microblaze_mmu_v2: entry.S, entry.h

/*

 * Definitions used by low-level trap handlers

 *

 * Copyright (C) 2008 Michal Simek

 * Copyright (C) 2007 - 2008 PetaLogix

 * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>

 * Copyright (C) 2007-2009 PetaLogix

 * Copyright (C) 2007 John Williams <john.williams@petalogix.com>

 *

 * This file is subject to the terms and conditions of the GNU General

DECLARE_PER_CPU(unsigned int, CURRENT_SAVE); /* Saved current pointer */

# endif /* __ASSEMBLY__ */

#ifndef CONFIG_MMU

/* noMMU hasn't any space for args */

# define STATE_SAVE_ARG_SPACE	(0)

#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 */

#endif /* _ASM_MICROBLAZE_ENTRY_H */