new helper: current_user_stack_pointer()

Cross-architecture equivalent of rdusp(); default is
user_stack_pointer(current_pt_regs()) - that works for almost all
platforms that have usp saved in pt_regs.  The only exception from
that is ia64 - we want memory stack, not the backing store for
register one.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
2012-11-18 12:50:10 -05:00
parent 5208ba24e7
commit 1ca97bb541
7 changed files with 14 additions and 0 deletions

View File

@@ -78,6 +78,11 @@ static inline long regs_return_value(struct pt_regs *regs)
unsigned long __ip = instruction_pointer(regs); \
(__ip & ~3UL) + ((__ip & 3UL) << 2); \
})
/*
* Why not default? Because user_stack_pointer() on ia64 gives register
* stack backing store instead...
*/
#define current_user_stack_pointer() (current_pt_regs()->r12)
/* given a pointer to a task_struct, return the user's pt_regs */
# define task_pt_regs(t) (((struct pt_regs *) ((char *) (t) + IA64_STK_OFFSET)) - 1)