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Certain user space programs that run on virtual-8086 mode may utilize instructions protected by the User-Mode Instruction Prevention (UMIP) security feature present in new Intel processors: SGDT, SIDT and SMSW. In such a case, a general protection fault is issued if UMIP is enabled. When such a fault happens, the kernel traps it and emulates the results of these instructions with dummy values. The purpose of this new test is to verify whether the impacted instructions can be executed without causing such #GP. If no #GP exceptions occur, we expect to exit virtual-8086 mode from INT3. The instructions protected by UMIP are executed in representative use cases: a) displacement-only memory addressing b) register-indirect memory addressing c) results stored directly in operands Unfortunately, it is not possible to check the results against a set of expected values because no emulation will occur in systems that do not have the UMIP feature. Instead, results are printed for verification. A simple verification is done to ensure that results of all tests are identical. Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bp@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Chen Yucong <slaoub@gmail.com> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Huang Rui <ray.huang@amd.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi V. Shankar <ravi.v.shankar@intel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Tony Luck <tony.luck@intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: ricardo.neri@intel.com Link: http://lkml.kernel.org/r/1509935277-22138-12-git-send-email-ricardo.neri-calderon@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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.