linux-kernel - [PATCH 1/6] x86/asm: Define the kernel TSS limit in a macro

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Message-Id: <b63a2b69fd6a03cd6beea38f2049d2c4c8656436.1487609329.git.luto@kernel.org>
Date:   Mon, 20 Feb 2017 08:56:09 -0800
From:   Andy Lutomirski <luto@...nel.org>
To:     Paolo Bonzini <pbonzini@...hat.com>, X86 ML <x86@...nel.org>
Cc:     kvm list <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Borislav Petkov <bpetkov@...e.de>,
        Thomas Garnier <thgarnie@...gle.com>,
        Jim Mattson <jmattson@...gle.com>,
        Andy Lutomirski <luto@...nel.org>
Subject: [PATCH 1/6] x86/asm: Define the kernel TSS limit in a macro

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@...gle.com>
Cc: Jim Mattson <jmattson@...gle.com>
Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
 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