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-rw-r--r--arch/x86/kernel/process_32.c36
1 files changed, 9 insertions, 27 deletions
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 646da41a620..a59314e877f 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -248,11 +248,8 @@ void exit_thread(void)
/*
* Careful, clear this in the TSS too:
*/
- memset(tss->io_bitmap, 0xff, tss->io_bitmap_max);
+ memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
t->io_bitmap_max = 0;
- tss->io_bitmap_owner = NULL;
- tss->io_bitmap_max = 0;
- tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
put_cpu();
}
@@ -458,34 +455,19 @@ __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
hard_enable_TSC();
}
- if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
+ if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
/*
- * Disable the bitmap via an invalid offset. We still cache
- * the previous bitmap owner and the IO bitmap contents:
+ * Copy the relevant range of the IO bitmap.
+ * Normally this is 128 bytes or less:
*/
- tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
- return;
- }
-
- if (likely(next == tss->io_bitmap_owner)) {
+ memcpy(tss->io_bitmap, next->io_bitmap_ptr,
+ max(prev->io_bitmap_max, next->io_bitmap_max));
+ } else if (test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) {
/*
- * Previous owner of the bitmap (hence the bitmap content)
- * matches the next task, we dont have to do anything but
- * to set a valid offset in the TSS:
+ * Clear any possible leftover bits:
*/
- tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
- return;
+ memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
}
- /*
- * Lazy TSS's I/O bitmap copy. We set an invalid offset here
- * and we let the task to get a GPF in case an I/O instruction
- * is performed. The handler of the GPF will verify that the
- * faulting task has a valid I/O bitmap and, it true, does the
- * real copy and restart the instruction. This will save us
- * redundant copies when the currently switched task does not
- * perform any I/O during its timeslice.
- */
- tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
}
/*