[rfc/rft] [3/5] Untangle register_addr: CANNOT_FETCH/STORE_REGISTER

["Ulrich Weigand" <uweigand@de.ibm.com>]

Hello,

this patch removes the calls to CANNOT_FETCH_REGISTER / CANNOT_STORE_REGISTER
from within the inf_ptrace_trad_target routines.  This is enabled by two 
changes to the register_u_offset callback:
 - the routine is allowed to return (CORE_ADDR)-1 to indicate the 
   requested register cannot be accessed
 - the routine gains a new argument STORE_P that indicates whether
   the register is to be fetched or stored

There are three users of inf_ptrace_trad_target, vax-ultrix (which does
not have any CANNOT_FETCH_REGISTER / CANNOT_STORE_REGISTER anyway),
and alpha-linux and mips-linux via linux_trad_target.  For the latter,
this patch simply updates their register_u_offset routines to add
CANNOT_FETCH_REGISTER / CANNOT_STORE_REGISTER calls; this patch thus
should not cause any change in behaviour.  (Follow-on patches will
further clean up those two targets.)

Tested on i368-linux and powerpc-linux, and by verifying that alpha-linux,
mips-linux and vax-ultrix native targets still build.

Bye,
Ulrich


ChangeLog:

	* inf-ptrace.c (inf_ptrace_register_u_offset): Add STORE_P argument.
	(inf_ptrace_fetch_register): Update call.  Check for (CORE_ADDR)-1
	return value; replaces CANNOT_FETCH_REGISTER call.
	(inf_ptrace_store_register): Update call.  Check for (CORE_ADDR)-1
	return value; replaces CANNOT_STORE_REGISTER call.
	(inf_ptrace_trad_target): Update signature.
	* inf-ptrace.h (inf_ptrace_trad_target): Likewise.
	* linux-nat.c (linux_trad_target): Likewise.
	* linux-nat.h (linux_trad_target): Likewise.

	* alpha-linux-nat.c (alpha_linux_register_u_offset): Add STORE_P
	argument.  Call CANNOT_STORE_REGISTER / CANNOT_FETCH_REGISTER.
	* mips-linux-nat.c (mips_linux_register_u_offset): Likewise.
	* vax-nat.c (vax_register_u_addr): Add STORE_P argument.


diff -urNp gdb-orig/gdb/alpha-linux-nat.c gdb-head/gdb/alpha-linux-nat.c
--- gdb-orig/gdb/alpha-linux-nat.c	2007-04-14 00:46:45.843259816 +0200
+++ gdb-head/gdb/alpha-linux-nat.c	2007-04-14 00:46:32.987217952 +0200
@@ -24,8 +24,11 @@
 #include "gdbcore.h"
 
 static CORE_ADDR
-alpha_linux_register_u_offset (int regno)
+alpha_linux_register_u_offset (int regno, int store_p)
 {
+  if (store_p? CANNOT_STORE_REGISTER (regno) : CANNOT_FETCH_REGISTER (regno))
+    return (CORE_ADDR)-1;
+
   /* FIXME drow/2005-09-04: The hardcoded use of register_addr should go
      away.  This requires disentangling the various definitions of it
      (particularly alpha-nat.c's).  */
diff -urNp gdb-orig/gdb/inf-ptrace.c gdb-head/gdb/inf-ptrace.c
--- gdb-orig/gdb/inf-ptrace.c	2007-04-12 16:12:54.000000000 +0200
+++ gdb-head/gdb/inf-ptrace.c	2007-04-14 00:46:32.992217192 +0200
@@ -607,7 +607,7 @@ inf_ptrace_target (void)
 
 /* Pointer to a function that returns the offset within the user area
    where a particular register is stored.  */
-static CORE_ADDR (*inf_ptrace_register_u_offset)(int);
+static CORE_ADDR (*inf_ptrace_register_u_offset)(int, int);
 
 /* Fetch register REGNUM from the inferior.  */
 
@@ -619,7 +619,9 @@ inf_ptrace_fetch_register (int regnum)
   PTRACE_TYPE_RET *buf;
   int pid, i;
 
-  if (CANNOT_FETCH_REGISTER (regnum))
+  /* This isn't really an address, but ptrace thinks of it as one.  */
+  addr = inf_ptrace_register_u_offset (regnum, 0);
+  if (addr == (CORE_ADDR)-1)
     {
       regcache_raw_supply (current_regcache, regnum, NULL);
       return;
@@ -631,10 +633,7 @@ inf_ptrace_fetch_register (int regnum)
   if (pid == 0)
     pid = ptid_get_pid (inferior_ptid);
 
-  /* This isn't really an address, but ptrace thinks of it as one.  */
-  addr = inf_ptrace_register_u_offset (regnum);
   size = register_size (current_gdbarch, regnum);
-
   gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
   buf = alloca (size);
 
@@ -675,7 +674,9 @@ inf_ptrace_store_register (int regnum)
   PTRACE_TYPE_RET *buf;
   int pid, i;
 
-  if (CANNOT_STORE_REGISTER (regnum))
+  /* This isn't really an address, but ptrace thinks of it as one.  */
+  addr = inf_ptrace_register_u_offset (regnum, 1);
+  if (addr == (CORE_ADDR)-1)
     return;
 
   /* Cater for systems like GNU/Linux, that implement threads as
@@ -684,10 +685,7 @@ inf_ptrace_store_register (int regnum)
   if (pid == 0)
     pid = ptid_get_pid (inferior_ptid);
 
-  /* This isn't really an address, but ptrace thinks of it as one.  */
-  addr = inf_ptrace_register_u_offset (regnum);
   size = register_size (current_gdbarch, regnum);
-
   gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
   buf = alloca (size);
 
@@ -723,7 +721,7 @@ inf_ptrace_store_registers (int regnum)
    particular register is stored.  */
 
 struct target_ops *
-inf_ptrace_trad_target (CORE_ADDR (*register_u_offset)(int))
+inf_ptrace_trad_target (CORE_ADDR (*register_u_offset)(int, int))
 {
   struct target_ops *t = inf_ptrace_target();
 
diff -urNp gdb-orig/gdb/inf-ptrace.h gdb-head/gdb/inf-ptrace.h
--- gdb-orig/gdb/inf-ptrace.h	2007-04-12 16:12:54.000000000 +0200
+++ gdb-head/gdb/inf-ptrace.h	2007-04-14 00:46:32.996216584 +0200
@@ -32,6 +32,6 @@ extern struct target_ops *inf_ptrace_tar
    particular register is stored.  */
 
 extern struct target_ops *
-  inf_ptrace_trad_target (CORE_ADDR (*register_u_offset)(int));
+  inf_ptrace_trad_target (CORE_ADDR (*register_u_offset)(int, int));
 
 #endif
diff -urNp gdb-orig/gdb/linux-nat.c gdb-head/gdb/linux-nat.c
--- gdb-orig/gdb/linux-nat.c	2007-04-14 00:46:45.941244920 +0200
+++ gdb-head/gdb/linux-nat.c	2007-04-14 00:46:33.005215216 +0200
@@ -3196,7 +3196,7 @@ linux_target (void)
 }
 
 struct target_ops *
-linux_trad_target (CORE_ADDR (*register_u_offset)(int))
+linux_trad_target (CORE_ADDR (*register_u_offset)(int, int))
 {
   struct target_ops *t;
 
diff -urNp gdb-orig/gdb/linux-nat.h gdb-head/gdb/linux-nat.h
--- gdb-orig/gdb/linux-nat.h	2007-04-14 00:46:45.946244160 +0200
+++ gdb-head/gdb/linux-nat.h	2007-04-14 00:46:33.046208984 +0200
@@ -91,7 +91,7 @@ struct target_ops * linux_target (void);
 /* Create a generic GNU/Linux target using traditional 
    ptrace register access.  */
 struct target_ops *
-linux_trad_target (CORE_ADDR (*register_u_offset)(int));
+linux_trad_target (CORE_ADDR (*register_u_offset)(int, int));
 
 /* Register the customized GNU/Linux target.  This should be used
    instead of calling add_target directly.  */
diff -urNp gdb-orig/gdb/mips-linux-nat.c gdb-head/gdb/mips-linux-nat.c
--- gdb-orig/gdb/mips-linux-nat.c	2007-04-14 00:46:45.960242032 +0200
+++ gdb-head/gdb/mips-linux-nat.c	2007-04-14 00:46:33.062206552 +0200
@@ -251,8 +251,11 @@ mips64_linux_store_registers (int regnum
    REGNO.  */
 
 static CORE_ADDR
-mips_linux_register_u_offset (int regno)
+mips_linux_register_u_offset (int regno, int store_p)
 {
+  if (store_p? CANNOT_STORE_REGISTER (regno) : CANNOT_FETCH_REGISTER (regno))
+    return (CORE_ADDR)-1;
+
   /* FIXME drow/2005-09-04: The hardcoded use of register_addr should go
      away.  This requires disentangling the various definitions of it
      (particularly alpha-nat.c's).  */
diff -urNp gdb-orig/gdb/vax-nat.c gdb-head/gdb/vax-nat.c
--- gdb-orig/gdb/vax-nat.c	2007-04-13 20:40:05.608266416 +0200
+++ gdb-head/gdb/vax-nat.c	2007-04-14 00:46:33.066205944 +0200
@@ -69,7 +69,7 @@ vax_register_u_addr (CORE_ADDR u_ar0, in
 }
 
 static CORE_ADDR
-vax_register_u_offset (int regnum)
+vax_register_u_offset (int regnum, int store_p)
 {
   size_t u_ar0_offset = offsetof (struct user, u_ar0);
   CORE_ADDR u_ar0;
-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com