Messages in this thread | | | Subject | Re: [PATCH v7 03/14] x86/cet/ibt: Add IBT legacy code bitmap setup function | From | Yu-cheng Yu <> | Date | Fri, 14 Jun 2019 08:25:16 -0700 |
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On Mon, 2019-06-10 at 15:59 -0700, Dave Hansen wrote: > On 6/10/19 3:40 PM, Yu-cheng Yu wrote: > > Ok, we will go back to do_mmap() with MAP_PRIVATE, MAP_NORESERVE and > > VM_DONTDUMP. The bitmap will cover only 48-bit address space. > > Could you make sure to discuss the downsides of only doing a 48-bit > address space?
The downside is that we cannot load legacy lib's above 48-bit address space, but currently ld-linux does not do that. Should ld-linux do that in the future, dlopen() fails. Considering CRIU migration, we probably need to do this anyway?
> What are the reasons behind and implications of VM_DONTDUMP?
The bitmap is very big.
In GDB, it should be easy to tell why a control-protection fault occurred without the bitmap.
Yu-cheng
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