Re: [PATCH v7.2] Support software single step on ARM in GDBServer

Antoine Tremblay
2015-12-11T17:52:57Z

On 12/11/2015 12:28 PM, Yao Qi wrote:
> Antoine Tremblay <antoine.tremblay@ericsson.com> writes:
>
>> Change the name of the ops read_memory_unsigned_integer to read_mem_uint
>>
>> OK like that ?
>
> Yes.
>
>>
>> ---
>> This patch teaches GDBServer how to software single step on ARM
>> linux by sharing code with GDB.
>>
>> The arm_get_next_pcs function in GDB is now shared with GDBServer. So that
>> GDBServer can use the function to return the possible addresses of the next PC.
>>
>> A proper shared context was also needed so that we could share the code, this
>> context is described in the arm_get_next_pcs structure.
>>
>> Testing :
>>
>> No regressions, tested on ubuntu 14.04 ARMv7 and x86.
>> With gdbserver-{native,extended} / { -marm -mthumb }
>>
>> gdb/ChangeLog:
>>
>> * Makefile.in (ALL_TARGET_OBS): Append arm-get-next-pcs.o, arm-linux.o.
>> (ALLDEPFILES): Append arm-get-next-pcs.c, arm-linux.c
>> (arm-linux.o): New rule.
>> (arm-get-next-pcs.o): New rule.
>> * arch/arm-get-next-pcs.c: New file.
>> * arch/arm-get-next-pcs.h: New file.
>> * arch/arm-linux.h: New file.
>> * arch/arm-linux.c: New file.
>> * arm.c: Include common-regcache.c.
>> (thumb_advance_itstate): Moved from arm-tdep.c.
>> (arm_instruction_changes_pc): Likewise.
>> (thumb_instruction_changes_pc): Likewise.
>> (thumb2_instruction_changes_pc): Likewise.
>> (shifted_reg_val): Likewise.
>> * arm.h (submask): Move macro from arm-tdep.h
>> (bit): Likewise.
>> (bits): Likewise.
>> (sbits): Likewise.
>> (BranchDest): Likewise.
>> (thumb_advance_itstate): Moved declaration from arm-tdep.h
>> (arm_instruction_changes_pc): Likewise.
>> (thumb_instruction_changes_pc): Likewise.
>> (thumb2_instruction_changes_pc): Likewise.
>> (shifted_reg_val): Likewise.
>> * arm-linux-tdep.c: Include arch/arm.h, arch/arm-get-next-pcs.h
>> arch/arm-linux.h.
>> (arm_linux_get_next_pcs_ops): New struct.
>> (ARM_SIGCONTEXT_R0, ARM_UCONTEXT_SIGCONTEXT,
>> ARM_OLD_RT_SIGFRAME_SIGINFO, ARM_OLD_RT_SIGFRAME_UCONTEXT,
>> ARM_NEW_RT_SIGFRAME_UCONTEXT, ARM_NEW_SIGFRAME_MAGIC): Move stack
>> layout defines to arch/arm-linux.h.
>> (arm_linux_sigreturn_next_pc_offset): Move to arch/arm-linux.c.
>> (arm_linux_software_single_step): Adjust for arm_get_next_pcs
>> implementation.
>> * arm-tdep.c: Include arch/arm-get-next-pcs.h.
>> (arm_get_next_pcs_ops): New struct.
>> (submask): Move macro to arm.h.
>> (bit): Likewise.
>> (bits): Likewise.
>> (sbits): Likewise.
>> (BranchDest): Likewise.
>> (thumb_instruction_changes_pc): Move to arm.c
>> (thumb2_instruction_changes_pc): Likewise.
>> (arm_instruction_changes_pc): Likewise.
>> (shifted_reg_val): Likewise.
>> (thumb_advance_itstate): Likewise.
>> (thumb_get_next_pc_raw): Move to arm-get-next-pcs.c.
>> (arm_get_next_pc_raw): Likewise.
>> (arm_get_next_pc): Likewise.
>> (thumb_deal_with_atomic_sequence_raw): Likewise.
>> (arm_deal_with_atomic_sequence_raw): Likewise.
>> (arm_deal_with_atomic_sequence): Likewise.
>> (arm_get_next_pcs_read_memory_unsigned_integer): New function.
>> (arm_get_next_pcs_addr_bits_remove): Likewise.
>> (arm_get_next_pcs_syscall_next_pc): Likewise.
>> (arm_get_next_pcs_is_thumb): Likewise.
>> (arm_software_single_step): Adjust for arm_get_next_pcs
>> implementation.
>> * arm-tdep.h: (arm_get_next_pc): Remove declaration.
>> (arm_get_next_pcs_read_memory_unsigned_integer):
>> New declaration.
>> (arm_get_next_pcs_addr_bits_remove): Likewise.
>> (arm_get_next_pcs_syscall_next_pc): Likewise.
>> (arm_get_next_pcs_is_thumb): Likewise.
>> (arm_deal_with_atomic_sequence: Remove declaration.
>> * common/gdb_vecs.h: Add CORE_ADDR vector definition.
>> * configure.tgt (aarch64*-*-linux): Add arm-get-next-pcs.o, arm-linux.o.
>
> ChangeLog line max length is 74.
> https://sourceware.org/gdb/wiki/ContributionChecklist
>

Yes thanks, I have to edit my changelog mode for that.

Fixed.

>> (arm*-wince-pe): Add arm-get-next-pcs.o.
>> (arm*-*-linux*): Add arm-get-next-pcs.o, arm-linux.o, arm-get-next-pcs.o
>> (arm*-*-netbsd* | arm*-*-knetbsd*-gnu): Add arm-get-next-pcs.o.
>
> Replace "|" with ",".
>

Done.

>> (arm*-*-openbsd*): Likewise.
>> (arm*-*-symbianelf*): Likewise.
>> (arm*-*-*): Likewise.
>> * symtab.h: Move CORE_ADDR vector definition to gdb_vecs.h.
>>
>> gdb/gdbserver/ChangeLog:
>>
>> * Makefile.in (SFILES): Append arch/arm-linux.c,
>> arch/arm-get-next-pcs.c.
>> (arm-linux.o): New rule.
>> (arm-get-next-pcs.o): New rule.
>> * configure.srv (arm*-*-linux*): Add arm-get-next-pcs.o,
>> arm-linux.o.
>> * linux-aarch32-low.c (arm_abi_breakpoint): Remove macro. Moved
>> to linux-aarch32-low.c.
>> (arm_eabi_breakpoint, arm_breakpoint): Likewise.
>> (arm_breakpoint_len, thumb_breakpoint): Likewise.
>> (thumb_breakpoint_len, thumb2_breakpoint): Likewise.
>> (thumb2_breakpoint_len): Likewise.
>
> These are not started with TAB.
>
Fixed.

>> +
>> + if ((inst1 & 0xff00) == 0xbd00) /* pop {rlist, pc} */
>> + {
>> + CORE_ADDR sp;
>> +
>> + /* Fetch the saved PC from the stack. It's stored above
>> + all of the other registers. */
>> + offset = bitcount (bits (inst1, 0, 7)) * INT_REGISTER_SIZE;
>> + sp = regcache_raw_get_unsigned (regcache, ARM_SP_REGNUM);
>> + nextpc = self->ops->read_mem_uint (sp + offset, 4, byte_order);
>
> Redundant spaces.
>

Yes this somehow was showing up ok in emacs, strange, but fixed.

Thanks for the review!!