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Subject[tip:x86/asm] x86/fsgsbase/64: Clean up various details
Commit-ID:  ec3a94188df7d28b374868d9a2a0face910e62ab
Gitweb: https://git.kernel.org/tip/ec3a94188df7d28b374868d9a2a0face910e62ab
Author: Ingo Molnar <mingo@kernel.org>
AuthorDate: Mon, 8 Oct 2018 10:41:59 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 8 Oct 2018 10:45:04 +0200

x86/fsgsbase/64: Clean up various details

So:

- use 'extern' consistently for APIs

- fix weird header guard

- clarify code comments

- reorder APIs by type

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chang S. Bae <chang.seok.bae@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Markus T Metzger <markus.t.metzger@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1537312139-5580-2-git-send-email-chang.seok.bae@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/entry/vdso/vgetcpu.c | 1 +
arch/x86/include/asm/fsgsbase.h | 22 ++++++++++++----------
2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/arch/x86/entry/vdso/vgetcpu.c b/arch/x86/entry/vdso/vgetcpu.c
index edd214f5264d..f86ab0ae1777 100644
--- a/arch/x86/entry/vdso/vgetcpu.c
+++ b/arch/x86/entry/vdso/vgetcpu.c
@@ -14,6 +14,7 @@ notrace long
__vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
{
vdso_read_cpunode(cpu, node);
+
return 0;
}

diff --git a/arch/x86/include/asm/fsgsbase.h b/arch/x86/include/asm/fsgsbase.h
index 5e9cbcce318a..eb377b6e9eed 100644
--- a/arch/x86/include/asm/fsgsbase.h
+++ b/arch/x86/include/asm/fsgsbase.h
@@ -1,6 +1,6 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_FSGSBASE_H
-#define _ASM_FSGSBASE_H 1
+#define _ASM_FSGSBASE_H

#ifndef __ASSEMBLY__

@@ -9,14 +9,15 @@
#include <asm/msr-index.h>

/*
- * Read/write a task's fsbase or gsbase. This returns the value that
+ * Read/write a task's FSBASE or GSBASE. This returns the value that
* the FS/GS base would have (if the task were to be resumed). These
- * work on current or on a different non-running task.
+ * work on the current task or on a non-running (typically stopped
+ * ptrace child) task.
*/
-unsigned long x86_fsbase_read_task(struct task_struct *task);
-unsigned long x86_gsbase_read_task(struct task_struct *task);
-int x86_fsbase_write_task(struct task_struct *task, unsigned long fsbase);
-int x86_gsbase_write_task(struct task_struct *task, unsigned long gsbase);
+extern unsigned long x86_fsbase_read_task(struct task_struct *task);
+extern unsigned long x86_gsbase_read_task(struct task_struct *task);
+extern int x86_fsbase_write_task(struct task_struct *task, unsigned long fsbase);
+extern int x86_gsbase_write_task(struct task_struct *task, unsigned long gsbase);

/* Helper functions for reading/writing FS/GS base */

@@ -25,20 +26,21 @@ static inline unsigned long x86_fsbase_read_cpu(void)
unsigned long fsbase;

rdmsrl(MSR_FS_BASE, fsbase);
+
return fsbase;
}

-void x86_fsbase_write_cpu(unsigned long fsbase);
-
static inline unsigned long x86_gsbase_read_cpu_inactive(void)
{
unsigned long gsbase;

rdmsrl(MSR_KERNEL_GS_BASE, gsbase);
+
return gsbase;
}

-void x86_gsbase_write_cpu_inactive(unsigned long gsbase);
+extern void x86_fsbase_write_cpu(unsigned long fsbase);
+extern void x86_gsbase_write_cpu_inactive(unsigned long gsbase);

#endif /* CONFIG_X86_64 */

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