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.
Waiman Long
authored
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2090231 Conflcits: Fuzz in arch/x86/xen/xen-asm.S due to missing upstream commit 09c41307 ("x86/xen: Make irq_disable() noinstr"). commit 5c8f6a2e Author: Lai Jiangshan <laijs@linux.alibaba.com> Date: Fri, 26 Nov 2021 18:11:23 +0800 x86/xen: Add xenpv_restore_regs_and_return_to_usermode() In the native case, PER_CPU_VAR(cpu_tss_rw + TSS_sp0) is the trampoline stack. But XEN pv doesn't use trampoline stack, so PER_CPU_VAR(cpu_tss_rw + TSS_sp0) is also the kernel stack. In that case, source and destination stacks are identical, which means that reusing swapgs_restore_regs_and_return_to_usermode() in XEN pv would cause %rsp to move up to the top of the kernel stack and leave the IRET frame below %rsp. This is dangerous as it can be corrupted if #NMI / #MC hit as either of these events occurring in the middle of the stack pushing would clobber data on the (original) stack. And, with XEN pv, swapgs_restore_regs_and_return_to_usermode() pushing the IRET frame on to the original address is useless and error-prone when there is any future attempt to modify the code. [ bp: Massage commit message. ] Fixes: 7f2590a1 ("x86/entry/64: Use a per-CPU trampoline stack for IDT entries") Signed-off-by:Lai Jiangshan <laijs@linux.alibaba.com> Signed-off-by:
Borislav Petkov <bp@suse.de> Reviewed-by:
Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: https://lkml.kernel.org/r/20211126101209.8613-4-jiangshanlai@gmail.com Signed-off-by:
Waiman Long <longman@redhat.com>