Commit-ID: 6fc9dc81bff0ea461db534e2672acfdaf76f3e4e Gitweb: https://git.kernel.org/tip/6fc9dc81bff0ea461db534e2672acfdaf76f3e4e Author: Ricardo Neri <ricardo.neri-calde...@linux.intel.com> AuthorDate: Sun, 5 Nov 2017 18:27:55 -0800 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Wed, 8 Nov 2017 11:16:24 +0100
x86/traps: Fix up general protection faults caused by UMIP If the User-Mode Instruction Prevention CPU feature is available and enabled, a general protection fault will be issued if the instructions sgdt, sldt, sidt, str or smsw are executed from user-mode context (CPL > 0). If the fault was caused by any of the instructions protected by UMIP, fixup_umip_exception() will emulate dummy results for these instructions as follows: in virtual-8086 and protected modes, sgdt, sidt and smsw are emulated; str and sldt are not emulated. No emulation is done for user-space long mode processes. If emulation is successful, the emulated result is passed to the user space program and no SIGSEGV signal is emitted. Signed-off-by: Ricardo Neri <ricardo.neri-calde...@linux.intel.com> Reviewed-by: Thomas Gleixner <t...@linutronix.de> Reviewed-by: Andy Lutomirski <l...@kernel.org> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Borislav Petkov <b...@alien8.de> Cc: Borislav Petkov <b...@suse.de> Cc: Brian Gerst <brge...@gmail.com> Cc: Chen Yucong <sla...@gmail.com> Cc: Chris Metcalf <cmetc...@mellanox.com> Cc: Dave Hansen <dave.han...@linux.intel.com> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: Fenghua Yu <fenghua...@intel.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Huang Rui <ray.hu...@amd.com> Cc: Jiri Slaby <jsl...@suse.cz> Cc: Jonathan Corbet <cor...@lwn.net> Cc: Josh Poimboeuf <jpoim...@redhat.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Masami Hiramatsu <mhira...@kernel.org> Cc: Michael S. Tsirkin <m...@redhat.com> Cc: Paolo Bonzini <pbonz...@redhat.com> Cc: Paul Gortmaker <paul.gortma...@windriver.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Ravi V. Shankar <ravi.v.shan...@intel.com> Cc: Shuah Khan <sh...@kernel.org> Cc: Tony Luck <tony.l...@intel.com> Cc: Vlastimil Babka <vba...@suse.cz> Cc: ricardo.n...@intel.com Link: http://lkml.kernel.org/r/1509935277-22138-11-git-send-email-ricardo.neri-calde...@linux.intel.com [ Added curly braces. ] Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/kernel/traps.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 42a9c44..ab54bf3 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -60,6 +60,7 @@ #include <asm/trace/mpx.h> #include <asm/mpx.h> #include <asm/vm86.h> +#include <asm/umip.h> #ifdef CONFIG_X86_64 #include <asm/x86_init.h> @@ -513,6 +514,11 @@ do_general_protection(struct pt_regs *regs, long error_code) RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); cond_local_irq_enable(regs); + if (static_cpu_has(X86_FEATURE_UMIP)) { + if (user_mode(regs) && fixup_umip_exception(regs)) + return; + } + if (v8086_mode(regs)) { local_irq_enable(); handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
