Re: [PATCH 1/3] Fix inferior memory reading in GDBServer for arm/aarch32.

[Luis Machado <lgustavo@codesourcery.com>]

On 11/28/2016 06:27 AM, Antoine Tremblay wrote:
> Before this patch, some functions would read the inferior memory with
> (*the_target)->read_memory, which returns the raw memory, rather than the
> shadowed memory.
>
> This is wrong since these functions do not expect to read a breakpoint
> instruction and can lead to invalid behavior.
>
> Use of raw memory in get_next_pcs_read_memory_unsigned_integer for example
> could lead to get_next_pc returning an invalid pc.
>
> Tested on gdbserver-native/-m{thumb,arm} no regressions.
>
> gdb/gdbserver/ChangeLog:
>
> 	* linux-aarch32-low.c (arm_breakpoint_kind_from_pc): Use
> 	target_read_memory.
> 	* linux-arm-low.c (get_next_pcs_read_memory_unsigned_integer): Likewise.
> 	(arm_sigreturn_next_pc): Likewise.
> 	(get_next_pcs_syscall_next_pc): Likewise.
> 	(arm_get_syscall_trapinfo): Likewise.
> ---
>  gdb/gdbserver/linux-aarch32-low.c |  4 ++--
>  gdb/gdbserver/linux-arm-low.c     | 13 +++++++------
>  2 files changed, 9 insertions(+), 8 deletions(-)
>
> diff --git a/gdb/gdbserver/linux-aarch32-low.c b/gdb/gdbserver/linux-aarch32-low.c
> index 5547cf6..4ff34b6 100644
> --- a/gdb/gdbserver/linux-aarch32-low.c
> +++ b/gdb/gdbserver/linux-aarch32-low.c
> @@ -237,11 +237,11 @@ arm_breakpoint_kind_from_pc (CORE_ADDR *pcptr)
>        *pcptr = UNMAKE_THUMB_ADDR (*pcptr);
>
>        /* Check whether we are replacing a thumb2 32-bit instruction.  */
> -      if ((*the_target->read_memory) (*pcptr, buf, 2) == 0)
> +      if (target_read_memory (*pcptr, buf, 2) == 0)
>  	{
>  	  unsigned short inst1 = 0;
>
> -	  (*the_target->read_memory) (*pcptr, (gdb_byte *) &inst1, 2);
> +	  target_read_memory (*pcptr, (gdb_byte *) &inst1, 2);
>  	  if (thumb_insn_size (inst1) == 4)
>  	    return ARM_BP_KIND_THUMB2;
>  	}
> diff --git a/gdb/gdbserver/linux-arm-low.c b/gdb/gdbserver/linux-arm-low.c
> index ed9b356..b8365cf 100644
> --- a/gdb/gdbserver/linux-arm-low.c
> +++ b/gdb/gdbserver/linux-arm-low.c
> @@ -263,7 +263,8 @@ get_next_pcs_read_memory_unsigned_integer (CORE_ADDR memaddr,
>    ULONGEST res;
>
>    res = 0;
> -  (*the_target->read_memory) (memaddr, (unsigned char *) &res, len);
> +  target_read_memory (memaddr, (unsigned char *) &res, len);
> +
>    return res;
>  }
>
> @@ -769,15 +770,15 @@ arm_sigreturn_next_pc (struct regcache *regcache, int svc_number,
>    gdb_assert (svc_number == __NR_sigreturn || svc_number == __NR_rt_sigreturn);
>
>    collect_register_by_name (regcache, "sp", &sp);
> -  (*the_target->read_memory) (sp, (unsigned char *) &sp_data, 4);
> +  target_read_memory (sp, (unsigned char *) &sp_data, 4);
>
>    pc_offset = arm_linux_sigreturn_next_pc_offset
>      (sp, sp_data, svc_number, __NR_sigreturn == svc_number ? 1 : 0);
>
> -  (*the_target->read_memory) (sp + pc_offset, (unsigned char *) &next_pc, 4);
> +  target_read_memory (sp + pc_offset, (unsigned char *) &next_pc, 4);
>
>    /* Set IS_THUMB according the CPSR saved on the stack.  */
> -  (*the_target->read_memory) (sp + pc_offset + 4, (unsigned char *) &cpsr, 4);
> +  target_read_memory (sp + pc_offset + 4, (unsigned char *) &cpsr, 4);
>    *is_thumb = ((cpsr & CPSR_T) != 0);
>
>    return next_pc;
> @@ -804,7 +805,7 @@ get_next_pcs_syscall_next_pc (struct arm_get_next_pcs *self)
>        unsigned long this_instr;
>        unsigned long svc_operand;
>
> -      (*the_target->read_memory) (pc, (unsigned char *) &this_instr, 4);
> +      target_read_memory (pc, (unsigned char *) &this_instr, 4);
>        svc_operand = (0x00ffffff & this_instr);
>
>        if (svc_operand)  /* OABI.  */
> @@ -965,7 +966,7 @@ arm_get_syscall_trapinfo (struct regcache *regcache, int *sysno)
>
>        collect_register_by_name (regcache, "pc", &pc);
>
> -      if ((*the_target->read_memory) (pc - 4, (unsigned char *) &insn, 4))
> +      if (target_read_memory (pc - 4, (unsigned char *) &insn, 4))
>  	*sysno = UNKNOWN_SYSCALL;
>        else
>  	{
>

The series LGTM. Fairly mechanical changes.