/** * @file kernel/arch/x86_64/mmu.c * @brief Memory management facilities for x86-64 * * Frame allocation and mapping routines for x86-64. */ #include #include #include #include #include #include #include #include extern void arch_tlb_shootdown(void); /** * bitmap page allocator for 4KiB pages */ static volatile uint32_t *frames; static uint32_t nframes; #define PAGE_SHIFT 12 #define PAGE_SIZE 0x1000UL #define PAGE_SIZE_MASK 0xFFFFffffFFFFf000UL #define PAGE_LOW_MASK 0x0000000000000FFFUL #define LARGE_PAGE_SIZE 0x200000UL #define KERNEL_HEAP_START 0xFFFFff0000000000UL #define MMIO_BASE_START 0xffffff1fc0000000UL #define HIGH_MAP_REGION 0xffffff8000000000UL /* These are actually defined in the shm layer... */ #define USER_SHM_LOW 0x0000000200000000UL #define USER_SHM_HIGH 0x0000000400000000UL #define USER_DEVICE_MAP 0x0000000100000000UL #define USER_PML_ACCESS 0x07 #define KERNEL_PML_ACCESS 0x03 #define LARGE_PAGE_BIT 0x80 #define PDP_MASK 0x3fffffffUL #define PD_MASK 0x1fffffUL #define PT_MASK PAGE_LOW_MASK #define ENTRY_MASK 0x1FF #define PHYS_MASK 0x7fffffffffUL #define CANONICAL_MASK 0xFFFFffffFFFFUL #define INDEX_FROM_BIT(b) ((b) >> 5) #define OFFSET_FROM_BIT(b) ((b) & 0x1F) void mmu_frame_set(uintptr_t frame_addr) { /* If the frame is within bounds... */ if (frame_addr < nframes * 4 * 0x400) { uint64_t frame = frame_addr >> 12; uint64_t index = INDEX_FROM_BIT(frame); uint32_t offset = OFFSET_FROM_BIT(frame); frames[index] |= ((uint32_t)1 << offset); asm ("" ::: "memory"); } } void mmu_frame_clear(uintptr_t frame_addr) { /* If the frame is within bounds... */ if (frame_addr < nframes * 4 * 0x400) { uint64_t frame = frame_addr >> PAGE_SHIFT; uint64_t index = INDEX_FROM_BIT(frame); uint32_t offset = OFFSET_FROM_BIT(frame); frames[index] &= ~((uint32_t)1 << offset); asm ("" ::: "memory"); } } int mmu_frame_test(uintptr_t frame_addr) { if (!(frame_addr < nframes * 4 * 0x400)) return 0; uint64_t frame = frame_addr >> PAGE_SHIFT; uint64_t index = INDEX_FROM_BIT(frame); uint32_t offset = OFFSET_FROM_BIT(frame); asm ("" ::: "memory"); return !!(frames[index] & ((uint32_t)1 << offset)); } static spin_lock_t frame_alloc_lock = { 0 }; static spin_lock_t kheap_lock = { 0 }; static spin_lock_t mmio_space_lock = { 0 }; /** * @brief Find the first range of @p n contiguous frames. * * If a large enough region could not be found, results are fatal. */ uintptr_t mmu_first_n_frames(int n) { for (uint64_t i = 0; i < nframes * PAGE_SIZE; i += PAGE_SIZE) { int bad = 0; for (int j = 0; j < n; ++j) { if (mmu_frame_test(i + PAGE_SIZE * j)) { bad = j + 1; } } if (!bad) { return i / PAGE_SIZE; } } printf("failed to allocate %d contiguous frames\n", n); arch_fatal(); return (uintptr_t)-1; } /** * @brief Find the first available frame from the bitmap. */ uintptr_t mmu_first_frame(void) { uintptr_t i, j; for (i = 0; i < INDEX_FROM_BIT(nframes); ++i) { if (frames[i] != (uint32_t)-1) { for (j = 0; j < (sizeof(uint32_t)*8); ++j) { uint32_t testFrame = (uint32_t)1 << j; if (!(frames[i] & testFrame)) return (i << 5) + j; } } } printf("error: out allocatable frames\n"); arch_fatal(); return (uintptr_t)-1; } /** * @brief Set the flags for a page, and allocate a frame for it if needed. * * Sets the page bits based on the the value of @p flags. * If @p page->bits.page is unset, a new frame will be allocated. */ void mmu_frame_allocate(union PML * page, unsigned int flags) { if (page->bits.page == 0) { spin_lock(frame_alloc_lock); uintptr_t index = mmu_first_frame(); mmu_frame_set(index << PAGE_SHIFT); page->bits.page = index; spin_unlock(frame_alloc_lock); } page->bits.size = 0; page->bits.present = 1; page->bits.writable = (flags & MMU_FLAG_WRITABLE) ? 1 : 0; page->bits.user = (flags & MMU_FLAG_KERNEL) ? 0 : 1; page->bits.nocache = (flags & MMU_FLAG_NOCACHE) ? 1 : 0; page->bits.writethrough = (flags & MMU_FLAG_WRITETHROUGH) ? 1 : 0; page->bits.size = (flags & MMU_FLAG_SPEC) ? 1 : 0; page->bits.nx = (flags & MMU_FLAG_NOEXECUTE) ? 1 : 0; } /** * @brief Map the given page to the requested physical address. */ void mmu_frame_map_address(union PML * page, unsigned int flags, uintptr_t physAddr) { mmu_frame_set(physAddr); page->bits.page = physAddr >> PAGE_SHIFT; mmu_frame_allocate(page, flags); } /* Initial memory maps loaded by boostrap */ #define _pagemap __attribute__((aligned(PAGE_SIZE))) = {0} union PML init_page_region[3][512] _pagemap; union PML high_base_pml[512] _pagemap; union PML heap_base_pml[512] _pagemap; union PML heap_base_pd[512] _pagemap; union PML heap_base_pt[512] _pagemap; union PML low_base_pmls[34][512] _pagemap; union PML twom_high_pds[4][512] _pagemap; /** * @brief Maps a frame address to a virtual address. * * Returns the virtual address within the general-purpose * identity mapping region for the given physical frame address. * This address is not suitable for some operations, such as MMIO. */ void * mmu_map_from_physical(uintptr_t frameaddress) { return (void*)(frameaddress | HIGH_MAP_REGION); } /** * @brief Find the physical address at a given virtual address. * * Calculates the physical address of the page backing the virtual * address @p virtAddr. If no page is mapped, a negative value * is returned indicating which level of the page directory is * unmapped from -1 (no PDP) to -4 (page not present in table). */ uintptr_t mmu_map_to_physical(uintptr_t virtAddr) { uintptr_t realBits = virtAddr & CANONICAL_MASK; uintptr_t pageAddr = realBits >> PAGE_SHIFT; unsigned int pml4_entry = (pageAddr >> 27) & ENTRY_MASK; unsigned int pdp_entry = (pageAddr >> 18) & ENTRY_MASK; unsigned int pd_entry = (pageAddr >> 9) & ENTRY_MASK; unsigned int pt_entry = (pageAddr) & ENTRY_MASK; union PML * root = this_core->current_pml; /* Get the PML4 entry for this address */ if (!root[pml4_entry].bits.present) return (uintptr_t)-1; union PML * pdp = mmu_map_from_physical((uintptr_t)root[pml4_entry].bits.page << PAGE_SHIFT); if (!pdp[pdp_entry].bits.present) return (uintptr_t)-2; if (pdp[pdp_entry].bits.size) return ((uintptr_t)pdp[pdp_entry].bits.page << PAGE_SHIFT) | (virtAddr & PDP_MASK); union PML * pd = mmu_map_from_physical((uintptr_t)pdp[pdp_entry].bits.page << PAGE_SHIFT); if (!pd[pd_entry].bits.present) return (uintptr_t)-3; if (pd[pd_entry].bits.size) return ((uintptr_t)pd[pd_entry].bits.page << PAGE_SHIFT) | (virtAddr & PD_MASK); union PML * pt = mmu_map_from_physical((uintptr_t)pd[pd_entry].bits.page << PAGE_SHIFT); if (!pt[pt_entry].bits.present) return (uintptr_t)-4; return ((uintptr_t)pt[pt_entry].bits.page << PAGE_SHIFT) | (virtAddr & PT_MASK); } /** * @brief Obtain the page entry for a virtual address. * * Digs into the current page directory to obtain the page entry * for a requested address @p virtAddr. If new intermediary directories * need to be allocated and @p flags has @c MMU_GET_MAKE set, they * will be allocated with the user access bits set. Otherwise, * NULL will be returned. If the requested virtual address is within * a large page, NULL will be returned. * * @param virtAddr Canonical virtual address offset. * @param flags See @c MMU_GET_MAKE * @returns the requested page entry, or NULL if doing so required allocating * an intermediary paging level and @p flags did not have @c MMU_GET_MAKE set. */ union PML * mmu_get_page(uintptr_t virtAddr, int flags) { uintptr_t realBits = virtAddr & CANONICAL_MASK; uintptr_t pageAddr = realBits >> PAGE_SHIFT; unsigned int pml4_entry = (pageAddr >> 27) & ENTRY_MASK; unsigned int pdp_entry = (pageAddr >> 18) & ENTRY_MASK; unsigned int pd_entry = (pageAddr >> 9) & ENTRY_MASK; unsigned int pt_entry = (pageAddr) & ENTRY_MASK; union PML * root = this_core->current_pml; /* Get the PML4 entry for this address */ if (!root[pml4_entry].bits.present) { if (!(flags & MMU_GET_MAKE)) goto _noentry; spin_lock(frame_alloc_lock); uintptr_t newPage = mmu_first_frame() << PAGE_SHIFT; mmu_frame_set(newPage); spin_unlock(frame_alloc_lock); /* zero it */ memset(mmu_map_from_physical(newPage), 0, PAGE_SIZE); root[pml4_entry].raw = (newPage) | USER_PML_ACCESS; } union PML * pdp = mmu_map_from_physical((uintptr_t)root[pml4_entry].bits.page << PAGE_SHIFT); if (!pdp[pdp_entry].bits.present) { if (!(flags & MMU_GET_MAKE)) goto _noentry; spin_lock(frame_alloc_lock); uintptr_t newPage = mmu_first_frame() << PAGE_SHIFT; mmu_frame_set(newPage); spin_unlock(frame_alloc_lock); /* zero it */ memset(mmu_map_from_physical(newPage), 0, PAGE_SIZE); pdp[pdp_entry].raw = (newPage) | USER_PML_ACCESS; } if (pdp[pdp_entry].bits.size) { printf("Warning: Tried to get page for a 1GiB page!\n"); return NULL; } union PML * pd = mmu_map_from_physical((uintptr_t)pdp[pdp_entry].bits.page << PAGE_SHIFT); if (!pd[pd_entry].bits.present) { if (!(flags & MMU_GET_MAKE)) goto _noentry; spin_lock(frame_alloc_lock); uintptr_t newPage = mmu_first_frame() << PAGE_SHIFT; mmu_frame_set(newPage); spin_unlock(frame_alloc_lock); /* zero it */ memset(mmu_map_from_physical(newPage), 0, PAGE_SIZE); pd[pd_entry].raw = (newPage) | USER_PML_ACCESS; } if (pd[pd_entry].bits.size) { printf("Warning: Tried to get page for a 2MiB page!\n"); return NULL; } union PML * pt = mmu_map_from_physical((uintptr_t)pd[pd_entry].bits.page << PAGE_SHIFT); return (union PML *)&pt[pt_entry]; _noentry: printf("no entry for requested page\n"); return NULL; } /** * @brief Create a new address space with the same contents of an existing one. * * Allocates all of the necessary intermediary directory levels for a new address space * and also copies data from the existing address space. * * TODO: This doesn't do any CoW and it's kinda complicated. * * @param from The directory to clone, or NULL to clone the kernel map. * @returns a pointer to the new page directory, suitable for mapping to a physical address. */ union PML * mmu_clone(union PML * from) { /* Clone the current PMLs... */ if (!from) from = this_core->current_pml; /* First get a page for ourselves. */ spin_lock(frame_alloc_lock); uintptr_t newPage = mmu_first_frame() << PAGE_SHIFT; mmu_frame_set(newPage); spin_unlock(frame_alloc_lock); union PML * pml4_out = mmu_map_from_physical(newPage); /* Zero bottom half */ memset(&pml4_out[0], 0, 256 * sizeof(union PML)); /* Copy top half */ memcpy(&pml4_out[256], &from[256], 256 * sizeof(union PML)); /* Copy PDPs */ for (size_t i = 0; i < 256; ++i) { if (from[i].bits.present) { union PML * pdp_in = mmu_map_from_physical((uintptr_t)from[i].bits.page << PAGE_SHIFT); spin_lock(frame_alloc_lock); uintptr_t newPage = mmu_first_frame() << PAGE_SHIFT; mmu_frame_set(newPage); spin_unlock(frame_alloc_lock); union PML * pdp_out = mmu_map_from_physical(newPage); memset(pdp_out, 0, 512 * sizeof(union PML)); pml4_out[i].raw = (newPage) | USER_PML_ACCESS; /* Copy the PDs */ for (size_t j = 0; j < 512; ++j) { if (pdp_in[j].bits.present) { union PML * pd_in = mmu_map_from_physical((uintptr_t)pdp_in[j].bits.page << PAGE_SHIFT); spin_lock(frame_alloc_lock); uintptr_t newPage = mmu_first_frame() << PAGE_SHIFT; mmu_frame_set(newPage); spin_unlock(frame_alloc_lock); union PML * pd_out = mmu_map_from_physical(newPage); memset(pd_out, 0, 512 * sizeof(union PML)); pdp_out[j].raw = (newPage) | USER_PML_ACCESS; /* Now copy the PTs */ for (size_t k = 0; k < 512; ++k) { if (pd_in[k].bits.present) { union PML * pt_in = mmu_map_from_physical((uintptr_t)pd_in[k].bits.page << PAGE_SHIFT); spin_lock(frame_alloc_lock); uintptr_t newPage = mmu_first_frame() << PAGE_SHIFT; mmu_frame_set(newPage); spin_unlock(frame_alloc_lock); union PML * pt_out = mmu_map_from_physical(newPage); memset(pt_out, 0, 512 * sizeof(union PML)); pd_out[k].raw = (newPage) | USER_PML_ACCESS; /* Now, finally, copy pages */ for (size_t l = 0; l < 512; ++l) { uintptr_t address = ((i << (9 * 3 + 12)) | (j << (9*2 + 12)) | (k << (9 + 12)) | (l << PAGE_SHIFT)); if (address >= USER_DEVICE_MAP && address <= USER_SHM_HIGH) continue; if (pt_in[l].bits.present) { if (pt_in[l].bits.user) { char * page_in = mmu_map_from_physical((uintptr_t)pt_in[l].bits.page << PAGE_SHIFT); spin_lock(frame_alloc_lock); uintptr_t newPage = mmu_first_frame() << PAGE_SHIFT; mmu_frame_set(newPage); spin_unlock(frame_alloc_lock); char * page_out = mmu_map_from_physical(newPage); memcpy(page_out,page_in,PAGE_SIZE); pt_out[l].bits.page = newPage >> PAGE_SHIFT; pt_out[l].bits.present = 1; pt_out[l].bits.user = 1; pt_out[l].bits.writable = pt_in[l].bits.writable; pt_out[l].bits.writethrough = pt_out[l].bits.writethrough; pt_out[l].bits.accessed = pt_out[l].bits.accessed; pt_out[l].bits.size = pt_out[l].bits.size; pt_out[l].bits.global = pt_out[l].bits.global; pt_out[l].bits.nx = pt_out[l].bits.nx; } else { /* If it's not a user page, just copy directly */ pt_out[l].raw = pt_in[l].raw; } } } } } } } } } return pml4_out; } /** * @brief Allocate one physical page. * * @returns a frame index, not an address */ uintptr_t mmu_allocate_a_frame(void) { spin_lock(frame_alloc_lock); uintptr_t index = mmu_first_frame(); mmu_frame_set(index << PAGE_SHIFT); spin_unlock(frame_alloc_lock); return index; } /** * @brief Allocate a number of contiguous physical pages. * * @returns a frame index, not an address */ uintptr_t mmu_allocate_n_frames(int n) { spin_lock(frame_alloc_lock); uintptr_t index = mmu_first_n_frames(n); for (int i = 0; i < n; ++i) { mmu_frame_set((index+i) << PAGE_SHIFT); } spin_unlock(frame_alloc_lock); return index; } /** * @brief Scans a directory to calculate how many user pages are in use. * * Calculates how many pages a userspace application has mapped, between * its general memory space and stack. Excludes shared mappings, such * as SHM or mapped devices. * * TODO: This can probably be reduced to check a smaller range, but as we * currently stick the user stack at the top of the low half of the * address space we just scan everything and exclude shared memory... * * @param from Top-level page directory to scan. */ size_t mmu_count_user(union PML * from) { size_t out = 0; for (size_t i = 0; i < 256; ++i) { if (from[i].bits.present) { union PML * pdp_in = mmu_map_from_physical((uintptr_t)from[i].bits.page << PAGE_SHIFT); for (size_t j = 0; j < 512; ++j) { if (pdp_in[j].bits.present) { union PML * pd_in = mmu_map_from_physical((uintptr_t)pdp_in[j].bits.page << PAGE_SHIFT); for (size_t k = 0; k < 512; ++k) { if (pd_in[k].bits.present) { union PML * pt_in = mmu_map_from_physical((uintptr_t)pd_in[k].bits.page << PAGE_SHIFT); for (size_t l = 0; l < 512; ++l) { /* Calculate final address to skip SHM */ uintptr_t address = ((i << (9 * 3 + 12)) | (j << (9*2 + 12)) | (k << (9 + 12)) | (l << PAGE_SHIFT)); if (address >= USER_DEVICE_MAP && address <= USER_SHM_HIGH) continue; if (pt_in[l].bits.present) { if (pt_in[l].bits.user) { out++; } } } } } } } } } return out; } /** * @brief Scans a directory to calculate how many shared memory pages are in use. * * At the moment, we only ever map shared pages to a specific region, so we just figure * out how many present pages are in that region and that's the answer. * * @param from Top-level page directory to scan. */ size_t mmu_count_shm(union PML * from) { size_t out = 0; if (from[0].bits.present) { union PML * pdp_in = mmu_map_from_physical((uintptr_t)from[0].bits.page << PAGE_SHIFT); /* [0,8,0,0] through [0,15,511,511] map to our current SHM mapping region; * if you change the bounds of that region, be sure to update this! */ for (size_t j = 8; j < 16; ++j) { if (pdp_in[j].bits.present) { union PML * pd_in = mmu_map_from_physical((uintptr_t)pdp_in[j].bits.page << PAGE_SHIFT); for (size_t k = 0; k < 512; ++k) { if (pd_in[k].bits.present) { union PML * pt_in = mmu_map_from_physical((uintptr_t)pd_in[k].bits.page << PAGE_SHIFT); for (size_t l = 0; l < 512; ++l) { if (pt_in[l].bits.present) { if (pt_in[l].bits.user) { out++; } } } } } } } } return out; } /** * @brief Return the total amount of usable memory. * * Just returns the number of frames in the bitmap allocator, times 4. * * @returns the total amount of usable memory in KiB. */ size_t mmu_total_memory(void) { return nframes * 4; } /** * @brief Return the amount of used memory. * * Calculates the number of pages currently marked as allocated. * Multiplies it by 4 because pages are 4KiB. * * @returns the amount of memory in use in KiB. */ size_t mmu_used_memory(void) { size_t ret = 0; size_t i, j; for (i = 0; i < INDEX_FROM_BIT(nframes); ++i) { for (j = 0; j < 32; ++j) { uint32_t testFrame = (uint32_t)0x1 << j; if (frames[i] & testFrame) { ret++; } } } return ret * 4; } /** * @brief Relinquish pages owned by a top-level directory. * * Frees the underlying pages for a page directory within the lower (user) region. * Does not free kernel pages, as those are generally shared in the lower region. * * @param from Virtual pointer to top-level directory. */ void mmu_free(union PML * from) { if (!from) { printf("can't clear NULL directory\n"); return; } spin_lock(frame_alloc_lock); for (size_t i = 0; i < 256; ++i) { if (from[i].bits.present) { union PML * pdp_in = mmu_map_from_physical((uintptr_t)from[i].bits.page << PAGE_SHIFT); for (size_t j = 0; j < 512; ++j) { if (pdp_in[j].bits.present) { union PML * pd_in = mmu_map_from_physical((uintptr_t)pdp_in[j].bits.page << PAGE_SHIFT); for (size_t k = 0; k < 512; ++k) { if (pd_in[k].bits.present) { union PML * pt_in = mmu_map_from_physical((uintptr_t)pd_in[k].bits.page << PAGE_SHIFT); for (size_t l = 0; l < 512; ++l) { uintptr_t address = ((i << (9 * 3 + 12)) | (j << (9*2 + 12)) | (k << (9 + 12)) | (l << PAGE_SHIFT)); /* Do not free shared mappings; SHM subsystem does that for SHM, devices don't need it. */ if (address >= USER_DEVICE_MAP && address <= USER_SHM_HIGH) continue; if (pt_in[l].bits.present) { /* Free only user pages */ if (pt_in[l].bits.user) { mmu_frame_clear((uintptr_t)pt_in[l].bits.page << PAGE_SHIFT); } } } mmu_frame_clear((uintptr_t)pd_in[k].bits.page << PAGE_SHIFT); } } mmu_frame_clear((uintptr_t)pdp_in[j].bits.page << PAGE_SHIFT); } } mmu_frame_clear((uintptr_t)from[i].bits.page << PAGE_SHIFT); } } mmu_frame_clear((((uintptr_t)from) & PHYS_MASK)); spin_unlock(frame_alloc_lock); } union PML * mmu_get_kernel_directory(void) { return mmu_map_from_physical((uintptr_t)&init_page_region[0]); } /** * @brief Switch the active page directory for this core. * * Generally called during task creation and switching to change * the active page directory of a core. Updates @c this_core->current_pml. * * x86-64: Loads a given PML into CR3. * * @param new_pml Either the physical address or the shadow mapping virtual address * of the new PML4 directory to switch into, general obtained from * a process struct; if NULL is passed, the initial kernel directory * will be used and no userspace mappings will be present. */ void mmu_set_directory(union PML * new_pml) { if (!new_pml) new_pml = mmu_map_from_physical((uintptr_t)&init_page_region[0]); this_core->current_pml = new_pml; asm volatile ( "movq %0, %%cr3" : : "r"((uintptr_t)new_pml & PHYS_MASK)); } /** * @brief Mark a virtual address's mappings as invalid in the TLB. * * Generally should be called when a mapping is relinquished, as this is what * the TLB caches, but is also called in a bunch of places where we're just mapping * new pages... * * @param addr Virtual address in the current address space to invalidate. */ void mmu_invalidate(uintptr_t addr) { asm volatile ( "invlpg (%0)" : : "r"(addr)); arch_tlb_shootdown(); } static char * heapStart = NULL; extern char end[]; /** * @brief Prepare virtual page mappings for use by the kernel. * * Called during early boot to switch from the loader/bootstrap mappings * to ones suitable for general use. Sets up the bitmap allocator, high * identity mapping, kernel heap, and various mid-level structures to * ensure that future kernelspace mappings apply to all kernel threads. * * @param memsize The maximum accessible physical address. * @param firstFreePage The address of the first frame the kernel may use for new allocations. */ void mmu_init(size_t memsize, uintptr_t firstFreePage) { this_core->current_pml = (union PML *)&init_page_region[0]; /* Map the high base PDP */ init_page_region[0][511].raw = (uintptr_t)&high_base_pml | KERNEL_PML_ACCESS; init_page_region[0][510].raw = (uintptr_t)&heap_base_pml | KERNEL_PML_ACCESS; /* Identity map from -128GB in the boot PML using 2MiB pages */ high_base_pml[0].raw = (uintptr_t)&twom_high_pds[0] | KERNEL_PML_ACCESS; high_base_pml[1].raw = (uintptr_t)&twom_high_pds[1] | KERNEL_PML_ACCESS; high_base_pml[2].raw = (uintptr_t)&twom_high_pds[2] | KERNEL_PML_ACCESS; high_base_pml[3].raw = (uintptr_t)&twom_high_pds[3] | KERNEL_PML_ACCESS; for (uintptr_t i = 0; i < 512; i += 1) { twom_high_pds[0][i].raw = (0x00000000 + i * LARGE_PAGE_SIZE) | LARGE_PAGE_BIT | KERNEL_PML_ACCESS; twom_high_pds[1][i].raw = (0x40000000 + i * LARGE_PAGE_SIZE) | LARGE_PAGE_BIT | KERNEL_PML_ACCESS; twom_high_pds[2][i].raw = (0x80000000 + i * LARGE_PAGE_SIZE) | LARGE_PAGE_BIT | KERNEL_PML_ACCESS; twom_high_pds[3][i].raw = (0xC0000000 + i * LARGE_PAGE_SIZE) | LARGE_PAGE_BIT | KERNEL_PML_ACCESS; } /* Map low base PDP */ low_base_pmls[0][0].raw = (uintptr_t)&low_base_pmls[1] | USER_PML_ACCESS; /* How much memory do we need to map low for our *kernel* to fit? */ uintptr_t endPtr = ((uintptr_t)&end + PAGE_LOW_MASK) & PAGE_SIZE_MASK; /* How many pages does that need? */ size_t lowPages = endPtr >> PAGE_SHIFT; /* And how many 512-page blocks does that fit in? */ size_t pdCount = (lowPages + ENTRY_MASK) >> 9; for (size_t j = 0; j < pdCount; ++j) { low_base_pmls[1][j].raw = (uintptr_t)&low_base_pmls[2+j] | KERNEL_PML_ACCESS; for (int i = 0; i < 512; ++i) { low_base_pmls[2+j][i].raw = (uintptr_t)(LARGE_PAGE_SIZE * j + PAGE_SIZE * i) | KERNEL_PML_ACCESS; } } /* Unmap null */ low_base_pmls[2][0].raw = 0; /* Now map our new low base */ init_page_region[0][0].raw = (uintptr_t)&low_base_pmls[0] | USER_PML_ACCESS; /* Set up the page allocator bitmap... */ nframes = (memsize >> 12); size_t bytesOfFrames = INDEX_FROM_BIT(nframes * 8); bytesOfFrames = (bytesOfFrames + PAGE_LOW_MASK) & PAGE_SIZE_MASK; firstFreePage = (firstFreePage + PAGE_LOW_MASK) & PAGE_SIZE_MASK; size_t pagesOfFrames = bytesOfFrames >> 12; /* Set up heap map for that... */ heap_base_pml[0].raw = (uintptr_t)&heap_base_pd | KERNEL_PML_ACCESS; heap_base_pd[0].raw = (uintptr_t)&heap_base_pt | KERNEL_PML_ACCESS; if (pagesOfFrames > 512) { printf("Warning: Too much available memory for current setup. Need %zu pages to represent allocation bitmap.\n", pagesOfFrames); } for (size_t i = 0; i < pagesOfFrames; i++) { heap_base_pt[i].raw = (firstFreePage + (i << 12)) | KERNEL_PML_ACCESS; } asm volatile ("" : : : "memory"); this_core->current_pml = mmu_map_from_physical((uintptr_t)this_core->current_pml); asm volatile ("" : : : "memory"); /* We are now in the new stuff. */ frames = (void*)((uintptr_t)KERNEL_HEAP_START); memset((void*)frames, 0, bytesOfFrames); /* Now mark everything up to (firstFreePage + bytesOfFrames) as in use */ for (uintptr_t i = 0; i < firstFreePage + bytesOfFrames; i += PAGE_SIZE) { mmu_frame_set(i); } heapStart = (char*)KERNEL_HEAP_START + bytesOfFrames; } /** * @brief Allocate space in the kernel virtual heap. * * Called by the kernel heap allocator to obtain space for new heap allocations. * * @warning Not to be confused with sys_sbrk * * @param bytes Bytes to allocate. Must be a multiple of PAGE_SIZE. * @returns The previous address of the break point, after which @p bytes may now be used. */ void * sbrk(size_t bytes) { if (!heapStart) { printf("sbrk: Called before heap was ready.\n"); arch_fatal(); } if (!bytes) { /* Skip lock acquisition if we just wanted to know where the break was. */ return heapStart; } if (bytes & PAGE_LOW_MASK) { printf("sbrk: Size must be multiple of 4096, was %#zx\n", bytes); arch_fatal(); } if (bytes > 0xF00000) { printf("sbrk: Size must be within a reasonable bound, was %#zx\n", bytes); arch_fatal(); } spin_lock(kheap_lock); void * out = heapStart; for (uintptr_t p = (uintptr_t)out; p < (uintptr_t)out + bytes; p += PAGE_SIZE) { union PML * page = mmu_get_page(p, MMU_GET_MAKE); mmu_frame_allocate(page, MMU_FLAG_WRITABLE | MMU_FLAG_KERNEL); mmu_invalidate(p); } memset(out, 0xAA, bytes); heapStart += bytes; spin_unlock(kheap_lock); return out; } static uintptr_t mmio_base_address = MMIO_BASE_START; /** * @brief Obtain a writethrough region mapped to the given physical address. * * For use by device drivers to obtain mappings suitable for MMIO accesses. Note that the * virtual address space for these mappings can not be reclaimed, so drivers should keep * them around or use the other MMU facilities to repurpose them. * * @param physical_address Physical memory offset of the destination MMIO space. * @param size Size of the requested space, which must be a multiple of PAGE_SIZE. * @returns a virtual address suitable for MMIO accesses. */ void * mmu_map_mmio_region(uintptr_t physical_address, size_t size) { if (size & PAGE_LOW_MASK) { printf("mmu_map_mmio_region: MMIO region size must be multiple of 4096 bytes, was %#zx.\n", size); arch_fatal(); } spin_lock(mmio_space_lock); void * out = (void*)mmio_base_address; for (size_t i = 0; i < size; i += PAGE_SIZE) { union PML * p = mmu_get_page(mmio_base_address + i, MMU_GET_MAKE); mmu_frame_map_address(p, MMU_FLAG_KERNEL | MMU_FLAG_WRITABLE | MMU_FLAG_NOCACHE | MMU_FLAG_WRITETHROUGH, physical_address + i); mmu_invalidate(mmio_base_address + i); } mmio_base_address += size; spin_unlock(mmio_space_lock); return out; }