[PATCH v2 1/7] x86/asm: Define the kernel TSS limit in a macro

From: Andy Lutomirski
Date: Tue Feb 21 2017 - 14:16:58 EST


Rather than open-coding the kernel TSS limit in set_tss_desc(), make
it a real macro near the TSS layout definition.

This is purely a cleanup.

Cc: Thomas Garnier <thgarnie@xxxxxxxxxx>
Cc: Jim Mattson <jmattson@xxxxxxxxxx>
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
---
arch/x86/include/asm/desc.h | 10 +---------
arch/x86/include/asm/processor.h | 10 ++++++++++
2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
index 12080d87da3b..2e781bcc5e12 100644
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -177,16 +177,8 @@ 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);
+ __KERNEL_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 e6cfe7ba2d65..feb2ab95b8f6 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -342,6 +342,16 @@ struct tss_struct {

DECLARE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss);

+/*
+ * sizeof(unsigned long) coming from an extra "long" at the end
+ * of the iobitmap.
+ *
+ * -1? seg base+limit should be pointing to the address of the
+ * last valid byte
+ */
+#define __KERNEL_TSS_LIMIT \
+ (IO_BITMAP_OFFSET + IO_BITMAP_BYTES + sizeof(unsigned long) - 1)
+
#ifdef CONFIG_X86_32
DECLARE_PER_CPU(unsigned long, cpu_current_top_of_stack);
#endif
--
2.9.3