diff options
Diffstat (limited to 'arch/i386/kernel/ioport.c')
| -rw-r--r-- | arch/i386/kernel/ioport.c | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/arch/i386/kernel/ioport.c b/arch/i386/kernel/ioport.c new file mode 100644 index 00000000000..8b25160393c --- /dev/null +++ b/arch/i386/kernel/ioport.c @@ -0,0 +1,147 @@ +/* + * linux/arch/i386/kernel/ioport.c + * + * This contains the io-permission bitmap code - written by obz, with changes + * by Linus. + */ + +#include <linux/sched.h> +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/types.h> +#include <linux/ioport.h> +#include <linux/smp.h> +#include <linux/smp_lock.h> +#include <linux/stddef.h> +#include <linux/slab.h> +#include <linux/thread_info.h> + +/* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */ +static void set_bitmap(unsigned long *bitmap, unsigned int base, unsigned int extent, int new_value) +{ + unsigned long mask; + unsigned long *bitmap_base = bitmap + (base / BITS_PER_LONG); + unsigned int low_index = base & (BITS_PER_LONG-1); + int length = low_index + extent; + + if (low_index != 0) { + mask = (~0UL << low_index); + if (length < BITS_PER_LONG) + mask &= ~(~0UL << length); + if (new_value) + *bitmap_base++ |= mask; + else + *bitmap_base++ &= ~mask; + length -= BITS_PER_LONG; + } + + mask = (new_value ? ~0UL : 0UL); + while (length >= BITS_PER_LONG) { + *bitmap_base++ = mask; + length -= BITS_PER_LONG; + } + + if (length > 0) { + mask = ~(~0UL << length); + if (new_value) + *bitmap_base++ |= mask; + else + *bitmap_base++ &= ~mask; + } +} + + +/* + * this changes the io permissions bitmap in the current task. + */ +asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on) +{ + unsigned long i, max_long, bytes, bytes_updated; + struct thread_struct * t = ¤t->thread; + struct tss_struct * tss; + unsigned long *bitmap; + + if ((from + num <= from) || (from + num > IO_BITMAP_BITS)) + return -EINVAL; + if (turn_on && !capable(CAP_SYS_RAWIO)) + return -EPERM; + + /* + * If it's the first ioperm() call in this thread's lifetime, set the + * IO bitmap up. ioperm() is much less timing critical than clone(), + * this is why we delay this operation until now: + */ + if (!t->io_bitmap_ptr) { + bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); + if (!bitmap) + return -ENOMEM; + + memset(bitmap, 0xff, IO_BITMAP_BYTES); + t->io_bitmap_ptr = bitmap; + } + + /* + * do it in the per-thread copy and in the TSS ... + * + * Disable preemption via get_cpu() - we must not switch away + * because the ->io_bitmap_max value must match the bitmap + * contents: + */ + tss = &per_cpu(init_tss, get_cpu()); + + set_bitmap(t->io_bitmap_ptr, from, num, !turn_on); + + /* + * Search for a (possibly new) maximum. This is simple and stupid, + * to keep it obviously correct: + */ + max_long = 0; + for (i = 0; i < IO_BITMAP_LONGS; i++) + if (t->io_bitmap_ptr[i] != ~0UL) + max_long = i; + + bytes = (max_long + 1) * sizeof(long); + bytes_updated = max(bytes, t->io_bitmap_max); + + t->io_bitmap_max = bytes; + + /* + * Sets the lazy trigger so that the next I/O operation will + * reload the correct bitmap. + */ + tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY; + + put_cpu(); + + return 0; +} + +/* + * sys_iopl has to be used when you want to access the IO ports + * beyond the 0x3ff range: to get the full 65536 ports bitmapped + * you'd need 8kB of bitmaps/process, which is a bit excessive. + * + * Here we just change the eflags value on the stack: we allow + * only the super-user to do it. This depends on the stack-layout + * on system-call entry - see also fork() and the signal handling + * code. + */ + +asmlinkage long sys_iopl(unsigned long unused) +{ + volatile struct pt_regs * regs = (struct pt_regs *) &unused; + unsigned int level = regs->ebx; + unsigned int old = (regs->eflags >> 12) & 3; + + if (level > 3) + return -EINVAL; + /* Trying to gain more privileges? */ + if (level > old) { + if (!capable(CAP_SYS_RAWIO)) + return -EPERM; + } + regs->eflags = (regs->eflags &~ 0x3000UL) | (level << 12); + /* Make sure we return the long way (not sysenter) */ + set_thread_flag(TIF_IRET); + return 0; +} |