linux-kernel - [PATCH] um: Adjust current_thread

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Message-Id: <1303467614-7585-1-git-send-email-richard@nod.at>
Date:	Fri, 22 Apr 2011 12:20:14 +0200
From:	Richard Weinberger <richard@....at>
To:	akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org,
	user-mode-linux-devel@...ts.sourceforge.net, kirill@...temov.name,
	Richard Weinberger <richard@....at>
Subject: [PATCH] um: Adjust current_thread_info() for newer gcc versions

In some cases gcc >= 4.5.2 will optimize away current_thread_info().
To prevent gcc from doing so the stack address has to be obtained
via inline asm.

LKML-Reference: http://marc.info/?i=201104132150.05623.richard@nod.at

Acked-by: Kirill A. Shutemov <kirill@...temov.name>
Signed-off-by: Richard Weinberger <richard@....at>
---
 arch/um/include/asm/thread_info.h |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/arch/um/include/asm/thread_info.h b/arch/um/include/asm/thread_info.h
index e2cf786..5bd1bad 100644
--- a/arch/um/include/asm/thread_info.h
+++ b/arch/um/include/asm/thread_info.h
@@ -49,7 +49,10 @@ static inline struct thread_info *current_thread_info(void)
 {
 	struct thread_info *ti;
 	unsigned long mask = THREAD_SIZE - 1;
-	ti = (struct thread_info *) (((unsigned long) &ti) & ~mask);
+	void *p;
+
+	asm volatile ("" : "=r" (p) : "0" (&ti));
+	ti = (struct thread_info *) (((unsigned long)p) & ~mask);
 	return ti;
 }
 
-- 
1.7.4.2

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