Enclave TCS control

[raoulstrackx]

Intel SGXv2 enables the dynamic creation of TCSes. To use this correctly, the enclave needs to be in charge of controlling which TCS will be used for new threads. This PR implements such control for SGXv1 enclaves, as a preliminary step for SGXv2 support.

cc: @jethrogb

[rust-highfive]

r? @cramertj

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[raoulstrackx]

Blocked by fortanix/rust-sgx#300

[bors]

☔ The latest upstream changes (presumably #79128) made this pull request unmergeable. Please resolve the merge conflicts.

Note that reviewers usually do not review pull requests until merge conflicts are resolved! Once you resolve the conflicts, you should change the labels applied by bors to indicate that your PR is ready for review. Post this as a comment to change the labels:

@rustbot modify labels: +S-waiting-on-review -S-waiting-on-author

[jethrogb]

Review can be delegated to me

[bors]

☔ The latest upstream changes (presumably #85014) made this pull request unmergeable. Please resolve the merge conflicts.

[rust-log-analyzer]

The job mingw-check failed! Check out the build log: (web)(plain)

Click to see the possible cause of the failure (guessed by this bot)

# 2.7%
######################################################################## 100.0%
extracting /checkout/obj/build/cache/2021-03-25/rustfmt-nightly-x86_64-unknown-linux-gnu.tar.xz
Updating git repository `https://github.com/fortanix/rust-sgx.git`
---
configure: rust.channel := nightly
configure: rust.debug-assertions := True
configure: llvm.assertions := True
configure: dist.missing-tools := True
configure: build.configure-args := ['--enable-sccache', '--disable-manage-submodu ...
configure: writing `config.toml` in current directory
configure: configure: run `python /checkout/x.py --help`
configure: ---
Compiling tidy v0.1.0 (/checkout/src/tools/tidy)
Finished release [optimized] target(s) in 12.27s
tidy check
tidy: Skipping binary file check, read-only filesystem
tidy error: invalid source: "git+https://github.com/fortanix/rust-sgx.git?branch=raoul/tcs_control#495f16cb6cd0d8f6a7b25ade5196a96a0d22fe35"
* 625 error codes
* highest error code: E0783
Found 499 error codes
Found 0 error codes with no tests
Found 0 error codes with no tests
Done!
* 340 features
some tidy checks failed
command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/rust-tidy" "/checkout" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "/checkout/obj/build" "16"
Build completed unsuccessfully in 0:00:15

[bors]

☔ The latest upstream changes (presumably #90188) made this pull request unmergeable. Please resolve the merge conflicts.

[bjorn3]

Why these changes?

[Mark-Simulacrum]

I'm going to go ahead and close this PR, but please feel free to reopen or re-file when the upstream blocking concerns are addressed. Thanks!