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

Stephen Wilson
2011-03-09T00:31:58Z

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@start.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