0b24cae4d5
Add a missing EHB (Execution Hazard Barrier) in mtc0 -> mfc0 sequence. Without this execution hazard barrier it's possible for the value read back from the KScratch register to be the value from before the mtc0. Reproducible on P5600 & P6600. The hazard is documented in the MIPS Architecture Reference Manual Vol. III: MIPS32/microMIPS32 Privileged Resource Architecture (MD00088), rev 6.03 table 8.1 which includes: Producer | Consumer | Hazard ----------|----------|---------------------------- mtc0 | mfc0 | any coprocessor 0 register Signed-off-by: Dmitry Korotin <dkorotin@wavecomp.com> [paul.burton@mips.com: - Commit message tweaks. - Add Fixes tags. - Mark for stable back to v3.15 where P5600 support was introduced.] Signed-off-by: Paul Burton <paul.burton@mips.com> Fixes:3d8bfdd030("MIPS: Use C0_KScratch (if present) to hold PGD pointer.") Fixes:829dcc0a95("MIPS: Add MIPS P5600 probe support") Cc: linux-mips@vger.kernel.org Cc: stable@vger.kernel.org # v3.15+
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 Restructured Text 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.