From 292e4141078d18993b1395820631503ac852eb3d Mon Sep 17 00:00:00 2001 From: Alex Auvolat Date: Thu, 4 Dec 2014 10:43:58 +0100 Subject: Make paging work ! \o/ --- kernel/config.h | 4 +- kernel/include/paging.h | 10 ++- kernel/include/region.h | 5 -- kernel/include/sys.h | 11 +++ kernel/l0/dbglog.c | 2 +- kernel/l0/frame.c | 10 +-- kernel/l0/idt.c | 10 +-- kernel/l0/kmain.c | 40 ++++++++++- kernel/l0/loader.s | 8 +-- kernel/l0/paging.c | 183 +++++++++++++++++++++++++++++++----------------- kernel/l0/region.c | 25 ++----- run_qemu.sh | 2 +- 12 files changed, 192 insertions(+), 118 deletions(-) diff --git a/kernel/config.h b/kernel/config.h index ad3dfb2..d198295 100644 --- a/kernel/config.h +++ b/kernel/config.h @@ -14,9 +14,7 @@ #endif -extern char k_highhalf_addr, k_end_addr; // defined in linker script : 0xC0000000 -#define K_HIGHHALF_ADDR ((size_t)&k_highhalf_addr) -#define K_END_ADDR ((size_t)&k_end_addr) +#define K_HIGHHALF_ADDR ((size_t)0xC0000000) #define OS_NAME "macrO.Scope" #define OS_VERSION "0.0.1" diff --git a/kernel/include/paging.h b/kernel/include/paging.h index 7082e2e..2e1f844 100644 --- a/kernel/include/paging.h +++ b/kernel/include/paging.h @@ -13,13 +13,11 @@ pagedir_t *get_kernel_pagedir(); void switch_pagedir(pagedir_t *pd); -// The three functions below DO NOT DEPEND on argument pd for -// addresses above K_HIGHHALF_ADDR, so just pass 0 to map/unmap in kernel space. -uint32_t pd_get_frame(pagedir_t *pd, size_t vaddr); // get physical frame for virtual address -int pd_map_page(pagedir_t *pd, - size_t vaddr, uint32_t frame_id, +// these functions are always relative to the currently mapped page directory +uint32_t pd_get_frame(size_t vaddr); // get physical frame for virtual address +int pd_map_page(size_t vaddr, uint32_t frame_id, uint32_t rw); // returns nonzero on error -void pd_unmap_page(pagedir_t *pd, size_t vaddr); // does nothing if page wasn't mapped +void pd_unmap_page(size_t vaddr); // does nothing if page not mapped pagedir_t *create_pagedir(); // returns zero on error void delete_pagedir(pagedir_t *pd); diff --git a/kernel/include/region.h b/kernel/include/region.h index 3c64081..1628370 100644 --- a/kernel/include/region.h +++ b/kernel/include/region.h @@ -29,9 +29,4 @@ size_t region_alloc(size_t size, uint32_t type, page_fault_handler_t pf); // ret region_info_t *find_region(size_t addr); void region_free(size_t addr); -#define N_PAGES_IN_PT_REGION 4 -// special call for use by paging code -// allocates a region of N_PAGES_IN_PT_REGION pages -size_t region_alloc_for_pt(); - void dbg_print_region_stats(); diff --git a/kernel/include/sys.h b/kernel/include/sys.h index a9d2d4c..ff98c60 100644 --- a/kernel/include/sys.h +++ b/kernel/include/sys.h @@ -22,6 +22,10 @@ static inline uint16_t inw(uint16_t port) { return ret; } +static inline void invlpg(size_t addr) { + asm volatile("invlpg (%0)" : : "r"(addr) : "memory"); +} + void panic(const char* message, const char* file, int line); void panic_assert(const char* assertion, const char* file, int line); #define PANIC(s) panic(s, __FILE__, __LINE__); @@ -37,6 +41,13 @@ void panic_assert(const char* assertion, const char* file, int line); #define PAGE_ALIGN_DOWN(x) (((size_t)x) & PAGE_MASK) #define PAGE_ALIGN_UP(x) ((((size_t)x)&(~PAGE_MASK)) == 0 ? ((size_t)x) : (((size_t)x) & PAGE_MASK) + PAGE_SIZE) #define PAGE_ID(x) (((size_t)x) / PAGE_SIZE) +#define PAGE_SHIFT 12 +#define PT_SHIFT 10 +// PAGE_SHIFT + PT_SHIFT + PT_SHIFT = 32 +#define N_PAGES_IN_PT 1024 +#define PD_MIRROR_ADDR 0xFFC00000 // last 4MB used for PD mirroring +#define LAST_KERNEL_ADDR PD_MIRROR_ADDR +#define FIRST_KERNEL_PT (K_HIGHHALF_ADDR >> (PAGE_SHIFT+PT_SHIFT)) // must be 768 #define MASK4 0xFFFFFFFC #define ALIGN4_UP(x) ((((size_t)x)&(~MASK4)) == 0 ? ((size_t)x) : (((size_t)x) & MASK4) + 4) diff --git a/kernel/l0/dbglog.c b/kernel/l0/dbglog.c index 377e6c8..5a7251b 100644 --- a/kernel/l0/dbglog.c +++ b/kernel/l0/dbglog.c @@ -38,7 +38,7 @@ static void vga_update_cursor() { static void vga_init() { vga_row = 0; vga_column = 0; - vga_buffer = (uint16_t*) (&k_highhalf_addr + 0xB8000); + vga_buffer = (uint16_t*) (K_HIGHHALF_ADDR + 0xB8000); for (size_t y = 0; y < VGA_HEIGHT; y++) { for (size_t x = 0; x < VGA_WIDTH; x++) { diff --git a/kernel/l0/frame.c b/kernel/l0/frame.c index 1f16eaf..c646a48 100644 --- a/kernel/l0/frame.c +++ b/kernel/l0/frame.c @@ -4,8 +4,8 @@ // TODO: buddy allocator // this is a simple bitmap allocator -#define INDEX_FROM_BIT(a) (a/(8*4)) -#define OFFSET_FROM_BIT(a) (a%(8*4)) +#define INDEX_FROM_BIT(a) ((a)/(8*4)) +#define OFFSET_FROM_BIT(a) ((a)%(8*4)) static uint32_t *frame_bitset; static uint32_t nframes, nused_frames; @@ -54,9 +54,9 @@ uint32_t frame_alloc(size_t n) { } void frame_free(uint32_t base, size_t n) { - for (size_t x = 0; x < n; x++) { - uint32_t idx = INDEX_FROM_BIT(base + n); - uint32_t ofs = OFFSET_FROM_BIT(base + n); + for (size_t i = 0; i < n; i++) { + uint32_t idx = INDEX_FROM_BIT(base + i); + uint32_t ofs = OFFSET_FROM_BIT(base + i); if (frame_bitset[idx] & (0x1 << ofs)) { frame_bitset[idx] &= ~(0x1 << ofs); nused_frames--; diff --git a/kernel/l0/idt.c b/kernel/l0/idt.c index 8a981af..3bfcfc5 100644 --- a/kernel/l0/idt.c +++ b/kernel/l0/idt.c @@ -66,11 +66,11 @@ static isr_handler_t ex_handlers[32] = {0}; /* Called in interrupt.s when an exception fires (interrupt 0 to 31) */ void idt_exHandler(registers_t *regs) { - dbg_printf("/ Exception %i\n", regs->int_no); - dbg_printf("| EAX: 0x%p EBX: 0x%p ECX: 0x%p EDX: 0x%p\n", regs->eax, regs->ebx, regs->ecx, regs->edx); - dbg_printf("| EDI: 0x%p ESI: 0x%p ESP: 0x%p EBP: 0x%p\n", regs->edi, regs->esi, regs->esp, regs->ebp); - dbg_printf("| EIP: 0x%p CS : 0x%p DS : 0x%p SS : 0x%p\n", regs->eip, regs->cs, regs->ds, regs->ss); - dbg_printf("\\ EFl: 0x%p I# : 0x%p Err: 0x%p\n", regs->eflags, regs->int_no, regs->err_code); + /*dbg_printf("/ Exception %i\n", regs->int_no);*/ + /*dbg_printf("| EAX: 0x%p EBX: 0x%p ECX: 0x%p EDX: 0x%p\n", regs->eax, regs->ebx, regs->ecx, regs->edx);*/ + /*dbg_printf("| EDI: 0x%p ESI: 0x%p ESP: 0x%p EBP: 0x%p\n", regs->edi, regs->esi, regs->esp, regs->ebp);*/ + /*dbg_printf("| EIP: 0x%p CS : 0x%p DS : 0x%p SS : 0x%p\n", regs->eip, regs->cs, regs->ds, regs->ss);*/ + /*dbg_printf("\\ EFl: 0x%p I# : 0x%p Err: 0x%p\n", regs->eflags, regs->int_no, regs->err_code);*/ if (ex_handlers[regs->int_no] != 0) { ex_handlers[regs->int_no](regs); diff --git a/kernel/l0/kmain.c b/kernel/l0/kmain.c index f07e243..a221b0e 100644 --- a/kernel/l0/kmain.c +++ b/kernel/l0/kmain.c @@ -13,6 +13,19 @@ void breakpoint_handler(registers_t *regs) { dbg_printf("Breakpoint! (int3)\n"); BOCHS_BREAKPOINT; } + +void test_pf_handler(pagedir_t *pd, region_info_t *i, size_t addr) { + dbg_printf("0x%p", addr); + + uint32_t f = frame_alloc(1); + if (f == 0) PANIC("Out Of Memory"); + dbg_printf(" -> %i", f); + + int error = pd_map_page(addr, f, 1); + if (error) PANIC("Could not map frame (OOM)"); +} + +extern char k_end_addr; // defined in linker script : 0xC0000000 void kmain(struct multiboot_info_t *mbd, int32_t mb_magic) { dbglog_setup(); @@ -35,7 +48,7 @@ void kmain(struct multiboot_info_t *mbd, int32_t mb_magic) { // used for allocation of data structures before malloc is set up // a pointer to this pointer is passed to the functions that might have // to allocate memory ; they just increment it of the allocated quantity - void* kernel_data_end = (void*)K_END_ADDR; + void* kernel_data_end = (void*)&k_end_addr; frame_init_allocator(total_ram, &kernel_data_end); dbg_printf("kernel_data_end: 0x%p\n", kernel_data_end); @@ -72,6 +85,31 @@ void kmain(struct multiboot_info_t *mbd, int32_t mb_magic) { dbg_printf("Freed region 0x%p\n", s); dbg_print_region_stats(); + // allocate a big region and try to write into it + const size_t n = 1000; + size_t p0 = region_alloc(n * PAGE_SIZE, REGION_T_HW, test_pf_handler); + for (size_t i = 0; i < n; i++) { + uint32_t *x = (uint32_t*)(p0 + i * PAGE_SIZE); + dbg_printf("[%i : ", i); + x[0] = 12; + dbg_printf(" : ."); + x[1] = (i * 20422) % 122; + dbg_printf("]\n", i); + } + // unmap memory + for (size_t i = 0; i < n; i++) { + uint32_t *x = (uint32_t*)(p0 + i * PAGE_SIZE); + ASSERT(x[1] == (i * 20422) % 122); + + size_t f = pd_get_frame((size_t)x); + ASSERT(f != 0); + pd_unmap_page((size_t)x); + + frame_free(f, 1); + } + region_free(s); + + // TODO: // - setup allocator for physical pages (eg: buddy allocator, see OSDev wiki) // - setup allocator for virtual memory space diff --git a/kernel/l0/loader.s b/kernel/l0/loader.s index e4c4611..6ad4ff0 100644 --- a/kernel/l0/loader.s +++ b/kernel/l0/loader.s @@ -1,6 +1,6 @@ [EXTERN kmain] ; kmain is defined in kmain.c [GLOBAL loader] ; making entry point visible to linker -[GLOBAL kernel_pagedir] ; make kernel page directory visible +[GLOBAL kernel_pd] ; make kernel page directory visible ; higher-half kernel setup K_HIGHHALF_ADDR equ 0xC0000000 @@ -25,7 +25,7 @@ multiboot_header: loader: ; setup the boot page directory used for higher-half - mov ecx, kernel_pagedir + mov ecx, kernel_pd sub ecx, K_HIGHHALF_ADDR ; access its lower-half address mov cr3, ecx @@ -45,7 +45,7 @@ loader: [section .data] align 0x1000 -kernel_pagedir: +kernel_pd: ; uses 4MB pages ; identity-maps the first 4Mb of RAM, and also maps them with offset += k_highhalf_addr dd 0x00000083 @@ -56,7 +56,7 @@ kernel_pagedir: [section .text] higherhalf: ; now we're running in higher half ; unmap first 4Mb - mov dword [kernel_pagedir], 0 + mov dword [kernel_pd], 0 invlpg [0] mov esp, stack_top ; set up the stack diff --git a/kernel/l0/paging.c b/kernel/l0/paging.c index f076aa1..74f3d09 100644 --- a/kernel/l0/paging.c +++ b/kernel/l0/paging.c @@ -2,83 +2,112 @@ #include #include #include - -typedef union page { - struct { - uint32_t present : 1; - uint32_t rw : 1; - uint32_t user : 1; - uint32_t write_through : 1; - uint32_t disable_cache : 1; - uint32_t accessed : 1; - uint32_t dirty : 1; // only PTE - uint32_t size_4m : 1; // only PDE - uint32_t global : 1; // only PTE - uint32_t rsvd : 3; - uint32_t frame : 20; - }; - uint32_t as_int32; -} page_t; +#include + +#define PAGE_OF_ADDR(x) (((size_t)x >> PAGE_SHIFT) % N_PAGES_IN_PT) +#define PT_OF_ADDR(x) ((size_t)x >> (PAGE_SHIFT + PT_SHIFT)) + +#define PTE_PRESENT (1<<0) +#define PTE_RW (1<<1) +#define PTE_USER (1<<2) +#define PTE_WRITE_THROUGH (1<<3) +#define PTE_DISABLE_CACHE (1<<4) +#define PTE_ACCESSED (1<<5) +#define PTE_DIRTY (1<<6) // only PTE +#define PTE_SIZE_4M (1<<7) // only PDE +#define PTE_GLOBAL (1<<8) // only PTE +#define PTE_FRAME_SHIFT 12 typedef struct page_table { - page_t page[1024]; + uint32_t page[1024]; } pagetable_t; struct page_directory { - pagetable_t *pt[1024]; // virtual addresses of each page table - pagetable_t *dir; // virtual address of page directory size_t phys_addr; // physical address of page directory + // to modify a page directory, we first map it + // then we can use mirroring to edit it + // (the last 4M of the address space are mapped to the PD itself) + + // more info to be stored here, potentially }; // access kernel page directory page defined in loader.s // (this is a correct higher-half address) -extern pagetable_t kernel_pagedir; +extern pagetable_t kernel_pd; + +// pre-allocate a page table so that we can map the first 4M of kernel memory +static pagetable_t __attribute__((aligned(PAGE_SIZE))) kernel_pt0; -static pagetable_t __attribute__((aligned(PAGE_SIZE))) kernel_pt768; -static pagedir_t kernel_pd; +static pagedir_t kernel_pd_d; +static pagedir_t *current_pd_d; -static pagedir_t *current_pd; +#define current_pt ((pagetable_t*)PD_MIRROR_ADDR) +#define current_pd ((pagetable_t*)(PD_MIRROR_ADDR + (N_PAGES_IN_PT-1)*PAGE_SIZE)) void page_fault_handler(registers_t *regs) { - size_t addr; - asm volatile("movl %%cr2, %0":"=r"(addr)); - dbg_printf("Page fault at 0x%p\n", addr); - PANIC("PAGE FAULT"); - // not handled yet + size_t vaddr; + asm volatile("movl %%cr2, %0":"=r"(vaddr)); + + if (vaddr >= K_HIGHHALF_ADDR) { + uint32_t pt = PT_OF_ADDR(vaddr); + + if (current_pd != &kernel_pd && vaddr >= K_HIGHHALF_ADDR + && current_pd->page[pt] != kernel_pd.page[pt]) + { + current_pd->page[pt] = kernel_pd.page[pt]; + invlpg((size_t)(¤t_pt[pt])); + return; + } + + region_info_t *i = find_region(vaddr); + if (i == 0) { + dbg_printf("Kernel pagefault in non-existing region at 0x%p\n", vaddr); + PANIC("Unhandled kernel space page fault"); + } + if (i->pf == 0) { + dbg_printf("Kernel pagefault in region with no handler at 0x%p\n", vaddr); + PANIC("Unhandled kernel space page fault"); + } + i->pf(current_pd_d, i, vaddr); + } else { + dbg_printf("Userspace page fault at 0x%p\n", vaddr); + PANIC("Unhandled userspace page fault"); + // not handled yet + // TODO + } } void paging_setup(void* kernel_data_end) { size_t n_kernel_pages = PAGE_ALIGN_UP((size_t)kernel_data_end - K_HIGHHALF_ADDR)/PAGE_SIZE; - ASSERT(n_kernel_pages <= 1024); + ASSERT(n_kernel_pages <= 1024); // we use less than 4M for kernel - // setup kernel_pd structure - kernel_pd.dir = &kernel_pagedir; - kernel_pd.phys_addr = (size_t)kernel_pd.dir - K_HIGHHALF_ADDR; - for (size_t i = 0; i < 1024; i++) kernel_pd.pt[i] = 0; + // setup kernel_pd_d structure + kernel_pd_d.phys_addr = (size_t)&kernel_pd - K_HIGHHALF_ADDR; - // setup kernel_pt768 + // setup kernel_pt0 + ASSERT(PAGE_OF_ADDR(K_HIGHHALF_ADDR) == 0); // kernel is 4M-aligned + ASSERT(FIRST_KERNEL_PT == 768); for (size_t i = 0; i < n_kernel_pages; i++) { - kernel_pt768.page[i].as_int32 = 0; // clear any junk - kernel_pt768.page[i].present = 1; - kernel_pt768.page[i].user = 0; - kernel_pt768.page[i].rw = 1; - kernel_pt768.page[i].frame = i; + kernel_pt0.page[i] = (i << PTE_FRAME_SHIFT) | PTE_PRESENT | PTE_RW | PTE_GLOBAL; } for (size_t i = n_kernel_pages; i < 1024; i++){ - kernel_pt768.page[i].as_int32 = 0; + kernel_pt0.page[i] = 0; } - // replace 4M mapping by kernel_pt768 - kernel_pd.pt[768] = &kernel_pt768; - kernel_pd.dir->page[768].as_int32 = - (((size_t)&kernel_pt768 - K_HIGHHALF_ADDR) & PAGE_MASK) | 0x07; + // replace 4M mapping by kernel_pt0 + kernel_pd.page[FIRST_KERNEL_PT] = + (((size_t)&kernel_pt0 - K_HIGHHALF_ADDR) & PAGE_MASK) | PTE_PRESENT | PTE_RW; + // set up mirroring + kernel_pd.page[N_PAGES_IN_PT-1] = + (((size_t)&kernel_pd - K_HIGHHALF_ADDR) & PAGE_MASK) | PTE_PRESENT | PTE_RW; - current_pd = &kernel_pd; + invlpg(K_HIGHHALF_ADDR); // paging already enabled in loader, nothing to do. + switch_pagedir(&kernel_pd_d); // disable 4M pages (remove PSE bit in CR4) uint32_t cr4; @@ -90,45 +119,67 @@ void paging_setup(void* kernel_data_end) { } pagedir_t *get_current_pagedir() { - return current_pd; + return current_pd_d; } pagedir_t *get_kernel_pagedir() { - return &kernel_pd; + return &kernel_pd_d; } void switch_pagedir(pagedir_t *pd) { asm volatile("movl %0, %%cr3":: "r"(pd->phys_addr)); + invlpg((size_t)current_pd); + current_pd_d = pd; } // ============================== // // Mapping and unmapping of pages // // ============================== // -uint32_t pd_get_frame(pagedir_t *pd, size_t vaddr) { - uint32_t page = vaddr / PAGE_SIZE; - uint32_t pt = page / PAGE_SIZE; - uint32_t pt_page = page % PAGE_SIZE; +uint32_t pd_get_frame(size_t vaddr) { + uint32_t pt = PT_OF_ADDR(vaddr); + uint32_t page = PAGE_OF_ADDR(vaddr); + + pagetable_t *pd = (vaddr >= K_HIGHHALF_ADDR ? &kernel_pd : current_pd); - if (pd == 0) return 0; - if (pd->pt[pt] == 0) return 0; - if (!pd->pt[pt]->page[pt_page].present) return 0; - return pd->pt[pt]->page[pt_page].frame; + if (!pd->page[pt] & PTE_PRESENT) return 0; + if (!current_pt[pt].page[page] & PTE_PRESENT) return 0; + return current_pt[pt].page[page] >> PTE_FRAME_SHIFT; } -int pd_map_page(pagedir_t *pd, size_t vaddr, uint32_t frame_id, uint32_t rw) { - return 1; // TODO +int pd_map_page(size_t vaddr, uint32_t frame_id, uint32_t rw) { + uint32_t pt = PT_OF_ADDR(vaddr); + uint32_t page = PAGE_OF_ADDR(vaddr); + + pagetable_t *pd = (vaddr >= K_HIGHHALF_ADDR ? &kernel_pd : current_pd); + + if (!pd->page[pt] & PTE_PRESENT) { + size_t new_pt_frame = frame_alloc(1); + if (new_pt_frame == 0) return 1; // OOM + + current_pd->page[pt] = pd->page[pt] = + (new_pt_frame << PTE_FRAME_SHIFT) | PTE_PRESENT | PTE_RW; + invlpg((size_t)¤t_pt[pt]); + } + + current_pt[pt].page[page] = + frame_id << PTE_FRAME_SHIFT + | PTE_PRESENT + | (vaddr < K_HIGHHALF_ADDR ? PTE_USER : PTE_GLOBAL) + | (rw ? PTE_RW : 0); + + return 0; } -void pd_unmap_page(pagedir_t *pd, size_t vaddr) { - uint32_t page = vaddr / PAGE_SIZE; - uint32_t pt = page / PAGE_SIZE; - uint32_t pt_page = page % PAGE_SIZE; +void pd_unmap_page(size_t vaddr) { + uint32_t pt = PT_OF_ADDR(vaddr); + uint32_t page = PAGE_OF_ADDR(vaddr); + + pagetable_t *pd = (vaddr >= K_HIGHHALF_ADDR ? &kernel_pd : current_pd); - if (pd == 0) return; - if (pd->pt[pt] == 0) return; - if (!pd->pt[pt]->page[pt_page].present) return; - pd->pt[pt]->page[pt_page].as_int32 = 0; + if (!pd->page[pt] & PTE_PRESENT) return; + if (!current_pt[pt].page[page] & PTE_PRESENT) return; + current_pt[pt].page[page] &= ~PTE_PRESENT; // TODO (?) : if pagetable is completely empty, free it } diff --git a/kernel/l0/region.c b/kernel/l0/region.c index 63e464d..6001346 100644 --- a/kernel/l0/region.c +++ b/kernel/l0/region.c @@ -17,7 +17,7 @@ typedef union region_descriptor { } used; } descriptor_t; -#define N_RESERVE_DESCRIPTORS 3 // always keep at least 3 unused descriptors +#define N_RESERVE_DESCRIPTORS 2 // always keep at least 3 unused descriptors #define N_BASE_DESCRIPTORS 12 // pre-allocate memory for 12 descriptors static descriptor_t base_descriptors[N_BASE_DESCRIPTORS]; @@ -210,7 +210,7 @@ void region_allocator_init(void* kernel_data_end) { descriptor_t *f0 = &base_descriptors[1]; f0->free.addr = PAGE_ALIGN_UP(kernel_data_end); - f0->free.size = (0xFFFFF000-f0->free.addr); // last page cannot be used... + f0->free.size = (LAST_KERNEL_ADDR-f0->free.addr); f0->free.next_by_size = 0; f0->free.first_bigger = 0; first_free_region_by_size = first_free_region_by_addr = f0; @@ -234,8 +234,7 @@ static size_t region_alloc_inner(size_t size, uint32_t type, page_fault_handler_ return 0; } - // this assert is a bit tricky to prove, - // but basically it means that the allocation function + // this assert basically means that the allocation function // is called less than N_RESERVE_DESCRIPTORS times with // the use_reserve flag before more descriptors // are allocated. @@ -267,20 +266,6 @@ static size_t region_alloc_inner(size_t size, uint32_t type, page_fault_handler_ return 0; //No big enough block found } -bool region_alloc_for_pt_use_reserve = false; -size_t region_alloc_for_pt() { - if (region_alloc_for_pt_use_reserve) { - return region_alloc_inner( - N_PAGES_IN_PT_REGION * PAGE_SIZE, - REGION_T_PAGETABLE, - 0, true); - } else { - return region_alloc( - N_PAGES_IN_PT_REGION * PAGE_SIZE, - REGION_T_PAGETABLE, 0); - } -} - size_t region_alloc(size_t size, uint32_t type, page_fault_handler_t pf) { if (n_unused_descriptors <= N_RESERVE_DESCRIPTORS) { uint32_t frame = frame_alloc(1); @@ -289,9 +274,7 @@ size_t region_alloc(size_t size, uint32_t type, page_fault_handler_t pf) { size_t descriptor_region = region_alloc_inner(PAGE_SIZE, REGION_T_DESCRIPTORS, 0, true); ASSERT(descriptor_region != 0); - region_alloc_for_pt_use_reserve = true; - int error = pd_map_page(0, descriptor_region, frame, 1); - region_alloc_for_pt_use_reserve = false; + int error = pd_map_page(descriptor_region, frame, 1); if (error) { // this can happen if we weren't able to allocate a frame for // a new pagetable diff --git a/run_qemu.sh b/run_qemu.sh index c0b6906..8649d92 100755 --- a/run_qemu.sh +++ b/run_qemu.sh @@ -3,4 +3,4 @@ cd `dirname $0` make -C kernel -qemu-system-i386 -kernel kernel/kernel.bin -serial stdio +qemu-system-i386 -kernel kernel/kernel.bin -serial stdio -m 16 -- cgit v1.2.3