Archipelago » qemu

#include <inttypes.h>

/**********************************************/

/* segmentation tests */

#include <asm/ldt.h>

#include <linux/unistd.h>

_syscall3(int, modify_ldt, int, func, void *, ptr, unsigned long, bytecount)

uint8_t seg_data1[4096];

uint8_t seg_data2[4096];

#define MK_SEL(n) (((n) << 3) | 4)

/* NOTE: we use Linux modify_ldt syscall */

void test_segs(void)

{

    struct modify_ldt_ldt_s ldt;

    long long ldt_table[3];

    int i, res, res2;

    char tmp;

    ldt.entry_number = 1;

    ldt.base_addr = (unsigned long)&seg_data1;

    ldt.limit = (sizeof(seg_data1) + 0xfff) >> 12;

    ldt.seg_32bit = 1;

    ldt.contents = MODIFY_LDT_CONTENTS_DATA;

    ldt.read_exec_only = 0;

    ldt.limit_in_pages = 1;

    ldt.seg_not_present = 0;

    ldt.useable = 1;

    modify_ldt(1, &ldt, sizeof(ldt)); /* write ldt entry */

    ldt.entry_number = 2;

    ldt.base_addr = (unsigned long)&seg_data2;

    ldt.limit = (sizeof(seg_data2) + 0xfff) >> 12;

    ldt.seg_32bit = 1;

    ldt.contents = MODIFY_LDT_CONTENTS_DATA;

    ldt.read_exec_only = 0;

    ldt.limit_in_pages = 1;

    ldt.seg_not_present = 0;

    ldt.useable = 1;

    modify_ldt(1, &ldt, sizeof(ldt)); /* write ldt entry */

    modify_ldt(0, &ldt_table, sizeof(ldt_table)); /* read ldt entries */

    for(i=0;i<3;i++)

        printf("%d: %016Lx\n", i, ldt_table[i]);

    /* do some tests with fs or gs */

    asm volatile ("movl %0, %%fs" : : "r" (MK_SEL(1)));

    asm volatile ("movl %0, %%gs" : : "r" (MK_SEL(2)));

    seg_data1[1] = 0xaa;

    seg_data2[1] = 0x55;

    asm volatile ("fs movzbl 0x1, %0" : "=r" (res));

    printf("FS[1] = %02x\n", res);

    asm volatile ("gs movzbl 0x1, %0" : "=r" (res));

    printf("GS[1] = %02x\n", res);

    /* tests with ds/ss (implicit segment case) */

    tmp = 0xa5;

    asm volatile ("pushl %%ebp\n\t"

                  "pushl %%ds\n\t"

                  "movl %2, %%ds\n\t"

                  "movl %3, %%ebp\n\t"

                  "movzbl 0x1, %0\n\t"

                  "movzbl (%%ebp), %1\n\t"

                  "popl %%ds\n\t"

                  "popl %%ebp\n\t"

                  : "=r" (res), "=r" (res2)

                  : "r" (MK_SEL(1)), "r" (&tmp));

    printf("DS[1] = %02x\n", res);

    printf("SS[tmp] = %02x\n", res2);

}

    test_lea();

    test_segs();