sparc: We need to implement arch_ptrace_stop().

In order to always provide fully synchronized state to the debugger,
we might need to do a synchronize_user_stack().

A pair of hooks, arch_ptrace_stop_needed() and arch_ptrace_stop(),
exist to handle this kind of situation.  It was created for
the sake of IA64.

Use them, to flush the kernel side cached register windows
to the user stack, when necessary.
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/include/asm/ptrace_32.h

@@ -62,6 +62,8 @@ struct sparc_stackf {
 
 #ifdef __KERNEL__
 
+#include <asm/system.h>
+
 static inline bool pt_regs_is_syscall(struct pt_regs *regs)
 {
 	return (regs->psr & PSR_SYSCALL);
@@ -72,6 +74,14 @@ static inline bool pt_regs_clear_syscall(struct pt_regs *regs)
 	return (regs->psr &= ~PSR_SYSCALL);
 }
 
+#define arch_ptrace_stop_needed(exit_code, info) \
+({	flush_user_windows(); \
+	current_thread_info()->w_saved != 0;	\
+})
+
+#define arch_ptrace_stop(exit_code, info) \
+	synchronize_user_stack()
+
 #define user_mode(regs) (!((regs)->psr & PSR_PS))
 #define instruction_pointer(regs) ((regs)->pc)
 #define user_stack_pointer(regs) ((regs)->u_regs[UREG_FP])

arch/sparc/include/asm/ptrace_64.h

@@ -114,6 +114,7 @@ struct sparc_trapf {
 #ifdef __KERNEL__
 
 #include <linux/threads.h>
+#include <asm/system.h>
 
 static inline int pt_regs_trap_type(struct pt_regs *regs)
 {
@@ -130,6 +131,14 @@ static inline bool pt_regs_clear_syscall(struct pt_regs *regs)
 	return (regs->tstate &= ~TSTATE_SYSCALL);
 }
 
+#define arch_ptrace_stop_needed(exit_code, info) \
+({	flush_user_windows(); \
+	get_thread_wsaved() != 0; \
+})
+
+#define arch_ptrace_stop(exit_code, info) \
+	synchronize_user_stack()
+
 struct global_reg_snapshot {
 	unsigned long		tstate;
 	unsigned long		tpc;