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Subject[PATCH 74/74] lto, workaround: Mark do_futex noinline to prevent clobbering ebp
From: Andi Kleen <>

On a 32bit build gcc 4.7 with LTO decides to clobber the 6th argument on the
stack. Unfortunately this corrupts the user EBP and leads to later crashes.
For now mark do_futex noinline to prevent this.

I wish there was a generic way to handle this. Seems like a ticking time
bomb problem.

Signed-off-by: Andi Kleen <>
kernel/futex.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index 3717e7b..48b5a07 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2620,7 +2620,7 @@ void exit_robust_list(struct task_struct *curr)
curr, pip);

-long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
+noinline long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
u32 __user *uaddr2, u32 val2, u32 val3)
int cmd = op & FUTEX_CMD_MASK;

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