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Add pmap_change_prot on arm64

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Support changing the protection of preloaded kernel modules by
implementing pmap_change_prot on arm64 and calling it from
preload_protect.

Reviewed by:	alc (previous version)
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D32026
This commit is contained in:
Andrew Turner 2021-09-20 16:49:18 +00:00
parent dfe887b7d2
commit a85ce4ad72
3 changed files with 83 additions and 14 deletions
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94
sys/arm64/arm64/pmap.c
View File

@ -382,7 +382,8 @@ static pv_entry_t pmap_pvh_remove(struct md_page *pvh, pmap_t pmap,
static void pmap_abort_ptp(pmap_t pmap, vm_offset_t va, vm_page_t mpte);
static bool pmap_activate_int(pmap_t pmap);
static void pmap_alloc_asid(pmap_t pmap);
static int pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode);
static int pmap_change_props_locked(vm_offset_t va, vm_size_t size,
vm_prot_t prot, int mode);
static pt_entry_t *pmap_demote_l1(pmap_t pmap, pt_entry_t *l1, vm_offset_t va);
static pt_entry_t *pmap_demote_l2_locked(pmap_t pmap, pt_entry_t *l2,
vm_offset_t va, struct rwlock **lockp);
@ -5949,17 +5950,41 @@ pmap_change_attr(vm_offset_t va, vm_size_t size, int mode)
int error;
PMAP_LOCK(kernel_pmap);
error = pmap_change_attr_locked(va, size, mode);
error = pmap_change_props_locked(va, size, PROT_NONE, mode);
PMAP_UNLOCK(kernel_pmap);
return (error);
}
/*
* Changes the specified virtual address range's protections to those
* specified by "prot". Like pmap_change_attr(), protections for aliases
* in the direct map are updated as well. Protections on aliasing mappings may
* be a subset of the requested protections; for example, mappings in the direct
* map are never executable.
*/
int
pmap_change_prot(vm_offset_t va, vm_size_t size, vm_prot_t prot)
{
int error;
/* Only supported within the kernel map. */
if (va < VM_MIN_KERNEL_ADDRESS)
return (EINVAL);
PMAP_LOCK(kernel_pmap);
error = pmap_change_props_locked(va, size, prot, -1);
PMAP_UNLOCK(kernel_pmap);
return (error);
}
static int
pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode)
pmap_change_props_locked(vm_offset_t va, vm_size_t size, vm_prot_t prot,
int mode)
{
vm_offset_t base, offset, tmpva;
pt_entry_t l3, *pte, *newpte;
int lvl;
pt_entry_t bits, mask;
int lvl, rv;
PMAP_LOCK_ASSERT(kernel_pmap, MA_OWNED);
base = trunc_page(va);
@ -5970,12 +5995,44 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode)
!(base >= VM_MIN_KERNEL_ADDRESS && base < VM_MAX_KERNEL_ADDRESS))
return (EINVAL);
bits = 0;
mask = 0;
if (mode != -1) {
bits = ATTR_S1_IDX(mode);
mask = ATTR_S1_IDX_MASK;
if (mode == VM_MEMATTR_DEVICE) {
mask |= ATTR_S1_XN;
bits |= ATTR_S1_XN;
}
}
if (prot != VM_PROT_NONE) {
/* Don't mark the DMAP as executable. It never is on arm64. */
if (VIRT_IN_DMAP(base)) {
prot &= ~VM_PROT_EXECUTE;
/*
* XXX Mark the DMAP as writable for now. We rely
* on this in ddb & dtrace to insert breakpoint
* instructions.
*/
prot |= VM_PROT_WRITE;
}
if ((prot & VM_PROT_WRITE) == 0) {
bits |= ATTR_S1_AP(ATTR_S1_AP_RO);
}
if ((prot & VM_PROT_EXECUTE) == 0) {
bits |= ATTR_S1_PXN;
}
bits |= ATTR_S1_UXN;
mask |= ATTR_S1_AP_MASK | ATTR_S1_XN;
}
for (tmpva = base; tmpva < base + size; ) {
pte = pmap_pte(kernel_pmap, tmpva, &lvl);
if (pte == NULL)
return (EINVAL);
if ((pmap_load(pte) & ATTR_S1_IDX_MASK) == ATTR_S1_IDX(mode)) {
if ((pmap_load(pte) & mask) == bits) {
/*
* We already have the correct attribute,
* ignore this entry.
@ -6016,14 +6073,23 @@ pmap_change_attr_locked(vm_offset_t va, vm_size_t size, int mode)
case 3:
/* Update the entry */
l3 = pmap_load(pte);
l3 &= ~ATTR_S1_IDX_MASK;
l3 |= ATTR_S1_IDX(mode);
if (mode == VM_MEMATTR_DEVICE)
l3 |= ATTR_S1_XN;
l3 &= ~mask;
l3 |= bits;
pmap_update_entry(kernel_pmap, pte, l3, tmpva,
PAGE_SIZE);
if (!VIRT_IN_DMAP(tmpva)) {
/*
* Keep the DMAP memory in sync.
*/
rv = pmap_change_props_locked(
PHYS_TO_DMAP(l3 & ~ATTR_MASK),
L3_SIZE, prot, mode);
if (rv != 0)
return (rv);
}
/*
* If moving to a non-cacheable entry flush
* the cache.
@ -6185,12 +6251,14 @@ pmap_demote_l2_locked(pmap_t pmap, pt_entry_t *l2, vm_offset_t va,
/*
* If the page table page is missing and the mapping
* is for a kernel address, the mapping must belong to
* the direct map. Page table pages are preallocated
* for every other part of the kernel address space,
* so the direct map region is the only part of the
* either the direct map or the early kernel memory.
* Page table pages are preallocated for every other
* part of the kernel address space, so the direct map
* region and early kernel memory are the only parts of the
* kernel address space that must be handled here.
*/
KASSERT(!ADDR_IS_KERNEL(va) || VIRT_IN_DMAP(va),
KASSERT(!ADDR_IS_KERNEL(va) || VIRT_IN_DMAP(va) ||
(va >= VM_MIN_KERNEL_ADDRESS && va < kernel_vm_end),
("pmap_demote_l2: No saved mpte for va %#lx", va));
/*

1
sys/arm64/include/pmap.h
View File

@ -167,6 +167,7 @@ extern vm_offset_t virtual_end;
void pmap_activate_vm(pmap_t);
void pmap_bootstrap(vm_offset_t, vm_offset_t, vm_paddr_t, vm_size_t);
int pmap_change_attr(vm_offset_t va, vm_size_t size, int mode);
int pmap_change_prot(vm_offset_t va, vm_size_t size, vm_prot_t prot);
void pmap_kenter(vm_offset_t sva, vm_size_t size, vm_paddr_t pa, int mode);
void pmap_kenter_device(vm_offset_t, vm_size_t, vm_paddr_t);
bool pmap_klookup(vm_offset_t va, vm_paddr_t *pa);

2
sys/kern/link_elf.c
View File

@ -769,7 +769,7 @@ parse_vnet(elf_file_t ef)
static int
preload_protect(elf_file_t ef, vm_prot_t prot)
{
#ifdef __amd64__
#if defined(__aarch64__) || defined(__amd64__)
Elf_Ehdr *hdr;
Elf_Phdr *phdr, *phlimit;
vm_prot_t nprot;