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add demo of a user-level process

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dirty hack, map the function userfoo and its stack to user space
This commit is contained in:
Stefan Lankes 2014-12-04 22:19:18 +01:00
parent 49016fc0c2
commit c0d69c96be
2 changed files with 22 additions and 6 deletions
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2
arch/x86/kernel/gdt.c
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@ -36,7 +36,7 @@
#include <asm/tss.h>
#include <asm/page.h>
gdt_ptr_t gp;
gdt_ptr_t gp;
static tss_t task_state_segment __attribute__ ((aligned (PAGE_SIZE)));
// currently, our kernel has full access to the ioports
static gdt_entry_t gdt[GDT_ENTRIES] = {[0 ... GDT_ENTRIES-1] = {0, 0, 0, 0, 0, 0}};

26
kernel/main.c
View file

@ -58,15 +58,14 @@ extern atomic_int32_t total_available_pages;
static void userfoo(void* arg)
{
char str[256];
ksnprintf(str, 256, "hello from %s\n", (char*) arg);
SYSCALL1(__NR_write, "hello from userfoo\n");
SYSCALL1(__NR_exit, 0);
//kprintf("hello from %s\n", (char*) arg);
while(1) ;
}
static char ustack[KERNEL_STACK_SIZE];
static char ustack[KERNEL_STACK_SIZE] __attribute__ ((aligned (PAGE_SIZE)));
static int wrapper(void* arg)
{
@ -76,7 +75,24 @@ static int wrapper(void* arg)
*stack-- = (size_t) arg;
*stack = (size_t) leave_user_task; // put exit function as caller on the stack
#if 0
// this triggers a page fault because a user task is not able to access the kernel space
return jump_to_user_code((uint32_t) userfoo, (uint32_t) stack);
#else
// dirty hack, map userfoo to the user space
size_t phys = page_virt_to_phys(((size_t) userfoo) & PAGE_MASK);
size_t vuserfoo = 0x40000000;
page_map(vuserfoo, phys, 2, PG_PRESENT | PG_RW | PG_PCD | PG_USER);
vuserfoo += (size_t)userfoo & 0xFFF;
// dirty hack, map ustack to the user space
phys = page_virt_to_phys((size_t) ustack);
size_t vstack = 0x80000000;
page_map(vstack, phys, KERNEL_STACK_SIZE >> PAGE_BITS, PG_PRESENT | PG_RW | PG_PCD | PG_USER);
vstack = (vstack + KERNEL_STACK_SIZE - 16 - sizeof(size_t));
return jump_to_user_code(vuserfoo, vstack);
#endif
}
static int foo(void* arg)
@ -127,7 +143,7 @@ int main(void)
create_kernel_task(&id1, foo, "foo1", NORMAL_PRIO);
//create_kernel_task(&id2, wrapper, "userfoo", NORMAL_PRIO);
create_kernel_task(&id2, wrapper, "userfoo", NORMAL_PRIO);
while(1) {
HALT;