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Sweden-Number/memory/ldt.c

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C
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/*
* LDT manipulation functions
*
* Copyright 1993 Robert J. Amstadt
* Copyright 1995 Alexandre Julliard
*/
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include "ldt.h"
#include "debug.h"
DEFAULT_DEBUG_CHANNEL(ldt)
#ifdef __i386__
#ifdef linux
#include <sys/syscall.h>
struct modify_ldt_s
{
unsigned int entry_number;
unsigned long base_addr;
unsigned int limit;
unsigned int seg_32bit : 1;
unsigned int contents : 2;
unsigned int read_exec_only : 1;
unsigned int limit_in_pages : 1;
unsigned int seg_not_present : 1;
};
static inline int modify_ldt( int func, struct modify_ldt_s *ptr,
unsigned long count )
{
int res;
#ifdef __PIC__
__asm__ __volatile__( "pushl %%ebx\n\t"
"movl %2,%%ebx\n\t"
"int $0x80\n\t"
"popl %%ebx"
: "=a" (res)
: "0" (SYS_modify_ldt),
"r" (func),
"c" (ptr),
"d" (count) );
#else
__asm__ __volatile__("int $0x80"
: "=a" (res)
: "0" (SYS_modify_ldt),
"b" (func),
"c" (ptr),
"d" (count) );
#endif /* __PIC__ */
if (res >= 0) return res;
errno = -res;
return -1;
}
#endif /* linux */
#if defined(__svr4__) || defined(_SCO_DS)
#include <sys/sysi86.h>
#ifndef __sun__
#include <sys/seg.h>
#endif
#endif
#if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)
#include <machine/segments.h>
extern int i386_get_ldt(int, union descriptor *, int);
extern int i386_set_ldt(int, union descriptor *, int);
#endif /* __NetBSD__ || __FreeBSD__ || __OpenBSD__ */
#endif /* __i386__ */
ldt_copy_entry ldt_copy[LDT_SIZE];
unsigned char ldt_flags_copy[LDT_SIZE];
/***********************************************************************
* LDT_BytesToEntry
*
* Convert the raw bytes of the descriptor to an ldt_entry structure.
*/
void LDT_BytesToEntry( const unsigned long *buffer, ldt_entry *content )
{
content->base = (*buffer >> 16) & 0x0000ffff;
content->limit = *buffer & 0x0000ffff;
buffer++;
content->base |= (*buffer & 0xff000000) | ((*buffer << 16) & 0x00ff0000);
content->limit |= (*buffer & 0x000f0000);
content->type = (*buffer >> 10) & 3;
content->seg_32bit = (*buffer & 0x00400000) != 0;
content->read_only = (*buffer & 0x00000200) == 0;
content->limit_in_pages = (*buffer & 0x00800000) != 0;
}
/***********************************************************************
* LDT_EntryToBytes
*
* Convert an ldt_entry structure to the raw bytes of the descriptor.
*/
void LDT_EntryToBytes( unsigned long *buffer, const ldt_entry *content )
{
*buffer++ = ((content->base & 0x0000ffff) << 16) |
(content->limit & 0x0ffff);
*buffer = (content->base & 0xff000000) |
((content->base & 0x00ff0000)>>16) |
(content->limit & 0xf0000) |
(content->type << 10) |
((content->read_only == 0) << 9) |
((content->seg_32bit != 0) << 22) |
((content->limit_in_pages != 0) << 23) |
0xf000;
}
/***********************************************************************
* LDT_GetEntry
*
* Retrieve an LDT entry.
*/
int LDT_GetEntry( int entry, ldt_entry *content )
{
int ret = 0;
content->base = ldt_copy[entry].base;
content->limit = ldt_copy[entry].limit;
content->type = (ldt_flags_copy[entry] & LDT_FLAGS_TYPE);
content->seg_32bit = (ldt_flags_copy[entry] & LDT_FLAGS_32BIT) != 0;
content->read_only = (ldt_flags_copy[entry] & LDT_FLAGS_READONLY) !=0;
content->limit_in_pages = (ldt_flags_copy[entry] & LDT_FLAGS_BIG) !=0;
if (content->limit_in_pages) content->limit >>= 12;
return ret;
}
/***********************************************************************
* LDT_SetEntry
*
* Set an LDT entry.
*/
int LDT_SetEntry( int entry, const ldt_entry *content )
{
int ret = 0;
TRACE(ldt, "entry=%04x base=%08lx limit=%05lx %s %d-bit "
"flags=%c%c%c\n", entry, content->base, content->limit,
content->limit_in_pages ? "pages" : "bytes",
content->seg_32bit ? 32 : 16,
content->read_only && (content->type & SEGMENT_CODE) ? '-' : 'r',
content->read_only || (content->type & SEGMENT_CODE) ? '-' : 'w',
(content->type & SEGMENT_CODE) ? 'x' : '-' );
/* Entry 0 must not be modified; its base and limit are always 0 */
if (!entry) return 0;
#ifdef __i386__
#ifdef linux
{
struct modify_ldt_s ldt_info;
ldt_info.entry_number = entry;
ldt_info.base_addr = content->base;
ldt_info.limit = content->limit;
ldt_info.seg_32bit = content->seg_32bit != 0;
ldt_info.contents = content->type;
ldt_info.read_exec_only = content->read_only != 0;
ldt_info.limit_in_pages = content->limit_in_pages != 0;
ldt_info.seg_not_present = 0;
/* Make sure the info will be accepted by the kernel */
/* This is ugly, but what can I do? */
if (content->type == SEGMENT_STACK)
{
/* FIXME */
}
else
{
if (ldt_info.base_addr >= 0xc0000000)
{
WARN(ldt, "Invalid base addr %08lx\n",
ldt_info.base_addr );
return -1;
}
if (content->limit_in_pages)
{
if ((ldt_info.limit << 12) + 0xfff >
0xc0000000 - ldt_info.base_addr)
ldt_info.limit = (0xc0000000 - 0xfff - ldt_info.base_addr) >> 12;
}
else
{
if (ldt_info.limit > 0xc0000000 - ldt_info.base_addr)
ldt_info.limit = 0xc0000000 - ldt_info.base_addr;
}
}
if ((ret = modify_ldt(1, &ldt_info, sizeof(ldt_info))) < 0)
perror( "modify_ldt" );
}
#endif /* linux */
#if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)
{
long d[2];
LDT_EntryToBytes( d, content );
ret = i386_set_ldt(entry, (union descriptor *)d, 1);
if (ret < 0)
{
perror("i386_set_ldt");
MSG("Did you reconfigure the kernel with \"options USER_LDT\"?\n");
exit(1);
}
}
#endif /* __NetBSD__ || __FreeBSD__ || __OpenBSD__ */
#if defined(__svr4__) || defined(_SCO_DS)
{
struct ssd ldt_mod;
int i;
ldt_mod.sel = ENTRY_TO_SELECTOR(entry) | 4;
ldt_mod.bo = content->base;
ldt_mod.ls = content->limit;
i = ((content->limit & 0xf0000) |
(content->type << 10) |
(((content->read_only != 0) ^ 1) << 9) |
((content->seg_32bit != 0) << 22) |
((content->limit_in_pages != 0)<< 23) |
(1<<15) |
0x7000);
ldt_mod.acc1 = (i & 0xff00) >> 8;
ldt_mod.acc2 = (i & 0xf00000) >> 20;
if (content->base == 0)
{
ldt_mod.acc1 = 0;
ldt_mod.acc2 = 0;
}
if ((ret = sysi86(SI86DSCR, &ldt_mod)) == -1) perror("sysi86");
}
#endif
#endif /* __i386__ */
if (ret < 0) return ret;
ldt_copy[entry].base = content->base;
if (!content->limit_in_pages) ldt_copy[entry].limit = content->limit;
else ldt_copy[entry].limit = (content->limit << 12) | 0x0fff;
ldt_flags_copy[entry] = (content->type & LDT_FLAGS_TYPE) |
(content->read_only ? LDT_FLAGS_READONLY : 0) |
(content->seg_32bit ? LDT_FLAGS_32BIT : 0) |
(content->limit_in_pages ? LDT_FLAGS_BIG : 0) |
(ldt_flags_copy[entry] & LDT_FLAGS_ALLOCATED);
return ret;
}
/***********************************************************************
* LDT_Print
*
* Print the content of the LDT on stdout.
*/
void LDT_Print( int start, int length )
{
int i;
char flags[3];
if (length == -1) length = LDT_SIZE - start;
for (i = start; i < start + length; i++)
{
if (!ldt_copy[i].base && !ldt_copy[i].limit) continue; /* Free entry */
if ((ldt_flags_copy[i] & LDT_FLAGS_TYPE) == SEGMENT_CODE)
{
flags[0] = (ldt_flags_copy[i] & LDT_FLAGS_EXECONLY) ? '-' : 'r';
flags[1] = '-';
flags[2] = 'x';
}
else
{
flags[0] = 'r';
flags[1] = (ldt_flags_copy[i] & LDT_FLAGS_READONLY) ? '-' : 'w';
flags[2] = '-';
}
MSG("%04x: sel=%04x base=%08lx limit=%08lx %d-bit %c%c%c\n",
i, ENTRY_TO_SELECTOR(i), ldt_copy[i].base, ldt_copy[i].limit,
ldt_flags_copy[i] & LDT_FLAGS_32BIT ? 32 : 16,
flags[0], flags[1], flags[2] );
}
}
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