[PATCH] larger IO bitmaps

The previous discussion was started here:
http://www.uwsg.iu.edu/hypermail/linux/kernel/0211.0/0477.html but in 2.4
times this was kind of problematic.

Now, with the lazy bitmap allocation and per-CPU TSS, this will really not
drain any resources I think.  8K TSS increase and 8K per process *that does
ioperm()* - I think it is not very bad.

The reasons why I need that, are described in the URL above.  Basically this
will allow to use full-screen VESA under dosemu (without LFB though), and this
may be also helpfull for the XFree project and some other projects:

http://www.uwsg.iu.edu/hypermail/linux/kernel/9807.1/1079.htmlSigned-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/asm-i386/desc.h

@@ -44,7 +44,8 @@ __asm__ __volatile__ ("movw %w3,0(%2)\n\t" \
 
 static inline void __set_tss_desc(unsigned int cpu, unsigned int entry, void *addr)
 {
-	_set_tssldt_desc(&cpu_gdt_table[cpu][entry], (int)addr, 235, 0x89);
+	_set_tssldt_desc(&cpu_gdt_table[cpu][entry], (int)addr,
+		offsetof(struct tss_struct, __cacheline_filler) - 1, 0x89);
 }
 
 #define set_tss_desc(cpu,addr) __set_tss_desc(cpu, GDT_ENTRY_TSS, addr)

include/asm-i386/processor.h

@@ -297,9 +297,9 @@ extern unsigned int mca_pentium_flag;
 #define TASK_UNMAPPED_BASE	(PAGE_ALIGN(TASK_SIZE / 3))
 
 /*
- * Size of io_bitmap, covering ports 0 to 0x3ff.
+ * Size of io_bitmap.
  */
-#define IO_BITMAP_BITS  1024
+#define IO_BITMAP_BITS  65536
 #define IO_BITMAP_BYTES (IO_BITMAP_BITS/8)
 #define IO_BITMAP_LONGS (IO_BITMAP_BYTES/sizeof(long))
 #define IO_BITMAP_OFFSET offsetof(struct tss_struct,io_bitmap)
@@ -391,7 +391,7 @@ struct tss_struct {
 	/*
 	 * pads the TSS to be cacheline-aligned (size is 0x100)
 	 */
-	unsigned long __cacheline_filler[5];
+	unsigned long __cacheline_filler[37];
 	/*
 	 * .. and then another 0x100 bytes for emergency kernel stack
 	 */

include/asm-mips/processor.h

@@ -137,9 +137,9 @@ extern unsigned int vced_count, vcei_count;
 #endif
 
 /*
- * Size of io_bitmap in longwords: 32 is ports 0-0x3ff.
+ * Size of io_bitmap in longwords.
  */
-#define IO_BITMAP_SIZE	32
+#define IO_BITMAP_SIZE	2048
 
 #define NUM_FPU_REGS	32
 

include/asm-x86_64/processor.h

@@ -178,9 +178,9 @@ static inline void clear_in_cr4 (unsigned long mask)
 	(test_thread_flag(TIF_IA32) ? TASK_UNMAPPED_32 : TASK_UNMAPPED_64)  
 
 /*
- * Size of io_bitmap, covering ports 0 to 0x3ff.
+ * Size of io_bitmap.
  */
-#define IO_BITMAP_BITS  1024
+#define IO_BITMAP_BITS  65536
 #define IO_BITMAP_BYTES (IO_BITMAP_BITS/8)
 #define IO_BITMAP_LONGS (IO_BITMAP_BYTES/sizeof(long))
 #define IO_BITMAP_OFFSET offsetof(struct tss_struct,io_bitmap)