Re: [RFA] handle android bionic ptrace in gdbserver.

[Mark Kettenis <mark dot kettenis at xs4all dot nl>]

> From: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
> Date: Mon, 26 Mar 2012 19:46:42 -0300
> 
> Hi,
> 
> This patch fixes gdbserver compilation errors on Android. It expands on
> a patch addressing the same issue which was committed a while back:
> 
> http://sourceware.org/ml/gdb-patches/2010-01/msg00514.html
> 
> Explanation from the post above:
> 
> The signature of ptrace on Bionic is:
> 
> extern long ptrace(int request, pid_t pid, void *addr, void *data);
> 
> The linux manpage defines it as:
> 
> long ptrace(enum __ptrace_request request, pid_t pid,
>             void *addr, void *data);
> 
> But glibc defines it as a variadic function:
> 
> extern long int ptrace (enum __ptrace_request __request, ...) __THROW;
> 
> 
> Ok to commit? It doesn't affect compilation in i386-linux or
> armv5tel-linux-gnueabi.

Sad to see all this compatibility goo just a different prototype.
This could almost certainly be fixed by just fixing the header.

Anyway, you should test this on a 64-bit platform.  I have a strong
suspicion things will break there because of plain integers that are
being cast to void *.

> 2012-03-26  Thiago Jung Bauermann  <thiago.bauermann@linaro.org>
>   
> 	* linux-low.h (PTRACE_ARG3_TYPE): Move macro from linux-low.c.
> 	(PTRACE_ARG4_TYPE): Likewise.
> 	(PTRACE_XFER_TYPE): Likewise.
> 	* linux-arm-low.c (arm_prepare_to_resume): Cast third argument of
> 	ptrace to PTRACE_ARG3_TYPE.
> 	* linux-low.c (PTRACE_ARG3_TYPE): Move macro to linux-low.h.
> 	(PTRACE_ARG4_TYPE): Likewise.
> 	(PTRACE_XFER_TYPE): Likewise.
> 	(linux_detach_one_lwp): Cast fourth argument of
> 	ptrace to PTRACE_ARG4_TYPE.
> 	(regsets_fetch_inferior_registers): Cast third argument of
> 	ptrace to PTRACE_ARG3_TYPE.
> 	(regsets_store_inferior_registers): Likewise.
> 
> 
> diff --git a/gdb/gdbserver/linux-arm-low.c b/gdb/gdbserver/linux-arm-low.c
> index 01208ef..9490d7d 100644
> --- a/gdb/gdbserver/linux-arm-low.c
> +++ b/gdb/gdbserver/linux-arm-low.c
> @@ -709,13 +709,15 @@ arm_prepare_to_resume (struct lwp_info *lwp)
>  	errno = 0;
>  
>  	if (arm_hwbp_control_is_enabled (proc_info->bpts[i].control))
> -	  if (ptrace (PTRACE_SETHBPREGS, pid, ((i << 1) + 1),
> -	      &proc_info->bpts[i].address) < 0)
> +	  if (ptrace (PTRACE_SETHBPREGS, pid,
> +		      (PTRACE_ARG3_TYPE) ((i << 1) + 1),
> +		      &proc_info->bpts[i].address) < 0)
>  	    perror_with_name ("Unexpected error setting breakpoint address");
>  
>  	if (arm_hwbp_control_is_initialized (proc_info->bpts[i].control))
> -	  if (ptrace (PTRACE_SETHBPREGS, pid, ((i << 1) + 2),
> -	      &proc_info->bpts[i].control) < 0)
> +	  if (ptrace (PTRACE_SETHBPREGS, pid,
> +		      (PTRACE_ARG3_TYPE) ((i << 1) + 2),
> +		      &proc_info->bpts[i].control) < 0)
>  	    perror_with_name ("Unexpected error setting breakpoint");
>  
>  	lwp_info->bpts_changed[i] = 0;
> @@ -727,13 +729,15 @@ arm_prepare_to_resume (struct lwp_info *lwp)
>  	errno = 0;
>  
>  	if (arm_hwbp_control_is_enabled (proc_info->wpts[i].control))
> -	  if (ptrace (PTRACE_SETHBPREGS, pid, -((i << 1) + 1),
> -	      &proc_info->wpts[i].address) < 0)
> +	  if (ptrace (PTRACE_SETHBPREGS, pid,
> +		      (PTRACE_ARG3_TYPE) -((i << 1) + 1),
> +		      &proc_info->wpts[i].address) < 0)
>  	    perror_with_name ("Unexpected error setting watchpoint address");
>  
>  	if (arm_hwbp_control_is_initialized (proc_info->wpts[i].control))
> -	  if (ptrace (PTRACE_SETHBPREGS, pid, -((i << 1) + 2),
> -	      &proc_info->wpts[i].control) < 0)
> +	  if (ptrace (PTRACE_SETHBPREGS, pid,
> +		      (PTRACE_ARG3_TYPE) -((i << 1) + 2),
> +		      &proc_info->wpts[i].control) < 0)
>  	    perror_with_name ("Unexpected error setting watchpoint");
>  
>  	lwp_info->wpts_changed[i] = 0;
> diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
> index 1caff5a..2ebef9f 100644
> --- a/gdb/gdbserver/linux-low.c
> +++ b/gdb/gdbserver/linux-low.c
> @@ -239,10 +239,6 @@ struct pending_signals
>    struct pending_signals *prev;
>  };
>  
> -#define PTRACE_ARG3_TYPE void *
> -#define PTRACE_ARG4_TYPE void *
> -#define PTRACE_XFER_TYPE long
> -
>  #ifdef HAVE_LINUX_REGSETS
>  static char *disabled_regsets;
>  static int num_regsets;
> @@ -1149,7 +1145,7 @@ linux_detach_one_lwp (struct inferior_list_entry *entry, void *args)
>    /* Finally, let it resume.  */
>    if (the_low_target.prepare_to_resume != NULL)
>      the_low_target.prepare_to_resume (lwp);
> -  if (ptrace (PTRACE_DETACH, lwpid_of (lwp), 0, sig) < 0)
> +  if (ptrace (PTRACE_DETACH, lwpid_of (lwp), 0, (PTRACE_ARG4_TYPE) sig) < 0)
>      error (_("Can't detach %s: %s"),
>  	   target_pid_to_str (ptid_of (lwp)),
>  	   strerror (errno));
> @@ -3989,7 +3985,8 @@ regsets_fetch_inferior_registers (struct regcache *regcache)
>  	data = buf;
>  
>  #ifndef __sparc__
> -      res = ptrace (regset->get_request, pid, nt_type, data);
> +      res = ptrace (regset->get_request, pid,
> +		    (PTRACE_ARG3_TYPE) nt_type, data);
>  #else
>        res = ptrace (regset->get_request, pid, data, nt_type);
>  #endif
> @@ -4062,7 +4059,8 @@ regsets_store_inferior_registers (struct regcache *regcache)
>  	data = buf;
>  
>  #ifndef __sparc__
> -      res = ptrace (regset->get_request, pid, nt_type, data);
> +      res = ptrace (regset->get_request, pid,
> +		    (PTRACE_ARG3_TYPE) nt_type, data);
>  #else
>        res = ptrace (regset->get_request, pid, &iov, data);
>  #endif
> @@ -4074,7 +4072,8 @@ regsets_store_inferior_registers (struct regcache *regcache)
>  
>  	  /* Only now do we write the register set.  */
>  #ifndef __sparc__
> -	  res = ptrace (regset->set_request, pid, nt_type, data);
> +	  res = ptrace (regset->set_request, pid,
> +			(PTRACE_ARG3_TYPE) nt_type, data);
>  #else
>  	  res = ptrace (regset->set_request, pid, data, nt_type);
>  #endif
> diff --git a/gdb/gdbserver/linux-low.h b/gdb/gdbserver/linux-low.h
> index 3aeae70..cb26ebb 100644
> --- a/gdb/gdbserver/linux-low.h
> +++ b/gdb/gdbserver/linux-low.h
> @@ -24,6 +24,10 @@
>  
>  #include "gdb_proc_service.h"
>  
> +#define PTRACE_ARG3_TYPE void *
> +#define PTRACE_ARG4_TYPE void *
> +#define PTRACE_XFER_TYPE long
> +
>  #ifdef HAVE_LINUX_REGSETS
>  typedef void (*regset_fill_func) (struct regcache *, void *);
>  typedef void (*regset_store_func) (struct regcache *, const void *);
> 
> 
>