linux/include/asm-powerpc/paca.h
Paul Mackerras bf72aeba2f powerpc: Use 64k pages without needing cache-inhibited large pages
Some POWER5+ machines can do 64k hardware pages for normal memory but
not for cache-inhibited pages.  This patch lets us use 64k hardware
pages for most user processes on such machines (assuming the kernel
has been configured with CONFIG_PPC_64K_PAGES=y).  User processes
start out using 64k pages and get switched to 4k pages if they use any
non-cacheable mappings.

With this, we use 64k pages for the vmalloc region and 4k pages for
the imalloc region.  If anything creates a non-cacheable mapping in
the vmalloc region, the vmalloc region will get switched to 4k pages.
I don't know of any driver other than the DRM that would do this,
though, and these machines don't have AGP.

When a region gets switched from 64k pages to 4k pages, we do not have
to clear out all the 64k HPTEs from the hash table immediately.  We
use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page
was hashed in as a 64k page or a set of 4k pages.  If hash_page is
trying to insert a 4k page for a Linux PTE and it sees that it has
already been inserted as a 64k page, it first invalidates the 64k HPTE
before inserting the 4k HPTE.  The hash invalidation routines also use
the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a
set of 4k HPTEs to remove.  With those two changes, we can tolerate a
mix of 4k and 64k HPTEs in the hash table, and they will all get
removed when the address space is torn down.

Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-06-15 10:45:18 +10:00

109 lines
3.4 KiB
C

/*
* include/asm-powerpc/paca.h
*
* This control block defines the PACA which defines the processor
* specific data for each logical processor on the system.
* There are some pointers defined that are utilized by PLIC.
*
* 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.
*/
#ifndef _ASM_POWERPC_PACA_H
#define _ASM_POWERPC_PACA_H
#ifdef __KERNEL__
#include <linux/config.h>
#include <asm/types.h>
#include <asm/lppaca.h>
#include <asm/mmu.h>
register struct paca_struct *local_paca asm("r13");
#define get_paca() local_paca
#define get_lppaca() (get_paca()->lppaca_ptr)
struct task_struct;
/*
* Defines the layout of the paca.
*
* This structure is not directly accessed by firmware or the service
* processor except for the first two pointers that point to the
* lppaca area and the ItLpRegSave area for this CPU. The lppaca
* object is currently contained within the PACA but it doesn't need
* to be.
*/
struct paca_struct {
/*
* Because hw_cpu_id, unlike other paca fields, is accessed
* routinely from other CPUs (from the IRQ code), we stick to
* read-only (after boot) fields in the first cacheline to
* avoid cacheline bouncing.
*/
/*
* MAGIC: These first two pointers can't be moved - they're
* accessed by the firmware
*/
struct lppaca *lppaca_ptr; /* Pointer to LpPaca for PLIC */
#ifdef CONFIG_PPC_ISERIES
void *reg_save_ptr; /* Pointer to LpRegSave for PLIC */
#endif /* CONFIG_PPC_ISERIES */
/*
* MAGIC: the spinlock functions in arch/powerpc/lib/locks.c
* load lock_token and paca_index with a single lwz
* instruction. They must travel together and be properly
* aligned.
*/
u16 lock_token; /* Constant 0x8000, used in locks */
u16 paca_index; /* Logical processor number */
u64 kernel_toc; /* Kernel TOC address */
u64 stab_real; /* Absolute address of segment table */
u64 stab_addr; /* Virtual address of segment table */
void *emergency_sp; /* pointer to emergency stack */
u64 data_offset; /* per cpu data offset */
s16 hw_cpu_id; /* Physical processor number */
u8 cpu_start; /* At startup, processor spins until */
/* this becomes non-zero. */
/*
* Now, starting in cacheline 2, the exception save areas
*/
/* used for most interrupts/exceptions */
u64 exgen[10] __attribute__((aligned(0x80)));
u64 exmc[10]; /* used for machine checks */
u64 exslb[10]; /* used for SLB/segment table misses
* on the linear mapping */
mm_context_t context;
u16 vmalloc_sllp;
u16 slb_cache[SLB_CACHE_ENTRIES];
u16 slb_cache_ptr;
/*
* then miscellaneous read-write fields
*/
struct task_struct *__current; /* Pointer to current */
u64 kstack; /* Saved Kernel stack addr */
u64 stab_rr; /* stab/slb round-robin counter */
u64 saved_r1; /* r1 save for RTAS calls */
u64 saved_msr; /* MSR saved here by enter_rtas */
u8 proc_enabled; /* irq soft-enable flag */
/* Stuff for accurate time accounting */
u64 user_time; /* accumulated usermode TB ticks */
u64 system_time; /* accumulated system TB ticks */
u64 startpurr; /* PURR/TB value snapshot */
};
extern struct paca_struct paca[];
void setup_boot_paca(void);
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_PACA_H */