similar to: Spectre V1 Mitigation - Internals?

Hi, Thanks for your email, I understand that the execution stalls until the predicated state is computed, then we mask pointers with all_zeros_mask if there is a mis-prediction. But I understand that as soon as the condition value is available, the processor can check about it's assumptions and revert back. That is, If the branch prediction is correct during speculation, we mask with

Hi, Yeah, now I understand the problem here. Thanks. But I too have another doubt in "Bounds check bypass store" In this example in the Speculative load hardening : unsigned char local_buffer[4];unsigned char *untrusted_data_from_caller = ...;unsigned long untrusted_size_from_caller = ...;if (untrusted_size_from_caller < sizeof(local_buffer)) { // Speculative execution enters here

Hello all, I've been working for the last month or so on a comprehensive mitigation approach to variant #1 of Spectre. There are a bunch of reasons why this is desirable: - Critical software that is unlikely to be easily hand-mitigated (or where the performance tradeoff isn't worth it) will have a compelling option. - It gives us a baseline on performance for hand-mitigation. - Combined

In a code segment of my pass plugin, I try to gather AliasSets for all StoreInst, LoadInst and CallInst instructions in a function. Some behaviors of the pass puzzled me. Below is the *.ll of the test program which I run the pass on, it was get with "llvm-gcc -Wl,--disable-opt" from a rather simple *.c program. ---------------------------------- ; ModuleID = 'ptralias.bc'

Oh, I appologize that I should not have asked about __main() ---- it appears in FAQ. But the question remains that why call to __main() can alias stack location? I think the memory location pointed by data_X pointers are not visible to __main(). In comparison, calls to printf() do not have similar effect. On 5/14/06, Nai Xia <nelson.xia at gmail.com> wrote: > > In a code segment of

Hi Chris, I took a haste look at the "Points-to Analysis in Almost Linear Time" by Steens , your PHD thesis and SteensGaard.cpp in LLVM this afternoon. So I think: 1. Actually the basic algorithm described originally by SteensGaard does not provide MOD/REF information for functions. 2. The context insensitive part of Data Structure Analysis (LocalAnalysis) can be deemed as an

On Tuesday 16 May 2006 03:19, Chris Lattner wrote: > On Mon, 15 May 2006, Nai Xia wrote: > > > In other words, if I only use -steens-aa and the data_XXXs are all > > external global variables( and so inComplete ), > > Sounds right! > > > the call to printf will > > make the same effect, which I have tested it. > > > > Am I right ? :) >

On Wed, 17 May 2006, Nai Xia wrote: > Unfortunately, I did not locate the lines in steens-aa for "printf" special case. > In ds-aa, I found the lines below: Right, steens-aa and ds-aa share code for "local analysis", they just stitch it together into an interprocedural analysis in different ways. The code below is used for steens-aa. >

On Mon, 15 May 2006, Nai Xia wrote: > In other words, if I only use -steens-aa and the data_XXXs are all > external global variables( and so inComplete ), Sounds right! > the call to printf will > make the same effect, which I have tested it. > > Am I right ? :) If you've tested it then, yes you're right :). I haven't played with this stuff for a long time,

The changes to vorbisfile that I suggested earlier have now been committed - this is mostly a merge of my code with a similar patch from Martin Vogt (thanks Martin). The old ov_open() interface remains untouched - and for many people, this is all you'll need to use, ever. It now calls the new interface with appropriate arguments. The new ov_open_callbacks() function adds an extra argument to

Another thing to consider about your feature idea is that the output may be noisy depending on what you were hoping for. SLH tries to mitigate anything that could potentially be a problem and thus it instruments almost every branch, load, and function entry, for example. There isn't a lot of signal about what is really a gadget among the code instrumented by SLH. It really tries to be

Hi I think llvm-dev list (CC'ed) have more visibility in this. On Wed, 22 Apr 2020 at 22:18, milsegv via cfe-dev <cfe-dev at lists.llvm.org> wrote: > Hello everyone, > > It may not be the best place to ask this but I found nothing on the > internet about it. > I'm working on Spectre V1 detection and stumbled upon the mitigation > provided by clang, the

Has anyone applied patches to gluster storage node or fuse clients in an attempt to address Meltdown/Spectre issues? I'm curious if anyone has noticed or expects to see a performance impact. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.gluster.org/pipermail/gluster-users/attachments/20180117/28573776/attachment.html>

Hi All, Over the last few weeks I have been developing an LLVM Utility pass to check a program at the IR level for Spectre variant 1 (bounds check bypass) vulnerabilities. The pass was initially developed for internal use. However, as it has proved to be useful we have decided to share it with the LLVM community. The pass currently must be enabled with -mllvm -enable-sceptre. When it finds

On 4 January 2018 at 10:23, Chandler Carruth via llvm-dev <llvm-dev at lists.llvm.org> wrote: > Sending a note here as this seems likely to be of relatively broad interest. > > Thread: > http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20180101/513630.html > > Review link: > https://reviews.llvm.org/D41723# It seems the review link is getting wider coverage

The folks working on phab are busily propping it up. It should be relatively healthy now. On Thu, Jan 4, 2018 at 9:20 AM Alex Bradbury via llvm-dev < llvm-dev at lists.llvm.org> wrote: > On 4 January 2018 at 10:23, Chandler Carruth via llvm-dev > <llvm-dev at lists.llvm.org> wrote: > > Sending a note here as this seems likely to be of relatively broad > interest. >

> On Jan 4, 2018, at 04:23, Chandler Carruth via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > Sending a note here as this seems likely to be of relatively broad interest. It looks like this is producing code of the following form. call next loop: pause jmp loop next: mov [rsp], r11 ret As I understand it, the busy loop is to cause the speculative execution to be trapped

On 4 January 2018 at 16:49, Chandler Carruth <chandlerc at gmail.com> wrote: > The folks working on phab are busily propping it up. It should be relatively > healthy now. Many thanks to those good people! Have you considered developing the patch description into a blog post for blog.llvm.org, maybe after the patch lands? Best, Alex

Hi LLVM developers, Does it need to implement <Target>RetpolineThunksPass, `getOpcodeForRetpoline`, `EmitLoweredRetpoline`, etc. for other Targets? Or does it also need to implement `RetpolinePic` to inherit from <Target> for LLD's Backends? Alex is my mentor, he is leading me to maintain RISCV target, so I have such question, please give me suggestions, thanks for your

Does anyone know if Red Hat are working on backporting improved mitigation techniques and features from newer, 4.14.14+ kernels? $ grep . /sys/devices/system/cpu/vulnerabilities/* /sys/devices/system/cpu/vulnerabilities/meltdown:Mitigation: PTI /sys/devices/system/cpu/vulnerabilities/spectre_v1:Vulnerable /sys/devices/system/cpu/vulnerabilities/spectre_v2:Vulnerable: Minimal generic ASM retpoline