** Description changed: [Impact] In bug 1756096, we backported SDEI (Software Delegated Exception Interface) support for arm64. However, this backport missed 2 changes that make the SDEI entry point a trampoline which make sure the kernel is mapped before processing. (The kernel may not be mapped if KPTI is enabled and the exception comes in while e.g. executing in usermode). [Test Case] I haven't yet found a way to inject/simulate an SDEI, so I can only regression test by boot testing. [Regression Risk] - The code is restricted to arm64, and should only run on systems that support SDEI. + The code is restricted to arm64, and should only run on systems that support SDEI. I'm unaware of any production firmware that expose the SDEI ACPI table, which means this code isn't actively used yet anyway.
** Description changed: [Impact] - In bug 1756096, we backported SDEI (Software Delegated Exception Interface) support for arm64. However, this backport missed 2 changes that make the SDEI entry point a trampoline which make sure the kernel is mapped before processing. (The kernel may not be mapped if KPTI is enabled and the exception comes in while e.g. executing in usermode). + In bug 1756096, we backported SDEI (Software Delegated Exception Interface) support for arm64. However, this backport missed 2 changes that make the SDEI entry point a trampoline which make sure the kernel is mapped before processing. (The kernel may not be mapped if KPTI is enabled and the exception comes in while e.g. executing in usermode). This may lead to a crash. [Test Case] I haven't yet found a way to inject/simulate an SDEI, so I can only regression test by boot testing. [Regression Risk] The code is restricted to arm64, and should only run on systems that support SDEI. I'm unaware of any production firmware that expose the SDEI ACPI table, which means this code isn't actively used yet anyway. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1768630 Title: arm64 SDEI support needs trampoline code for KPTI Status in linux package in Ubuntu: In Progress Status in linux source package in Bionic: In Progress Bug description: [Impact] In bug 1756096, we backported SDEI (Software Delegated Exception Interface) support for arm64. However, this backport missed 2 changes that make the SDEI entry point a trampoline which make sure the kernel is mapped before processing. (The kernel may not be mapped if KPTI is enabled and the exception comes in while e.g. executing in usermode). This may lead to a crash. [Test Case] I haven't yet found a way to inject/simulate an SDEI, so I can only regression test by boot testing. [Regression Risk] The code is restricted to arm64, and should only run on systems that support SDEI. I'm unaware of any production firmware that expose the SDEI ACPI table, which means this code isn't actively used yet anyway. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1768630/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
