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2016-04-29x86/segments/64: When loadsegment(fs, ...) fails, clear the baseAndy Lutomirski1-0/+10
On AMD CPUs, a failed loadsegment currently may not clear the FS base. Fix it. While we're at it, prevent loadsegment(gs, xyz) from even compiling on 64-bit kernels. It shouldn't be used. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/a084c1b93b7b1408b58d3fd0b5d6e47da8e7d7cf.1461698311.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-13x86/extable: Add a comment about early exception handlersAndy Lutomirski1-0/+14
Borislav asked for a comment explaining why all exception handlers are allowed early. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Borislav Petkov <bp@suse.de> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: KVM list <kvm@vger.kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: xen-devel <Xen-devel@lists.xen.org> Link: http://lkml.kernel.org/r/5f1dcd6919f4a5923959a8065cb2c04d9dac1412.1459784772.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-13x86/msr: Carry on after a non-"safe" MSR access failsAndy Lutomirski1-0/+27
This demotes an OOPS and likely panic due to a failed non-"safe" MSR access to a WARN_ONCE() and, for RDMSR, a return value of zero. To be clear, this type of failure should *not* happen. This patch exists to minimize the chance of nasty undebuggable failures happening when a CONFIG_PARAVIRT=y bug in the non-"safe" MSR helpers gets fixed. Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Andy Lutomirski <luto@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: KVM list <kvm@vger.kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: xen-devel <Xen-devel@lists.xen.org> Link: http://lkml.kernel.org/r/26567b216aae70e795938f4b567eace5a0eb90ba.1459605520.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-13x86/traps: Enable all exception handler callbacks earlyAndy Lutomirski1-17/+2
Now that early_fixup_exception() has pt_regs, we can just call fixup_exception() from it. This will make fancy exception handlers work early. Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Andy Lutomirski <luto@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: KVM list <kvm@vger.kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: xen-devel <Xen-devel@lists.xen.org> Link: http://lkml.kernel.org/r/20fc047d926150cb08cb9b9f2923519b07ec1a15.1459605520.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-13x86/head: Move early exception panic code into early_fixup_exception()Andy Lutomirski1-5/+24
This removes a bunch of assembly and adds some C code instead. It changes the actual printouts on both 32-bit and 64-bit kernels, but they still seem okay. Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Andy Lutomirski <luto@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: KVM list <kvm@vger.kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: xen-devel <Xen-devel@lists.xen.org> Link: http://lkml.kernel.org/r/4085070316fc3ab29538d3fcfe282648d1d4ee2e.1459605520.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-13x86/head: Move the early NMI fixup into CAndy Lutomirski1-0/+5
C is nicer than asm. Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Andy Lutomirski <luto@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: KVM list <kvm@vger.kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: xen-devel <Xen-devel@lists.xen.org> Link: http://lkml.kernel.org/r/dd068269f8d59fe44e9e43a50d0efd67da65c2b5.1459605520.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-13x86/head: Pass a real pt_regs and trapnr to early_fixup_exception()Andy Lutomirski1-3/+3
early_fixup_exception() is limited by the fact that it doesn't have a real struct pt_regs. Change both the 32-bit and 64-bit asm and the C code to pass and accept a real pt_regs. Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Andy Lutomirski <luto@kernel.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: KVM list <kvm@vger.kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: xen-devel <Xen-devel@lists.xen.org> Link: http://lkml.kernel.org/r/e3fb680fcfd5e23e38237e8328b64a25cc121d37.1459605520.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-23x86/extable: use generic search and sort routinesArd Biesheuvel1-108/+0
Replace the arch specific versions of search_extable() and sort_extable() with calls to the generic ones, which now support relative exception tables as well. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: H. Peter Anvin <hpa@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-02-18x86/mm: Expand the exception table logic to allow new handling optionsTony Luck1-28/+72
Huge amounts of help from Andy Lutomirski and Borislav Petkov to produce this. Andy provided the inspiration to add classes to the exception table with a clever bit-squeezing trick, Boris pointed out how much cleaner it would all be if we just had a new field. Linus Torvalds blessed the expansion with: ' I'd rather not be clever in order to save just a tiny amount of space in the exception table, which isn't really criticial for anybody. ' The third field is another relative function pointer, this one to a handler that executes the actions. We start out with three handlers: 1: Legacy - just jumps the to fixup IP 2: Fault - provide the trap number in %ax to the fixup code 3: Cleaned up legacy for the uaccess error hack Signed-off-by: Tony Luck <tony.luck@intel.com> Reviewed-by: Borislav Petkov <bp@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/f6af78fcbd348cf4939875cfda9c19689b5e50b8.1455732970.git.tony.luck@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-04-21x86, extable: Switch to relative exception table entriesH. Peter Anvin1-8/+123
Switch to using relative exception table entries on x86. On i386, this has the advantage that the exception table entries don't need to be relocated; on x86-64 this means the exception table entries take up only half the space. In either case, a 32-bit delta is sufficient, as the range of kernel code addresses is limited. Since part of the goal is to avoid needing to adjust the entries when the kernel is relocated, the old trick of using addresses in the NULL pointer range to indicate uaccess_err no longer works (and unlike RISC architectures we can't use a flag bit); instead use an delta just below +2G to indicate these special entries. The reach is still limited to a single instruction. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: David Daney <david.daney@cavium.com> Link: http://lkml.kernel.org/r/CA%2B55aFyijf43qSu3N9nWHEBwaGbb7T2Oq9A=9EyR=Jtyqfq_cQ@mail.gmail.com
2012-04-20x86, extable: Add early_fixup_exception()H. Peter Anvin1-0/+17
Add a restricted version of fixup_exception() to be used during early boot only. In particular, this doesn't support the try..catch variant since we may not have a thread_info set up yet. This relies on the exception table being sorted already at build time. Link: http://lkml.kernel.org/r/1334794610-5546-1-git-send-email-hpa@zytor.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2011-12-05x86-64: Set siginfo and context on vsyscall emulation faultsAndy Lutomirski1-1/+1
To make this work, we teach the page fault handler how to send signals on failed uaccess. This only works for user addresses (kernel addresses will never hit the page fault handler in the first place), so we need to generate signals for those separately. This gets the tricky case right: if the user buffer spans multiple pages and only the second page is invalid, we set cr2 and si_addr correctly. UML relies on this behavior to "fault in" pages as needed. We steal a bit from thread_info.uaccess_err to enable this. Before this change, uaccess_err was a 32-bit boolean value. This fixes issues with UML when vsyscall=emulate. Reported-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andy Lutomirski <luto@amacapital.net> Cc: richard -rw- weinberger <richard.weinberger@gmail.com> Cc: H. Peter Anvin <hpa@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/4c8f91de7ec5cd2ef0f59521a04e1015f11e42b4.1320712291.git.luto@amacapital.net Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-10-12x86, 64-bit: Move K8 B step iret fixup to fault entry asmBrian Gerst1-31/+0
Move the handling of truncated %rip from an iret fault to the fault entry path. This allows x86-64 to use the standard search_extable() function. Signed-off-by: Brian Gerst <brgerst@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jan Beulich <jbeulich@novell.com> LKML-Reference: <1255357103-5418-1-git-send-email-brgerst@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-24x86: uaccess: introduce try and catch frameworkHiroshi Shimamoto1-0/+6
Impact: introduce new uaccess exception handling framework Introduce {get|put}_user_try and {get|put}_user_catch as new uaccess exception handling framework. {get|put}_user_try begins exception block and {get|put}_user_catch(err) ends the block and gets err if an exception occured in {get|put}_user_ex() in the block. The exception is stored thread_info->uaccess_err. The example usage of this framework is below; int func() { int err = 0; get_user_try { get_user_ex(...); get_user_ex(...); : } get_user_catch(err); return err; } Note: get_user_ex() is not clear the value when an exception occurs, it's different from the behavior of __get_user(), but I think it doesn't matter. Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2008-01-30x86: unify extable_{32|64}.cHarvey Harrison1-0/+62
Introduce fixup_exception() on 64-bit and use it in kprobes to eliminate an #ifdef. Only 64-bit needs search_extable() due to a stepping bug. Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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