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User pointer validity checks.

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Added routines that check whether a user pointer is accessible by the kernel,
and if not ask the pager to map-in those pages. I haven't implemented yet the
bit that asks the pager for paging-in.
This commit is contained in:
Bahadir Balban
2008-02-05 15:41:14 +00:00
parent 3a07ae70fd
commit a82cdd3456
8 changed files with 155 additions and 72 deletions
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16
src/arch/arm/exception.c
View File

@@ -1,7 +1,7 @@
/*
* Debug print support for unexpected exceptions
* Memory exception handling in process context.
*
* Copyright (C) 2007 Bahadir Balban
* Copyright (C) 2007, 2008 Bahadir Balban
*/
#include <l4/generic/scheduler.h>
#include <l4/generic/space.h>
@@ -62,11 +62,19 @@ void fault_ipc_to_pager(u32 faulty_pc, u32 fsr, u32 far)
ipc_sendrecv(current->pagerid, current->pagerid);
/*
* Pager is now notified and handling the fault. We now sleep on
* another queue.
* FIXME: CHECK TASK KILL REPLY !!!
* Here, pager has handled the request and sent us back a message.
* It is natural that a pager might want to kill the task due to
* illegal access. Here we ought to check this and kill it rather
* than return back to it.
*/
}
int pager_pagein_request(unsigned long addr, unsigned long size, unsigned int flags)
{
return 0;
}
int check_aborts(u32 faulted_pc, u32 fsr, u32 far)
{
int ret = 0;

129
src/arch/arm/v5/mm.c
View File

@@ -191,54 +191,6 @@ void attach_pmd(pgd_table_t *pgd, pmd_table_t *pmd, unsigned int vaddr)
pgd->entry[pgd_i] |= PGD_TYPE_COARSE;
}
/*
* Maps @paddr to @vaddr, covering @size bytes also allocates new pmd if
* necessary. This flavor explicitly supplies the pgd to modify. This is useful
* when modifying userspace of processes that are not currently running. (Only
* makes sense for userspace mappings since kernel mappings are common.)
*/
void add_mapping_pgd(unsigned int paddr, unsigned int vaddr,
unsigned int size, unsigned int flags,
pgd_table_t *pgd)
{
pmd_table_t *pmd;
unsigned int numpages = (size >> PAGE_BITS);
if (size < PAGE_SIZE) {
printascii("Error: Mapping size must be in bytes not pages.\n");
while(1);
}
if (size & PAGE_MASK)
numpages++;
/* Convert generic map flags to pagetable-specific */
BUG_ON(!(flags = space_flags_to_ptflags(flags)));
/* Map all consecutive pages that cover given size */
for (int i = 0; i < numpages; i++) {
/* Check if another mapping already has a pmd attached. */
pmd = pmd_exists(pgd, vaddr);
if (!pmd) {
/*
* If this is the first vaddr in
* this pmd, allocate new pmd
*/
pmd = alloc_pmd();
/* Attach pmd to its entry in pgd */
attach_pmd(pgd, pmd, vaddr);
}
/* Attach paddr to this pmd */
__add_mapping(page_align(paddr),
page_align(vaddr), flags, pmd);
/* Go to the next page to be mapped */
paddr += PAGE_SIZE;
vaddr += PAGE_SIZE;
}
}
#if 0
/* Maps @paddr to @vaddr, covering @size bytes,
* also allocates new pmd if necessary. */
@@ -326,12 +278,93 @@ void add_mapping(unsigned int paddr, unsigned int vaddr,
}
#endif
/*
* Maps @paddr to @vaddr, covering @size bytes also allocates new pmd if
* necessary. This flavor explicitly supplies the pgd to modify. This is useful
* when modifying userspace of processes that are not currently running. (Only
* makes sense for userspace mappings since kernel mappings are common.)
*/
void add_mapping_pgd(unsigned int paddr, unsigned int vaddr,
unsigned int size, unsigned int flags,
pgd_table_t *pgd)
{
pmd_table_t *pmd;
unsigned int numpages = (size >> PAGE_BITS);
if (size < PAGE_SIZE) {
printascii("Error: Mapping size must be in bytes not pages.\n");
while(1);
}
if (size & PAGE_MASK)
numpages++;
/* Convert generic map flags to pagetable-specific */
BUG_ON(!(flags = space_flags_to_ptflags(flags)));
/* Map all consecutive pages that cover given size */
for (int i = 0; i < numpages; i++) {
/* Check if another mapping already has a pmd attached. */
pmd = pmd_exists(pgd, vaddr);
if (!pmd) {
/*
* If this is the first vaddr in
* this pmd, allocate new pmd
*/
pmd = alloc_pmd();
/* Attach pmd to its entry in pgd */
attach_pmd(pgd, pmd, vaddr);
}
/* Attach paddr to this pmd */
__add_mapping(page_align(paddr),
page_align(vaddr), flags, pmd);
/* Go to the next page to be mapped */
paddr += PAGE_SIZE;
vaddr += PAGE_SIZE;
}
}
void add_mapping(unsigned int paddr, unsigned int vaddr,
unsigned int size, unsigned int flags)
{
add_mapping_pgd(paddr, vaddr, size, flags, current->pgd);
}
/*
* Checks if a virtual address range has same or more permissive
* flags than the given ones, returns 0 if not, and 1 if OK.
*/
int check_mapping_pgd(unsigned long vaddr, unsigned long size,
unsigned int flags, pgd_table_t *pgd)
{
unsigned int npages = __pfn(align_up(size, PAGE_SIZE));
pte_t pte;
/* Convert generic map flags to pagetable-specific */
BUG_ON(!(flags = space_flags_to_ptflags(flags)));
for (int i = 0; i < npages; i++) {
pte = virt_to_pte(vaddr + i * PAGE_SIZE);
/* Check if pte perms are equal or gt given flags */
if ((pte & PTE_PROT_MASK) >= (flags & PTE_PROT_MASK))
continue;
else
return 0;
}
return 1;
}
int check_mapping(unsigned long vaddr, unsigned long size,
unsigned int flags)
{
return check_mapping_pgd(vaddr, size, flags, current->pgd);
}
/* FIXME: Empty PMDs should be returned here !!! */
void __remove_mapping(pmd_table_t *pmd, unsigned long vaddr)
{