[PATCH] Add regs_return_value() helper

Add the regs_return_value() macro to extract the return value in an
architecture agnostic manner, given the pt_regs.

Other architecture maintainers may want to add similar helpers.

Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/asm-i386/ptrace.h

@@ -47,7 +47,10 @@ static inline int user_mode_vm(struct pt_regs *regs)
 {
 	return ((regs->xcs & SEGMENT_RPL_MASK) | (regs->eflags & VM_MASK)) >= USER_RPL;
 }
+
 #define instruction_pointer(regs) ((regs)->eip)
+#define regs_return_value(regs) ((regs)->eax)
+
 extern unsigned long profile_pc(struct pt_regs *regs);
 #endif /* __KERNEL__ */
 

include/asm-ia64/ptrace.h

@@ -241,6 +241,9 @@ struct switch_stack {
  * the canonical representation by adding to instruction pointer.
  */
 # define instruction_pointer(regs) ((regs)->cr_iip + ia64_psr(regs)->ri)
+
+#define regs_return_value(regs) ((regs)->r8)
+
 /* Conserve space in histogram by encoding slot bits in address
  * bits 2 and 3 rather than bits 0 and 1.
  */

include/asm-powerpc/ptrace.h

@@ -73,6 +73,8 @@ struct pt_regs {
 #ifndef __ASSEMBLY__
 
 #define instruction_pointer(regs) ((regs)->nip)
+#define regs_return_value(regs) ((regs)->gpr[3])
+
 #ifdef CONFIG_SMP
 extern unsigned long profile_pc(struct pt_regs *regs);
 #else

include/asm-s390/ptrace.h

@@ -472,6 +472,7 @@ struct user_regs_struct
 
 #define user_mode(regs) (((regs)->psw.mask & PSW_MASK_PSTATE) != 0)
 #define instruction_pointer(regs) ((regs)->psw.addr & PSW_ADDR_INSN)
+#define regs_return_value(regs)((regs)->gprs[2])
 #define profile_pc(regs) instruction_pointer(regs)
 extern void show_regs(struct pt_regs * regs);
 #endif

include/asm-x86_64/ptrace.h

@@ -39,6 +39,8 @@ struct pt_regs {
 #define user_mode(regs) (!!((regs)->cs & 3))
 #define user_mode_vm(regs) user_mode(regs)
 #define instruction_pointer(regs) ((regs)->rip)
+#define regs_return_value(regs) ((regs)->rax)
+
 extern unsigned long profile_pc(struct pt_regs *regs);
 void signal_fault(struct pt_regs *regs, void __user *frame, char *where);