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powerpc/mm: Split the various pgtable-* headers based on MMU type
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This patch moves the definition of the PTE format for each MMU type
to separate files instead of all in one file. This improves overall
maintainability and will make it easier to add new types.

On 64-bit, additionally, I've separated the headers relative to the
format of the page table tree (3 vs. 4 levels for 64K vs 4K pages)
from the headers specific to the PTE format for hash based processors,
this will make it easier to add support for Book3 "E" 64-bit
implementations.

There are still some type-related ifdef's in the generic headers,
we might remove them in the long run, but this patch shouldn't result
in any code change, -hopefully- just definitions being moved around.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Benjamin Herrenschmidt committed Mar 20, 2009
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319 changes: 21 additions & 298 deletions arch/powerpc/include/asm/pgtable-ppc32.h
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Original file line number Diff line number Diff line change
Expand Up @@ -18,55 +18,6 @@ extern int icache_44x_need_flush;

#endif /* __ASSEMBLY__ */

/*
* The PowerPC MMU uses a hash table containing PTEs, together with
* a set of 16 segment registers (on 32-bit implementations), to define
* the virtual to physical address mapping.
*
* We use the hash table as an extended TLB, i.e. a cache of currently
* active mappings. We maintain a two-level page table tree, much
* like that used by the i386, for the sake of the Linux memory
* management code. Low-level assembler code in hashtable.S
* (procedure hash_page) is responsible for extracting ptes from the
* tree and putting them into the hash table when necessary, and
* updating the accessed and modified bits in the page table tree.
*/

/*
* The PowerPC MPC8xx uses a TLB with hardware assisted, software tablewalk.
* We also use the two level tables, but we can put the real bits in them
* needed for the TLB and tablewalk. These definitions require Mx_CTR.PPM = 0,
* Mx_CTR.PPCS = 0, and MD_CTR.TWAM = 1. The level 2 descriptor has
* additional page protection (when Mx_CTR.PPCS = 1) that allows TLB hit
* based upon user/super access. The TLB does not have accessed nor write
* protect. We assume that if the TLB get loaded with an entry it is
* accessed, and overload the changed bit for write protect. We use
* two bits in the software pte that are supposed to be set to zero in
* the TLB entry (24 and 25) for these indicators. Although the level 1
* descriptor contains the guarded and writethrough/copyback bits, we can
* set these at the page level since they get copied from the Mx_TWC
* register when the TLB entry is loaded. We will use bit 27 for guard, since
* that is where it exists in the MD_TWC, and bit 26 for writethrough.
* These will get masked from the level 2 descriptor at TLB load time, and
* copied to the MD_TWC before it gets loaded.
* Large page sizes added. We currently support two sizes, 4K and 8M.
* This also allows a TLB hander optimization because we can directly
* load the PMD into MD_TWC. The 8M pages are only used for kernel
* mapping of well known areas. The PMD (PGD) entries contain control
* flags in addition to the address, so care must be taken that the
* software no longer assumes these are only pointers.
*/

/*
* At present, all PowerPC 400-class processors share a similar TLB
* architecture. The instruction and data sides share a unified,
* 64-entry, fully-associative TLB which is maintained totally under
* software control. In addition, the instruction side has a
* hardware-managed, 4-entry, fully-associative TLB which serves as a
* first level to the shared TLB. These two TLBs are known as the UTLB
* and ITLB, respectively (see "mmu.h" for definitions).
*/

/*
* The normal case is that PTEs are 32-bits and we have a 1-page
* 1024-entry pgdir pointing to 1-page 1024-entry PTE pages. -- paulus
Expand Down Expand Up @@ -135,261 +86,25 @@ extern int icache_44x_need_flush;
*/

#if defined(CONFIG_40x)

/* There are several potential gotchas here. The 40x hardware TLBLO
field looks like this:
0 1 2 3 4 ... 18 19 20 21 22 23 24 25 26 27 28 29 30 31
RPN..................... 0 0 EX WR ZSEL....... W I M G
Where possible we make the Linux PTE bits match up with this
- bits 20 and 21 must be cleared, because we use 4k pages (40x can
support down to 1k pages), this is done in the TLBMiss exception
handler.
- We use only zones 0 (for kernel pages) and 1 (for user pages)
of the 16 available. Bit 24-26 of the TLB are cleared in the TLB
miss handler. Bit 27 is PAGE_USER, thus selecting the correct
zone.
- PRESENT *must* be in the bottom two bits because swap cache
entries use the top 30 bits. Because 40x doesn't support SMP
anyway, M is irrelevant so we borrow it for PAGE_PRESENT. Bit 30
is cleared in the TLB miss handler before the TLB entry is loaded.
- All other bits of the PTE are loaded into TLBLO without
modification, leaving us only the bits 20, 21, 24, 25, 26, 30 for
software PTE bits. We actually use use bits 21, 24, 25, and
30 respectively for the software bits: ACCESSED, DIRTY, RW, and
PRESENT.
*/

/* Definitions for 40x embedded chips. */
#define _PAGE_GUARDED 0x001 /* G: page is guarded from prefetch */
#define _PAGE_FILE 0x001 /* when !present: nonlinear file mapping */
#define _PAGE_PRESENT 0x002 /* software: PTE contains a translation */
#define _PAGE_NO_CACHE 0x004 /* I: caching is inhibited */
#define _PAGE_WRITETHRU 0x008 /* W: caching is write-through */
#define _PAGE_USER 0x010 /* matches one of the zone permission bits */
#define _PAGE_RW 0x040 /* software: Writes permitted */
#define _PAGE_DIRTY 0x080 /* software: dirty page */
#define _PAGE_HWWRITE 0x100 /* hardware: Dirty & RW, set in exception */
#define _PAGE_HWEXEC 0x200 /* hardware: EX permission */
#define _PAGE_ACCESSED 0x400 /* software: R: page referenced */

#define _PMD_PRESENT 0x400 /* PMD points to page of PTEs */
#define _PMD_BAD 0x802
#define _PMD_SIZE 0x0e0 /* size field, != 0 for large-page PMD entry */
#define _PMD_SIZE_4M 0x0c0
#define _PMD_SIZE_16M 0x0e0
#define PMD_PAGE_SIZE(pmdval) (1024 << (((pmdval) & _PMD_SIZE) >> 4))

/* Until my rework is finished, 40x still needs atomic PTE updates */
#define PTE_ATOMIC_UPDATES 1

#include <asm/pte-40x.h>
#elif defined(CONFIG_44x)
/*
* Definitions for PPC440
*
* Because of the 3 word TLB entries to support 36-bit addressing,
* the attribute are difficult to map in such a fashion that they
* are easily loaded during exception processing. I decided to
* organize the entry so the ERPN is the only portion in the
* upper word of the PTE and the attribute bits below are packed
* in as sensibly as they can be in the area below a 4KB page size
* oriented RPN. This at least makes it easy to load the RPN and
* ERPN fields in the TLB. -Matt
*
* Note that these bits preclude future use of a page size
* less than 4KB.
*
*
* PPC 440 core has following TLB attribute fields;
*
* TLB1:
* 0 1 2 3 4 ... 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
* RPN................................. - - - - - - ERPN.......
*
* TLB2:
* 0 1 2 3 4 ... 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
* - - - - - - U0 U1 U2 U3 W I M G E - UX UW UR SX SW SR
*
* Newer 440 cores (440x6 as used on AMCC 460EX/460GT) have additional
* TLB2 storage attibute fields. Those are:
*
* TLB2:
* 0...10 11 12 13 14 15 16...31
* no change WL1 IL1I IL1D IL2I IL2D no change
*
* There are some constrains and options, to decide mapping software bits
* into TLB entry.
*
* - PRESENT *must* be in the bottom three bits because swap cache
* entries use the top 29 bits for TLB2.
*
* - FILE *must* be in the bottom three bits because swap cache
* entries use the top 29 bits for TLB2.
*
* - CACHE COHERENT bit (M) has no effect on original PPC440 cores,
* because it doesn't support SMP. However, some later 460 variants
* have -some- form of SMP support and so I keep the bit there for
* future use
*
* With the PPC 44x Linux implementation, the 0-11th LSBs of the PTE are used
* for memory protection related functions (see PTE structure in
* include/asm-ppc/mmu.h). The _PAGE_XXX definitions in this file map to the
* above bits. Note that the bit values are CPU specific, not architecture
* specific.
*
* The kernel PTE entry holds an arch-dependent swp_entry structure under
* certain situations. In other words, in such situations some portion of
* the PTE bits are used as a swp_entry. In the PPC implementation, the
* 3-24th LSB are shared with swp_entry, however the 0-2nd three LSB still
* hold protection values. That means the three protection bits are
* reserved for both PTE and SWAP entry at the most significant three
* LSBs.
*
* There are three protection bits available for SWAP entry:
* _PAGE_PRESENT
* _PAGE_FILE
* _PAGE_HASHPTE (if HW has)
*
* So those three bits have to be inside of 0-2nd LSB of PTE.
*
*/

#define _PAGE_PRESENT 0x00000001 /* S: PTE valid */
#define _PAGE_RW 0x00000002 /* S: Write permission */
#define _PAGE_FILE 0x00000004 /* S: nonlinear file mapping */
#define _PAGE_HWEXEC 0x00000004 /* H: Execute permission */
#define _PAGE_ACCESSED 0x00000008 /* S: Page referenced */
#define _PAGE_DIRTY 0x00000010 /* S: Page dirty */
#define _PAGE_SPECIAL 0x00000020 /* S: Special page */
#define _PAGE_USER 0x00000040 /* S: User page */
#define _PAGE_ENDIAN 0x00000080 /* H: E bit */
#define _PAGE_GUARDED 0x00000100 /* H: G bit */
#define _PAGE_COHERENT 0x00000200 /* H: M bit */
#define _PAGE_NO_CACHE 0x00000400 /* H: I bit */
#define _PAGE_WRITETHRU 0x00000800 /* H: W bit */

/* TODO: Add large page lowmem mapping support */
#define _PMD_PRESENT 0
#define _PMD_PRESENT_MASK (PAGE_MASK)
#define _PMD_BAD (~PAGE_MASK)

/* ERPN in a PTE never gets cleared, ignore it */
#define _PTE_NONE_MASK 0xffffffff00000000ULL

#define __HAVE_ARCH_PTE_SPECIAL

#include <asm/pte-44x.h>
#elif defined(CONFIG_FSL_BOOKE)
/*
MMU Assist Register 3:
32 33 34 35 36 ... 50 51 52 53 54 55 56 57 58 59 60 61 62 63
RPN...................... 0 0 U0 U1 U2 U3 UX SX UW SW UR SR
- PRESENT *must* be in the bottom three bits because swap cache
entries use the top 29 bits.
- FILE *must* be in the bottom three bits because swap cache
entries use the top 29 bits.
*/

/* Definitions for FSL Book-E Cores */
#define _PAGE_PRESENT 0x00001 /* S: PTE contains a translation */
#define _PAGE_USER 0x00002 /* S: User page (maps to UR) */
#define _PAGE_FILE 0x00002 /* S: when !present: nonlinear file mapping */
#define _PAGE_RW 0x00004 /* S: Write permission (SW) */
#define _PAGE_DIRTY 0x00008 /* S: Page dirty */
#define _PAGE_HWEXEC 0x00010 /* H: SX permission */
#define _PAGE_ACCESSED 0x00020 /* S: Page referenced */

#define _PAGE_ENDIAN 0x00040 /* H: E bit */
#define _PAGE_GUARDED 0x00080 /* H: G bit */
#define _PAGE_COHERENT 0x00100 /* H: M bit */
#define _PAGE_NO_CACHE 0x00200 /* H: I bit */
#define _PAGE_WRITETHRU 0x00400 /* H: W bit */
#define _PAGE_SPECIAL 0x00800 /* S: Special page */

#ifdef CONFIG_PTE_64BIT
/* ERPN in a PTE never gets cleared, ignore it */
#define _PTE_NONE_MASK 0xffffffffffff0000ULL
#endif

#define _PMD_PRESENT 0
#define _PMD_PRESENT_MASK (PAGE_MASK)
#define _PMD_BAD (~PAGE_MASK)

#define __HAVE_ARCH_PTE_SPECIAL

#include <asm/pte-fsl-booke.h>
#elif defined(CONFIG_8xx)
/* Definitions for 8xx embedded chips. */
#define _PAGE_PRESENT 0x0001 /* Page is valid */
#define _PAGE_FILE 0x0002 /* when !present: nonlinear file mapping */
#define _PAGE_NO_CACHE 0x0002 /* I: cache inhibit */
#define _PAGE_SHARED 0x0004 /* No ASID (context) compare */

/* These five software bits must be masked out when the entry is loaded
* into the TLB.
*/
#define _PAGE_EXEC 0x0008 /* software: i-cache coherency required */
#define _PAGE_GUARDED 0x0010 /* software: guarded access */
#define _PAGE_DIRTY 0x0020 /* software: page changed */
#define _PAGE_RW 0x0040 /* software: user write access allowed */
#define _PAGE_ACCESSED 0x0080 /* software: page referenced */

/* Setting any bits in the nibble with the follow two controls will
* require a TLB exception handler change. It is assumed unused bits
* are always zero.
*/
#define _PAGE_HWWRITE 0x0100 /* h/w write enable: never set in Linux PTE */
#define _PAGE_USER 0x0800 /* One of the PP bits, the other is USER&~RW */

#define _PMD_PRESENT 0x0001
#define _PMD_BAD 0x0ff0
#define _PMD_PAGE_MASK 0x000c
#define _PMD_PAGE_8M 0x000c

#define _PTE_NONE_MASK _PAGE_ACCESSED

/* Until my rework is finished, 8xx still needs atomic PTE updates */
#define PTE_ATOMIC_UPDATES 1

#include <asm/pte-8xx.h>
#else /* CONFIG_6xx */
/* Definitions for 60x, 740/750, etc. */
#define _PAGE_PRESENT 0x001 /* software: pte contains a translation */
#define _PAGE_HASHPTE 0x002 /* hash_page has made an HPTE for this pte */
#define _PAGE_FILE 0x004 /* when !present: nonlinear file mapping */
#define _PAGE_USER 0x004 /* usermode access allowed */
#define _PAGE_GUARDED 0x008 /* G: prohibit speculative access */
#define _PAGE_COHERENT 0x010 /* M: enforce memory coherence (SMP systems) */
#define _PAGE_NO_CACHE 0x020 /* I: cache inhibit */
#define _PAGE_WRITETHRU 0x040 /* W: cache write-through */
#define _PAGE_DIRTY 0x080 /* C: page changed */
#define _PAGE_ACCESSED 0x100 /* R: page referenced */
#define _PAGE_EXEC 0x200 /* software: i-cache coherency required */
#define _PAGE_RW 0x400 /* software: user write access allowed */
#define _PAGE_SPECIAL 0x800 /* software: Special page */

#ifdef CONFIG_PTE_64BIT
/* We never clear the high word of the pte */
#define _PTE_NONE_MASK (0xffffffff00000000ULL | _PAGE_HASHPTE)
#else
#define _PTE_NONE_MASK _PAGE_HASHPTE
#include <asm/pte-hash32.h>
#endif

#define _PMD_PRESENT 0
#define _PMD_PRESENT_MASK (PAGE_MASK)
#define _PMD_BAD (~PAGE_MASK)

/* Hash table based platforms need atomic updates of the linux PTE */
#define PTE_ATOMIC_UPDATES 1

/* If _PAGE_SPECIAL is defined, then we advertise our support for it */
#ifdef _PAGE_SPECIAL
#define __HAVE_ARCH_PTE_SPECIAL

#endif

/*
* Some bits are only used on some cpu families...
* Some bits are only used on some cpu families... Make sure that all
* the undefined gets defined as 0
*/
#ifndef _PAGE_HASHPTE
#define _PAGE_HASHPTE 0
Expand Down Expand Up @@ -600,11 +315,19 @@ extern void flush_hash_entry(struct mm_struct *mm, pte_t *ptep,
unsigned long address);

/*
* Atomic PTE updates.
* PTE updates. This function is called whenever an existing
* valid PTE is updated. This does -not- include set_pte_at()
* which nowadays only sets a new PTE.
*
* Depending on the type of MMU, we may need to use atomic updates
* and the PTE may be either 32 or 64 bit wide. In the later case,
* when using atomic updates, only the low part of the PTE is
* accessed atomically.
*
* pte_update clears and sets bit atomically, and returns
* the old pte value. In the 64-bit PTE case we lock around the
* low PTE word since we expect ALL flag bits to be there
* In addition, on 44x, we also maintain a global flag indicating
* that an executable user mapping was modified, which is needed
* to properly flush the virtually tagged instruction cache of
* those implementations.
*/
#ifndef CONFIG_PTE_64BIT
static inline unsigned long pte_update(pte_t *p,
Expand Down
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