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* Definitions used by low-level trap handlers
* Copyright (C) 2008-2009 Michal Simek <>
* Copyright (C) 2007-2009 PetaLogix
* Copyright (C) 2007 John Williams <>
* This file is subject to the terms and conditions of the GNU General
* Public License. See the file COPYING in the main directory of this
* archive for more details.
#include <asm/percpu.h>
#include <asm/ptrace.h>
* These are per-cpu variables required in entry.S, among other
* places
#define PER_CPU(var) per_cpu__##var
# ifndef __ASSEMBLY__
DECLARE_PER_CPU(unsigned int, KSP); /* Saved kernel stack pointer */
DECLARE_PER_CPU(unsigned int, KM); /* Kernel/user mode */
DECLARE_PER_CPU(unsigned int, ENTRY_SP); /* Saved SP on kernel entry */
DECLARE_PER_CPU(unsigned int, R11_SAVE); /* Temp variable for entry */
DECLARE_PER_CPU(unsigned int, CURRENT_SAVE); /* Saved current pointer */
# endif /* __ASSEMBLY__ */
#ifndef CONFIG_MMU
/* noMMU hasn't any space for args */
#else /* CONFIG_MMU */
/* If true, system calls save and restore all registers (except result
* registers, of course). If false, then `call clobbered' registers
* will not be preserved, on the theory that system calls are basically
* function calls anyway, and the caller should be able to deal with it.
* This is a security risk, of course, as `internal' values may leak out
* after a system call, but that certainly doesn't matter very much for
* a processor with no MMU protection! For a protected-mode kernel, it
* would be faster to just zero those registers before returning.
* I can not rely on the glibc implementation. If you turn it off make
* sure that r11/r12 is saved in user-space. --KAA
* These are special variables using by the kernel trap/interrupt code
* to save registers in, at a time when there are no spare registers we
* can use to do so, and we can't depend on the value of the stack
* pointer. This means that they must be within a signed 16-bit
* displacement of 0x00000000.
/* A `state save frame' is a struct pt_regs preceded by some extra space
* suitable for a function call stack frame. */
/* Amount of room on the stack reserved for arguments and to satisfy the
* C calling conventions, in addition to the space used by the struct
* pt_regs that actually holds saved values. */
#define STATE_SAVE_ARG_SPACE (6*4) /* Up to six arguments */
#endif /* CONFIG_MMU */