Introduce current_lwp_ptid

This commit introduces a new function, current_lwp_ptid, that
shared Linux code can use to obtain the ptid of the current
lightweight process.

gdb/ChangeLog:

	* nat/linux-nat.h (current_lwp_ptid): New declaration.
	* linux-nat.c (current_lwp_ptid): New function.
	* x86-linux-nat.c: Include nat/linux-nat.h.
	(x86_linux_dr_get_addr): Use current_lwp_ptid.
	(x86_linux_dr_get_control): Likewise.
	(x86_linux_dr_get_status): Likewise.
	(x86_linux_dr_set_control): Likewise.
	(x86_linux_dr_set_addr): Likewise.

gdb/gdbserver/ChangeLog:

	* linux-low.c (current_lwp_ptid): New function.
	* linux-x86-low.c: Include nat/linux-nat.h.
	(x86_dr_low_get_addr): Use current_lwp_ptid.
	(x86_dr_low_get_control): Likewise.
	(x86_dr_low_get_status): Likewise.

gdb/ChangeLog

@@ -1,3 +1,14 @@
+2015-03-24  Gary Benson  <gbenson@redhat.com>
+
+	* nat/linux-nat.h (current_lwp_ptid): New declaration.
+	* linux-nat.c (current_lwp_ptid): New function.
+	* x86-linux-nat.c: Include nat/linux-nat.h.
+	(x86_linux_dr_get_addr): Use current_lwp_ptid.
+	(x86_linux_dr_get_control): Likewise.
+	(x86_linux_dr_get_status): Likewise.
+	(x86_linux_dr_set_control): Likewise.
+	(x86_linux_dr_set_addr): Likewise.
+
 2015-03-24  Antoine Tremblay  <antoine.tremblay@ericsson.com>
 
 	PR breakpoints/16466

gdb/gdbserver/ChangeLog

@@ -1,3 +1,11 @@
+2015-03-24  Gary Benson  <gbenson@redhat.com>
+
+	* linux-low.c (current_lwp_ptid): New function.
+	* linux-x86-low.c: Include nat/linux-nat.h.
+	(x86_dr_low_get_addr): Use current_lwp_ptid.
+	(x86_dr_low_get_control): Likewise.
+	(x86_dr_low_get_status): Likewise.
+
 2015-03-20  Pedro Alves  <palves@redhat.com>
 
 	* tracepoint.c (cmd_qtstatus): Make "str" const.

gdb/gdbserver/linux-low.c

@@ -6218,6 +6218,14 @@ linux_low_btrace_conf (const struct btrace_target_info *tinfo,
 }
 #endif /* HAVE_LINUX_BTRACE */
 
+/* See nat/linux-nat.h.  */
+
+ptid_t
+current_lwp_ptid (void)
+{
+  return ptid_of (current_thread);
+}
+
 static struct target_ops linux_target_ops = {
   linux_create_inferior,
   linux_attach,

gdb/gdbserver/linux-x86-low.c

@@ -37,6 +37,7 @@
 #include "tdesc.h"
 #include "tracepoint.h"
 #include "ax.h"
+#include "nat/linux-nat.h"
 
 #ifdef __x86_64__
 /* Defined in auto-generated file amd64-linux.c.  */
@@ -615,11 +616,9 @@ x86_dr_low_set_addr (int regnum, CORE_ADDR addr)
 static CORE_ADDR
 x86_dr_low_get_addr (int regnum)
 {
-  ptid_t ptid = ptid_of (current_thread);
-
   gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR);
 
-  return x86_linux_dr_get (ptid, regnum);
+  return x86_linux_dr_get (current_lwp_ptid (), regnum);
 }
 
 /* Update the inferior's DR7 debug control register from STATE.  */
@@ -638,9 +637,7 @@ x86_dr_low_set_control (unsigned long control)
 static unsigned long
 x86_dr_low_get_control (void)
 {
-  ptid_t ptid = ptid_of (current_thread);
+  return x86_linux_dr_get (current_lwp_ptid (), DR_CONTROL);
-
-  return x86_linux_dr_get (ptid, DR_CONTROL);
 }
 
 /* Get the value of the DR6 debug status register from the inferior
@@ -649,9 +646,7 @@ x86_dr_low_get_control (void)
 static unsigned long
 x86_dr_low_get_status (void)
 {
-  ptid_t ptid = ptid_of (current_thread);
+  return x86_linux_dr_get (current_lwp_ptid (), DR_STATUS);
-
-  return x86_linux_dr_get (ptid, DR_STATUS);
 }
 
 /* Low-level function vector.  */

gdb/linux-nat.c

@@ -4938,6 +4938,15 @@ linux_nat_get_siginfo (ptid_t ptid, siginfo_t *siginfo)
   return 1;
 }
 
+/* See nat/linux-nat.h.  */
+
+ptid_t
+current_lwp_ptid (void)
+{
+  gdb_assert (ptid_lwp_p (inferior_ptid));
+  return inferior_ptid;
+}
+
 /* Provide a prototype to silence -Wmissing-prototypes.  */
 extern initialize_file_ftype _initialize_linux_nat;
 

gdb/nat/linux-nat.h

@@ -25,4 +25,11 @@
    instead SIGTRAP with bit 7 set.  */
 #define SYSCALL_SIGTRAP (SIGTRAP | 0x80)
 
+/* Return the ptid of the current lightweight process.  With NPTL
+   threads and LWPs map 1:1, so this is equivalent to returning the
+   ptid of the current thread.  This function must be provided by
+   the client. */
+
+extern ptid_t current_lwp_ptid (void);
+
 #endif /* LINUX_NAT_H */

gdb/x86-linux-nat.c

@@ -38,6 +38,7 @@
 #endif
 #include "x86-xstate.h"
 #include "nat/linux-btrace.h"
+#include "nat/linux-nat.h"
 
 /* Per-thread arch-specific data we want to keep.  */
 
@@ -107,7 +108,7 @@ x86_linux_dr_get_addr (int regnum)
   /* DR6 and DR7 are retrieved with some other way.  */
   gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR);
 
-  return x86_linux_dr_get (inferior_ptid, regnum);
+  return x86_linux_dr_get (current_lwp_ptid (), regnum);
 }
 
 /* Return the inferior's DR7 debug control register.  */
@@ -115,7 +116,7 @@ x86_linux_dr_get_addr (int regnum)
 static unsigned long
 x86_linux_dr_get_control (void)
 {
-  return x86_linux_dr_get (inferior_ptid, DR_CONTROL);
+  return x86_linux_dr_get (current_lwp_ptid (), DR_CONTROL);
 }
 
 /* Get DR_STATUS from only the one LWP of INFERIOR_PTID.  */
@@ -123,7 +124,7 @@ x86_linux_dr_get_control (void)
 static unsigned long
 x86_linux_dr_get_status (void)
 {
-  return x86_linux_dr_get (inferior_ptid, DR_STATUS);
+  return x86_linux_dr_get (current_lwp_ptid (), DR_STATUS);
 }
 
 /* Callback for iterate_over_lwps.  Update the debug registers of
@@ -153,7 +154,7 @@ update_debug_registers_callback (struct lwp_info *lwp, void *arg)
 static void
 x86_linux_dr_set_control (unsigned long control)
 {
-  ptid_t pid_ptid = pid_to_ptid (ptid_get_pid (inferior_ptid));
+  ptid_t pid_ptid = pid_to_ptid (ptid_get_pid (current_lwp_ptid ()));
 
   iterate_over_lwps (pid_ptid, update_debug_registers_callback, NULL);
 }
@@ -164,7 +165,7 @@ x86_linux_dr_set_control (unsigned long control)
 static void
 x86_linux_dr_set_addr (int regnum, CORE_ADDR addr)
 {
-  ptid_t pid_ptid = pid_to_ptid (ptid_get_pid (inferior_ptid));
+  ptid_t pid_ptid = pid_to_ptid (ptid_get_pid (current_lwp_ptid ()));
 
   gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR);