Re: [PATCH 7/8] UML - add virt_to_pte
On Sat, Nov 17, 2007 at 11:50:07AM +0100, Roel Kluin wrote: > > + if (!pte_present(*pte)) > > + pte = NULL; > > shouldn't you check again for (pte == NULL)? No, because if the page isn't mapped, handle_page_fault would have returned non-zero, and we would have already returned. This is leaving aside issues of whether the page could have been unmapped by another CPU (which isn't an issue right now, and for which I have a patch to fix anyway). Jeff -- Work email - jdike at linux dot intel dot com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 7/8] UML - add virt_to_pte
Jeff Dike wrote:
> Turn um_virt_to_phys into virt_to_pte, cleaning up a horrid interface.
>
> It's also made non-static and declared in pgtable.h because it'll be
> needed when the stubs get a vma.
>
> Signed-off-by: Jeff Dike <[EMAIL PROTECTED]>
> ---
> arch/um/kernel/skas/uaccess.c | 56
> +-
> include/asm-um/pgtable.h |3 ++
> 2 files changed, 26 insertions(+), 33 deletions(-)
>
> Index: linux-2.6.22/arch/um/kernel/skas/uaccess.c
> ===
> --- linux-2.6.22.orig/arch/um/kernel/skas/uaccess.c 2007-11-16
> 15:16:54.0 -0500
> +++ linux-2.6.22/arch/um/kernel/skas/uaccess.c2007-11-16
> 15:40:25.0 -0500
> @@ -13,70 +13,60 @@
> #include "kern_util.h"
> #include "os.h"
>
> -static void *um_virt_to_phys(struct task_struct *task, unsigned long addr,
> - pte_t *pte_out)
> +pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr)
> {
> pgd_t *pgd;
> pud_t *pud;
> pmd_t *pmd;
> - pte_t *pte;
> - pte_t ptent;
>
> - if (task->mm == NULL)
> - return ERR_PTR(-EINVAL);
> - pgd = pgd_offset(task->mm, addr);
> + if (mm == NULL)
> + return NULL;
> +
> + pgd = pgd_offset(mm, addr);
> if (!pgd_present(*pgd))
> - return ERR_PTR(-EINVAL);
> + return NULL;
>
> pud = pud_offset(pgd, addr);
> if (!pud_present(*pud))
> - return ERR_PTR(-EINVAL);
> + return NULL;
>
> pmd = pmd_offset(pud, addr);
> if (!pmd_present(*pmd))
> - return ERR_PTR(-EINVAL);
> -
> - pte = pte_offset_kernel(pmd, addr);
> - ptent = *pte;
> - if (!pte_present(ptent))
> - return ERR_PTR(-EINVAL);
> + return NULL;
>
> - if (pte_out != NULL)
> - *pte_out = ptent;
> - return (void *) (pte_val(ptent) & PAGE_MASK) + (addr & ~PAGE_MASK);
> + return pte_offset_kernel(pmd, addr);
> }
>
> -static unsigned long maybe_map(unsigned long virt, int is_write)
> +static pte_t *maybe_map(unsigned long virt, int is_write)
> {
> - pte_t pte;
> - int err;
> + pte_t *pte = virt_to_pte(current->mm, virt);
> + int err, dummy_code;
>
> - void *phys = um_virt_to_phys(current, virt, &pte);
> - int dummy_code;
> -
> - if (IS_ERR(phys) || (is_write && !pte_write(pte))) {
> + if ((pte == NULL) || !pte_present(*pte) ||
> + (is_write && !pte_write(*pte))) {
> err = handle_page_fault(virt, 0, is_write, 1, &dummy_code);
> if (err)
> - return -1UL;
> - phys = um_virt_to_phys(current, virt, NULL);
> + return NULL;
> + pte = virt_to_pte(current->mm, virt);
> }
> - if (IS_ERR(phys))
> - phys = (void *) -1;
> + if (!pte_present(*pte))
> + pte = NULL;
shouldn't you check again for (pte == NULL)?
>
> - return (unsigned long) phys;
> + return pte;
> }
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[PATCH 7/8] UML - add virt_to_pte
Turn um_virt_to_phys into virt_to_pte, cleaning up a horrid interface.
It's also made non-static and declared in pgtable.h because it'll be
needed when the stubs get a vma.
Signed-off-by: Jeff Dike <[EMAIL PROTECTED]>
---
arch/um/kernel/skas/uaccess.c | 56 +-
include/asm-um/pgtable.h |3 ++
2 files changed, 26 insertions(+), 33 deletions(-)
Index: linux-2.6.22/arch/um/kernel/skas/uaccess.c
===
--- linux-2.6.22.orig/arch/um/kernel/skas/uaccess.c 2007-11-16
15:16:54.0 -0500
+++ linux-2.6.22/arch/um/kernel/skas/uaccess.c 2007-11-16 15:40:25.0
-0500
@@ -13,70 +13,60 @@
#include "kern_util.h"
#include "os.h"
-static void *um_virt_to_phys(struct task_struct *task, unsigned long addr,
-pte_t *pte_out)
+pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
- pte_t *pte;
- pte_t ptent;
- if (task->mm == NULL)
- return ERR_PTR(-EINVAL);
- pgd = pgd_offset(task->mm, addr);
+ if (mm == NULL)
+ return NULL;
+
+ pgd = pgd_offset(mm, addr);
if (!pgd_present(*pgd))
- return ERR_PTR(-EINVAL);
+ return NULL;
pud = pud_offset(pgd, addr);
if (!pud_present(*pud))
- return ERR_PTR(-EINVAL);
+ return NULL;
pmd = pmd_offset(pud, addr);
if (!pmd_present(*pmd))
- return ERR_PTR(-EINVAL);
-
- pte = pte_offset_kernel(pmd, addr);
- ptent = *pte;
- if (!pte_present(ptent))
- return ERR_PTR(-EINVAL);
+ return NULL;
- if (pte_out != NULL)
- *pte_out = ptent;
- return (void *) (pte_val(ptent) & PAGE_MASK) + (addr & ~PAGE_MASK);
+ return pte_offset_kernel(pmd, addr);
}
-static unsigned long maybe_map(unsigned long virt, int is_write)
+static pte_t *maybe_map(unsigned long virt, int is_write)
{
- pte_t pte;
- int err;
+ pte_t *pte = virt_to_pte(current->mm, virt);
+ int err, dummy_code;
- void *phys = um_virt_to_phys(current, virt, &pte);
- int dummy_code;
-
- if (IS_ERR(phys) || (is_write && !pte_write(pte))) {
+ if ((pte == NULL) || !pte_present(*pte) ||
+ (is_write && !pte_write(*pte))) {
err = handle_page_fault(virt, 0, is_write, 1, &dummy_code);
if (err)
- return -1UL;
- phys = um_virt_to_phys(current, virt, NULL);
+ return NULL;
+ pte = virt_to_pte(current->mm, virt);
}
- if (IS_ERR(phys))
- phys = (void *) -1;
+ if (!pte_present(*pte))
+ pte = NULL;
- return (unsigned long) phys;
+ return pte;
}
static int do_op_one_page(unsigned long addr, int len, int is_write,
int (*op)(unsigned long addr, int len, void *arg), void *arg)
{
struct page *page;
+ pte_t *pte;
int n;
- addr = maybe_map(addr, is_write);
- if (addr == -1UL)
+ pte = maybe_map(addr, is_write);
+ if (pte == NULL)
return -1;
- page = phys_to_page(addr);
+ page = pte_page(*pte);
addr = (unsigned long) kmap_atomic(page, KM_UML_USERCOPY) +
(addr & ~PAGE_MASK);
Index: linux-2.6.22/include/asm-um/pgtable.h
===
--- linux-2.6.22.orig/include/asm-um/pgtable.h 2007-11-16 15:35:38.0
-0500
+++ linux-2.6.22/include/asm-um/pgtable.h 2007-11-16 15:39:44.0
-0500
@@ -323,6 +323,9 @@ static inline pte_t pte_modify(pte_t pte
#define pte_unmap(pte) do { } while (0)
#define pte_unmap_nested(pte) do { } while (0)
+struct mm_struct;
+extern pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr);
+
#define update_mmu_cache(vma,address,pte) do ; while (0)
/* Encode and de-code a swap entry */
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
