mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-22 16:46:30 -04:00
7cbdb25bed
The exact wording of the restrictions on branch prediction due to FEAT_ECBHB in DDI0487L.b is as follows: When FEAT_ECBHB is implemented, the branch history information created in a context before an exception to a higher Exception level using AArch64 cannot be used by code before that exception to exploitatively control the execution of any indirect branches in code in a different context after the exception. While vEL2 and EL1 are multiplexed at EL1, they exist in different hardware-described contexts as KVM uses different stage-2 MMUs to represent the corresponding translation regimes. Additionally, exception entries into vEL2 always imply a hardware exception entry into literal EL2 for the emulated regime change. Given all of this, and the fact that FEAT_ECBHB places no limitation on the EL of the protected context after the exception, we can claim FEAT_ECBHB on supporting hardware. Signed-off-by: Oliver Upton <oliver.upton@linux.dev> Signed-off-by: Marc Zyngier <maz@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.