Messages in this thread | ![/](/images/icornerl.gif) | | From | "Chen, Kenneth W" <> | Subject | RE: [PATCH] connector: Some fixes for ia64 unaligned access errors | Date | Mon, 11 Dec 2006 18:07:08 -0800 |
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Pete Zaitcev wrote on Monday, December 11, 2006 5:29 PM > On Mon, 11 Dec 2006 15:52:47 -0800, Matt Helsley <matthltc@us.ibm.com> wrote: > > > I'm shocked memcpy() introduces 8-byte stores that violate architecture > > alignment rules. Is there any chance this a bug in ia64's memcpy() > > implementation? I've tried to read it but since I'm not familiar with > > ia64 asm I can't make out significant parts of it in > > arch/ia64/lib/memcpy.S. > > The arch/ia64/lib/memcpy.S is probably fine, it must be gcc doing > an inline substitution of a well-known function.
arch/ia64/lib/memcpy.S is fine because it does alignment check at the very beginning of the function and depends on the alignment of dst/src alignment, it does different thing. The unaligned access is coming from gcc inlined version of memcpy.
But looking deeply, memory allocation for proc_event in proc_for_connector doesn't looked correct at all:
In drivers/connector/cn_proc.c: #define CN_PROC_MSG_SIZE (sizeof(struct cn_msg) + sizeof(struct proc_event))
void proc_fork_connector(struct task_struct *task) { struct cn_msg *msg; struct proc_event *ev; __u8 buffer[CN_PROC_MSG_SIZE];
You can't do that because gcc assumes struct proc_event aligns on certain boundary. Doing fancy hand crafting like that breaks code generated by gcc.
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