Add support for RNDR/RNDRRS for AArch64 on Linux #26839

john-moffett · 2023-01-06T20:20:03Z

This checks whether the ARMv8.5-A optional TRNG extensions RNDR and RNDRRS are available and, if they are, uses them for random entropy purposes.

They are nearly functionally identical to the x86 RDRAND/RDSEED extensions and are used in a similar manner.

Currently, there appears to be only one actual hardware implementation -- the Amazon Graviton 3. (See the rnd column in the link.) However, future hardware implementations may become available.

It's not possible to directly query for the capability in userspace, but the Linux kernel added support for querying the extension via getauxval in version 5.6 (in 2020), so this is limited to Linux-only for now.

Reviewers may want to launch any of the c7g instances from AWS to test the Graviton 3 hardware. Alternatively, QEMU emulates these opcodes for aarch64 with CPU setting max.

Output from Graviton 3 hardware:

ubuntu@ip:~/bitcoin$ src/bitcoind -regtest
2023-01-06T20:01:48Z Bitcoin Core version v24.99.0-3670266ce89a (release build)
2023-01-06T20:01:48Z Using the 'arm_shani(1way,2way)' SHA256 implementation
2023-01-06T20:01:48Z Using RNDR and RNDRRS as additional entropy sources
2023-01-06T20:01:48Z Default data directory /home/ubuntu/.bitcoin

Graviton 2 (doesn't support extensions):

ubuntu@ip:~/bitcoin$ src/bitcoind -regtest
2023-01-06T20:05:04Z Bitcoin Core version v24.99.0-3670266ce89a (release build)
2023-01-06T20:05:04Z Using the 'arm_shani(1way,2way)' SHA256 implementation
2023-01-06T20:05:04Z Default data directory /home/ubuntu/.bitcoin

This partially closes #26796. As noted in that issue, OpenSSL added support for these extensions a little over a year ago.

DrahtBot · 2023-01-06T20:20:05Z

The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

Code Coverage

For detailed information about the code coverage, see the test coverage report.

Reviews

See the guideline for information on the review process.

Type	Reviewers
ACK	laanwj, achow101
Concept ACK	fanquake, sipa, kristapsk

If your review is incorrectly listed, please react with 👎 to this comment and the bot will ignore it on the next update.

fanquake · 2023-01-09T10:07:02Z

Concept ACK

sipa · 2023-01-09T15:38:13Z

Concept ACK

src/random.cpp

laanwj · 2023-04-27T08:43:57Z

It's not possible to directly query for the capability in userspace, but the Linux kernel added support for querying the extension via getauxval in version 5.6 (in 2020), so this is limited to Linux-only for now.

That's the correct way to do it. We might actually want to define WCAP2_RNG ourselves instead of checking for its existence, to reduce dependency on compiling with specific kernel version headers (especially relevant for the GUIX release binary).

Code review ACK. I don't have access to hardware supporting this at the moment so wasn't able to test.

kristapsk · 2023-04-27T08:57:01Z

Concept ACK

achow101 · 2023-09-20T16:34:30Z

Are you still working on this?

john-moffett · 2023-09-20T16:41:17Z

Yes, I can update to address the nits.

src/random.cpp

This checks whether the ARMv8.5 extensions RNDR and RNDRRS are available and uses them for random entropy purposes. They are functionally identical to the x86 RDRAND/RDSEED extensions and are used in a similar manner.

laanwj

Tested ACK aee5404
I have verified this PR on the only available hardware (Amazon Graviton 3, m7g.medium instance). I was hoping for real hardware to become available but it looks like the recent crop of SoCs (such as RPI5) still doesn't have support for this extension.
In any case I've checked that the capability is detected correctly, and that RNDRRS is called four times at startup and RNDR frequently during runtime, and that the returned values look random. IMO this can be merged.

achow101 · 2023-11-07T19:58:53Z

ACK aee5404

The code looks correct to me, although I do not have hardware to test it.

aee5404 Add support for RNDR/RNDRRS for aarch64 on Linux (John Moffett) Pull request description: This checks whether the ARMv8.5-A optional TRNG extensions [RNDR](https://developer.arm.com/documentation/ddi0601/2022-12/AArch64-Registers/RNDR--Random-Number) and [RNDRRS](https://developer.arm.com/documentation/ddi0601/2022-12/AArch64-Registers/RNDRRS--Reseeded-Random-Number) are available and, if they are, uses them for random entropy purposes. They are nearly functionally identical to the x86 RDRAND/RDSEED extensions and are used in a similar manner. Currently, there [appears to be](https://marcin.juszkiewicz.com.pl/download/tables/arm-socs.html) only one actual hardware implementation -- the Amazon Graviton 3. (See the `rnd` column in the link.) However, future hardware implementations may become available. It's not possible to directly query for the capability in userspace, but the Linux kernel [added support](torvalds/linux@1a50ec0) for querying the extension via `getauxval` in version 5.6 (in 2020), so this is limited to Linux-only for now. Reviewers may want to launch any of the `c7g` instances from AWS to test the Graviton 3 hardware. Alternatively, QEMU emulates these opcodes for `aarch64` with CPU setting `max`. Output from Graviton 3 hardware: ``` ubuntu@ip:~/bitcoin$ src/bitcoind -regtest 2023-01-06T20:01:48Z Bitcoin Core version v24.99.0-3670266ce89a (release build) 2023-01-06T20:01:48Z Using the 'arm_shani(1way,2way)' SHA256 implementation 2023-01-06T20:01:48Z Using RNDR and RNDRRS as additional entropy sources 2023-01-06T20:01:48Z Default data directory /home/ubuntu/.bitcoin ``` Graviton 2 (doesn't support extensions): ``` ubuntu@ip:~/bitcoin$ src/bitcoind -regtest 2023-01-06T20:05:04Z Bitcoin Core version v24.99.0-3670266ce89a (release build) 2023-01-06T20:05:04Z Using the 'arm_shani(1way,2way)' SHA256 implementation 2023-01-06T20:05:04Z Default data directory /home/ubuntu/.bitcoin ``` This partially closes bitcoin#26796. As noted in that issue, OpenSSL [added support](openssl/openssl#15361) for these extensions a little over a year ago. ACKs for top commit: achow101: ACK aee5404 laanwj: Tested ACK aee5404 Tree-SHA512: 1c1eb345d6690f5307a87e9bac8f06a0d1fdc7ca35db38fa22192510a44289a03252e4677dc7cbf731a27e6e3a9a4e42b6eb4149fe063bc1c905eb2536cdb1d3

c75a0d4 Merge bitcoin#29177: build: Fix check whether `-latomic` needed (fanquake) f670118 Merge bitcoin#28851: build: Patch Qt to handle minimum macOS version properly (fanquake) 685ee8a Merge bitcoin#28884: doc: remove x86_64 build assumption from depends doc (fanquake) 47f6126 Merge bitcoin#28881: doc: remove mention of missing bdb being a configure error (fanquake) a9021db Merge bitcoin#28777: doc: update docs for `CHECK_ATOMIC` macro (fanquake) d5e15df Merge bitcoin#26839: Add support for RNDR/RNDRRS for AArch64 on Linux (Andrew Chow) 5aedcbf Merge bitcoin#28778: depends: drop -O1 workaround from arm64 apple Qt build (fanquake) 95a8d8c Merge bitcoin#21161: Fee estimation: extend bucket ranges consistently (glozow) f4ea48e Merge bitcoin#28693: build: Include `config/bitcoin-config.h` explicitly in `util/trace.h` (fanquake) f160e0d Merge bitcoin#28691: refactor: Remove CBlockFileInfo::SetNull (fanquake) 0278163 Merge bitcoin#28697: fuzz: Increase merge -rss_limit_mb (fanquake) 90a1fb0 Merge bitcoin#28650: fuzz: Merge with -set_cover_merge=1 (fanquake) f007abd Merge bitcoin#28459: build: add `-mbranch-protection=bti` (aarch64) to hardening flags (fanquake) af8d124 Merge bitcoin#28624: docs: fix typo (fanquake) c740264 Merge bitcoin#28532: qt: enable` -ltcg` for windows under LTO (fanquake) ccd3920 Merge bitcoin#28556: doc: fix link to developer-notes.md file in multiprocess.md (fanquake) Pull request description: ## Issue being fixed or feature implemented Batch of trivial backports ## What was done? See commits ## How Has This Been Tested? built locally; large combined merge passed tests locally ## Breaking Changes Should be none ## Checklist: _Go over all the following points, and put an `x` in all the boxes that apply._ - [ ] I have performed a self-review of my own code - [ ] I have commented my code, particularly in hard-to-understand areas - [ ] I have added or updated relevant unit/integration/functional/e2e tests - [ ] I have made corresponding changes to the documentation - [x] I have assigned this pull request to a milestone _(for repository code-owners and collaborators only)_ ACKs for top commit: UdjinM6: utACK c75a0d4 Tree-SHA512: 035dc3fa9812c7f381946ae4798b8e729a58b38a090d94502a8d992e9cfaab3307173c602d7b782c637a79c5c41b62570dc73bb4bb367e4505a039964926181b

laanwj · 2025-04-11T06:37:21Z

This was removed again in #32248 due to problems in #31817.

john-moffett force-pushed the 2023_01_RNDRSupportLinux branch from 3670266 to c38f168 Compare January 6, 2023 20:41

achow101 requested review from laanwj and sipa April 25, 2023 15:50

laanwj reviewed Apr 27, 2023

View reviewed changes

src/random.cpp Outdated Show resolved Hide resolved

laanwj reviewed Apr 27, 2023

View reviewed changes

src/random.cpp Show resolved Hide resolved

laanwj reviewed Apr 27, 2023

View reviewed changes

src/random.cpp Outdated Show resolved Hide resolved

achow101 added the Up for grabs label Sep 20, 2023

john-moffett force-pushed the 2023_01_RNDRSupportLinux branch from c38f168 to 8f065fd Compare September 20, 2023 20:32

DrahtBot added the CI failed label Sep 21, 2023

maflcko removed the Up for grabs label Sep 21, 2023

DrahtBot removed the CI failed label Sep 21, 2023

sipa reviewed Sep 29, 2023

View reviewed changes

src/random.cpp Outdated Show resolved Hide resolved

Add support for RNDR/RNDRRS for aarch64 on Linux

aee5404

This checks whether the ARMv8.5 extensions RNDR and RNDRRS are available and uses them for random entropy purposes. They are functionally identical to the x86 RDRAND/RDSEED extensions and are used in a similar manner.

john-moffett force-pushed the 2023_01_RNDRSupportLinux branch from 8f065fd to aee5404 Compare September 29, 2023 18:35

laanwj approved these changes Nov 7, 2023

View reviewed changes

DrahtBot requested review from sipa and fanquake November 7, 2023 15:38

achow101 merged commit c8a883a into bitcoin:master Nov 7, 2023

bitcoin locked and limited conversation to collaborators Nov 6, 2024

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Add support for RNDR/RNDRRS for AArch64 on Linux #26839

Add support for RNDR/RNDRRS for AArch64 on Linux #26839

Uh oh!

john-moffett commented Jan 6, 2023

Uh oh!

DrahtBot commented Jan 6, 2023 •

edited

Loading

Uh oh!

fanquake commented Jan 9, 2023

Uh oh!

sipa commented Jan 9, 2023

Uh oh!

Uh oh!

Uh oh!

Uh oh!

laanwj commented Apr 27, 2023 •

edited

Loading

Uh oh!

kristapsk commented Apr 27, 2023

Uh oh!

achow101 commented Sep 20, 2023

Uh oh!

john-moffett commented Sep 20, 2023

Uh oh!

Uh oh!

laanwj left a comment

Uh oh!

achow101 commented Nov 7, 2023

Uh oh!

laanwj commented Apr 11, 2025 •

edited

Loading

Uh oh!

Uh oh!

Add support for RNDR/RNDRRS for AArch64 on Linux #26839

Add support for RNDR/RNDRRS for AArch64 on Linux #26839

Uh oh!

Conversation

john-moffett commented Jan 6, 2023

Uh oh!

DrahtBot commented Jan 6, 2023 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Code Coverage

Reviews

Uh oh!

fanquake commented Jan 9, 2023

Uh oh!

sipa commented Jan 9, 2023

Uh oh!

Uh oh!

Uh oh!

Uh oh!

laanwj commented Apr 27, 2023 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

kristapsk commented Apr 27, 2023

Uh oh!

achow101 commented Sep 20, 2023

Uh oh!

john-moffett commented Sep 20, 2023

Uh oh!

Uh oh!

laanwj left a comment

Choose a reason for hiding this comment

Uh oh!

achow101 commented Nov 7, 2023

Uh oh!

laanwj commented Apr 11, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Uh oh!

DrahtBot commented Jan 6, 2023 •

edited

Loading

laanwj commented Apr 27, 2023 •

edited

Loading

laanwj commented Apr 11, 2025 •

edited

Loading