Module Name: src
Committed By: maxv
Date: Thu Mar 7 13:02:13 UTC 2019
Modified Files:
src/sys/arch/i386/include: pte.h
Log Message:
Style, and remove useless comments.
To generate a diff of this commit:
cvs rdiff -u -r1.27 -r1.28 src/sys/arch/i386/include/pte.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/i386/include/pte.h
diff -u src/sys/arch/i386/include/pte.h:1.27 src/sys/arch/i386/include/pte.h:1.28
--- src/sys/arch/i386/include/pte.h:1.27 Tue Feb 1 20:09:08 2011
+++ src/sys/arch/i386/include/pte.h Thu Mar 7 13:02:13 2019
@@ -1,4 +1,4 @@
-/* $NetBSD: pte.h,v 1.27 2011/02/01 20:09:08 chuck Exp $ */
+/* $NetBSD: pte.h,v 1.28 2019/03/07 13:02:13 maxv Exp $ */
/*
* Copyright (c) 2001 Wasabi Systems, Inc.
@@ -60,14 +60,6 @@
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
-/*
- * pte.h rewritten by chuck based on the jolitz version, plus random
- * info on the pentium and other processors found on the net. the
- * goal of this rewrite is to provide enough documentation on the MMU
- * hardware that the reader will be able to understand it without having
- * to refer to a hardware manual.
- */
-
#ifndef _I386_PTE_H_
#define _I386_PTE_H_
#ifdef _KERNEL_OPT
@@ -75,86 +67,6 @@
#endif
/*
- * i386 MMU hardware structure (without PAE extension):
- *
- * the i386 MMU is a two-level MMU which maps 4GB of virtual memory.
- * the pagesize is 4K (4096 [0x1000] bytes), although newer pentium
- * processors can support a 4MB pagesize as well.
- *
- * the first level table (segment table?) is called a "page directory"
- * and it contains 1024 page directory entries (PDEs). each PDE is
- * 4 bytes (an int), so a PD fits in a single 4K page. this page is
- * the page directory page (PDP). each PDE in a PDP maps 4MB of space
- * (1024 * 4MB = 4GB). a PDE contains the physical address of the
- * second level table: the page table. or, if 4MB pages are being used,
- * then the PDE contains the PA of the 4MB page being mapped.
- *
- * a page table consists of 1024 page table entries (PTEs). each PTE is
- * 4 bytes (an int), so a page table also fits in a single 4K page. a
- * 4K page being used as a page table is called a page table page (PTP).
- * each PTE in a PTP maps one 4K page (1024 * 4K = 4MB). a PTE contains
- * the physical address of the page it maps and some flag bits (described
- * below).
- *
- * the processor has a special register, "cr3", which points to the
- * the PDP which is currently controlling the mappings of the virtual
- * address space.
- *
- * the following picture shows the translation process for a 4K page:
- *
- * %cr3 register [PA of PDP]
- * |
- * |
- * | bits <31-22> of VA bits <21-12> of VA bits <11-0>
- * | index the PDP (0 - 1023) index the PTP are the page offset
- * | | | |
- * | v | |
- * +--->+----------+ | |
- * | PD Page | PA of v |
- * | |---PTP-------->+------------+ |
- * | 1024 PDE | | page table |--PTE--+ |
- * | entries | | (aka PTP) | | |
- * +----------+ | 1024 PTE | | |
- * | entries | | |
- * +------------+ | |
- * | |
- * bits <31-12> bits <11-0>
- * p h y s i c a l a d d r
- *
- * the i386 caches PTEs in a TLB. it is important to flush out old
- * TLB mappings when making a change to a mappings. writing to the
- * %cr3 will flush the entire TLB. newer processors also have an
- * instruction that will invalidate the mapping of a single page (which
- * is useful if you are changing a single mappings because it preserves
- * all the cached TLB entries).
- *
- * as shows, bits 31-12 of the PTE contain PA of the page being mapped.
- * the rest of the PTE is defined as follows:
- * bit# name use
- * 11 n/a available for OS use, hardware ignores it
- * 10 n/a available for OS use, hardware ignores it
- * 9 n/a available for OS use, hardware ignores it
- * 8 G global bit (see discussion below)
- * 7 PS page size [for PDEs] (0=4k, 1=4M <if supported>)
- * 6 D dirty (modified) page
- * 5 A accessed (referenced) page
- * 4 PCD cache disable
- * 3 PWT prevent write through (cache)
- * 2 U/S user/supervisor bit (0=supervisor only, 1=both u&s)
- * 1 R/W read/write bit (0=read only, 1=read-write)
- * 0 P present (valid)
- *
- * notes:
- * - PS is only supported on newer processors
- * - PTEs with the G bit are global in the sense that they are not
- * flushed from the TLB when %cr3 is written (to flush, use the
- * "flush single page" instruction). this is only supported on
- * newer processors. this bit can be used to keep the kernel's
- * TLB entries around while context switching. since the kernel
- * is mapped into all processes at the same place it does not make
- * sense to flush these entries when switching from one process'
- * pmap to another.
- *
* The PAE extension extends the size of the PTE to 64 bits (52bits physical
* address) and is compatible with the amd64 PTE format. The first level
* maps 2M, the second 1G, so a third level page table is introduced to
@@ -162,7 +74,7 @@
* We can't use recursive mapping at level 3 to map the PD pages, as this
* would eat one GB of address space. In addition, Xen imposes restrictions
* on the entries we put in the L3 page (for example, the page pointed to by
- * the last slot can't be shared among different L3 pages), which makes
+ * the last slot can't be shared among different L3 pages), which makes
* handling this L3 page in the same way we do for L2 on i386 (or L4 on amd64)
* difficult. For most things we'll just pretend to have only 2 levels,
* with the 2 high bits of the L2 index being in fact the index in the
@@ -189,24 +101,24 @@ typedef uint32_t pt_entry_t; /* PTE */
*/
#ifdef PAE
-#define L1_SHIFT 12
-#define L2_SHIFT 21
-#define L3_SHIFT 30
-#define NBPD_L1 (1ULL << L1_SHIFT) /* # bytes mapped by L1 ent (4K) */
-#define NBPD_L2 (1ULL << L2_SHIFT) /* # bytes mapped by L2 ent (2MB) */
-#define NBPD_L3 (1ULL << L3_SHIFT) /* # bytes mapped by L3 ent (1GB) */
-
-#define L3_MASK 0xc0000000
-#define L2_REALMASK 0x3fe00000
-#define L2_MASK (L2_REALMASK | L3_MASK)
-#define L1_MASK 0x001ff000
-
-#define L3_FRAME (L3_MASK)
-#define L2_FRAME (L3_FRAME | L2_MASK)
-#define L1_FRAME (L2_FRAME|L1_MASK)
+#define L1_SHIFT 12
+#define L2_SHIFT 21
+#define L3_SHIFT 30
+#define NBPD_L1 (1ULL << L1_SHIFT) /* # bytes mapped by L1 ent (4K) */
+#define NBPD_L2 (1ULL << L2_SHIFT) /* # bytes mapped by L2 ent (2MB) */
+#define NBPD_L3 (1ULL << L3_SHIFT) /* # bytes mapped by L3 ent (1GB) */
+
+#define L3_MASK 0xc0000000
+#define L2_REALMASK 0x3fe00000
+#define L2_MASK (L2_REALMASK | L3_MASK)
+#define L1_MASK 0x001ff000
+
+#define L3_FRAME (L3_MASK)
+#define L2_FRAME (L3_FRAME | L2_MASK)
+#define L1_FRAME (L2_FRAME|L1_MASK)
-#define PG_FRAME 0x000ffffffffff000ULL /* page frame mask */
-#define PG_LGFRAME 0x000fffffffe00000ULL /* large (2MB) page frame mask */
+#define PG_FRAME 0x000ffffffffff000ULL /* page frame mask */
+#define PG_LGFRAME 0x000fffffffe00000ULL /* large (2MB) page frame mask */
/* macros to get real L2 and L3 index, from our "extended" L2 index */
#define l2tol3(idx) ((idx) >> (L3_SHIFT - L2_SHIFT))
@@ -214,10 +126,10 @@ typedef uint32_t pt_entry_t; /* PTE */
#else /* PAE */
-#define L1_SHIFT 12
-#define L2_SHIFT 22
-#define NBPD_L1 (1UL << L1_SHIFT) /* # bytes mapped by L1 ent (4K) */
-#define NBPD_L2 (1UL << L2_SHIFT) /* # bytes mapped by L2 ent (4MB) */
+#define L1_SHIFT 12
+#define L2_SHIFT 22
+#define NBPD_L1 (1UL << L1_SHIFT) /* # bytes mapped by L1 ent (4K) */
+#define NBPD_L2 (1UL << L2_SHIFT) /* # bytes mapped by L2 ent (4MB) */
#define L2_MASK 0xffc00000
#define L1_MASK 0x003ff000
@@ -225,25 +137,25 @@ typedef uint32_t pt_entry_t; /* PTE */
#define L2_FRAME (L2_MASK)
#define L1_FRAME (L2_FRAME|L1_MASK)
-#define PG_FRAME 0xfffff000 /* page frame mask */
-#define PG_LGFRAME 0xffc00000 /* large (4MB) page frame mask */
+#define PG_FRAME 0xfffff000 /* page frame mask */
+#define PG_LGFRAME 0xffc00000 /* large (4MB) page frame mask */
#endif /* PAE */
+
/*
* here we define the bits of the PDE/PTE, as described above:
*
* XXXCDC: need to rename these (PG_u == ugly).
*/
-
-#define PG_V 0x00000001 /* valid entry */
-#define PG_RO 0x00000000 /* read-only page */
-#define PG_RW 0x00000002 /* read-write page */
-#define PG_u 0x00000004 /* user accessible page */
-#define PG_PROT 0x00000806 /* all protection bits */
+#define PG_V 0x00000001 /* valid entry */
+#define PG_RO 0x00000000 /* read-only page */
+#define PG_RW 0x00000002 /* read-write page */
+#define PG_u 0x00000004 /* user accessible page */
+#define PG_PROT 0x00000806 /* all protection bits */
#define PG_WT 0x00000008 /* write through */
-#define PG_N 0x00000010 /* non-cacheable */
-#define PG_U 0x00000020 /* has been used */
-#define PG_M 0x00000040 /* has been modified */
+#define PG_N 0x00000010 /* non-cacheable */
+#define PG_U 0x00000020 /* has been used */
+#define PG_M 0x00000040 /* has been modified */
#define PG_PAT 0x00000080 /* PAT (on pte) */
#define PG_PS 0x00000080 /* 4MB page size (2MB for PAE) */
#define PG_G 0x00000100 /* global, don't TLB flush */
@@ -255,14 +167,13 @@ typedef uint32_t pt_entry_t; /* PTE */
/*
* various short-hand protection codes
*/
-
-#define PG_KR 0x00000000 /* kernel read-only */
-#define PG_KW 0x00000002 /* kernel read-write */
+#define PG_KR 0x00000000 /* kernel read-only */
+#define PG_KW 0x00000002 /* kernel read-write */
#ifdef PAE
-#define PG_NX 0x8000000000000000ULL /* No-execute */
+#define PG_NX 0x8000000000000000ULL /* No-execute */
#else
-#define PG_NX 0 /* dummy */
+#define PG_NX 0 /* dummy */
#endif
#include <x86/pte.h>
