njn | 912ec7c | 2002-10-02 10:36:46 +0000 | [diff] [blame] | 1 | |
| 2 | #include <stdio.h> |
| 3 | #include <errno.h> |
| 4 | #include <string.h> |
| 5 | |
| 6 | /* Stuff from Wine. */ |
| 7 | |
| 8 | typedef unsigned short WORD; /* I guess */ |
| 9 | typedef unsigned char BYTE; |
| 10 | |
| 11 | typedef struct _LDT_ENTRY { |
| 12 | WORD LimitLow; |
| 13 | WORD BaseLow; |
| 14 | union { |
| 15 | struct { |
| 16 | BYTE BaseMid; |
| 17 | BYTE Flags1; |
| 18 | /*Declare as bytes to avoid alignment problems */ |
| 19 | BYTE Flags2; |
| 20 | BYTE BaseHi; |
| 21 | } Bytes; |
| 22 | struct { |
| 23 | unsigned BaseMid : 8; |
| 24 | unsigned Type : 5; |
| 25 | unsigned Dpl : 2; |
| 26 | unsigned Pres : 1; |
| 27 | unsigned LimitHi : 4; |
| 28 | unsigned Sys : 1; |
| 29 | unsigned Reserved_0 : 1; |
| 30 | unsigned Default_Big : 1; |
| 31 | unsigned Granularity : 1; |
| 32 | unsigned BaseHi : 8; |
| 33 | } Bits; |
| 34 | } HighWord; |
| 35 | } LDT_ENTRY; |
| 36 | |
| 37 | inline static void *wine_ldt_get_base( const LDT_ENTRY *ent ) |
| 38 | { |
| 39 | return (void *)(ent->BaseLow | |
| 40 | (unsigned long)ent->HighWord.Bits.BaseMid << 16 | |
| 41 | (unsigned long)ent->HighWord.Bits.BaseHi << 24); |
| 42 | } |
| 43 | inline static unsigned int wine_ldt_get_limit( const LDT_ENTRY *ent ) |
| 44 | { |
| 45 | unsigned int limit = ent->LimitLow | (ent->HighWord.Bits.LimitHi << 16); |
| 46 | if (ent->HighWord.Bits.Granularity) limit = (limit << 12) | 0xfff; |
| 47 | return limit; |
| 48 | } |
| 49 | |
| 50 | |
| 51 | /* our copy of the ldt */ |
| 52 | LDT_ENTRY ldt_copy[8192]; |
| 53 | |
| 54 | /* System call to set LDT entry. */ |
| 55 | //extern int __modify_ldt (int, struct modify_ldt_ldt_s *, size_t); |
| 56 | extern int __modify_ldt (int, void *, size_t); |
| 57 | |
| 58 | void print_ldt ( void ) |
| 59 | { |
| 60 | int res; |
| 61 | res = __modify_ldt( 0, ldt_copy, 8192*sizeof(LDT_ENTRY) ); |
| 62 | printf("got %d bytes\n", res ); |
| 63 | perror("error is"); |
| 64 | } |
| 65 | |
| 66 | /* Structure passed on `modify_ldt' call. */ |
| 67 | #define MODIFY_LDT_CONTENTS_DATA 0 |
| 68 | #define MODIFY_LDT_CONTENTS_STACK 1 |
| 69 | #define MODIFY_LDT_CONTENTS_CODE 2 |
| 70 | |
| 71 | struct modify_ldt_ldt_s |
| 72 | { |
| 73 | unsigned int entry_number; |
| 74 | unsigned long int base_addr; |
| 75 | unsigned int limit; |
| 76 | unsigned int seg_32bit:1; |
| 77 | unsigned int contents:2; |
| 78 | unsigned int read_exec_only:1; |
| 79 | unsigned int limit_in_pages:1; |
| 80 | unsigned int seg_not_present:1; |
| 81 | unsigned int useable:1; |
| 82 | unsigned int empty:25; |
| 83 | }; |
| 84 | |
| 85 | /* System call to set LDT entry. */ |
| 86 | //extern int __modify_ldt (int, struct modify_ldt_ldt_s *, size_t); |
| 87 | |
| 88 | void set_ldt1 ( void* base ) |
| 89 | { |
| 90 | int stat; |
| 91 | struct modify_ldt_ldt_s ldt_entry; |
| 92 | |
| 93 | /* stop valgrind yelping about initialised holes in this struct. */ |
| 94 | memset(&ldt_entry, 0, sizeof(ldt_entry)); |
| 95 | |
| 96 | ldt_entry.entry_number = 1; |
| 97 | ldt_entry.base_addr = (unsigned)base; //0x12345678; |
| 98 | ldt_entry.limit = 10; |
| 99 | ldt_entry.seg_32bit = 1; |
| 100 | ldt_entry.contents = MODIFY_LDT_CONTENTS_DATA; |
| 101 | ldt_entry.read_exec_only = 0; |
| 102 | ldt_entry.limit_in_pages = 0; |
| 103 | ldt_entry.seg_not_present = 0; |
| 104 | stat = __modify_ldt (1, &ldt_entry, sizeof (ldt_entry)); |
| 105 | printf("stat = %d\n", stat); |
| 106 | } |
| 107 | |
| 108 | |
| 109 | void ldt_seg_write ( int ldt_entno, unsigned offset, unsigned val ) |
| 110 | { |
| 111 | asm volatile("movl %2, %%eax\n\t" |
| 112 | "movl %1, %%edx\n\t" |
fitzhardinge | 47735af | 2004-01-21 01:27:27 +0000 | [diff] [blame] | 113 | "movl %0, %%fs\n\t" |
| 114 | "movl %%eax, %%fs:(%%edx)\t" |
njn | 912ec7c | 2002-10-02 10:36:46 +0000 | [diff] [blame] | 115 | : |
| 116 | : "r" (7 /* LDT(TI), least privilege */ + (ldt_entno << 3)), |
| 117 | "r" (offset), "r" (val) |
| 118 | : "eax", "edx", "cc" ); |
| 119 | } |
| 120 | |
| 121 | int main ( void ) |
| 122 | { |
| 123 | int i; |
| 124 | int arr[9]; |
| 125 | |
| 126 | for (i = 0; i < 9; i++) arr[i] = 11*i; |
| 127 | |
| 128 | set_ldt1( &arr[4] ); |
| 129 | print_ldt(); |
| 130 | |
| 131 | ldt_seg_write(1 /* ldt entry # */, 4 /* offset */, 4444); |
| 132 | |
| 133 | for (i = 0; i < 9; i++) printf("%d ", arr[i]); |
| 134 | printf("\n"); |
| 135 | |
| 136 | return 0; |
| 137 | } |
| 138 | |