search for: pagerando

This RFC describes pagerando, an improvement upon ASLR for shared libraries. We're planning to submit this work for upstreaming and would appreciate feedback before we get to the patch submission stage. Pagerando randomizes the location of individual memory pages (ASLR only randomizes the library base address). This incre...

On Sat, Jun 10, 2017 at 4:09 PM, Davide Italiano <davide at freebsd.org> wrote: > On Tue, Jun 6, 2017 at 10:55 AM, Stephen Crane via llvm-dev > <llvm-dev at lists.llvm.org> wrote: >> This RFC describes pagerando, an improvement upon ASLR for shared >> libraries. We're planning to submit this work for upstreaming and >> would appreciate feedback before we get to the patch submission stage. >> >> Pagerando randomizes the location of individual memory pages (ASLR >> only rand...

On Mon, Jun 12, 2017 at 1:03 PM, Stephen Crane <sjc at immunant.com> wrote: > I don't have performance measurements for the new LTO version of > pagerando yet. I'll definitely be thoroughly measuring performance > once the current prototype is finished before moving forward, and will > post results when I have them. > > I'm definitely curious about your work and its performance impact. > Were you randomizing the layout of funct...

I could understand a TLB hit if functions that originally happened to be on the same page were spread across many pages, raising the iTLB footprint for a given loop, etc. (reduced spatial locality). For pagerando, since we're splitting on 4k page boundaries and can keep spatial locality (or attempt to improve it), I'm not sure that TLB misses will be a large factor. I expect that the runtime overhead of inter-page indirection will dominate any TLB impact. On Mon, Jun 12, 2017 at 3:31 PM, Sean Silva...

I've been digging into COMDAT with regular LTO, specifically in the context of the LLVM gold plugin. The GCC WHOPR documentation specifies that the linker will resolve all COMDAT groups to the IR-provided definitions, if available. Additionally it specifies that "When the WPA phase produces the definition of the COMDAT symbol in a new object file, that definition should not be in a COMDAT