ > + /* Skip verify of program_breakpoint_here_p, invalid_p == 0 */ > /* Skip verify of auxv_parse, has predicate. */ > /* Skip verify of print_auxv_entry, invalid_p == 0 */ > /* Skip verify of vsyscall_range, invalid_p == 0 */ > @@ -1248,6 +1251,9 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file) > fprintf_unfiltered (file, > "gdbarch_dump: process_record_signal = <%s>\n", > host_address_to_string (gdbarch->process_record_signal)); > + fprintf_unfiltered (file, > + "gdbarch_dump: program_breakpoint_here_p = <%s>\n", > + host_address_to_string (gdbarch->program_breakpoint_here_p)); > fprintf_unfiltered (file, > "gdbarch_dump: ps_regnum = %s\n", > plongest (gdbarch->ps_regnum)); > @@ -4928,6 +4934,23 @@ set_gdbarch_insn_is_jump (struct gdbarch *gdbarch, > gdbarch->insn_is_jump = insn_is_jump; > } > > +bool > +gdbarch_program_breakpoint_here_p (struct gdbarch *gdbarch, CORE_ADDR address) > +{ > + gdb_assert (gdbarch != NULL); > + gdb_assert (gdbarch->program_breakpoint_here_p != NULL); > + if (gdbarch_debug >= 2) > + fprintf_unfiltered (gdb_stdlog, "gdbarch_program_breakpoint_here_p called\n"); > + return gdbarch->program_breakpoint_here_p (gdbarch, address); > +} > + > +void > +set_gdbarch_program_breakpoint_here_p (struct gdbarch *gdbarch, > + gdbarch_program_breakpoint_here_p_ftype program_breakpoint_here_p) > +{ > + gdbarch->program_breakpoint_here_p = program_breakpoint_here_p; > +} > + > int > gdbarch_auxv_parse_p (struct gdbarch *gdbarch) > { > diff --git a/gdb/gdbarch.h b/gdb/gdbarch.h > index 9f32ac23ab..800a4e8b16 100644 > --- a/gdb/gdbarch.h > +++ b/gdb/gdbarch.h > @@ -1545,6 +1545,13 @@ typedef int (gdbarch_insn_is_jump_ftype) (struct gdbarch *gdbarch, CORE_ADDR add > extern int gdbarch_insn_is_jump (struct gdbarch *gdbarch, CORE_ADDR addr); > extern void set_gdbarch_insn_is_jump (struct gdbarch *gdbarch, gdbarch_insn_is_jump_ftype *insn_is_jump); > > +/* Return true if there's a program/permanent breakpoint planted in > + memory at ADDRESS, return false otherwise. */ > + > +typedef bool (gdbarch_program_breakpoint_here_p_ftype) (struct gdbarch *gdbarch, CORE_ADDR address); > +extern bool gdbarch_program_breakpoint_here_p (struct gdbarch *gdbarch, CORE_ADDR address); > +extern void set_gdbarch_program_breakpoint_here_p (struct gdbarch *gdbarch, gdbarch_program_breakpoint_here_p_ftype *program_breakpoint_here_p); > + > /* Read one auxv entry from *READPTR, not reading locations >= ENDPTR. > Return 0 if *READPTR is already at the end of the buffer. > Return -1 if there is insufficient buffer for a whole entry. > diff --git a/gdb/gdbarch.sh b/gdb/gdbarch.sh > index 0be3e88bb2..66b54dd700 100755 > --- a/gdb/gdbarch.sh > +++ b/gdb/gdbarch.sh > @@ -1152,6 +1152,10 @@ m;int;insn_is_ret;CORE_ADDR addr;addr;;default_insn_is_ret;;0 > # Return non-zero if the instruction at ADDR is a jump; zero otherwise. > m;int;insn_is_jump;CORE_ADDR addr;addr;;default_insn_is_jump;;0 > > +# Return true if there's a program/permanent breakpoint planted in > +# memory at ADDRESS, return false otherwise. > +m;bool;program_breakpoint_here_p;CORE_ADDR address;address;;default_program_breakpoint_here_p;;0 > + > # Read one auxv entry from *READPTR, not reading locations >= ENDPTR. > # Return 0 if *READPTR is already at the end of the buffer. > # Return -1 if there is insufficient buffer for a whole entry. > diff --git a/gdb/infrun.c b/gdb/infrun.c > index a0583a8e65..c45d8e1b46 100644 > --- a/gdb/infrun.c > +++ b/gdb/infrun.c > @@ -6157,8 +6157,8 @@ handle_signal_stop (struct execution_control_state *ecs) > been removed. */ > if (random_signal && target_stopped_by_sw_breakpoint ()) > { > - if (program_breakpoint_here_p (gdbarch, > - ecs->event_thread->suspend.stop_pc)) > + if (gdbarch_program_breakpoint_here_p (gdbarch, > + ecs->event_thread->suspend.stop_pc)) > { > struct regcache *regcache; > int decr_pc; >
diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c index 1d5fb2001d..c69361d4ea 100644 --- a/gdb/aarch64-tdep.c +++ b/gdb/aarch64-tdep.c @@ -1201,6 +1201,28 @@ aarch64_execute_dwarf_cfa_vendor_op (struct gdbarch *gdbarch, gdb_byte op, return false; } +#define BRK_INSN_MASK 0xd4200000 + +/* Implementation of gdbarch_insn_is_breakpoint for aarch64. */ + +static bool +aarch64_insn_is_breakpoint (gdbarch *gdbarch, + const gdb_byte *insn, + unsigned int insn_size) +{ + gdb_assert (insn != nullptr); + + uint32_t i; + + i = (uint32_t) extract_unsigned_integer (insn, insn_size, + gdbarch_byte_order (gdbarch)); + + /* Check if INSN is a BRK instruction pattern. There are multiple choices + of such instructions with different immediate values. Different OS' may + use a different variation, but they have the same outcome. */ + return (i & BRK_INSN_MASK) == BRK_INSN_MASK; +} + /* When arguments must be pushed onto the stack, they go on in reverse order. The code below implements a FILO (stack) to do this. */ @@ -3357,6 +3379,9 @@ aarch64_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches) set_gdbarch_execute_dwarf_cfa_vendor_op (gdbarch, aarch64_execute_dwarf_cfa_vendor_op); + /* Permanent/Program breakpoint handling. */ + set_gdbarch_insn_is_breakpoint (gdbarch, aarch64_insn_is_breakpoint); + /* Add some default predicates. */ frame_unwind_append_unwinder (gdbarch, &aarch64_stub_unwind); dwarf2_append_unwinders (gdbarch); diff --git a/gdb/arch-utils.c b/gdb/arch-utils.c index a1a003f91f..99c9f281be 100644 --- a/gdb/arch-utils.c +++ b/gdb/arch-utils.c @@ -876,6 +876,13 @@ int default_insn_is_jump (struct gdbarch *gdbarch, CORE_ADDR addr) return 0; } +bool default_insn_is_breakpoint (struct gdbarch *gdbarch, + const gdb_byte *insn, + unsigned int insn_size) +{ + return false; +} + void default_skip_permanent_breakpoint (struct regcache *regcache) { diff --git a/gdb/arch-utils.h b/gdb/arch-utils.h index 48ff3bb9a1..77ffe8190c 100644 --- a/gdb/arch-utils.h +++ b/gdb/arch-utils.h @@ -227,6 +227,9 @@ extern int default_return_in_first_hidden_param_p (struct gdbarch *, extern int default_insn_is_call (struct gdbarch *, CORE_ADDR); extern int default_insn_is_ret (struct gdbarch *, CORE_ADDR); extern int default_insn_is_jump (struct gdbarch *, CORE_ADDR); +extern bool default_insn_is_breakpoint (struct gdbarch *gdbarch, + const gdb_byte *insn, + unsigned int insn_size); /* Do-nothing version of vsyscall_range. Returns false. */ diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c index 904abda8db..ffb7f7f8be 100644 --- a/gdb/breakpoint.c +++ b/gdb/breakpoint.c @@ -8599,14 +8599,23 @@ program_breakpoint_here_p (struct gdbarch *gdbarch, CORE_ADDR address) target_mem = (gdb_byte *) alloca (len); /* Enable the automatic memory restoration from breakpoints while - we read the memory. Otherwise we could say about our temporary - breakpoints they are permanent. */ + we read the memory. Otherwise we may find temporary breakpoints, ones + inserted by GDB, and flag them as permanent breakpoints. */ scoped_restore restore_memory = make_scoped_restore_show_memory_breakpoints (0); - if (target_read_memory (address, target_mem, len) == 0 - && memcmp (target_mem, bpoint, len) == 0) - return 1; + if (target_read_memory (address, target_mem, len) == 0) + { + /* Check if this is a breakpoint instruction for this architecture, + including ones used by GDB. + + Some architectures have more than one possible breakpoint + instruction, but GDB does not use all of them. We should detect those + as well. */ + if (gdbarch_insn_is_breakpoint (gdbarch, target_mem, len) + || memcmp (target_mem, bpoint, len) == 0) + return 1; + } return 0; } diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c index 59c97da985..9e21ba7eca 100644 --- a/gdb/gdbarch.c +++ b/gdb/gdbarch.c @@ -345,6 +345,7 @@ struct gdbarch gdbarch_insn_is_call_ftype *insn_is_call; gdbarch_insn_is_ret_ftype *insn_is_ret; gdbarch_insn_is_jump_ftype *insn_is_jump; + gdbarch_insn_is_breakpoint_ftype *insn_is_breakpoint; gdbarch_auxv_parse_ftype *auxv_parse; gdbarch_print_auxv_entry_ftype *print_auxv_entry; gdbarch_vsyscall_range_ftype *vsyscall_range; @@ -464,6 +465,7 @@ gdbarch_alloc (const struct gdbarch_info *info, gdbarch->insn_is_call = default_insn_is_call; gdbarch->insn_is_ret = default_insn_is_ret; gdbarch->insn_is_jump = default_insn_is_jump; + gdbarch->insn_is_breakpoint = default_insn_is_breakpoint; gdbarch->print_auxv_entry = default_print_auxv_entry; gdbarch->vsyscall_range = default_vsyscall_range; gdbarch->infcall_mmap = default_infcall_mmap; @@ -708,6 +710,7 @@ verify_gdbarch (struct gdbarch *gdbarch) /* Skip verify of insn_is_call, invalid_p == 0 */ /* Skip verify of insn_is_ret, invalid_p == 0 */ /* Skip verify of insn_is_jump, invalid_p == 0 */ + /* Skip verify of insn_is_breakpoint, invalid_p == 0 */ /* Skip verify of auxv_parse, has predicate. */ /* Skip verify of print_auxv_entry, invalid_p == 0 */ /* Skip verify of vsyscall_range, invalid_p == 0 */ @@ -1137,6 +1140,9 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file) fprintf_unfiltered (file, "gdbarch_dump: inner_than = <%s>\n", host_address_to_string (gdbarch->inner_than)); + fprintf_unfiltered (file, + "gdbarch_dump: insn_is_breakpoint = <%s>\n", + host_address_to_string (gdbarch->insn_is_breakpoint)); fprintf_unfiltered (file, "gdbarch_dump: insn_is_call = <%s>\n", host_address_to_string (gdbarch->insn_is_call)); @@ -4928,6 +4934,23 @@ set_gdbarch_insn_is_jump (struct gdbarch *gdbarch, gdbarch->insn_is_jump = insn_is_jump; } +bool +gdbarch_insn_is_breakpoint (struct gdbarch *gdbarch, const gdb_byte *insn, unsigned int insn_size) +{ + gdb_assert (gdbarch != NULL); + gdb_assert (gdbarch->insn_is_breakpoint != NULL); + if (gdbarch_debug >= 2) + fprintf_unfiltered (gdb_stdlog, "gdbarch_insn_is_breakpoint called\n"); + return gdbarch->insn_is_breakpoint (gdbarch, insn, insn_size); +} + +void +set_gdbarch_insn_is_breakpoint (struct gdbarch *gdbarch, + gdbarch_insn_is_breakpoint_ftype insn_is_breakpoint) +{ + gdbarch->insn_is_breakpoint = insn_is_breakpoint; +} + int gdbarch_auxv_parse_p (struct gdbarch *gdbarch) { diff --git a/gdb/gdbarch.h b/gdb/gdbarch.h index 78e05ecdcb..d94950b8f2 100644 --- a/gdb/gdbarch.h +++ b/gdb/gdbarch.h @@ -1545,6 +1545,13 @@ typedef int (gdbarch_insn_is_jump_ftype) (struct gdbarch *gdbarch, CORE_ADDR add extern int gdbarch_insn_is_jump (struct gdbarch *gdbarch, CORE_ADDR addr); extern void set_gdbarch_insn_is_jump (struct gdbarch *gdbarch, gdbarch_insn_is_jump_ftype *insn_is_jump); +/* Return true if INSN of size INSN_SIZE acts like a permanent breakpoint and + false otherwise. */ + +typedef bool (gdbarch_insn_is_breakpoint_ftype) (struct gdbarch *gdbarch, const gdb_byte *insn, unsigned int insn_size); +extern bool gdbarch_insn_is_breakpoint (struct gdbarch *gdbarch, const gdb_byte *insn, unsigned int insn_size); +extern void set_gdbarch_insn_is_breakpoint (struct gdbarch *gdbarch, gdbarch_insn_is_breakpoint_ftype *insn_is_breakpoint); + /* Read one auxv entry from *READPTR, not reading locations >= ENDPTR. Return 0 if *READPTR is already at the end of the buffer. Return -1 if there is insufficient buffer for a whole entry. diff --git a/gdb/gdbarch.sh b/gdb/gdbarch.sh index 331eb39278..dbf31ee8ae 100755 --- a/gdb/gdbarch.sh +++ b/gdb/gdbarch.sh @@ -1152,6 +1152,10 @@ m;int;insn_is_ret;CORE_ADDR addr;addr;;default_insn_is_ret;;0 # Return non-zero if the instruction at ADDR is a jump; zero otherwise. m;int;insn_is_jump;CORE_ADDR addr;addr;;default_insn_is_jump;;0 +# Return true if INSN of size INSN_SIZE acts like a permanent breakpoint and +# false otherwise. +m;bool;insn_is_breakpoint;const gdb_byte *insn, unsigned int insn_size;insn, insn_size;;default_insn_is_breakpoint;;0 + # Read one auxv entry from *READPTR, not reading locations >= ENDPTR. # Return 0 if *READPTR is already at the end of the buffer. # Return -1 if there is insufficient buffer for a whole entry.
It was reported to me that program breakpoints (permanent ones inserted into the code itself) other than the one GDB uses for AArch64 (0xd4200000) do not generate visible stops when continuing, and GDB will continue spinning infinitely. This happens because GDB, upon hitting one of those program breakpoints, thinks the SIGTRAP came from a delayed breakpoint hit... (gdb) x/i $pc => 0x4005c0 <problem_function>: brk #0x90f (gdb) c Continuing. infrun: clear_proceed_status_thread (process 14198) infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT) infrun: proceed: resuming process 14198 infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0 infrun: infrun_async(1) infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: 14198.14198.0 [process 14198], infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP infrun: stop_pc = 0x4005c0 infrun: delayed software breakpoint trap, ignoring infrun: no stepping, continue infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0 infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: 14198.14198.0 [process 14198], infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP infrun: stop_pc = 0x4005c0 infrun: delayed software breakpoint trap, ignoring infrun: no stepping, continue infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0 infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: 14198.14198.0 [process 14198], infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP infrun: stop_pc = 0x4005c0 infrun: delayed software breakpoint trap, ignoring infrun: no stepping, continue infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0 infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: 14198.14198.0 [process 14198], infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP infrun: stop_pc = 0x4005c0 infrun: delayed software breakpoint trap, ignoring infrun: no stepping, continue infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0 infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: 14198.14198.0 [process 14198], infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP ... ... which is not the case. If the program breakpoint is one GDB recognizes, then it will stop when it hits it. (gdb) x/i $pc => 0x4005c0 <problem_function>: brk #0x0 (gdb) c Continuing. infrun: clear_proceed_status_thread (process 14193) infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT) infrun: proceed: resuming process 14193 infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14193] at 0x4005c0 infrun: infrun_async(1) infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: 14193.14193.0 [process 14193], infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP infrun: stop_pc = 0x4005c0 infrun: random signal (GDB_SIGNAL_TRAP) infrun: stop_waiting infrun: stop_all_threads infrun: stop_all_threads, pass=0, iterations=0 infrun: process 14193 not executing infrun: stop_all_threads, pass=1, iterations=1 infrun: process 14193 not executing infrun: stop_all_threads done Program received signal SIGTRAP, Trace/breakpoint trap. problem_function () at brk_0.c:7 7 asm("brk %0\n\t" ::"n"(0x0)); infrun: infrun_async(0) Otherwise GDB will keep trying to resume the inferior and will keep seeing the SIGTRAP's, without stopping. To the user it appears GDB has gone into an infinite loop, interruptible only by Ctrl-C. Also, windbg seems to use a different variation of AArch64 breakpoint compared to GDB. This causes problems when debugging Windows on ARM binaries, when program breakpoints are being used. The proposed patch creates a new gdbarch method (gdbarch_insn_is_breakpoint) that tells GDB whether the underlying instruction is a breakpoint instruction or not. This is more general than only checking for the instruction GDB uses as breakpoint. The existing logic is still preserved for targets that do not implement this new gdbarch method. The end result is like so: (gdb) x/i $pc => 0x4005c0 <problem_function>: brk #0x90f (gdb) c Continuing. infrun: clear_proceed_status_thread (process 16417) infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT) infrun: proceed: resuming process 16417 infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 16417] at 0x4005c0 infrun: infrun_async(1) infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: 16417.16417.0 [process 16417], infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP infrun: stop_pc = 0x4005c0 infrun: random signal (GDB_SIGNAL_TRAP) infrun: stop_waiting infrun: stop_all_threads infrun: stop_all_threads, pass=0, iterations=0 infrun: process 16417 not executing infrun: stop_all_threads, pass=1, iterations=1 infrun: process 16417 not executing infrun: stop_all_threads done Program received signal SIGTRAP, Trace/breakpoint trap. problem_function () at brk.c:7 7 asm("brk %0\n\t" ::"n"(0x900 + 0xf)); infrun: infrun_async(0) Does this change look ok? gdb/ChangeLog: 2019-12-23 Luis Machado <luis.machado@linaro.org> * aarch64-tdep.c (BRK_INSN_MASK): Define to 0xd4200000. (aarch64_insn_is_breakpoint): New function. (aarch64_gdbarch_init): Set gdbarch_insn_is_breakpoint hook. * arch-utils.c (default_insn_is_breakpoint): New function. * arch-utils.h (default_insn_is_breakpoint): New prototype. * breakpoint.c (program_breakpoint_here): Updated to use gdbarch_insn_is_breakpoint. Update documentation to clarify behavior. * gdbarch.c: Regenerate. * gdbarch.h: Regenerate. * gdbarch.sh (gdbarch_insn_is_breakpoint): New method. Change-Id: I96eb27151442f435560a58c87eac48b0f68432bc --- gdb/aarch64-tdep.c | 25 +++++++++++++++++++++++++ gdb/arch-utils.c | 7 +++++++ gdb/arch-utils.h | 3 +++ gdb/breakpoint.c | 19 ++++++++++++++----- gdb/gdbarch.c | 23 +++++++++++++++++++++++ gdb/gdbarch.h | 7 +++++++ gdb/gdbarch.sh | 4 ++++ 7 files changed, 83 insertions(+), 5 deletions(-) -- 2.17.1