kevin/linux
1
Fork 0
Code
7d15d6a4dc
linux/include/asm-xtensa/processor.h
Chris Zankel c658eac628 [XTENSA] Add support for configurable registers and coprocessors 
The Xtensa architecture allows to define custom instructions and
registers. Registers that are bound to a coprocessor are only
accessible if the corresponding enable bit is set, which allows
to implement a 'lazy' context switch mechanism. Other registers
needs to be saved and restore at the time of the context switch
or during interrupt handling.

This patch adds support for these additional states:

- save and restore registers that are used by the compiler upon
  interrupt entry and exit.
- context switch additional registers unbound to any coprocessor
- 'lazy' context switch of registers bound to a coprocessor
- ptrace interface to provide access to additional registers
- update configuration files in include/asm-xtensa/variant-fsf

Signed-off-by: Chris Zankel <chris@zankel.net>
2008-02-13 17:41:43 -08:00

194 lines
5.7 KiB
C
Raw Blame History

/*
* include/asm-xtensa/processor.h
*
* 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.
*
* Copyright (C) 2001 - 2005 Tensilica Inc.
*/
#ifndef _XTENSA_PROCESSOR_H
#define _XTENSA_PROCESSOR_H
#include <asm/variant/core.h>
#include <asm/coprocessor.h>
#include <linux/compiler.h>
#include <asm/ptrace.h>
#include <asm/types.h>
#include <asm/regs.h>
/* Assertions. */
#if (XCHAL_HAVE_WINDOWED != 1)
# error Linux requires the Xtensa Windowed Registers Option.
#endif
/*
* User space process size: 1 GB.
* Windowed call ABI requires caller and callee to be located within the same
* 1 GB region. The C compiler places trampoline code on the stack for sources
* that take the address of a nested C function (a feature used by glibc), so
* the 1 GB requirement applies to the stack as well.
*/
#define TASK_SIZE __XTENSA_UL_CONST(0x40000000)
#define STACK_TOP TASK_SIZE
#define STACK_TOP_MAX STACK_TOP
/*
* General exception cause assigned to debug exceptions. Debug exceptions go
* to their own vector, rather than the general exception vectors (user,
* kernel, double); and their specific causes are reported via DEBUGCAUSE
* rather than EXCCAUSE. However it is sometimes convenient to redirect debug
* exceptions to the general exception mechanism. To do this, an otherwise
* unused EXCCAUSE value was assigned to debug exceptions for this purpose.
*/
#define EXCCAUSE_MAPPED_DEBUG 63
/*
* We use DEPC also as a flag to distinguish between double and regular
* exceptions. For performance reasons, DEPC might contain the value of
* EXCCAUSE for regular exceptions, so we use this definition to mark a
* valid double exception address.
* (Note: We use it in bgeui, so it should be 64, 128, or 256)
*/
#define VALID_DOUBLE_EXCEPTION_ADDRESS 64
/* LOCKLEVEL defines the interrupt level that masks all
* general-purpose interrupts.
*/
#define LOCKLEVEL 1
/* WSBITS and WBBITS are the width of the WINDOWSTART and WINDOWBASE
* registers
*/
#define WSBITS (XCHAL_NUM_AREGS / 4) /* width of WINDOWSTART in bits */
#define WBBITS (XCHAL_NUM_AREGS_LOG2 - 2) /* width of WINDOWBASE in bits */
#ifndef __ASSEMBLY__
/* Build a valid return address for the specified call winsize.
* winsize must be 1 (call4), 2 (call8), or 3 (call12)
*/
#define MAKE_RA_FOR_CALL(ra,ws) (((ra) & 0x3fffffff) | (ws) << 30)
/* Convert return address to a valid pc
* Note: We assume that the stack pointer is in the same 1GB ranges as the ra
*/
#define MAKE_PC_FROM_RA(ra,sp) (((ra) & 0x3fffffff) | ((sp) & 0xc0000000))
typedef struct {
unsigned long seg;
} mm_segment_t;
struct thread_struct {
/* kernel's return address and stack pointer for context switching */
unsigned long ra; /* kernel's a0: return address and window call size */
unsigned long sp; /* kernel's a1: stack pointer */
mm_segment_t current_ds; /* see uaccess.h for example uses */
/* struct xtensa_cpuinfo info; */
unsigned long bad_vaddr; /* last user fault */
unsigned long bad_uaddr; /* last kernel fault accessing user space */
unsigned long error_code;
unsigned long ibreak[XCHAL_NUM_IBREAK];
unsigned long dbreaka[XCHAL_NUM_DBREAK];
unsigned long dbreakc[XCHAL_NUM_DBREAK];
/* Make structure 16 bytes aligned. */
int align[0] __attribute__ ((aligned(16)));
};
/*
* Default implementation of macro that returns current
* instruction pointer ("program counter").
*/
#define current_text_addr() ({ __label__ _l; _l: &&_l;})
/* This decides where the kernel will search for a free chunk of vm
* space during mmap's.
*/
#define TASK_UNMAPPED_BASE (TASK_SIZE / 2)
#define INIT_THREAD \
{ \
ra: 0, \
sp: sizeof(init_stack) + (long) &init_stack, \
current_ds: {0}, \
/*info: {0}, */ \
bad_vaddr: 0, \
bad_uaddr: 0, \
error_code: 0, \
}
/*
* Do necessary setup to start up a newly executed thread.
* Note: We set-up ps as if we did a call4 to the new pc.
* set_thread_state in signal.c depends on it.
*/
#define USER_PS_VALUE ((1 << PS_WOE_BIT) | \
(1 << PS_CALLINC_SHIFT) | \
(USER_RING << PS_RING_SHIFT) | \
(1 << PS_UM_BIT) | \
(1 << PS_EXCM_BIT))
/* Clearing a0 terminates the backtrace. */
#define start_thread(regs, new_pc, new_sp) \
regs->pc = new_pc; \
regs->ps = USER_PS_VALUE; \
regs->areg[1] = new_sp; \
regs->areg[0] = 0; \
regs->wmask = 1; \
regs->depc = 0; \
regs->windowbase = 0; \
regs->windowstart = 1;
/* Forward declaration */
struct task_struct;
struct mm_struct;
/* Free all resources held by a thread. */
#define release_thread(thread) do { } while(0)
/* Prepare to copy thread state - unlazy all lazy status */
extern void prepare_to_copy(struct task_struct*);
/* Create a kernel thread without removing it from tasklists */
extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
/* Copy and release all segment info associated with a VM */
#define copy_segments(p, mm) do { } while(0)
#define release_segments(mm) do { } while(0)
#define forget_segments() do { } while (0)
#define thread_saved_pc(tsk) (task_pt_regs(tsk)->pc)
extern unsigned long get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc)
#define KSTK_ESP(tsk) (task_pt_regs(tsk)->areg[1])
#define cpu_relax() barrier()
/* Special register access. */
#define WSR(v,sr) __asm__ __volatile__ ("wsr %0,"__stringify(sr) :: "a"(v));
#define RSR(v,sr) __asm__ __volatile__ ("rsr %0,"__stringify(sr) : "=a"(v));
#define set_sr(x,sr) ({unsigned int v=(unsigned int)x; WSR(v,sr);})
#define get_sr(sr) ({unsigned int v; RSR(v,sr); v; })
#endif /* __ASSEMBLY__ */
#endif /* _XTENSA_PROCESSOR_H */
View Git Blame Copy Permalink