* [uml-devel] Implement vsyscall/sysenter, patch 2/4
@ 2004-10-08 19:12 bodo.stroesser
2004-10-11 19:29 ` Adam Heath
0 siblings, 1 reply; 2+ messages in thread
From: bodo.stroesser @ 2004-10-08 19:12 UTC (permalink / raw)
To: user-mode-linux-devel; +Cc: jdike, blaisorblade_spam
To make the vsyscall-page available for copy_from_user() and
ptrace(), we should use kernel's "gate-vma" mechanism.
Therefore we need a valid page structure. To have this, one
page (or more) is allocated at boot time, the contents of the
vsyscall-page is copied into this page and the page's pte is
inserted in swapper's pagetables.
Now it will be copied into the pagetables of all processes.
Note: this alone doesn't work, since FIXADDR_USER_START and
FIXADDR_USER_END are not yet defined correctly. Also
access_ok_skas() does not yet grant read accesses to
pages not in the normal user area.
Risks:
Please check the first hunk! I don't know, whether this change is OK.
Maybe fixrange_init() is wrong anyway with 3-level-pagetables?
Signed-off-by: Bodo Stroesser <bodo.stroesser@fujitsu-siemens.com>
---
--- linux-2.6.9-rc2-orig/arch/um/kernel/mem.c 2004-09-27 19:24:56.000000000 +0200
+++ linux-2.6.9-rc2/arch/um/kernel/mem.c 2004-10-05 15:36:57.032218318 +0200
@@ -121,7 +121,7 @@
for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
pmd = (pmd_t *)pgd;
- for (; (j < PTRS_PER_PMD) && (vaddr != end); pmd++, j++) {
+ for (; (j < PTRS_PER_PMD) && (vaddr < end); pmd++, j++) {
if (pmd_none(*pmd)) {
pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
set_pmd(pmd, __pmd(_KERNPG_TABLE +
@@ -175,6 +175,29 @@
}
#endif /* CONFIG_HIGHMEM */
+static void __init fixaddr_user_init( void)
+{
+ long size = FIXADDR_USER_END - FIXADDR_USER_START;
+ pgd_t *pgd;
+ pmd_t *pmd;
+ pte_t *pte;
+ unsigned long paddr, vaddr = FIXADDR_USER_START;
+
+ if ( ! size )
+ return;
+
+ fixrange_init( FIXADDR_USER_START, FIXADDR_USER_END, swapper_pg_dir);
+ paddr = (unsigned long)alloc_bootmem_low_pages( size);
+ memcpy( (void *)paddr, (void *)FIXADDR_USER_START, size);
+ paddr = __pa(paddr);
+ for ( ; size > 0; size-=PAGE_SIZE, vaddr+=PAGE_SIZE, paddr+=PAGE_SIZE) {
+ pgd = swapper_pg_dir + pgd_index(vaddr);
+ pmd = pmd_offset(pgd, vaddr);
+ pte = pte_offset_kernel(pmd, vaddr);
+ pte_set_val( (*pte), paddr, PAGE_READONLY);
+ }
+}
+
void paging_init(void)
{
unsigned long zones_size[MAX_NR_ZONES], vaddr;
@@ -195,6 +218,8 @@
vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
fixrange_init(vaddr, FIXADDR_TOP, swapper_pg_dir);
+ fixaddr_user_init();
+
#ifdef CONFIG_HIGHMEM
init_highmem();
#endif
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^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [uml-devel] Implement vsyscall/sysenter, patch 2/4
2004-10-08 19:12 [uml-devel] Implement vsyscall/sysenter, patch 2/4 bodo.stroesser
@ 2004-10-11 19:29 ` Adam Heath
0 siblings, 0 replies; 2+ messages in thread
From: Adam Heath @ 2004-10-11 19:29 UTC (permalink / raw)
To: bodo.stroesser; +Cc: user-mode-linux-devel, jdike, blaisorblade_spam
On Fri, 8 Oct 2004, wrote:
> To make the vsyscall-page available for copy_from_user() and
> ptrace(), we should use kernel's "gate-vma" mechanism.
> Therefore we need a valid page structure. To have this, one
> page (or more) is allocated at boot time, the contents of the
> vsyscall-page is copied into this page and the page's pte is
> inserted in swapper's pagetables.
> Now it will be copied into the pagetables of all processes.
>
> Note: this alone doesn't work, since FIXADDR_USER_START and
> FIXADDR_USER_END are not yet defined correctly. Also
> access_ok_skas() does not yet grant read accesses to
> pages not in the normal user area.
>
> Risks:
> Please check the first hunk! I don't know, whether this change is OK.
> Maybe fixrange_init() is wrong anyway with 3-level-pagetables?
>
>
> Signed-off-by: Bodo Stroesser <bodo.stroesser@fujitsu-siemens.com>
>
> ---
>
>
> --- linux-2.6.9-rc2-orig/arch/um/kernel/mem.c 2004-09-27 19:24:56.000000000 +0200
> +++ linux-2.6.9-rc2/arch/um/kernel/mem.c 2004-10-05 15:36:57.032218318 +0200
> @@ -121,7 +121,7 @@
>
> for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
> pmd = (pmd_t *)pgd;
> - for (; (j < PTRS_PER_PMD) && (vaddr != end); pmd++, j++) {
> + for (; (j < PTRS_PER_PMD) && (vaddr < end); pmd++, j++) {
> if (pmd_none(*pmd)) {
> pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
> set_pmd(pmd, __pmd(_KERNPG_TABLE +
> @@ -175,6 +175,29 @@
> }
> #endif /* CONFIG_HIGHMEM */
>
> +static void __init fixaddr_user_init( void)
> +{
> + long size = FIXADDR_USER_END - FIXADDR_USER_START;
> + pgd_t *pgd;
> + pmd_t *pmd;
> + pte_t *pte;
> + unsigned long paddr, vaddr = FIXADDR_USER_START;
> +
> + if ( ! size )
> + return;
> +
> + fixrange_init( FIXADDR_USER_START, FIXADDR_USER_END, swapper_pg_dir);
> + paddr = (unsigned long)alloc_bootmem_low_pages( size);
> + memcpy( (void *)paddr, (void *)FIXADDR_USER_START, size);
Use consistent spacing.
> + paddr = __pa(paddr);
> + for ( ; size > 0; size-=PAGE_SIZE, vaddr+=PAGE_SIZE, paddr+=PAGE_SIZE) {
> + pgd = swapper_pg_dir + pgd_index(vaddr);
> + pmd = pmd_offset(pgd, vaddr);
> + pte = pte_offset_kernel(pmd, vaddr);
> + pte_set_val( (*pte), paddr, PAGE_READONLY);
> + }
> +}
> +
> void paging_init(void)
> {
> unsigned long zones_size[MAX_NR_ZONES], vaddr;
> @@ -195,6 +218,8 @@
> vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
> fixrange_init(vaddr, FIXADDR_TOP, swapper_pg_dir);
>
> + fixaddr_user_init();
> +
> #ifdef CONFIG_HIGHMEM
> init_highmem();
> #endif
>
>
> -------------------------------------------------------
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>
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2004-10-11 19:29 ` Adam Heath
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