Messages in this thread | | | Subject | Re: [PATCH v2] sparc64: Add support for Application Data Integrity (ADI) | From | Khalid Aziz <> | Date | Mon, 7 Mar 2016 14:06:43 -0700 |
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On 03/07/2016 10:46 AM, Dave Hansen wrote: > On 03/07/2016 08:06 AM, Khalid Aziz wrote: >> Top 4-bits of sparc64 virtual address are used for version tag only when >> a process has its PSTATE.mcde bit set and it is accessing a memory >> region that has ADI enabled on it (TTE.mcd set) and a version tag was >> set on the virtual address being accessed. These 4-bits retain their >> original semantics in all other cases. > > OK, so this effectively reduces the address space of a process using the > feature. Do we need to do anything explicit to keep an app from using > that address space? Do we make sure the kernel doesn't place VMAs > there? Do we respect mmap() hints that try to place memory there? >
Good questions. Isn't set of valid VAs already constrained by VA_BITS (set to 44 in arch/sparc/include/asm/processor_64.h)? As I see it we are already not using the top 4 bits. Please correct me if I am wrong.
Thanks, Khalid
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