Setup_FS_Segment() for VoxWare audio

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@237 b3059339-0415-0410-9bf9-f77b7e298cf2

loader/driver.c

@@ -98,6 +98,7 @@ static NPDRVR DrvAlloc(HDRVR*lpDriver, LPUINT lpDrvResult)
 static void DrvFree(HDRVR hDriver)
 {
     int i;
+    setup_FS_Segment();
     if(hDriver)
     	if(((DRVR*)hDriver)->hDriverModule)
     	if(((DRVR*)hDriver)->DriverProc)
@@ -131,6 +132,8 @@ DrvOpen(LPARAM lParam2)
     char unknown[0x24];
 //    char* codec_name=icopen->fccHandler;
 
+    Setup_LDT_Keeper();
+
     if (!(npDriver = DrvAlloc(&hDriver, &uDrvResult)))
 	return ((HDRVR) 0);
 
@@ -193,6 +196,8 @@ DrvOpen(LPARAM lParam2)
     //TRACE("DriverProc == %X\n", npDriver->DriverProc);
      npDriver->dwDriverID = ++dwDrvID;
 
+     setup_FS_Segment();
+
 	STORE_ALL;
         (npDriver->DriverProc)(0, hDriver, DRV_LOAD, 0, 0);
 	REST_ALL;

loader/setup_FS.c

@@ -0,0 +1,201 @@
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#ifdef __linux__
+#include <asm/unistd.h>
+#include <asm/ldt.h>
+#else
+
+#if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)
+#include <machine/sysarch.h>
+#endif
+
+#ifdef __svr4__
+#include <sys/segment.h>
+#include <sys/sysi86.h>
+/* solaris x86: add missing prototype for sysi86() */
+extern int sysi86(int, void*);
+#define       TEB_SEL_IDX     NUMSYSLDTS
+#endif
+
+#define LDT_ENTRIES     8192
+#define LDT_ENTRY_SIZE  8
+#pragma pack(4)
+struct modify_ldt_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;
+        unsigned int  useable:1;
+};
+
+#define MODIFY_LDT_CONTENTS_DATA        0
+#define MODIFY_LDT_CONTENTS_STACK       1
+#define MODIFY_LDT_CONTENTS_CODE        2
+#endif
+
+
+/* user level (privilege level: 3) ldt (1<<2) segment selector */
+#define       LDT_SEL(idx) ((idx) << 3 | 1 << 2 | 3)
+
+#ifndef       TEB_SEL_IDX
+#define       TEB_SEL_IDX     1
+#endif
+
+#define       TEB_SEL LDT_SEL(TEB_SEL_IDX)
+
+void setup_FS_Segment()
+{
+    printf("Setup FS...");fflush(stdout);
+    __asm__ __volatile__(
+	"movl %0,%%eax; movw %%ax, %%fs" : : "i" (TEB_SEL)
+    );
+    printf("OK!\n");
+}
+
+
+/**
+ *
+ *  This should be performed before we create first thread. See remarks
+ *  for write_ldt(), linux/kernel/ldt.c.
+ *
+ */
+
+static void* fs_seg=NULL;
+
+#ifdef __linux__
+    /* XXX: why is this routine from libc redefined here? */
+    /* NOTE: the redefined version ignores the count param, count is hardcoded as 16 */
+    static int modify_ldt( int func, struct modify_ldt_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" (__NR_modify_ldt),
+                            "r" (func),
+                            "c" (ptr),
+			    "d"(16)//sizeof(*ptr) from kernel point of view
+			  :"esi"     );
+#else
+        __asm__ __volatile__("int $0x80"
+                         : "=a" (res)
+                         : "0" (__NR_modify_ldt),
+                           "b" (func),
+                           "c" (ptr),
+			    "d"(16)
+			   :"esi");
+#endif  /* __PIC__ */
+	if (res >= 0) return res;
+	errno = -res;
+        return -1;
+    }
+#endif
+
+#if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)
+    static void LDT_EntryToBytes( unsigned long *buffer, const struct modify_ldt_ldt_s *content )
+    {
+	*buffer++ = ((content->base_addr & 0x0000ffff) << 16) |
+             (content->limit & 0x0ffff);
+        *buffer = (content->base_addr & 0xff000000) |
+              ((content->base_addr & 0x00ff0000)>>16) |
+              (content->limit & 0xf0000) |
+              (content->contents << 10) |
+              ((content->read_exec_only == 0) << 9) |
+              ((content->seg_32bit != 0) << 22) |
+              ((content->limit_in_pages != 0) << 23) |
+              0xf000;
+    }
+#endif
+
+void Setup_LDT_Keeper(){
+    struct modify_ldt_ldt_s array;
+    int fd;
+    int ret;
+    void* prev_struct;
+    
+    if(fs_seg) return; // already set!
+    
+    fd=open("/dev/zero", O_RDWR);
+    fs_seg=mmap(NULL, getpagesize(), PROT_READ | PROT_WRITE, MAP_PRIVATE,
+	fd, 0);
+    if(fs_seg==(void*)-1)
+    {
+	perror("ERROR: Couldn't allocate memory for fs segment");
+	return;
+    }	
+    array.base_addr=(int)fs_seg;
+    array.entry_number=TEB_SEL_IDX;
+    array.limit=array.base_addr+getpagesize()-1;
+    array.seg_32bit=1;
+    array.read_exec_only=0;
+    array.seg_not_present=0;
+    array.contents=MODIFY_LDT_CONTENTS_DATA;
+    array.limit_in_pages=0;
+#ifdef __linux__
+    ret=modify_ldt(0x1, &array, sizeof(struct modify_ldt_ldt_s));
+    if(ret<0)
+    {
+	perror("install_fs");
+	printf("Couldn't install fs segment, expect segfault\n");
+    }	
+#endif /*linux*/
+
+#if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)
+    {
+        unsigned long d[2];
+
+        LDT_EntryToBytes( d, &array );
+        ret = i386_set_ldt(array.entry_number, (union descriptor *)d, 1);
+        if (ret < 0)
+        {
+            perror("install_fs");
+	    printf("Couldn't install fs segment, expect segfault\n");
+            printf("Did you reconfigure the kernel with \"options USER_LDT\"?\n");
+        }
+	printf("Set_LDT\n");
+    }
+#endif  /* __NetBSD__ || __FreeBSD__ || __OpenBSD__ */
+
+#if defined(__svr4__)
+    struct ssd ssd;
+    ssd.sel = TEB_SEL;
+    ssd.bo = array.base_addr;
+    ssd.ls = array.limit - array.base_addr;
+    ssd.acc1 = ((array.read_exec_only == 0) << 1) |
+               (array.contents << 2) |
+               0xf0;   /* P(resent) | DPL3 | S */
+    ssd.acc2 = 0x4;   /* byte limit, 32-bit segment */
+    if (sysi86(SI86DSCR, &ssd) < 0) {
+	perror("sysi86(SI86DSCR)");
+	printf("Couldn't install fs segment, expect segfault\n");
+    }
+#endif
+
+    setup_FS_Segment();
+
+    prev_struct=malloc(8);
+    *(void**)array.base_addr=prev_struct;
+    close(fd);
+}
+
+void Restore_LDT_Keeper()
+{
+    if(fs_seg==0) return;
+    munmap((char*)fs_seg, getpagesize());
+}
+