[Xen-devel] [patch 03/20] XEN-paravirt: paravirt: page-table accessors

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

Add a set of accessors to pack, unpack and modify page table entries
(at all levels).  This allows a paravirt implementation to control the
contents of pgd/pmd/pte entries.  For example, Xen uses this to
convert the (pseudo-)physical address into a machine address when
populating a pagetable entry, and converting back to pphys address
when an entry is read.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Cc: Chris Wright <chris@xxxxxxxxxxxx>
Cc: Zachary Amsden <zach@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>

--
 arch/i386/kernel/paravirt.c       |  113 +++++++++++++++++++++++++++++++++----
 arch/i386/kernel/vmlinux.lds.S    |    3 
 include/asm-i386/page.h           |   18 ++++-
 include/asm-i386/paravirt.h       |   68 +++++++++++++++++++++-
 include/asm-i386/pgtable-2level.h |    5 -
 include/asm-i386/pgtable-3level.h |   27 ++++----
 6 files changed, 199 insertions(+), 35 deletions(-)

===================================================================
--- a/arch/i386/kernel/paravirt.c
+++ b/arch/i386/kernel/paravirt.c
@@ -34,7 +34,7 @@
 #include <asm/tlbflush.h>
 
 /* nop stub */
-static void native_nop(void)
+void native_nop(void)
 {
 }
 
@@ -400,38 +400,74 @@ static fastcall void native_flush_tlb_si
 }
 
 #ifndef CONFIG_X86_PAE
-static fastcall void native_set_pte(pte_t *ptep, pte_t pteval)
+fastcall void native_set_pte(pte_t *ptep, pte_t pteval)
 {
        *ptep = pteval;
 }
 
-static fastcall void native_set_pte_at(struct mm_struct *mm, u32 addr, pte_t 
*ptep, pte_t pteval)
+fastcall void native_set_pte_at(struct mm_struct *mm, u32 addr, pte_t *ptep, 
pte_t pteval)
 {
        *ptep = pteval;
 }
 
-static fastcall void native_set_pmd(pmd_t *pmdp, pmd_t pmdval)
+fastcall void native_set_pmd(pmd_t *pmdp, pmd_t pmdval)
 {
        *pmdp = pmdval;
 }
 
+fastcall unsigned long native_pte_val(pte_t pte)
+{
+       return pte.pte_low;
+}
+
+fastcall unsigned long native_pmd_val(pmd_t pmd)
+{
+       BUG();
+       return 0;
+}
+
+fastcall unsigned long native_pgd_val(pgd_t pgd)
+{
+       return pgd.pgd;
+}
+
+fastcall pte_t native_make_pte(unsigned long pte)
+{
+       return (pte_t){ pte };
+}
+
+fastcall pmd_t native_make_pmd(unsigned long pmd)
+{
+       BUG();
+}
+
+fastcall pgd_t native_make_pgd(unsigned long pgd)
+{
+       return (pgd_t){ pgd };
+}
+
+fastcall pte_t native_ptep_get_and_clear(pte_t *ptep)
+{
+       return __pte(xchg(&(ptep)->pte_low, 0));
+}
+
 #else /* CONFIG_X86_PAE */
 
-static fastcall void native_set_pte(pte_t *ptep, pte_t pte)
+fastcall void native_set_pte(pte_t *ptep, pte_t pte)
 {
        ptep->pte_high = pte.pte_high;
        smp_wmb();
        ptep->pte_low = pte.pte_low;
 }
 
-static fastcall void native_set_pte_at(struct mm_struct *mm, u32 addr, pte_t 
*ptep, pte_t pte)
+fastcall void native_set_pte_at(struct mm_struct *mm, u32 addr, pte_t *ptep, 
pte_t pte)
 {
        ptep->pte_high = pte.pte_high;
        smp_wmb();
        ptep->pte_low = pte.pte_low;
 }
 
-static fastcall void native_set_pte_present(struct mm_struct *mm, unsigned 
long addr, pte_t *ptep, pte_t pte)
+fastcall void native_set_pte_present(struct mm_struct *mm, u32 addr, pte_t 
*ptep, pte_t pte)
 {
        ptep->pte_low = 0;
        smp_wmb();
@@ -440,34 +476,76 @@ static fastcall void native_set_pte_pres
        ptep->pte_low = pte.pte_low;
 }
 
-static fastcall void native_set_pte_atomic(pte_t *ptep, pte_t pteval)
+fastcall void native_set_pte_atomic(pte_t *ptep, pte_t pteval)
 {
        set_64bit((unsigned long long *)ptep,pte_val(pteval));
 }
 
-static fastcall void native_set_pmd(pmd_t *pmdp, pmd_t pmdval)
+fastcall void native_set_pmd(pmd_t *pmdp, pmd_t pmdval)
 {
        set_64bit((unsigned long long *)pmdp,pmd_val(pmdval));
 }
 
-static fastcall void native_set_pud(pud_t *pudp, pud_t pudval)
+fastcall void native_set_pud(pud_t *pudp, pud_t pudval)
 {
        *pudp = pudval;
 }
 
-static fastcall void native_pte_clear(struct mm_struct *mm, unsigned long 
addr, pte_t *ptep)
+fastcall void native_pte_clear(struct mm_struct *mm, u32 addr, pte_t *ptep)
 {
        ptep->pte_low = 0;
        smp_wmb();
        ptep->pte_high = 0;
 }
 
-static fastcall void native_pmd_clear(pmd_t *pmd)
+fastcall void native_pmd_clear(pmd_t *pmd)
 {
        u32 *tmp = (u32 *)pmd;
        *tmp = 0;
        smp_wmb();
        *(tmp + 1) = 0;
+}
+
+fastcall unsigned long long native_pte_val(pte_t pte)
+{
+       return pte.pte_low | ((unsigned long long)pte.pte_high << 32);
+}
+
+fastcall unsigned long long native_pmd_val(pmd_t pmd)
+{
+       return pmd.pmd;
+}
+
+fastcall unsigned long long native_pgd_val(pgd_t pgd)
+{
+       return pgd.pgd;
+}
+
+fastcall pte_t native_make_pte(unsigned long long pte)
+{
+       return (pte_t){ pte };
+}
+
+fastcall pmd_t native_make_pmd(unsigned long long pmd)
+{
+       return (pmd_t){ pmd };
+}
+
+fastcall pgd_t native_make_pgd(unsigned long long pgd)
+{
+       return (pgd_t){ pgd };
+}
+
+fastcall pte_t native_ptep_get_and_clear(pte_t *ptep)
+{
+       pte_t res;
+
+       /* xchg acts as a barrier before the setting of the high bits */
+       res.pte_low = xchg(&ptep->pte_low, 0);
+       res.pte_high = ptep->pte_high;
+       ptep->pte_high = 0;
+
+       return res;
 }
 #endif /* CONFIG_X86_PAE */
 
@@ -564,6 +642,9 @@ struct paravirt_ops paravirt_ops = {
        .set_pmd = native_set_pmd,
        .pte_update = (void *)native_nop,
        .pte_update_defer = (void *)native_nop,
+
+       .ptep_get_and_clear = native_ptep_get_and_clear,
+
 #ifdef CONFIG_X86_PAE
        .set_pte_atomic = native_set_pte_atomic,
        .set_pte_present = native_set_pte_present,
@@ -572,6 +653,14 @@ struct paravirt_ops paravirt_ops = {
        .pmd_clear = native_pmd_clear,
 #endif
 
+       .pte_val = native_pte_val,
+       .pmd_val = native_pmd_val,
+       .pgd_val = native_pgd_val,
+
+       .make_pte = native_make_pte,
+       .make_pmd = native_make_pmd,
+       .make_pgd = native_make_pgd,
+
        .irq_enable_sysexit = native_irq_enable_sysexit,
        .iret = native_iret,
 
===================================================================
--- a/arch/i386/kernel/vmlinux.lds.S
+++ b/arch/i386/kernel/vmlinux.lds.S
@@ -21,6 +21,9 @@
 #include <asm/page.h>
 #include <asm/cache.h>
 #include <asm/boot.h>
+
+#undef ENTRY
+#undef ALIGN
 
 OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
 OUTPUT_ARCH(i386)
===================================================================
--- a/include/asm-i386/page.h
+++ b/include/asm-i386/page.h
@@ -11,7 +11,6 @@
 
 #ifdef __KERNEL__
 #ifndef __ASSEMBLY__
-
 
 #ifdef CONFIG_X86_USE_3DNOW
 
@@ -48,9 +47,11 @@ typedef struct { unsigned long long pmd;
 typedef struct { unsigned long long pmd; } pmd_t;
 typedef struct { unsigned long long pgd; } pgd_t;
 typedef struct { unsigned long long pgprot; } pgprot_t;
+#ifndef CONFIG_PARAVIRT
 #define pmd_val(x)     ((x).pmd)
 #define pte_val(x)     ((x).pte_low | ((unsigned long long)(x).pte_high << 32))
 #define __pmd(x) ((pmd_t) { (x) } )
+#endif /* CONFIG_PARAVIRT */
 #define HPAGE_SHIFT    21
 #include <asm-generic/pgtable-nopud.h>
 #else
@@ -58,7 +59,9 @@ typedef struct { unsigned long pgd; } pg
 typedef struct { unsigned long pgd; } pgd_t;
 typedef struct { unsigned long pgprot; } pgprot_t;
 #define boot_pte_t pte_t /* or would you rather have a typedef */
+#ifndef CONFIG_PARAVIRT
 #define pte_val(x)     ((x).pte_low)
+#endif
 #define HPAGE_SHIFT    22
 #include <asm-generic/pgtable-nopmd.h>
 #endif
@@ -71,12 +74,14 @@ typedef struct { unsigned long pgprot; }
 #define HAVE_ARCH_HUGETLB_UNMAPPED_AREA
 #endif
 
+#define pgprot_val(x)  ((x).pgprot)
+#define __pgprot(x)    ((pgprot_t) { (x) } )
+
+#ifndef CONFIG_PARAVIRT
 #define pgd_val(x)     ((x).pgd)
-#define pgprot_val(x)  ((x).pgprot)
-
 #define __pte(x) ((pte_t) { (x) } )
 #define __pgd(x) ((pgd_t) { (x) } )
-#define __pgprot(x)    ((pgprot_t) { (x) } )
+#endif
 
 #endif /* !__ASSEMBLY__ */
 
@@ -143,6 +148,11 @@ extern int page_is_ram(unsigned long pag
 #include <asm-generic/memory_model.h>
 #include <asm-generic/page.h>
 
+#ifdef CONFIG_PARAVIRT
+/* After pte_t, etc, have been defined */
+#include <asm/paravirt.h>
+#endif
+
 #define __HAVE_ARCH_GATE_AREA 1
 #endif /* __KERNEL__ */
 
===================================================================
--- a/include/asm-i386/paravirt.h
+++ b/include/asm-i386/paravirt.h
@@ -25,6 +25,8 @@
 #define CLBR_ANY 0x7
 
 #ifndef __ASSEMBLY__
+#include <linux/types.h>
+
 struct thread_struct;
 struct Xgt_desc_struct;
 struct tss_struct;
@@ -140,12 +142,31 @@ struct paravirt_ops
        void (fastcall *set_pmd)(pmd_t *pmdp, pmd_t pmdval);
        void (fastcall *pte_update)(struct mm_struct *mm, u32 addr, pte_t 
*ptep);
        void (fastcall *pte_update_defer)(struct mm_struct *mm, u32 addr, pte_t 
*ptep);
+
+       pte_t (fastcall *ptep_get_and_clear)(pte_t *ptep);
+
 #ifdef CONFIG_X86_PAE
        void (fastcall *set_pte_atomic)(pte_t *ptep, pte_t pteval);
-       void (fastcall *set_pte_present)(struct mm_struct *mm, unsigned long 
addr, pte_t *ptep, pte_t pte);
+       void (fastcall *set_pte_present)(struct mm_struct *mm, u32 addr, pte_t 
*ptep, pte_t pte);
        void (fastcall *set_pud)(pud_t *pudp, pud_t pudval);
-       void (fastcall *pte_clear)(struct mm_struct *mm, unsigned long addr, 
pte_t *ptep);
+       void (fastcall *pte_clear)(struct mm_struct *mm, u32 addr, pte_t *ptep);
        void (fastcall *pmd_clear)(pmd_t *pmdp);
+
+       unsigned long long (fastcall *pte_val)(pte_t);
+       unsigned long long (fastcall *pmd_val)(pmd_t);
+       unsigned long long (fastcall *pgd_val)(pgd_t);
+
+       pte_t (fastcall *make_pte)(unsigned long long pte);
+       pmd_t (fastcall *make_pmd)(unsigned long long pmd);
+       pgd_t (fastcall *make_pgd)(unsigned long long pgd);
+#else  /* !CONFIG_X86_PAE */
+       unsigned long (fastcall *pte_val)(pte_t);
+       unsigned long (fastcall *pmd_val)(pmd_t);
+       unsigned long (fastcall *pgd_val)(pgd_t);
+
+       pte_t (fastcall *make_pte)(unsigned long pte);
+       pmd_t (fastcall *make_pmd)(unsigned long pmd);
+       pgd_t (fastcall *make_pgd)(unsigned long pgd);
 #endif
 
        void (fastcall *set_lazy_mode)(int mode);
@@ -163,6 +184,24 @@ struct paravirt_ops
                __attribute__((__section__(".paravirtprobe"))) = fn
 
 extern struct paravirt_ops paravirt_ops;
+
+#ifdef CONFIG_X86_PAE
+fastcall unsigned long long native_pte_val(pte_t);
+fastcall unsigned long long native_pmd_val(pmd_t);
+fastcall unsigned long long native_pgd_val(pgd_t);
+
+fastcall pte_t native_make_pte(unsigned long long pte);
+fastcall pmd_t native_make_pmd(unsigned long long pmd);
+fastcall pgd_t native_make_pgd(unsigned long long pgd);
+#else
+fastcall unsigned long native_pte_val(pte_t);
+fastcall unsigned long native_pmd_val(pmd_t);
+fastcall unsigned long native_pgd_val(pgd_t);
+
+fastcall pte_t native_make_pte(unsigned long pte);
+fastcall pmd_t native_make_pmd(unsigned long pmd);
+fastcall pgd_t native_make_pgd(unsigned long pgd);
+#endif
 
 #define paravirt_enabled() (paravirt_ops.paravirt_enabled)
 
@@ -215,6 +254,8 @@ static inline void __cpuid(unsigned int 
 #define read_cr4() paravirt_ops.read_cr4()
 #define read_cr4_safe(x) paravirt_ops.read_cr4_safe()
 #define write_cr4(x) paravirt_ops.write_cr4(x)
+
+#define raw_ptep_get_and_clear(xp)     (paravirt_ops.ptep_get_and_clear(xp))
 
 static inline void raw_safe_halt(void)
 {
@@ -297,6 +338,17 @@ static inline void halt(void)
        (paravirt_ops.write_idt_entry((dt), (entry), (low), (high)))
 #define set_iopl_mask(mask) (paravirt_ops.set_iopl_mask(mask))
 
+#define __pte(x)       paravirt_ops.make_pte(x)
+#define __pgd(x)       paravirt_ops.make_pgd(x)
+
+#define pte_val(x)     paravirt_ops.pte_val(x)
+#define pgd_val(x)     paravirt_ops.pgd_val(x)
+
+#ifdef CONFIG_X86_PAE
+#define __pmd(x)       paravirt_ops.make_pmd(x)
+#define pmd_val(x)     paravirt_ops.pmd_val(x)
+#endif
+
 /* The paravirtualized I/O functions */
 static inline void slow_down_io(void) {
        paravirt_ops.io_delay();
@@ -336,6 +388,18 @@ static inline void setup_secondary_clock
        paravirt_ops.setup_secondary_clock();
 }
 #endif
+
+
+fastcall void native_set_pte(pte_t *ptep, pte_t pteval);
+fastcall void native_set_pte_at(struct mm_struct *mm, u32 addr, pte_t *ptep, 
pte_t pteval);
+fastcall void native_set_pmd(pmd_t *pmdp, pmd_t pmdval);
+fastcall void native_set_pte_present(struct mm_struct *mm, u32 addr, pte_t 
*ptep, pte_t pte);
+fastcall void native_set_pte_atomic(pte_t *ptep, pte_t pteval);
+fastcall void native_set_pud(pud_t *pudp, pud_t pudval);
+fastcall void native_pte_clear(struct mm_struct *mm, u32 addr, pte_t *ptep);
+fastcall void native_pmd_clear(pmd_t *pmd);
+fastcall pte_t native_ptep_get_and_clear(pte_t *ptep);
+void native_nop(void);
 
 #ifdef CONFIG_SMP
 static inline void startup_ipi_hook(int phys_apicid, unsigned long start_eip,
===================================================================
--- a/include/asm-i386/pgtable-2level.h
+++ b/include/asm-i386/pgtable-2level.h
@@ -15,6 +15,7 @@
 #define set_pte(pteptr, pteval) (*(pteptr) = pteval)
 #define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)
 #define set_pmd(pmdptr, pmdval) (*(pmdptr) = (pmdval))
+#define raw_ptep_get_and_clear(xp)     __pte(xchg(&(xp)->pte_low, 0))
 #endif
 
 #define set_pte_atomic(pteptr, pteval) set_pte(pteptr,pteval)
@@ -23,11 +24,9 @@
 #define pte_clear(mm,addr,xp)  do { set_pte_at(mm, addr, xp, __pte(0)); } 
while (0)
 #define pmd_clear(xp)  do { set_pmd(xp, __pmd(0)); } while (0)
 
-#define raw_ptep_get_and_clear(xp)     __pte(xchg(&(xp)->pte_low, 0))
-
 #define pte_page(x)            pfn_to_page(pte_pfn(x))
 #define pte_none(x)            (!(x).pte_low)
-#define pte_pfn(x)             ((unsigned long)(((x).pte_low >> PAGE_SHIFT)))
+#define pte_pfn(x)             (pte_val(x) >> PAGE_SHIFT)
 #define pfn_pte(pfn, prot)     __pte(((pfn) << PAGE_SHIFT) | pgprot_val(prot))
 #define pfn_pmd(pfn, prot)     __pmd(((pfn) << PAGE_SHIFT) | pgprot_val(prot))
 
===================================================================
--- a/include/asm-i386/pgtable-3level.h
+++ b/include/asm-i386/pgtable-3level.h
@@ -98,6 +98,18 @@ static inline void pmd_clear(pmd_t *pmd)
        smp_wmb();
        *(tmp + 1) = 0;
 }
+
+static inline pte_t raw_ptep_get_and_clear(pte_t *ptep)
+{
+       pte_t res;
+
+       /* xchg acts as a barrier before the setting of the high bits */
+       res.pte_low = xchg(&ptep->pte_low, 0);
+       res.pte_high = ptep->pte_high;
+       ptep->pte_high = 0;
+
+       return res;
+}
 #endif
 
 /*
@@ -119,18 +131,6 @@ static inline void pud_clear (pud_t * pu
 #define pmd_offset(pud, address) ((pmd_t *) pud_page(*(pud)) + \
                        pmd_index(address))
 
-static inline pte_t raw_ptep_get_and_clear(pte_t *ptep)
-{
-       pte_t res;
-
-       /* xchg acts as a barrier before the setting of the high bits */
-       res.pte_low = xchg(&ptep->pte_low, 0);
-       res.pte_high = ptep->pte_high;
-       ptep->pte_high = 0;
-
-       return res;
-}
-
 #define __HAVE_ARCH_PTE_SAME
 static inline int pte_same(pte_t a, pte_t b)
 {
@@ -146,8 +146,7 @@ static inline int pte_none(pte_t pte)
 
 static inline unsigned long pte_pfn(pte_t pte)
 {
-       return (pte.pte_low >> PAGE_SHIFT) |
-               (pte.pte_high << (32 - PAGE_SHIFT));
+       return pte_val(pte) >> PAGE_SHIFT;
 }
 
 extern unsigned long long __supported_pte_mask;

-- 


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