void i386_init(void)
{
extern char edata[], end[];
// Before doing anything else, complete the ELF loading process.
// Clear the uninitialized global data (BSS) section of our program.
// This ensures that all static/global variables start out zero.
memset(edata, 0, end - edata);
// Initialize the console.
// Can't call cprintf until after we do this!
cons_init();
cprintf("6828 decimal is %o octal!\n", 6828);
//check page_alloc() this is a test,not my code
check_page_alloc();
// Test the stack backtrace function (lab 1 only)
test_backtrace(5);
// Drop into the kernel monitor.
while (1)
monitor(NULL);
}
// Set up a two-level page table:
// kern_pgdir is its linear (virtual) address of the root
//
// This function only sets up the kernel part of the address space
// (ie. addresses >= UTOP). The user part of the address space
// will be setup later.
//
// From UTOP to ULIM, the user is allowed to read but not write.
// Above ULIM the user cannot read or write.
void
mem_init(void)
{
uint32_t cr0;
size_t n;
// Find out how much memory the machine has (npages & npages_basemem).
i386_detect_memory();
//////////////////////////////////////////////////////////////////////
// create initial page directory.
kern_pgdir = (pde_t *) boot_alloc(PGSIZE);
memset(kern_pgdir, 0, PGSIZE);
//////////////////////////////////////////////////////////////////////
// Recursively insert PD in itself as a page table, to form
// a virtual page table at virtual address UVPT.
// (For now, you don't have understand the greater purpose of the
// following line.)
// Permissions: kernel R, user R
kern_pgdir[PDX(UVPT)] = PADDR(kern_pgdir) | PTE_U | PTE_P;
//////////////////////////////////////////////////////////////////////
// Allocate an array of npages 'struct Page's and store it in 'pages'.
// The kernel uses this array to keep track of physical pages: for
// each physical page, there is a corresponding struct Page in this
// array. 'npages' is the number of physical pages in memory.
// Your code goes here:
pages = boot_alloc(npages*sizeof(* pages));
//////////////////////////////////////////////////////////////////////
// Make 'envs' point to an array of size 'NENV' of 'struct Env'.
// LAB 3: Your code here.
envs = boot_alloc(NENV * sizeof(* envs));
//////////////////////////////////////////////////////////////////////
// Now that we've allocated the initial kernel data structures, we set
// up the list of free physical pages. Once we've done so, all further
// memory management will go through the page_* functions. In
// particular, we can now map memory using boot_map_region
// or page_insert
page_init();
check_page_free_list(1);
check_page_alloc();
check_page();
//////////////////////////////////////////////////////////////////////
// Now we set up virtual memory
//////////////////////////////////////////////////////////////////////
// Map 'pages' read-only by the user at linear address UPAGES
// Permissions:
// - the new image at UPAGES -- kernel R, user R
// (ie. perm = PTE_U | PTE_P)
// - pages itself -- kernel RW, user NONE
// Your code goes here:
boot_map_region( kern_pgdir, (uintptr_t) UPAGES, npages*(sizeof(* pages)),
PADDR(pages), PTE_U | PTE_P);
boot_map_region( kern_pgdir, (uintptr_t) pages, npages*(sizeof(* pages)),
PADDR(pages), PTE_W | PTE_P);
//////////////////////////////////////////////////////////////////////
// Map the 'envs' array read-only by the user at linear address UENVS
// (ie. perm = PTE_U | PTE_P).
// Permissions:
// - the new image at UENVS -- kernel R, user R
// - envs itself -- kernel RW, user NONE
// LAB 3: Your code here.
boot_map_region( kern_pgdir, (uintptr_t) UENVS, npages*(sizeof(* envs)),
PADDR(envs), PTE_U | PTE_P);
boot_map_region( kern_pgdir, (uintptr_t) envs, npages*(sizeof(* envs)),
PADDR(envs), PTE_W | PTE_P);
//////////////////////////////////////////////////////////////////////
// Use the physical memory that 'bootstack' refers to as the kernel
// stack. The kernel stack grows down from virtual address KSTACKTOP.
// We consider the entire range from [KSTACKTOP-PTSIZE, KSTACKTOP)
// to be the kernel stack, but break this into two pieces:
// * [KSTACKTOP-KSTKSIZE, KSTACKTOP) -- backed by physical memory
// * [KSTACKTOP-PTSIZE, KSTACKTOP-KSTKSIZE) -- not backed; so if
// the kernel overflows its stack, it will fault rather than
// overwrite memory. Known as a "guard page".
// Permissions: kernel RW, user NONE
// Your code goes here:
boot_map_region( kern_pgdir, KSTACKTOP-KSTKSIZE, KSTKSIZE,
PADDR(bootstack), PTE_W | PTE_P );
//////////////////////////////////////////////////////////////////////
// Map all of physical memory at KERNBASE.
// Ie. the VA range [KERNBASE, 2^32) should map to
// the PA range [0, 2^32 - KERNBASE)
// We might not have 2^32 - KERNBASE bytes of physical memory, but
// we just set up the mapping anyway.
// Permissions: kernel RW, user NONE
// Your code goes here:
boot_map_region( kern_pgdir, (uintptr_t) KERNBASE, 0xFFFFFFFF, 0,
PTE_W | PTE_P);
// Initialize the SMP-related parts of the memory map
mem_init_mp();
// Check that the initial page directory has been set up correctly.
check_kern_pgdir();
// Switch from the minimal entry page directory to the full kern_pgdir
// page table we just created. Our instruction pointer should be
// somewhere between KERNBASE and KERNBASE+4MB right now, which is
// mapped the same way by both page tables.
//
// If the machine reboots at this point, you've probably set up your
// kern_pgdir wrong.
lcr3(PADDR(kern_pgdir));
check_page_free_list(0);
// entry.S set the really important flags in cr0 (including enabling
// paging). Here we configure the rest of the flags that we care about.
cr0 = rcr0();
cr0 |= CR0_PE|CR0_PG|CR0_AM|CR0_WP|CR0_NE|CR0_MP;
cr0 &= ~(CR0_TS|CR0_EM);
lcr0(cr0);
// Some more checks, only possible after kern_pgdir is installed.
check_page_installed_pgdir();
}
// Set up a four-level page table:
// boot_pml4e is its linear (virtual) address of the root
//
// This function only sets up the kernel part of the address space
// (ie. addresses >= UTOP). The user part of the address space
// will be setup later.
//
// From UTOP to ULIM, the user is allowed to read but not write.
// Above ULIM the user cannot read or write.
void
x64_vm_init(void)
{
pml4e_t* pml4e;
uint32_t cr0;
int i;
size_t n;
int r;
struct Env *env;
i386_detect_memory();
//panic("i386_vm_init: This function is not finished\n");
//////////////////////////////////////////////////////////////////////
// create initial page directory.
///panic("x64_vm_init: this function is not finished\n");
pml4e = boot_alloc(PGSIZE);
memset(pml4e, 0, PGSIZE);
boot_pml4e = pml4e;
boot_cr3 = PADDR(pml4e);
//////////////////////////////////////////////////////////////////////
// Allocate an array of npage 'struct Page's and store it in 'pages'.
// The kernel uses this array to keep track of physical pages: for
// each physical page, there is a corresponding struct Page in this
// array. 'npage' is the number of physical pages in memory.
// User-level programs will get read-only access to the array as well.
// Your code goes here:
pages = boot_alloc(npages * sizeof(struct Page));
//////////////////////////////////////////////////////////////////////
// Make 'envs' point to an array of size 'NENV' of 'struct Env'.
// LAB 3: Your code here.
envs = boot_alloc(NENV * sizeof(struct Env));
//////////////////////////////////////////////////////////////////////
// Now that we've allocated the initial kernel data structures, we set
// up the list of free physical pages. Once we've done so, all further
// memory management will go through the page_* functions. In
// particular, we can now map memory using boot_map_segment or page_insert
page_init();
check_page_free_list(1);
check_page_alloc();
page_check();
//////////////////////////////////////////////////////////////////////
// Now we set up virtual memory
//////////////////////////////////////////////////////////////////////
// Map 'pages' read-only by the user at linear address UPAGES
// Permissions:
// - the new image at UPAGES -- kernel R, user R
// (ie. perm = PTE_U | PTE_P)
// - pages itself -- kernel RW, user NONE
// Your code goes here:
//////////////////////////////////////////////////////////////////////
// Map the 'envs' array read-only by the user at linear address UENVS
// (ie. perm = PTE_U | PTE_P).
// Permissions:
// - the new image at UENVS -- kernel R, user R
// - envs itself -- kernel RW, user NONE
// LAB 3: Your code here.
boot_map_segment(boot_pml4e, UPAGES, ROUNDUP(npages*sizeof(struct Page), PGSIZE), PADDR(pages), PTE_U | PTE_P);
boot_map_segment(boot_pml4e, (uintptr_t)pages, ROUNDUP(npages *sizeof(struct Page), PGSIZE), PADDR(pages), PTE_P | PTE_W);
boot_map_segment(boot_pml4e, UENVS, ROUNDUP(NENV*sizeof(struct Env), PGSIZE), PADDR(envs), PTE_U | PTE_P);
boot_map_segment(boot_pml4e, (uintptr_t)envs, ROUNDUP(NENV *sizeof(struct Env), PGSIZE), PADDR(envs), PTE_P | PTE_W);
//////////////////////////////////////////////////////////////////////
// Use the physical memory that 'bootstack' refers to as the kernel
// stack. The kernel stack grows down from virtual address KSTACKTOP.
// We consider the entire range from [KSTACKTOP-PTSIZE, KSTACKTOP)
// to be the kernel stack, but break this into two pieces:
// * [KSTACKTOP-KSTKSIZE, KSTACKTOP) -- backed by physical memory
// * [KSTACKTOP-PTSIZE, KSTACKTOP-KSTKSIZE) -- not backed; so if
// the kernel overflows its stack, it will fault rather than
// overwrite memory. Known as a "guard page".
// Permissions: kernel RW, user NONE
// Your code goes here:
boot_map_segment(boot_pml4e, KSTACKTOP-KSTKSIZE, KSTKSIZE, PADDR(bootstack), PTE_P | PTE_W);
///////////////////////////////////////////////////////////////////////
// Map all of physical memory at KERNBASE.
// Ie. the VA range [KERNBASE, 2^32) should map to
// the PA range [0, 2^32 - KERNBASE)
// We might not have 2^32 - KERNBASE bytes of physical memory, but
// we just set up the mapping anyway.
// Permissions: kernel RW, user NONE
// Your code goes here:
boot_map_segment(boot_pml4e, KERNBASE, ~(uint32_t)0 - KERNBASE + 1, 0, PTE_P | PTE_W);
// Check that the initial page directory has been set up correctly.
// Initialize the SMP-related parts of the memory map
mem_init_mp();
check_boot_pml4e(boot_pml4e);
//////////////////////////////////////////////////////////////////////
// Permissions: kernel RW, user NONE
pdpe_t *pdpe = KADDR(PTE_ADDR(pml4e[0]));
pde_t *pgdir = KADDR(PTE_ADDR(pdpe[3]));
lcr3(boot_cr3);
check_page_free_list(0);
}
// Set up a two-level page table:
// kern_pgdir is its linear (virtual) address of the root
// Then turn on paging. Then effectively turn off segmentation.
// (i.e., the segment base addrs are set to zero).
//
// This function only sets up the kernel part of the address space
// (ie. addresses >= UTOP). The user part of the address space
// will be setup later.
//
// From UTOP to ULIM, the user is allowed to read but not write.
// Above ULIM the user cannot read or write.
void
mem_init(void)
{
uint32_t cr0;
size_t n;
// Ensure user & kernel struct Pages agree.
static_assert(sizeof(struct Page) == sizeof(struct UserPage));
// Find out how much memory the machine has (npages & npages_basemem).
i386_detect_memory();
// Remove this line when you're ready to test this function.
//panic("mem_init: This function is not finished\n");
//////////////////////////////////////////////////////////////////////
// create initial page directory.
kern_pgdir = (pde_t *) boot_alloc(PGSIZE);
memset(kern_pgdir, 0, PGSIZE);
//////////////////////////////////////////////////////////////////////
// Recursively insert PD in itself as a page table, to form
// a virtual page table at virtual address UVPT.
// (For now, you don't have understand the greater purpose of the
// following line.)
// Permissions: kernel R, user R
kern_pgdir[PDX(UVPT)] = PADDR(kern_pgdir) | PTE_U | PTE_P;
//////////////////////////////////////////////////////////////////////
// Allocate an array of npages 'struct Page's and store it in 'pages'.
// The kernel uses this array to keep track of physical pages: for
// each physical page, there is a corresponding struct Page in this
// array. 'npages' is the number of physical pages in memory.
pages = (Page *) boot_alloc(npages * sizeof(struct Page));
//////////////////////////////////////////////////////////////////////
// Make 'envs' point to an array of size 'NENV' of 'struct Env'.
// LAB 3: Your code here.
envs = (Env *) boot_alloc(NENV * sizeof(struct Env));
//////////////////////////////////////////////////////////////////////
// Now that we've allocated the initial kernel data structures, we set
// up the list of free physical pages. Once we've done so, all further
// memory management will go through the page_* functions. In
// particular, we can now map memory using page_map_segment
// or page_insert
page_init();
check_page_free_list(true);
check_page_alloc();
check_page();
//////////////////////////////////////////////////////////////////////
// Now we set up virtual memory
//////////////////////////////////////////////////////////////////////
// Use the physical memory that 'entry_stack' refers to as the kernel
// stack. The kernel stack grows down from virtual address KSTACKTOP.
// We consider the entire range from [KSTACKTOP-PTSIZE, KSTACKTOP)
// to be the kernel stack, but break this into two pieces:
// * [KSTACKTOP-KSTKSIZE, KSTACKTOP) -- backed by physical memory
// * [KSTACKTOP-PTSIZE, KSTACKTOP-KSTKSIZE) -- not backed; so if
// the kernel overflows its stack, it will fault rather than
// overwrite memory. Known as a "guard page".
// Permissions: kernel RW, user NONE
Page *pp = pa2page((physaddr_t)entry_stack-KERNBASE);
for (uintptr_t ptr = KSTACKTOP-KSTKSIZE; ptr < KSTACKTOP; ptr += PGSIZE) {
if (page_insert(kern_pgdir, pp, ptr, PTE_W | PTE_P) < 0)
panic("Couldn't create page table entries for stack.\n");
pp++;
}
//////////////////////////////////////////////////////////////////////
// Map all of physical memory at KERNBASE.
// Ie. the VA range [KERNBASE, 2^32) should map to
// the PA range [0, 2^32 - KERNBASE)
// We might not have 2^32 - KERNBASE bytes of physical memory, but
// we just set up the mapping anyway.
// Permissions: kernel RW, user NONE
page_map_segment(kern_pgdir, KERNBASE, 0xFFFFFFFF-KERNBASE, 0x0, PTE_W | PTE_P);
//print_page_table(kern_pgdir, false, false);
//////////////////////////////////////////////////////////////////////
// Map the 'envs' array read-only by the user at linear address UENVS.
// Permissions: kernel R, user R
// (That's the UENVS version; 'envs' itself is kernel RW, user NONE.)
// LAB 3: Your code here.
page_map_segment(kern_pgdir, (uintptr_t) UENVS, ROUNDUP(NENV*sizeof(struct Env), PGSIZE), PADDR(envs), PTE_U | PTE_P);
//////////////////////////////////////////////////////////////////////
// Map 'pages' read-only by the user at linear address UPAGES.
// Permissions: kernel R, user R
// (That's the UPAGES version; 'pages' itself is kernel RW, user NONE.)
// LAB 3: Your code here.
page_map_segment(kern_pgdir, UPAGES, ROUNDUP(npages*sizeof(struct Page), PGSIZE), PADDR(pages), PTE_U | PTE_P);
// Check that the initial page directory has been set up correctly.
check_kern_pgdir();
// Switch from the minimal entry page directory to the full kern_pgdir
// page table we just created. Our instruction pointer should be
// somewhere between KERNBASE and KERNBASE+4MB right now, which is
// mapped the same way by both page tables.
//
// If the machine reboots at this point, you've probably set up your
// kern_pgdir wrong.
lcr3(PADDR(kern_pgdir));
// entry.S set the really important flags in cr0 (including enabling
// paging). Here we configure the rest of the flags we need.
cr0 = rcr0();
cr0 |= CR0_PE|CR0_PG|CR0_AM|CR0_WP|CR0_NE|CR0_MP;
cr0 &= ~(CR0_TS|CR0_EM);
lcr0(cr0);
// Some more checks, only possible after kern_pgdir is installed.
check_page_installed_pgdir();
}