minix/kernel/system/do_vm.c

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/* The system call implemented in this file:
* m_type: SYS_VM_MAP
*
* The parameters for this system call are:
* m4_l1: Process that requests map
* m4_l2: Map (TRUE) or unmap (FALSE)
* m4_l3: Base address
* m4_l4: Size
* m4_l5: Memory address
*/
#include "../system.h"
#include <sys/vm.h>
PRIVATE int vm_needs_init= 1;
PRIVATE u32_t vm_cr3;
FORWARD _PROTOTYPE( void vm_init, (void) );
FORWARD _PROTOTYPE( void phys_put32, (phys_bytes addr, u32_t value) );
FORWARD _PROTOTYPE( u32_t phys_get32, (phys_bytes addr) );
FORWARD _PROTOTYPE( void vm_set_cr3, (u32_t value) );
FORWARD _PROTOTYPE( void set_cr3, (void) );
FORWARD _PROTOTYPE( void vm_enable_paging, (void) );
FORWARD _PROTOTYPE( void map_range, (u32_t base, u32_t size,
u32_t offset) );
/*===========================================================================*
* do_vm_setbuf *
*===========================================================================*/
PUBLIC int do_vm_map(m_ptr)
message *m_ptr; /* pointer to request message */
{
int proc_nr, do_map;
phys_bytes base, size, offset, p_phys;
struct proc *pp;
/* do_serial_debug= 1; */
if (vm_needs_init)
{
vm_needs_init= 0;
vm_init();
}
proc_nr= m_ptr->m4_l1;
do_map= m_ptr->m4_l2;
base= m_ptr->m4_l3;
size= m_ptr->m4_l4;
offset= m_ptr->m4_l5;
pp= proc_addr(proc_nr);
p_phys= umap_local(pp, D, base, size);
if (p_phys == 0)
return EFAULT;
if (do_map)
{
pp->p_misc_flags |= MF_VM;
map_range(p_phys, size, offset);
}
else
{
map_range(p_phys, size, p_phys);
}
vm_set_cr3(vm_cr3);
return OK;
}
/*===========================================================================*
* vm_map_default *
*===========================================================================*/
PUBLIC void vm_map_default(pp)
struct proc *pp;
{
phys_bytes base_clicks, size_clicks;
if (vm_needs_init)
panic("vm_map_default: VM not initialized?", NO_NUM);
pp->p_misc_flags &= ~MF_VM;
base_clicks= pp->p_memmap[D].mem_phys;
size_clicks= pp->p_memmap[S].mem_phys+pp->p_memmap[S].mem_len -
base_clicks;
map_range(base_clicks << CLICK_SHIFT, size_clicks << CLICK_SHIFT,
base_clicks << CLICK_SHIFT);
vm_set_cr3(vm_cr3);
}
PRIVATE void vm_init(void)
{
int o;
phys_bytes p, pt_size;
phys_bytes vm_dir_base, vm_pt_base, phys_mem;
u32_t entry;
unsigned pages;
if (!vm_size)
panic("vm_init: no space for page tables", NO_NUM);
/* Align page directory */
o= (vm_base % PAGE_SIZE);
if (o != 0)
o= PAGE_SIZE-o;
vm_dir_base= vm_base+o;
/* Page tables start after the page directory */
vm_pt_base= vm_dir_base+PAGE_SIZE;
pt_size= (vm_base+vm_size)-vm_pt_base;
pt_size -= (pt_size % PAGE_SIZE);
/* Compute the number of pages based on vm_mem_high */
pages= (vm_mem_high-1)/PAGE_SIZE + 1;
if (pages * I386_VM_PT_ENT_SIZE > pt_size)
panic("vm_init: page table too small", NO_NUM);
for (p= 0; p*I386_VM_PT_ENT_SIZE < pt_size; p++)
{
phys_mem= p*PAGE_SIZE;
entry= phys_mem | I386_VM_USER | I386_VM_WRITE |
I386_VM_PRESENT;
if (phys_mem >= vm_mem_high)
entry= 0;
phys_put32(vm_pt_base + p*I386_VM_PT_ENT_SIZE, entry);
}
for (p= 0; p < I386_VM_DIR_ENTRIES; p++)
{
phys_mem= vm_pt_base + p*PAGE_SIZE;
entry= phys_mem | I386_VM_USER | I386_VM_WRITE |
I386_VM_PRESENT;
if (phys_mem >= vm_pt_base + pt_size)
entry= 0;
phys_put32(vm_dir_base + p*I386_VM_PT_ENT_SIZE, entry);
}
vm_set_cr3(vm_dir_base);
level0(vm_enable_paging);
}
PRIVATE void phys_put32(addr, value)
phys_bytes addr;
u32_t value;
{
phys_copy(vir2phys((vir_bytes)&value), addr, sizeof(value));
}
PRIVATE u32_t phys_get32(addr)
phys_bytes addr;
{
u32_t value;
phys_copy(addr, vir2phys((vir_bytes)&value), sizeof(value));
return value;
}
PRIVATE void vm_set_cr3(value)
u32_t value;
{
vm_cr3= value;
level0(set_cr3);
}
PRIVATE void set_cr3()
{
write_cr3(vm_cr3);
}
PRIVATE void vm_enable_paging(void)
{
u32_t cr0;
cr0= read_cr0();
write_cr0(cr0 | I386_CR0_PG);
}
PRIVATE void map_range(base, size, offset)
u32_t base;
u32_t size;
u32_t offset;
{
u32_t curr_pt, curr_pt_addr, entry;
int dir_ent, pt_ent;
if (base % PAGE_SIZE != 0)
panic("map_range: bad base", base);
if (size % PAGE_SIZE != 0)
panic("map_range: bad size", size);
if (offset % PAGE_SIZE != 0)
panic("map_range: bad offset", offset);
curr_pt= -1;
curr_pt_addr= 0;
while (size != 0)
{
dir_ent= (base >> I386_VM_DIR_ENT_SHIFT);
pt_ent= (base >> I386_VM_PT_ENT_SHIFT) & I386_VM_PT_ENT_MASK;
if (dir_ent != curr_pt)
{
/* Get address of page table */
curr_pt= dir_ent;
curr_pt_addr= phys_get32(vm_cr3 +
dir_ent * I386_VM_PT_ENT_SIZE);
curr_pt_addr &= I386_VM_ADDR_MASK;
}
entry= offset | I386_VM_USER | I386_VM_WRITE |
I386_VM_PRESENT;
phys_put32(curr_pt_addr + pt_ent * I386_VM_PT_ENT_SIZE, entry);
offset += PAGE_SIZE;
base += PAGE_SIZE;
size -= PAGE_SIZE;
}
}