mirror of https://github.com/mpv-player/mpv
279 lines
7.3 KiB
C
279 lines
7.3 KiB
C
/**
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* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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* This file MUST be in main library because LDT must
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* be modified before program creates first thread
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* - avifile includes this file from C++ code
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* and initializes it at the start of player!
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* it might sound like a hack and it really is - but
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* as aviplay is deconding video with more than just one
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* thread currently it's necessary to do it this way
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* this might change in the future
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*/
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/* applied some modification to make make our xine friend more happy */
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#include "ldt_keeper.h"
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#include <string.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <sys/mman.h>
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#include <sys/types.h>
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#include <stdio.h>
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#include <unistd.h>
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#ifdef __linux__
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#include <asm/unistd.h>
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#include <asm/ldt.h>
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// 2.5.xx+ calls this user_desc:
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#include <linux/version.h>
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#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,5,47)
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#define modify_ldt_ldt_s user_desc
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#endif
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/* prototype it here, so we won't depend on kernel headers */
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#ifdef __cplusplus
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extern "C" {
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#endif
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/// declare modify_ldt with the _syscall3 macro for older glibcs
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#if defined(__GLIBC__) && (__GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 0))
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_syscall3( int, modify_ldt, int, func, void *, ptr, unsigned long, bytecount );
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#else
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int modify_ldt(int func, void *ptr, unsigned long bytecount);
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#endif
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#ifdef __cplusplus
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}
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#endif
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#else
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#if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)
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#include <machine/segments.h>
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#include <machine/sysarch.h>
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#endif
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#ifdef __svr4__
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#include <sys/segment.h>
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#include <sys/sysi86.h>
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/* solaris x86: add missing prototype for sysi86() */
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#ifdef __cplusplus
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extern "C" {
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#endif
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int sysi86(int, void*);
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#ifdef __cplusplus
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}
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#endif
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#ifndef NUMSYSLDTS /* SunOS 2.5.1 does not define NUMSYSLDTS */
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#define NUMSYSLDTS 6 /* Let's hope the SunOS 5.8 value is OK */
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#endif
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#define TEB_SEL_IDX NUMSYSLDTS
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#endif
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#define LDT_ENTRIES 8192
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#define LDT_ENTRY_SIZE 8
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#pragma pack(4)
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struct modify_ldt_ldt_s {
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unsigned int entry_number;
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unsigned long base_addr;
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unsigned int limit;
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unsigned int seg_32bit:1;
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unsigned int contents:2;
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unsigned int read_exec_only:1;
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unsigned int limit_in_pages:1;
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unsigned int seg_not_present:1;
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unsigned int useable:1;
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};
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#define MODIFY_LDT_CONTENTS_DATA 0
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#define MODIFY_LDT_CONTENTS_STACK 1
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#define MODIFY_LDT_CONTENTS_CODE 2
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#endif
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/* user level (privilege level: 3) ldt (1<<2) segment selector */
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#define LDT_SEL(idx) ((idx) << 3 | 1 << 2 | 3)
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/* i got this value from wine sources, it's the first free LDT entry */
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#if defined(__FreeBSD__) && defined(LDT_AUTO_ALLOC)
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#define TEB_SEL_IDX LDT_AUTO_ALLOC
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#endif
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#ifndef TEB_SEL_IDX
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#define TEB_SEL_IDX 17
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#endif
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static unsigned int fs_ldt = TEB_SEL_IDX;
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/**
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* here is a small logical problem with Restore for multithreaded programs -
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* in C++ we use static class for this...
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*/
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#ifdef __cplusplus
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extern "C"
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#endif
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void Setup_FS_Segment(void)
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{
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unsigned int ldt_desc = LDT_SEL(fs_ldt);
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__asm__ __volatile__(
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"movl %0,%%eax; movw %%ax, %%fs" : : "r" (ldt_desc)
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:"eax"
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);
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}
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/* we don't need this - use modify_ldt instead */
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#if 0
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#ifdef __linux__
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/* XXX: why is this routine from libc redefined here? */
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/* NOTE: the redefined version ignores the count param, count is hardcoded as 16 */
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static int LDT_Modify( int func, struct modify_ldt_ldt_s *ptr,
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unsigned long count )
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{
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int res;
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#ifdef __PIC__
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__asm__ __volatile__( "pushl %%ebx\n\t"
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"movl %2,%%ebx\n\t"
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"int $0x80\n\t"
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"popl %%ebx"
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: "=a" (res)
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: "0" (__NR_modify_ldt),
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"r" (func),
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"c" (ptr),
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"d"(16)//sizeof(*ptr) from kernel point of view
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:"esi" );
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#else
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__asm__ __volatile__("int $0x80"
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: "=a" (res)
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: "0" (__NR_modify_ldt),
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"b" (func),
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"c" (ptr),
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"d"(16)
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:"esi");
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#endif /* __PIC__ */
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if (res >= 0) return res;
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errno = -res;
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return -1;
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}
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#endif
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#endif
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#if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)
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static void LDT_EntryToBytes( unsigned long *buffer, const struct modify_ldt_ldt_s *content )
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{
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*buffer++ = ((content->base_addr & 0x0000ffff) << 16) |
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(content->limit & 0x0ffff);
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*buffer = (content->base_addr & 0xff000000) |
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((content->base_addr & 0x00ff0000)>>16) |
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(content->limit & 0xf0000) |
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(content->contents << 10) |
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((content->read_exec_only == 0) << 9) |
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((content->seg_32bit != 0) << 22) |
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((content->limit_in_pages != 0) << 23) |
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0xf000;
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}
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#endif
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void* fs_seg=0;
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ldt_fs_t* Setup_LDT_Keeper(void)
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{
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struct modify_ldt_ldt_s array;
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int ret;
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ldt_fs_t* ldt_fs = (ldt_fs_t*) malloc(sizeof(ldt_fs_t));
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if (!ldt_fs)
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return NULL;
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ldt_fs->fd = open("/dev/zero", O_RDWR);
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if(ldt_fs->fd<0){
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perror( "Cannot open /dev/zero for READ+WRITE. Check permissions! error: ");
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return NULL;
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}
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fs_seg=
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ldt_fs->fs_seg = mmap(NULL, getpagesize(), PROT_READ | PROT_WRITE, MAP_PRIVATE,
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ldt_fs->fd, 0);
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if (ldt_fs->fs_seg == (void*)-1)
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{
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perror("ERROR: Couldn't allocate memory for fs segment");
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close(ldt_fs->fd);
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free(ldt_fs);
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return NULL;
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}
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*(void**)((char*)ldt_fs->fs_seg+0x18) = ldt_fs->fs_seg;
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array.base_addr=(int)ldt_fs->fs_seg;
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array.entry_number=TEB_SEL_IDX;
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array.limit=array.base_addr+getpagesize()-1;
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array.seg_32bit=1;
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array.read_exec_only=0;
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array.seg_not_present=0;
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array.contents=MODIFY_LDT_CONTENTS_DATA;
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array.limit_in_pages=0;
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#ifdef __linux__
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//ret=LDT_Modify(0x1, &array, sizeof(struct modify_ldt_ldt_s));
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ret=modify_ldt(0x1, &array, sizeof(struct modify_ldt_ldt_s));
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if(ret<0)
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{
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perror("install_fs");
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printf("Couldn't install fs segment, expect segfault\n");
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}
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#endif /*linux*/
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#if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)
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{
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unsigned long d[2];
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LDT_EntryToBytes( d, &array );
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#if defined(__FreeBSD__) && defined(LDT_AUTO_ALLOC)
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ret = i386_set_ldt(LDT_AUTO_ALLOC, (union descriptor *)d, 1);
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array.entry_number = ret;
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fs_ldt = ret;
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#else
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ret = i386_set_ldt(array.entry_number, (union descriptor *)d, 1);
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#endif
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if (ret < 0)
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{
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perror("install_fs");
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printf("Couldn't install fs segment, expect segfault\n");
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printf("Did you reconfigure the kernel with \"options USER_LDT\"?\n");
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}
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}
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#endif /* __NetBSD__ || __FreeBSD__ || __OpenBSD__ */
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#if defined(__svr4__)
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{
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struct ssd ssd;
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ssd.sel = LDT_SEL(TEB_SEL_IDX);
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ssd.bo = array.base_addr;
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ssd.ls = array.limit - array.base_addr;
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ssd.acc1 = ((array.read_exec_only == 0) << 1) |
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(array.contents << 2) |
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0xf0; /* P(resent) | DPL3 | S */
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ssd.acc2 = 0x4; /* byte limit, 32-bit segment */
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if (sysi86(SI86DSCR, &ssd) < 0) {
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perror("sysi86(SI86DSCR)");
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printf("Couldn't install fs segment, expect segfault\n");
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}
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}
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#endif
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Setup_FS_Segment();
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ldt_fs->prev_struct = (char*)malloc(sizeof(char) * 8);
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*(void**)array.base_addr = ldt_fs->prev_struct;
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return ldt_fs;
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}
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void Restore_LDT_Keeper(ldt_fs_t* ldt_fs)
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{
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if (ldt_fs == NULL || ldt_fs->fs_seg == 0)
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return;
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if (ldt_fs->prev_struct)
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free(ldt_fs->prev_struct);
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munmap((char*)ldt_fs->fs_seg, getpagesize());
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ldt_fs->fs_seg = 0;
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close(ldt_fs->fd);
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free(ldt_fs);
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}
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