On x86_32, modify_ldt() implicitly refreshes the cached DS and ES segments because they are refreshed on return to usermode. On x86_64, they're not refreshed on return to usermode. To improve determinism and match x86_32's behavior, refresh them when we update the LDT. This avoids a situation in which the DS points to a descriptor that is changed but the old cached segment persists until the next reschedule. If this happens, then the user-visible state will change nondeterministically some time after modify_ldt() returns, which is unfortunate. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Chang Seok <chang.seok.bae@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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README
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.