This patch fixes the GDB internal error on AArch64 when running
watchpoint-fork.exp
top?bt 15
internal_error (file=file@entry=0x79d558 "../../binutils-gdb/gdb/linux-nat.c", line=line@entry=4866, fmt=0x793b20 "%s: Assertion `%s' failed.")
at ../../binutils-gdb/gdb/common/errors.c:51
#1 0x0000000000495bc4 in linux_nat_thread_address_space (t=<optimized out>, ptid=<error reading variable: Cannot access memory at address 0x1302>)
at ../../binutils-gdb/gdb/linux-nat.c:4866
#2 0x00000000005db2c8 in delegate_thread_address_space (self=<optimized out>, arg1=<error reading variable: Cannot access memory at address 0x1302>)
at ../../binutils-gdb/gdb/target-delegates.c:2447
#3 0x00000000005e8c7c in target_thread_address_space (ptid=<error reading variable: Cannot access memory at address 0x1302>)
at ../../binutils-gdb/gdb/target.c:2727
#4 0x000000000054eef8 in get_thread_arch_regcache (ptid=..., gdbarch=0xad51e0) at ../../binutils-gdb/gdb/regcache.c:529
#5 0x000000000054efcc in get_thread_regcache (ptid=...) at ../../binutils-gdb/gdb/regcache.c:546
#6 0x000000000054f120 in get_thread_regcache_for_ptid (ptid=...) at ../../binutils-gdb/gdb/regcache.c:560
#7 0x00000000004a2278 in aarch64_point_is_aligned (is_watchpoint=0, addr=34168, len=2) at ../../binutils-gdb/gdb/nat/aarch64-linux-hw-point.c:122
#8 0x00000000004a2e68 in aarch64_handle_breakpoint (type=hw_execute, addr=34168, len=2, is_insert=0, state=0xae8880)
at ../../binutils-gdb/gdb/nat/aarch64-linux-hw-point.c:465
#9 0x000000000048edf0 in aarch64_linux_remove_hw_breakpoint (self=<optimized out>, gdbarch=<optimized out>, bp_tgt=<optimized out>)
at ../../binutils-gdb/gdb/aarch64-linux-nat.c:657
#10 0x00000000005da8dc in delegate_remove_hw_breakpoint (self=<optimized out>, arg1=<optimized out>, arg2=<optimized out>)
at ../../binutils-gdb/gdb/target-delegates.c:492
#11 0x0000000000536a24 in bkpt_remove_location (bl=<optimized out>) at ../../binutils-gdb/gdb/breakpoint.c:13065
#12 0x000000000053351c in remove_breakpoint_1 (bl=0xb3fe70, is=is@entry=mark_inserted) at ../../binutils-gdb/gdb/breakpoint.c:4026
#13 0x000000000053ccc0 in detach_breakpoints (ptid=...) at ../../binutils-gdb/gdb/breakpoint.c:3930
#14 0x00000000005a3ac0 in handle_inferior_event_1 (ecs=0x7ffffff048) at ../../binutils-gdb/gdb/infrun.c:5042
After the fork, GDB will physically remove the breakpoints from the child
process (in frame #14), but at that time, GDB doesn't create an inferior
yet for child, but inferior_ptid is set to child's ptid (in frame #13).
In aarch64_point_is_aligned, we'll get the regcache of current_lwp_ptid
to determine if the current process is 32-bit or 64-bit, so the inferior
can't be found, and the internal error is caused.
I don't find a better fix other than not checking alignment on removing
breakpoint.
gdb:
2015-11-27 Yao Qi <yao.qi@linaro.org>
* nat/aarch64-linux-hw-point.c (aarch64_dr_state_remove_one_point):
Don't assert on alignment.
(aarch64_handle_breakpoint): Only check alignment when IS_INSERT
is true.
There is this build failure when building in C++:
/home/simark/src/binutils-gdb/gdb/nat/aarch64-linux-hw-point.c: In function ‘void aarch64_linux_set_debug_regs(const aarch64_debug_reg_state*, int, int)’:
/home/simark/src/binutils-gdb/gdb/nat/aarch64-linux-hw-point.c:564:64: error: ‘count’ cannot appear in a constant-expression
iov.iov_len = (offsetof (struct user_hwdebug_state, dbg_regs[count - 1])
^
We can simplify the computation and make g++ happy at the same time by
formulating as:
size of fixed part + size of variable part
thus...
size of fixed part + count * size of one variable part element
thus...
offsetof (struct user_hwdebug_state, dbg_regs) + count * sizeof (regs.dbg_reg[0]);
gdb/ChangeLog:
* nat/aarch64-linux-hw-point.c (aarch64_linux_set_debug_regs): Change
form of iov_len computation.
Nowadays, both aarch64 GDB and linux kernel assumes that address for
setting breakpoint should be 4-byte aligned. However that is not true
after we support multi-arch, because thumb instruction can be at 2-byte
aligned address. Patch http://lists.infradead.org/pipermail/linux-arm-kernel/2015-October/375141.html
to linux kernel is to teach kernel to handle 2-byte aligned address for
HW breakpoint, while this patch is to teach aarch64 GDB handle 2-byte
aligned address.
First of all, we call gdbarch_breakpoint_from_pc to get the instruction
length rather than using hard-coded 4. Secondly, in GDBserver, we set
length back to 2 if it is 3, because GDB encode 3 in it to indicate it
is a 32-bit thumb breakpoint. Then we relax the address alignment
check from 4-byte aligned to 2-byte aligned.
This patch enables some tests (such as gdb.base/break-idempotent.exp,
gdb.base/cond-eval-mode.exp, gdb.base/watchpoint-reuse-slot.exp,) and
fixes many fails (such as gdb.base/hbreak2.exp) when the program is
compiled in thumb mode on aarch64.
Regression tested on aarch64-linux, both native and gdbserver. This
is the last patch of multi-arch work.
gdb:
2015-10-15 Yao Qi <yao.qi@linaro.org>
* aarch64-linux-nat.c (aarch64_linux_insert_hw_breakpoint):
Call gdbarch_breakpoint_from_pc to instruction length.
(aarch64_linux_remove_hw_breakpoint): Likewise.
* common/common-regcache.h (regcache_register_size): Declare.
* nat/aarch64-linux-hw-point.c: Include "common-regcache.h".
(aarch64_point_is_aligned): Set alignment to 2 for breakpoint if
the process is 32bit, otherwise set alignment to 4.
(aarch64_handle_breakpoint): Update comments.
* regcache.c (regcache_register_size): New function.
gdb/gdbserver:
2015-10-15 Yao Qi <yao.qi@linaro.org>
* linux-aarch64-low.c (aarch64_insert_point): Set len to 2
if it is 3.
(aarch64_remove_point): Likewise.
* regcache.c (regcache_register_size): New function.
Nowadays, if user requests HW watchpoint to monitor a large memory area
or unaligned area, aarch64 GDB will split into multiple aligned areas,
and use multiple debugging registers to watch them. However, the
registers are not updated in a transaction way. GDBserver doesn't revert
updates in previous iterations if some debugging registers fail to update
due to some reason, like no free debugging registers available, in the
latter iteration. For example, if we have a char buf[34], and watch buf
in gdb,
(gdb) watch buf
Hardware watchpoint 2: buf
(gdb) c
Continuing.
infrun: clear_proceed_status_thread (Thread 13466)
infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT)
infrun: step-over queue now empty
infrun: resuming [Thread 13466] for step-over
Sending packet: $m410838,22#35...Packet received: 00000000000000000000000000000000000000000000000000000000000000000000
infrun: skipping breakpoint: stepping past insn at: 0x400524
infrun: skipping breakpoint: stepping past insn at: 0x400524
Sending packet: $Z2,410838,22#80...Packet received: E01 <----- [1]
Packet Z2 (write-watchpoint) is supported
Sending packet: $Z0,7fb7fe0a8c,4#43...Packet received: OK
Warning:
Could not insert hardware watchpoint 2.
Could not insert hardware breakpoints:
You may have requested too many hardware breakpoints/watchpoints.
GDB receives E01 for Z2 packet [1] but GDBserver updates the debugging
register status,
insert_point (addr=0x00410838, len=34, type=hw-write-watchpoint):
BREAKPOINTs:
BP0: addr=0x0, ctrl=0x00000000, ref.count=0
BP1: addr=0x0, ctrl=0x00000000, ref.count=0
BP2: addr=0x0, ctrl=0x00000000, ref.count=0
BP3: addr=0x0, ctrl=0x00000000, ref.count=0
BP4: addr=0x0, ctrl=0x00000000, ref.count=0
BP5: addr=0x0, ctrl=0x00000000, ref.count=0
WATCHPOINTs:
WP0: addr=0x410850, ctrl=0x00001ff5, ref.count=1
WP1: addr=0x410848, ctrl=0x00001ff5, ref.count=1
WP2: addr=0x410840, ctrl=0x00001ff5, ref.count=1
WP3: addr=0x410838, ctrl=0x00001ff5, ref.count=1
four debugging registers can not monitor 34-byte long area, so the last
iteration of updating debugging register state fails but previous
iterations succeed. This makes GDB think no HW watchpoint is inserted
but some debugging registers are used.
This problem was exposed by "watch buf" gdb.base/watchpoint.exp with
aarch64 GDBserver debugging arm 32-bit program. The buf is 30-byte long
but 4-byte aligned, and four debugging registers can't cover 34-byte
(extend 4 bytes to be 8-byte aligned) area. However, this problem
does exist on non-multi-arch debugging scenario as well.
This patch moves code in aarch64_linux_region_ok_for_hw_watchpoint to
aarch64_linux_region_ok_for_watchpoint in nat/aarch64-linux-hw-point.c.
Then, checks with aarch64_linux_region_ok_for_watchpoint, like what we
are doing in GDB. If the region is OK, call aarch64_handle_watchpoint.
Regression tested on aarch64 with both 64-bit program and 32-bit
program. Some fails in gdb.base/watchpoint.exp are fixed.
gdb:
2015-09-03 Yao Qi <yao.qi@linaro.org>
* aarch64-linux-nat.c (aarch64_linux_region_ok_for_hw_watchpoint):
Move code to aarch64_linux_region_ok_for_watchpoint. Call
aarch64_linux_region_ok_for_watchpoint.
* nat/aarch64-linux-hw-point.c (aarch64_linux_region_ok_for_watchpoint):
New function.
* nat/aarch64-linux-hw-point.h (aarch64_linux_region_ok_for_watchpoint):
Declare it.
gdb/gdbserver:
2015-09-03 Yao Qi <yao.qi@linaro.org>
* linux-aarch64-low.c (aarch64_insert_point): Call
aarch64_handle_watchpoint if aarch64_linux_region_ok_for_watchpoint
returns true.
In debug_reg_change_callback, we change debug registers of each LWP.
It makes more sense to print LWP's pid rather than group leader's pid.
gdb:
2015-08-25 Yao Qi <yao.qi@linaro.org>
* nat/aarch64-linux-hw-point.c (debug_reg_change_callback):
Rename local variable pid to tid, and get lwpid of lwp. Update
debug output.
There are also some duplication on getting HW watchpoint/breakpoint
registers info between GDB and GDBserver. This patch moves them
to nat/aarch64-linux-hw-point.c.
Note that ENABLE_NLS is not defined in GDBserver, so it should be OK
to use _( markup.
gdb:
2015-07-21 Yao Qi <yao.qi@linaro.org>
* aarch64-linux-nat.c (aarch64_linux_get_debug_reg_capacity):
Move it to nat/aarch64-linux-hw-point.c.
(aarch64_linux_child_post_startup_inferior): Update.
* nat/aarch64-linux-hw-point.c (aarch64_linux_get_debug_reg_capacity):
New function.
* nat/aarch64-linux-hw-point.h (aarch64_linux_get_debug_reg_capacity):
Declare it.
gdb/gdbserver:
2015-07-21 Yao Qi <yao.qi@linaro.org>
* linux-aarch64-low.c (aarch64_arch_setup): Remove code and call
aarch64_linux_get_debug_reg_capacity.
This patch is to fix two ARI warnings for nat/aarch64-linux-hw-point.{c,h}.
gdb:
2015-07-20 Yao Qi <yao.qi@linaro.org>
* nat/aarch64-linux-hw-point.c (aarch64_handle_unaligned_watchpoint):
Re-indent the code.
* nat/aarch64-linux-hw-point.h: Use ULONGEST rather than
"unsigned long long".
When I look at test fails related to watchpoint on aarch64-linux,
I find there are some code duplicates between GDB and GDBserver.
This patch is to move some of them to a nat/aarch64-linux-hw-point.{h,c}.
The only change I do is about the dr_changed_t typedef, which was
ULONGEST in GDB and 'unsigned long long' in GDBserver. Each bit
of dr_changed_t represents a status of each HW breakpoint or
watchpoint register, and the max number of HW breakpoint or watchpoint
registers is 16, so the width of 'unsigned long long' is sufficient.
gdb:
2015-07-17 Yao Qi <yao.qi@linaro.org>
* Makefile.in (HFILES_NO_SRCDIR): Add
nat/aarch64-linux-hw-point.h.
(aarch64-linux-hw-point.o): New rule.
* nat/aarch64-linux-hw-point.h: New file.
* nat/aarch64-linux-hw-point.c: New file.
* aarch64-linux-nat.c: Include nat/aarch64-linux-hw-point.h.
(AARCH64_HBP_MAX_NUM): Move to nat/aarch64-linux-hw-point.h.
(AARCH64_HWP_MAX_NUM, AARCH64_HBP_ALIGNMENT): Likewise.
(AARCH64_HWP_ALIGNMENT): Likewise.
(AARCH64_HWP_MAX_LEN_PER_REG): Likewise.
(AARCH64_DEBUG_NUM_SLOTS, AARCH64_DEBUG_ARCH): Likewise.
(AARCH64_DEBUG_ARCH_V8, DR_MARK_ALL_CHANGED): Likewise.
(DR_MARK_N_CHANGED, DR_CLEAR_CHANGED): Likewise.
(DR_HAS_CHANGED, DR_N_HAS_CHANGE): Likewise.
(aarch64_num_bp_regs, aarch64_num_wp_regs): Likewise.
(struct aarch64_debug_reg_state): Likewise.
(struct arch_lwp_info): Likewise.
(aarch64_linux_set_debug_regs): Likewise.
(aarch64_notify_debug_reg_change): Remove static.
(aarch64_align_watchpoint): Likewise.
(DR_CONTROL_ENABLED, DR_CONTROL_LENGTH): Likewise.
(aarch64_watchpoint_length): Likewise.
(aarch64_point_encode_ctrl_reg): Likewise
(aarch64_point_is_aligned): Likewise.
(aarch64_dr_state_insert_one_point): Likewise.
(aarch64_dr_state_remove_one_point): Likewise.
(aarch64_handle_breakpoint): Likewise.
(aarch64_handle_aligned_watchpoint): Likewise.
(aarch64_handle_unaligned_watchpoint): Likewise.
(aarch64_handle_watchpoint): Likewise.
* config/aarch64/linux.mh (NAT_FILE): Add
aarch64-linux-hw-point.o.
gdb/gdbserver:
2015-07-17 Yao Qi <yao.qi@linaro.org>
* Makefile.in (aarch64-linux-hw-point.o): New rule.
* configure.srv (srv_tgtobj): Append aarch64-linux-hw-point.o.
* linux-aarch64-low.c: Include nat/aarch64-linux-hw-point.h.
(AARCH64_HBP_MAX_NUM): Move to nat/aarch64-linux-hw-point.h.
(AARCH64_HWP_MAX_NUM, AARCH64_HBP_ALIGNMENT): Likewise.
(AARCH64_HWP_ALIGNMENT): Likewise.
(AARCH64_HWP_MAX_LEN_PER_REG): Likewise.
(AARCH64_DEBUG_NUM_SLOTS, AARCH64_DEBUG_ARCH): Likewise.
(aarch64_num_bp_regs, aarch64_num_wp_regs): Likewise.
(AARCH64_DEBUG_ARCH_V8, DR_MARK_ALL_CHANGED): Likewise.
(DR_MARK_N_CHANGED, DR_CLEAR_CHANGED): Likewise.
(DR_HAS_CHANGED, DR_N_HAS_CHANGE): Likewise.
(struct aarch64_debug_reg_state): Likewise.
(struct arch_lwp_info): Likewise.
(aarch64_align_watchpoint): Likewise.
(DR_CONTROL_ENABLED, DR_CONTROL_LENGTH): Likewise.
(aarch64_watchpoint_length): Likewise.
(aarch64_point_encode_ctrl_reg): Likewise
(aarch64_point_is_aligned): Likewise.
(aarch64_align_watchpoint): Likewise.
(aarch64_linux_set_debug_regs):
(aarch64_dr_state_insert_one_point): Likewise.
(aarch64_dr_state_remove_one_point): Likewise.
(aarch64_handle_breakpoint): Likewise.
(aarch64_handle_aligned_watchpoint): Likewise.
(aarch64_handle_unaligned_watchpoint): Likewise.
(aarch64_handle_watchpoint): Likewise.
Joel Brobecker