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remarkable-linux/include/asm-powerpc/processor.h
Arnd Bergmann ddf5f75a16 [POWERPC] disable floating point exceptions for init 
Floating point exceptions should not be enabled by default,
as this setting impacts the performance on some CPUs, in
particular the Cell BE. Since the bits are inherited from
parent processes, the place to change the default is the
thread struct used for init.

glibc sets this up correctly per thread in its fesetenv
function, so user space should not be impacted by this
setting. None of the other common libc implementations
(uClibc, dietlibc, newlib, klibc) has support for fp
exceptions, so they are unlikely to be hit by this either.

There is a small risk that somebody wrote their own
application that manually sets the fpscr bits instead
of calling fesetenv, without changing the MSR bits as well.
Those programs will break with this change.

It probably makes sense to change glibc in the future
to be more clever about FE bits, so that when running
on a CPU where this is expensive, it disables exceptions
ASAP, while it keeps them enabled on CPUs where running
with exceptions on is cheaper than changing the state
often.

Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-21 15:01:33 +10:00

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#ifndef _ASM_POWERPC_PROCESSOR_H
#define _ASM_POWERPC_PROCESSOR_H
/*
* Copyright (C) 2001 PPC 64 Team, IBM Corp
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <asm/reg.h>
#ifndef __ASSEMBLY__
#include <linux/compiler.h>
#include <asm/ptrace.h>
#include <asm/types.h>
/* We do _not_ want to define new machine types at all, those must die
* in favor of using the device-tree
* -- BenH.
*/
/* PREP sub-platform types see residual.h for these */
#define _PREP_Motorola 0x01 /* motorola prep */
#define _PREP_Firm 0x02 /* firmworks prep */
#define _PREP_IBM 0x00 /* ibm prep */
#define _PREP_Bull 0x03 /* bull prep */
/* CHRP sub-platform types. These are arbitrary */
#define _CHRP_Motorola 0x04 /* motorola chrp, the cobra */
#define _CHRP_IBM 0x05 /* IBM chrp, the longtrail and longtrail 2 */
#define _CHRP_Pegasos 0x06 /* Genesi/bplan's Pegasos and Pegasos2 */
#if defined(__KERNEL__) && defined(CONFIG_PPC32)
extern int _chrp_type;
#ifdef CONFIG_PPC_PREP
/* what kind of prep workstation we are */
extern int _prep_type;
/*
* This is used to identify the board type from a given PReP board
* vendor. Board revision is also made available. This will be moved
* elsewhere soon
*/
extern unsigned char ucBoardRev;
extern unsigned char ucBoardRevMaj, ucBoardRevMin;
#endif /* CONFIG_PPC_PREP */
#ifndef CONFIG_PPC_MULTIPLATFORM
#define _machine 0
#endif /* CONFIG_PPC_MULTIPLATFORM */
#endif /* defined(__KERNEL__) && defined(CONFIG_PPC32) */
/*
* Default implementation of macro that returns current
* instruction pointer ("program counter").
*/
#define current_text_addr() ({ __label__ _l; _l: &&_l;})
/* Macros for adjusting thread priority (hardware multi-threading) */
#define HMT_very_low() asm volatile("or 31,31,31 # very low priority")
#define HMT_low() asm volatile("or 1,1,1 # low priority")
#define HMT_medium_low() asm volatile("or 6,6,6 # medium low priority")
#define HMT_medium() asm volatile("or 2,2,2 # medium priority")
#define HMT_medium_high() asm volatile("or 5,5,5 # medium high priority")
#define HMT_high() asm volatile("or 3,3,3 # high priority")
#ifdef __KERNEL__
extern int have_of;
struct task_struct;
void start_thread(struct pt_regs *regs, unsigned long fdptr, unsigned long sp);
void release_thread(struct task_struct *);
/* Prepare to copy thread state - unlazy all lazy status */
extern void prepare_to_copy(struct task_struct *tsk);
/* Create a new kernel thread. */
extern long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
/* Lazy FPU handling on uni-processor */
extern struct task_struct *last_task_used_math;
extern struct task_struct *last_task_used_altivec;
extern struct task_struct *last_task_used_spe;
#ifdef CONFIG_PPC32
#define TASK_SIZE (CONFIG_TASK_SIZE)
/* This decides where the kernel will search for a free chunk of vm
* space during mmap's.
*/
#define TASK_UNMAPPED_BASE (TASK_SIZE / 8 * 3)
#endif
#ifdef CONFIG_PPC64
/* 64-bit user address space is 44-bits (16TB user VM) */
#define TASK_SIZE_USER64 (0x0000100000000000UL)
/*
* 32-bit user address space is 4GB - 1 page
* (this 1 page is needed so referencing of 0xFFFFFFFF generates EFAULT
*/
#define TASK_SIZE_USER32 (0x0000000100000000UL - (1*PAGE_SIZE))
#define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \
TASK_SIZE_USER32 : TASK_SIZE_USER64)
/* This decides where the kernel will search for a free chunk of vm
* space during mmap's.
*/
#define TASK_UNMAPPED_BASE_USER32 (PAGE_ALIGN(TASK_SIZE_USER32 / 4))
#define TASK_UNMAPPED_BASE_USER64 (PAGE_ALIGN(TASK_SIZE_USER64 / 4))
#define TASK_UNMAPPED_BASE ((test_thread_flag(TIF_32BIT)) ? \
TASK_UNMAPPED_BASE_USER32 : TASK_UNMAPPED_BASE_USER64 )
#endif
typedef struct {
unsigned long seg;
} mm_segment_t;
struct thread_struct {
unsigned long ksp; /* Kernel stack pointer */
#ifdef CONFIG_PPC64
unsigned long ksp_vsid;
#endif
struct pt_regs *regs; /* Pointer to saved register state */
mm_segment_t fs; /* for get_fs() validation */
#ifdef CONFIG_PPC32
void *pgdir; /* root of page-table tree */
signed long last_syscall;
#endif
#if defined(CONFIG_4xx) || defined (CONFIG_BOOKE)
unsigned long dbcr0; /* debug control register values */
unsigned long dbcr1;
#endif
double fpr[32]; /* Complete floating point set */
struct { /* fpr ... fpscr must be contiguous */
unsigned int pad;
unsigned int val; /* Floating point status */
} fpscr;
int fpexc_mode; /* floating-point exception mode */
unsigned int align_ctl; /* alignment handling control */
#ifdef CONFIG_PPC64
unsigned long start_tb; /* Start purr when proc switched in */
unsigned long accum_tb; /* Total accumilated purr for process */
#endif
unsigned long dabr; /* Data address breakpoint register */
#ifdef CONFIG_ALTIVEC
/* Complete AltiVec register set */
vector128 vr[32] __attribute((aligned(16)));
/* AltiVec status */
vector128 vscr __attribute((aligned(16)));
unsigned long vrsave;
int used_vr; /* set if process has used altivec */
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
unsigned long evr[32]; /* upper 32-bits of SPE regs */
u64 acc; /* Accumulator */
unsigned long spefscr; /* SPE & eFP status */
int used_spe; /* set if process has used spe */
#endif /* CONFIG_SPE */
};
#define ARCH_MIN_TASKALIGN 16
#define INIT_SP (sizeof(init_stack) + (unsigned long) &init_stack)
#ifdef CONFIG_PPC32
#define INIT_THREAD { \
.ksp = INIT_SP, \
.fs = KERNEL_DS, \
.pgdir = swapper_pg_dir, \
.fpexc_mode = MSR_FE0 | MSR_FE1, \
}
#else
#define INIT_THREAD { \
.ksp = INIT_SP, \
.regs = (struct pt_regs *)INIT_SP - 1, /* XXX bogus, I think */ \
.fs = KERNEL_DS, \
.fpr = {0}, \
.fpscr = { .val = 0, }, \
.fpexc_mode = 0, \
}
#endif
/*
* Return saved PC of a blocked thread. For now, this is the "user" PC
*/
#define thread_saved_pc(tsk) \
((tsk)->thread.regs? (tsk)->thread.regs->nip: 0)
unsigned long get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) ((tsk)->thread.regs? (tsk)->thread.regs->nip: 0)
#define KSTK_ESP(tsk) ((tsk)->thread.regs? (tsk)->thread.regs->gpr[1]: 0)
/* Get/set floating-point exception mode */
#define GET_FPEXC_CTL(tsk, adr) get_fpexc_mode((tsk), (adr))
#define SET_FPEXC_CTL(tsk, val) set_fpexc_mode((tsk), (val))
extern int get_fpexc_mode(struct task_struct *tsk, unsigned long adr);
extern int set_fpexc_mode(struct task_struct *tsk, unsigned int val);
#define GET_ENDIAN(tsk, adr) get_endian((tsk), (adr))
#define SET_ENDIAN(tsk, val) set_endian((tsk), (val))
extern int get_endian(struct task_struct *tsk, unsigned long adr);
extern int set_endian(struct task_struct *tsk, unsigned int val);
#define GET_UNALIGN_CTL(tsk, adr) get_unalign_ctl((tsk), (adr))
#define SET_UNALIGN_CTL(tsk, val) set_unalign_ctl((tsk), (val))
extern int get_unalign_ctl(struct task_struct *tsk, unsigned long adr);
extern int set_unalign_ctl(struct task_struct *tsk, unsigned int val);
static inline unsigned int __unpack_fe01(unsigned long msr_bits)
{
return ((msr_bits & MSR_FE0) >> 10) | ((msr_bits & MSR_FE1) >> 8);
}
static inline unsigned long __pack_fe01(unsigned int fpmode)
{
return ((fpmode << 10) & MSR_FE0) | ((fpmode << 8) & MSR_FE1);
}
#ifdef CONFIG_PPC64
#define cpu_relax() do { HMT_low(); HMT_medium(); barrier(); } while (0)
#else
#define cpu_relax() barrier()
#endif
/* Check that a certain kernel stack pointer is valid in task_struct p */
int validate_sp(unsigned long sp, struct task_struct *p,
unsigned long nbytes);
/*
* Prefetch macros.
*/
#define ARCH_HAS_PREFETCH
#define ARCH_HAS_PREFETCHW
#define ARCH_HAS_SPINLOCK_PREFETCH
static inline void prefetch(const void *x)
{
if (unlikely(!x))
return;
__asm__ __volatile__ ("dcbt 0,%0" : : "r" (x));
}
static inline void prefetchw(const void *x)
{
if (unlikely(!x))
return;
__asm__ __volatile__ ("dcbtst 0,%0" : : "r" (x));
}
#define spin_lock_prefetch(x) prefetchw(x)
#ifdef CONFIG_PPC64
#define HAVE_ARCH_PICK_MMAP_LAYOUT
#endif
#endif /* __KERNEL__ */
#endif /* __ASSEMBLY__ */
#endif /* _ASM_POWERPC_PROCESSOR_H */
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