__set_tss_desc has a complex calculation of the TSS segment limit,
duplicating the quirky details of the I/O bitmap array length, and
requiring a complex comment to explain. Replace that calculation with a
simpler one based on the offsetof the "stack" field that follows the
array.
That then removes the last use of IO_BITMAP_OFFSET, so delete it.
Signed-off-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Acked-by: Alexander van Heukelum <heukelum@xxxxxxxxxxx>
---
v2: Rebased. Added a comment explaining the -1 in the calculation.
arch/x86/include/asm/desc.h | 11 +----------
arch/x86/include/asm/processor.h | 4 +++-
2 files changed, 4 insertions(+), 11 deletions(-)
diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
index 50d033a..f8dc455 100644
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -177,16 +177,7 @@ static inline void __set_tss_desc(unsigned cpu, unsigned int entry, void *addr)
struct desc_struct *d = get_cpu_gdt_table(cpu);
tss_desc tss;
- /*
- * sizeof(unsigned long) coming from an extra "long" at the end
- * of the iobitmap. See tss_struct definition in processor.h
- *
- * -1? seg base+limit should be pointing to the address of the
- * last valid byte
- */
- set_tssldt_descriptor(&tss, (unsigned long)addr, DESC_TSS,
- IO_BITMAP_OFFSET + IO_BITMAP_BYTES +
- sizeof(unsigned long) - 1);
+ set_tssldt_descriptor(&tss, (unsigned long)addr, DESC_TSS, TSS_LIMIT);
write_gdt_entry(d, entry, &tss, DESC_TSS);
}
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index fdedd38..7da8794 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -259,9 +259,11 @@ struct x86_hw_tss {
#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)
#define INVALID_IO_BITMAP_OFFSET 0x8000
+/* Segment limits point to the last valid byte, hence the -1 */
+#define TSS_LIMIT (offsetof(struct tss_struct, stack) - 1)
+
struct tss_struct {
/*
* The hardware state:
--
1.9.0
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