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Russell King (Oracle)andGreg Kroah-Hartman
b38d9750f8
commit fd2dee1c6e upstream.
__do_user_fault() may be called with indeterminent interrupt enable
state, which means we may be preemptive at this point. This causes
problems when calling harden_branch_predictor(). For example, when
called from a data abort, do_alignment_fault()->do_bad_area().
Move harden_branch_predictor() out of __do_user_fault() and into the
calling contexts.
Moving it into do_kernel_address_page_fault(), we can be sure that
interrupts will be disabled here.
Converting do_translation_fault() to use do_kernel_address_page_fault()
rather than do_bad_area() means that we keep branch predictor handling
for translation faults. Interrupts will also be disabled at this call
site.
do_sect_fault() needs special handling, so detect user mode accesses
to kernel-addresses, and add an explicit call to branch predictor
hardening.
Finally, add branch predictor hardening to do_alignment() for the
faulting case (user mode accessing kernel addresses) before interrupts
are enabled.
This should cover all cases where harden_branch_predictor() is called,
ensuring that it is always has interrupts disabled, also ensuring that
it is called early in each call path.
Reviewed-by: Xie Yuanbin <xieyuanbin1@huawei.com>
Tested-by: Xie Yuanbin <xieyuanbin1@huawei.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Sasha Levin <sashal@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 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.