From: kettenis Date: Sat, 30 Jul 2022 17:56:54 +0000 (+0000) Subject: Kill virtual address randomization for the EFI runtime. It was a neat idea X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=511ed226e2e28a981fbee8fe70407cd9a12614ba;p=openbsd Kill virtual address randomization for the EFI runtime. It was a neat idea but it appears to be too fragile and now that we are using a 48-bit VA space for the EFI runtime we no longer need to call SetVirtualAddressMap() to make address fit into our pmap. Unbreaks the x13s. ok mlarkin@, patrick@ --- diff --git a/sys/arch/arm64/dev/efi.c b/sys/arch/arm64/dev/efi.c index d4de1572a84..46034ef319f 100644 --- a/sys/arch/arm64/dev/efi.c +++ b/sys/arch/arm64/dev/efi.c @@ -1,4 +1,4 @@ -/* $OpenBSD: efi.c,v 1.13 2022/07/27 21:01:38 kettenis Exp $ */ +/* $OpenBSD: efi.c,v 1.14 2022/07/30 17:56:54 kettenis Exp $ */ /* * Copyright (c) 2017 Mark Kettenis @@ -71,7 +71,7 @@ struct cfdriver efi_cd = { NULL, "efi", DV_DULL }; -void efi_remap_runtime(struct efi_softc *); +void efi_map_runtime(struct efi_softc *); void efi_enter(struct efi_softc *); void efi_leave(struct efi_softc *); int efi_gettime(struct todr_chip_handle *, struct timeval *); @@ -120,13 +120,11 @@ efi_attach(struct device *parent, struct device *self, void *aux) printf(".%d", minor % 10); printf("\n"); - efi_remap_runtime(sc); - sc->sc_rs = st->RuntimeServices; + efi_map_runtime(sc); /* - * The FirmwareVendor and ConfigurationTable fields have been - * converted from a physical pointer to a virtual pointer, so - * we have to activate our pmap to access them. + * Activate our pmap such that we can access the + * FirmwareVendor and ConfigurationTable fields. */ efi_enter(sc); if (st->FirmwareVendor) { @@ -171,17 +169,9 @@ efi_attach(struct device *parent, struct device *self, void *aux) } void -efi_remap_runtime(struct efi_softc *sc) +efi_map_runtime(struct efi_softc *sc) { - EFI_MEMORY_DESCRIPTOR *src; - EFI_MEMORY_DESCRIPTOR *dst; - EFI_MEMORY_DESCRIPTOR *vmap; - EFI_PHYSICAL_ADDRESS phys_start = ~0ULL; - EFI_PHYSICAL_ADDRESS phys_end = 0; - EFI_VIRTUAL_ADDRESS virt_start; - EFI_STATUS status; - vsize_t space; - int count = 0; + EFI_MEMORY_DESCRIPTOR *desc; int i; /* @@ -193,157 +183,34 @@ efi_remap_runtime(struct efi_softc *sc) sc->sc_pm->pm_privileged = 1; sc->sc_pm->have_4_level_pt = 1; - /* - * We need to provide identity mappings for the complete - * memory map for the first SetVirtualAddressMap() call. - */ - src = mmap; + desc = mmap; for (i = 0; i < mmap_size / mmap_desc_size; i++) { - if (src->Type != EfiConventionalMemory) { - vaddr_t va = src->PhysicalStart; - paddr_t pa = src->PhysicalStart; - int npages = src->NumberOfPages; - vm_prot_t prot = PROT_READ | PROT_WRITE | PROT_EXEC; + if (desc->Attribute & EFI_MEMORY_RUNTIME) { + vaddr_t va = desc->VirtualStart; + paddr_t pa = desc->PhysicalStart; + int npages = desc->NumberOfPages; + vm_prot_t prot = PROT_READ | PROT_WRITE; #ifdef EFI_DEBUG printf("type 0x%x pa 0x%llx va 0x%llx pages 0x%llx attr 0x%llx\n", - src->Type, src->PhysicalStart, - src->VirtualStart, src->NumberOfPages, - src->Attribute); + desc->Type, desc->PhysicalStart, + desc->VirtualStart, desc->NumberOfPages, + desc->Attribute); #endif /* - * Normal memory is expected to be "write - * back" cacheable. Everything else is mapped - * as device memory. + * If the virtual address is still zero, use + * an identity mapping. */ - if ((src->Attribute & EFI_MEMORY_WB) == 0) - pa |= PMAP_DEVICE; - - if (src->Attribute & EFI_MEMORY_RP) - prot &= ~PROT_READ; - if (src->Attribute & EFI_MEMORY_XP) - prot &= ~PROT_EXEC; - if (src->Attribute & EFI_MEMORY_RO) - prot &= ~PROT_WRITE; - - while (npages--) { - pmap_enter(sc->sc_pm, va, pa, prot, - prot | PMAP_WIRED); - va += PAGE_SIZE; - pa += PAGE_SIZE; - } - } - - if (src->Attribute & EFI_MEMORY_RUNTIME) { - if (src->Attribute & EFI_MEMORY_WB) { - phys_start = MIN(phys_start, - src->PhysicalStart); - phys_end = MAX(phys_end, src->PhysicalStart + - src->NumberOfPages * PAGE_SIZE); - } - count++; - } - - src = NextMemoryDescriptor(src, mmap_desc_size); - } - - /* Allocate memory descriptors for new mappings. */ - vmap = km_alloc(round_page(count * mmap_desc_size), - &kv_any, &kp_zero, &kd_waitok); - - /* - * Pick a random address somewhere in the lower half of the - * usable virtual address space. - */ - space = 3 * (VM_MAX_ADDRESS - VM_MIN_ADDRESS) / 4; - virt_start = VM_MIN_ADDRESS + - ((vsize_t)arc4random_uniform(space >> PAGE_SHIFT) << PAGE_SHIFT); - - /* - * Establish new mappings. Apparently some EFI code relies on - * the offset between code and data remaining the same so pick - * virtual addresses for normal memory that meets that - * constraint. Other mappings are simply tagged on to the end - * of the last normal memory mapping. - */ - src = mmap; - dst = vmap; - for (i = 0; i < mmap_size / mmap_desc_size; i++) { - if (src->Attribute & EFI_MEMORY_RUNTIME) { - memcpy(dst, src, mmap_desc_size); - if (dst->Attribute & EFI_MEMORY_WB) { - dst->VirtualStart = virt_start + - (dst->PhysicalStart - phys_start); - } else { - dst->VirtualStart = virt_start + - (phys_end - phys_start); - phys_end += dst->NumberOfPages * PAGE_SIZE; - } - /* Mask address to make sure it fits in our pmap. */ - dst->VirtualStart &= ((1ULL << EFI_SPACE_BITS) - 1); - dst = NextMemoryDescriptor(dst, mmap_desc_size); - } - - src = NextMemoryDescriptor(src, mmap_desc_size); - } - - efi_enter(sc); - status = sc->sc_rs->SetVirtualAddressMap(count * mmap_desc_size, - mmap_desc_size, mmap_desc_ver, vmap); - efi_leave(sc); - - /* - * If remapping fails, undo the translations. - */ - if (status != EFI_SUCCESS) { - src = mmap; - dst = vmap; - for (i = 0; i < mmap_size / mmap_desc_size; i++) { - if (src->Attribute & EFI_MEMORY_RUNTIME) { - dst->VirtualStart = src->PhysicalStart; - dst = NextMemoryDescriptor(dst, mmap_desc_size); - } - src = NextMemoryDescriptor(src, mmap_desc_size); - } - } - - /* - * Remove all mappings from the pmap. - */ - src = mmap; - for (i = 0; i < mmap_size / mmap_desc_size; i++) { - if (src->Type != EfiConventionalMemory) { - pmap_remove(sc->sc_pm, src->PhysicalStart, - src->PhysicalStart + src->NumberOfPages * PAGE_SIZE); - } - src = NextMemoryDescriptor(src, mmap_desc_size); - } - - /* - * Add back the (translated) runtime mappings. - */ - src = vmap; - for (i = 0; i < count; i++) { - if (src->Attribute & EFI_MEMORY_RUNTIME) { - vaddr_t va = src->VirtualStart; - paddr_t pa = src->PhysicalStart; - int npages = src->NumberOfPages; - vm_prot_t prot = PROT_READ | PROT_WRITE; - -#ifdef EFI_DEBUG - printf("type 0x%x pa 0x%llx va 0x%llx pages 0x%llx attr 0x%llx\n", - src->Type, src->PhysicalStart, - src->VirtualStart, src->NumberOfPages, - src->Attribute); -#endif + if (va == 0) + va = pa; /* * Normal memory is expected to be "write * back" cacheable. Everything else is mapped * as device memory. */ - if ((src->Attribute & EFI_MEMORY_WB) == 0) + if ((desc->Attribute & EFI_MEMORY_WB) == 0) pa |= PMAP_DEVICE; /* @@ -351,14 +218,14 @@ efi_remap_runtime(struct efi_softc *sc) * executable. This violates the standard but it * seems we can get away with it. */ - if (src->Type == EfiRuntimeServicesCode) + if (desc->Type == EfiRuntimeServicesCode) prot |= PROT_EXEC; - if (src->Attribute & EFI_MEMORY_RP) + if (desc->Attribute & EFI_MEMORY_RP) prot &= ~PROT_READ; - if (src->Attribute & EFI_MEMORY_XP) + if (desc->Attribute & EFI_MEMORY_XP) prot &= ~PROT_EXEC; - if (src->Attribute & EFI_MEMORY_RO) + if (desc->Attribute & EFI_MEMORY_RO) prot &= ~PROT_WRITE; while (npages--) { @@ -369,10 +236,8 @@ efi_remap_runtime(struct efi_softc *sc) } } - src = NextMemoryDescriptor(src, mmap_desc_size); + desc = NextMemoryDescriptor(desc, mmap_desc_size); } - - km_free(vmap, round_page(count * mmap_desc_size), &kv_any, &kp_zero); } void