Tag: Sai Praneeth Prakhya

Linux kernel EGP_PGT_DUMP build option

~ hucktech ~ Leave a comment

Sai Praneeth Prakhya of Intel submitted V2 of an Intel UEFI diagnostic patch for the Linux kernel, the new version adds x86 support.

[PATCH V2] x86/efi: Add EFI_PGT_DUMP support for x86_32, kexec
EFI_PGT_DUMP, as the name suggests dumps efi page tables to dmesg during kernel boot. This feature is very useful while debugging page faults/null pointer dereferences to efi related addresses. Presently, this feature is limited only to x86_64, so let’s extend it to other efi configurations like kexec kernel, efi=old_map and to x86_32 as well. This doesn’t effect normal boot path because this config option should be used only for debug purposes.

Changes since v1:
1. Call efi_dump_pagetable() only once from efi_enter_virtual_mode() – as suggested by Boris

For more info, see the patch on the linux-(kernel,efi) lists.

LUV adds EFI_WARN_ON_ILLEGAL_ACCESSES

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Sai Praneeth Prakhya of Intel has posted a patch to the LUV project list, with new clever new abilities to increase LUV’s ability to detect bad UEFI firmware.

Presently, LUV detects illegal accesses by firmware to EFI_BOOT_SERVICES_* regions only during “SetVirtualAddressMap()”. According to UEFI spec, this function will be called only once; by kernel during boot. Hence, LUV cannot detect any other illegal accesses that firmware might do after boot. Moreover, LUV can detect illegal accesses *only* to EFI_BOOT_SERVICES_CODE/DATA regions. This patch set tries to address the above mentioned two issues:
1. Detect illegal accesses to other EFI regions (like EFI_LOADER_CODE/DATA, EFI_CONVENTIONAL_MEMORY)
2. Detect illegal accesses to these regions even after kernel has booted
Recently, we came across machines with buggy firmware that access EFI memory regions like EFI_CONVENTIONAL_MEMORY, EFI_BOOT_SERVICES_CODE/DATA and EFI_LOADER_CODE/DATA even after kernel has booted. Firmware accesses these regions when some efi_runtime_service() is invoked by test cases like FWTS. These illegal accesses can potentially cause kernel hang. Hence, it’s good to have a test case in LUV which can detect these illegal accesses and hence report them to user. This requires making changes to kernel and searching dmesg for relative warnings. As there are 9 patches to linux kernel to enable this feature and putting all these 9 kernel patches in a single LUV patch makes the LUV patch gigantic; hence I have split them into smaller ones (as suggested by Ricardo). The first patch in this series (“linux-yocto-efi-test: Do not support EFI_BOOT_SERVICES_WARN”) removes support to “EFI_BOOT_SERVICES_WARN” and the later patches add all the bits and pieces together and the 10th patch (“linux-yocto-efi-test: Introduce EFI_WARN_ON_ILLEGAL_ACCESSES”) enables the (new) feature.

Full patch:
https://lists.01.org/mailman/listinfo/luv
.

LUV-live 2.0-RC4 released

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Ricardo Neri of Intel announced Linux UEFI Validation (LUV) v2.0-rc4 release, with lots of changes, new versions of CHIPSEC, BITS, FWTS, and multiple UEFI improvements in LUV. IMO, one of the most important features it that LUV-live’s CHIPSEC should properly log results now! Excerpts from Ricardo’s announcement:

This release touches many areas. Here are some highlights:

Naresh Bhat implemented changes to build from Linus’ tree when building LUV for ARM. While doing this, he got rid of the leg-kernel recipe. Now the kernel is built from linux-yocto-efi-test for all architectures. Also, he took the opportunity to remove some of the LUV-specific changes we had in the meta layer (i.e., our genericarmv8 machine). It always good to restrict ourselves to the meta-luv layer, unless we plan to upstream to the Yocto Project. Now LUV for aarch64 is built using qemuarm64.

It was reported that CHIPSEC was not running correctly in LUV due to missing configuration files and Python modules. This release includes a major rework of CHIPSEC integration into LUV. It ran correctly on all the systems in which we tested. Also, we bumped to v1.2.2; the CHIPSEC latest release.

This release includes new functionality to build BITS from its source rather than just deploying its binaries. BITS is a challenging piece of software when it comes to integration into a bitbake recipe. The build process was broken into several steps. This work help for future work to customize BITS for other CPU architectures and netboot.

The UEFI specification v2.5 includes a Properties Table for the memory map. Under this feature, it is possible to split into separate memory sections the code and data regions of the PE/COFF image. Unfortunately, kernels previous to v4.3 crash if this features is enabled. We have backported a fix pushed to Linux v4.3. We will be bumping the kernel for x86 to 4.3 in our next release.

The EFI stub feature in the kernel allows to run the kernel as an EFI application. Also, it allows the kernel to parse the memory map directly from the firmware rather than taking the map from the bootloader. This is clearly advantageous in case of bugs in the bootloader.

Now that LUV support storing the results of multiple bots, it may happen that disk runs out of space. Gayatri Kammela made updates to increase the size of the results partition and issue a warning when available space runs below 2MB.

Finally, keeping up with the latest changes in the Yocto Project has paid off handsomely. This release is based on Jethro, the latest version of the Yocto Project. Rebasing to this new version as done with very little effort. In the LUV tree you can find the jethro and jethro-next branches; the bases of this release. The fido and fido-next branches are still maintained.

We have bumped the following test suite versions:

 *FTWS is now V15.12.00
 *CHIPSEC is now v1.2.2
 *BITS is 2005

Time to update your LUV-live images! It is a Release Candidate, so please help the LUV team by testing it out and pointing out any issues on the LUV mailing list. This version of CHIPSEC includes VMM tests, so time to test LUV-luv in your virtual machines, not just on bare-metal boxes.

Many people contributed to this release, including: Ricardo Neri, Naresh Bhat, Darren Bilby, Megha Dey, Gayatri Kammela, John Loucaides, Sai Praneeth Prakhya, and Thiebaud Weksteen. It was nice to see the LUV and CHIPSEC teams work together in this release!

More information:
https://lists.01.org/pipermail/luv/2015-December/000745.html
https://download.01.org/linux-uefi-validation/v2.0/luv-live-v2.0-rc4.tar.bz2
https://download.01.org/linux-uefi-validation/v2.0/sha256_sums.asc

https://01.org/linux-uefi-validation/