b12bdaf11f
Some syscalls need to access the pt_regs structure, either to copy user register state or to modifiy it. This patch adds stubs to load the address of the pt_regs struct into the %eax register, and changes the syscalls to take the pointer as an argument instead of relying on the assumption that the pt_regs structure overlaps the function arguments. Drop the use of regparm(1) due to concern about gcc bugs, and to move in the direction of the eventual removal of regparm(0) for asmlinkage. Signed-off-by: Brian Gerst <brgerst@gmail.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
155 lines
3.7 KiB
C
155 lines
3.7 KiB
C
/*
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* This contains the io-permission bitmap code - written by obz, with changes
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* by Linus. 32/64 bits code unification by Miguel Botón.
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*/
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/capability.h>
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#include <linux/errno.h>
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#include <linux/types.h>
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#include <linux/ioport.h>
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#include <linux/smp.h>
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#include <linux/stddef.h>
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#include <linux/slab.h>
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#include <linux/thread_info.h>
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#include <linux/syscalls.h>
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#include <asm/syscalls.h>
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/* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */
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static void set_bitmap(unsigned long *bitmap, unsigned int base,
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unsigned int extent, int new_value)
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{
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unsigned int i;
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for (i = base; i < base + extent; i++) {
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if (new_value)
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__set_bit(i, bitmap);
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else
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__clear_bit(i, bitmap);
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}
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}
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/*
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* this changes the io permissions bitmap in the current task.
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*/
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asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
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{
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struct thread_struct *t = ¤t->thread;
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struct tss_struct *tss;
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unsigned int i, max_long, bytes, bytes_updated;
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if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
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return -EINVAL;
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if (turn_on && !capable(CAP_SYS_RAWIO))
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return -EPERM;
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/*
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* If it's the first ioperm() call in this thread's lifetime, set the
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* IO bitmap up. ioperm() is much less timing critical than clone(),
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* this is why we delay this operation until now:
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*/
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if (!t->io_bitmap_ptr) {
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unsigned long *bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
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if (!bitmap)
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return -ENOMEM;
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memset(bitmap, 0xff, IO_BITMAP_BYTES);
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t->io_bitmap_ptr = bitmap;
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set_thread_flag(TIF_IO_BITMAP);
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}
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/*
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* do it in the per-thread copy and in the TSS ...
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*
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* Disable preemption via get_cpu() - we must not switch away
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* because the ->io_bitmap_max value must match the bitmap
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* contents:
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*/
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tss = &per_cpu(init_tss, get_cpu());
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set_bitmap(t->io_bitmap_ptr, from, num, !turn_on);
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/*
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* Search for a (possibly new) maximum. This is simple and stupid,
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* to keep it obviously correct:
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*/
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max_long = 0;
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for (i = 0; i < IO_BITMAP_LONGS; i++)
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if (t->io_bitmap_ptr[i] != ~0UL)
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max_long = i;
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bytes = (max_long + 1) * sizeof(unsigned long);
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bytes_updated = max(bytes, t->io_bitmap_max);
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t->io_bitmap_max = bytes;
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#ifdef CONFIG_X86_32
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/*
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* Sets the lazy trigger so that the next I/O operation will
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* reload the correct bitmap.
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* Reset the owner so that a process switch will not set
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* tss->io_bitmap_base to IO_BITMAP_OFFSET.
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*/
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tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
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tss->io_bitmap_owner = NULL;
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#else
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/* Update the TSS: */
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memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated);
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#endif
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put_cpu();
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return 0;
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}
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/*
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* sys_iopl has to be used when you want to access the IO ports
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* beyond the 0x3ff range: to get the full 65536 ports bitmapped
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* you'd need 8kB of bitmaps/process, which is a bit excessive.
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*
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* Here we just change the flags value on the stack: we allow
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* only the super-user to do it. This depends on the stack-layout
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* on system-call entry - see also fork() and the signal handling
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* code.
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*/
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static int do_iopl(unsigned int level, struct pt_regs *regs)
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{
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unsigned int old = (regs->flags >> 12) & 3;
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if (level > 3)
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return -EINVAL;
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/* Trying to gain more privileges? */
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if (level > old) {
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if (!capable(CAP_SYS_RAWIO))
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return -EPERM;
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}
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regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12);
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return 0;
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}
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#ifdef CONFIG_X86_32
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long sys_iopl(struct pt_regs *regs)
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{
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unsigned int level = regs->bx;
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struct thread_struct *t = ¤t->thread;
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int rc;
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rc = do_iopl(level, regs);
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if (rc < 0)
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goto out;
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t->iopl = level << 12;
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set_iopl_mask(t->iopl);
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out:
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return rc;
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}
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#else
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asmlinkage long sys_iopl(unsigned int level, struct pt_regs *regs)
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{
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return do_iopl(level, regs);
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}
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#endif
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