linux-kernel - [PATCH 2/5] x86: mark associated mm when running a task in 32 bit compatibility mode

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Date:	Tue,  8 Mar 2011 19:31:58 -0500
From:	Stephen Wilson <wilsons@...rt.ca>
To:	x86@...nel.org
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	linux390@...ibm.com, Paul Mundt <lethal@...ux-sh.org>,
	Andi Kleen <ak@...ux.intel.com>,
	Michel Lespinasse <walken@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
	linux-sh@...r.kernel.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Stephen Wilson <wilsons@...rt.ca>
Subject: [PATCH 2/5] x86: mark associated mm when running a task in 32 bit compatibility mode

This patch simply follows the same practice as for setting the TIF_IA32 flag.
In particular, an mm is marked as holding 32-bit tasks when a 32-bit binary is
exec'ed.  Both ELF and a.out formats are updated.

Signed-off-by: Stephen Wilson <wilsons@...rt.ca>
---
 arch/x86/ia32/ia32_aout.c    |    1 +
 arch/x86/kernel/process_64.c |    8 ++++++++
 2 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/arch/x86/ia32/ia32_aout.c b/arch/x86/ia32/ia32_aout.c
index 2d93bdb..95cde43 100644
--- a/arch/x86/ia32/ia32_aout.c
+++ b/arch/x86/ia32/ia32_aout.c
@@ -298,6 +298,7 @@ static int load_aout_binary(struct linux_binprm *bprm, struct pt_regs *regs)
 	/* OK, This is the point of no return */
 	set_personality(PER_LINUX);
 	set_thread_flag(TIF_IA32);
+	current->mm->context.compat = 1;
 
 	setup_new_exec(bprm);
 
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index bd387e8..35f1221 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -501,6 +501,10 @@ void set_personality_64bit(void)
 	/* Make sure to be in 64bit mode */
 	clear_thread_flag(TIF_IA32);
 
+	/* Ensure the corresponding mm is not marked. */
+	if (current->mm)
+		current->mm->context.compat = 0;
+
 	/* TBD: overwrites user setup. Should have two bits.
 	   But 64bit processes have always behaved this way,
 	   so it's not too bad. The main problem is just that
@@ -516,6 +520,10 @@ void set_personality_ia32(void)
 	set_thread_flag(TIF_IA32);
 	current->personality |= force_personality32;
 
+	/* Mark the associated mm as containing 32-bit tasks. */
+	if (current->mm)
+		current->mm->context.compat = 1;
+
 	/* Prepare the first "return" to user space */
 	current_thread_info()->status |= TS_COMPAT;
 }
-- 
1.7.3.5

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