Stream: git-wasmtime

Topic: wasmtime / PR #3265 Don't copy executable code into a `Co...

Wasmtime GitHub notifications bot (Aug 30 2021 at 15:35):

alexcrichton opened PR #3265 from no-copy-code-memory to main:

This commit moves a copy from compiled artifacts into a CodeMemory. In
general this commit drastically changes the meaning of a CodeMemory.
Previously it was an iteratively-pushed-on structure that would
accumulate executable code over time. Afterwards, however, it's a
manager for an MmapVec which updates the permissions on text section
to ensure that the pages are executable.

By taking ownership of an MmapVec within a CodeMemory there's no
need to copy any data around, which means that the .text section in
the ELF image produced by Wasmtime is usable as-is after placement in
memory and relocations have been resolved. This moves Wasmtime one step
closer to being able to directly use a module after it's mmap'd into
memory, optimizing when a module is loaded.

<!--

Please ensure that the following steps are all taken care of before submitting
the PR.

• [ ] This has been discussed in issue #..., or if not, please tell us why
  here.

• [ ] A short description of what this does, why it is needed; if the
  description becomes long, the matter should probably be discussed in an issue
  first.

• [ ] This PR contains test cases, if meaningful.

• [ ] A reviewer from the core maintainer team has been assigned for this PR.
  If you don't know who could review this, please indicate so. The list of
  suggested reviewers on the right can help you.

Please ensure all communication adheres to the code of conduct.
-->

Wasmtime GitHub notifications bot (Aug 30 2021 at 15:36):

alexcrichton edited PR #3265 from no-copy-code-memory to main:

This commit moves a copy from compiled artifacts into a CodeMemory. In
general this commit drastically changes the meaning of a CodeMemory.
Previously it was an iteratively-pushed-on structure that would
accumulate executable code over time. Afterwards, however, it's a
manager for an MmapVec which updates the permissions on text section
to ensure that the pages are executable.

By taking ownership of an MmapVec within a CodeMemory there's no
need to copy any data around, which means that the .text section in
the ELF image produced by Wasmtime is usable as-is after placement in
memory and relocations have been resolved. This moves Wasmtime one step
closer to being able to directly use a module after it's mmap'd into
memory, optimizing when a module is loaded.

cc #3230

Wasmtime GitHub notifications bot (Aug 30 2021 at 15:37):

alexcrichton requested peterhuene for a review on PR #3265.

Wasmtime GitHub notifications bot (Aug 30 2021 at 16:04):

alexcrichton updated PR #3265 from no-copy-code-memory to main.

Wasmtime GitHub notifications bot (Aug 30 2021 at 16:17):

alexcrichton updated PR #3265 from no-copy-code-memory to main.

Wasmtime GitHub notifications bot (Aug 30 2021 at 16:18):

alexcrichton updated PR #3265 from no-copy-code-memory to main.

Wasmtime GitHub notifications bot (Aug 30 2021 at 18:23):

peterhuene submitted PR review.

Wasmtime GitHub notifications bot (Aug 30 2021 at 18:23):

peterhuene submitted PR review.

Wasmtime GitHub notifications bot (Aug 30 2021 at 18:23):

peterhuene created PR review comment:

                .with_context(|| "failed to parse internal compilation artifact")?,

Wasmtime GitHub notifications bot (Aug 30 2021 at 18:23):

peterhuene created PR review comment:

    /// `publish` method is used to actually make the memory executable.

Wasmtime GitHub notifications bot (Aug 30 2021 at 18:38):

alexcrichton updated PR #3265 from no-copy-code-memory to main.

Wasmtime GitHub notifications bot (Aug 30 2021 at 18:38):

alexcrichton merged PR #3265.

Last updated: Dec 23 2024 at 12:05 UTC