BMC/Intel-BMC/linux.git/arch/x86/entry/common.c, branch dev-5.2

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 257

2019-06-05T15:30:27+00:00

Based on 1 normalized pattern(s): gpl v2 extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 19 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Reviewed-by: Richard Fontana Reviewed-by: Steve Winslow Reviewed-by: Kate Stewart Reviewed-by: Alexios Zavras Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190529141333.108140152@linutronix.de Signed-off-by: Greg Kroah-Hartman

Merge branch 'x86-mds-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2019-05-14T14:57:29+00:00

Pull x86 MDS mitigations from Thomas Gleixner: "Microarchitectural Data Sampling (MDS) is a hardware vulnerability which allows unprivileged speculative access to data which is available in various CPU internal buffers. This new set of misfeatures has the following CVEs assigned: CVE-2018-12126 MSBDS Microarchitectural Store Buffer Data Sampling CVE-2018-12130 MFBDS Microarchitectural Fill Buffer Data Sampling CVE-2018-12127 MLPDS Microarchitectural Load Port Data Sampling CVE-2019-11091 MDSUM Microarchitectural Data Sampling Uncacheable Memory MDS attacks target microarchitectural buffers which speculatively forward data under certain conditions. Disclosure gadgets can expose this data via cache side channels. Contrary to other speculation based vulnerabilities the MDS vulnerability does not allow the attacker to control the memory target address. As a consequence the attacks are purely sampling based, but as demonstrated with the TLBleed attack samples can be postprocessed successfully. The mitigation is to flush the microarchitectural buffers on return to user space and before entering a VM. It's bolted on the VERW instruction and requires a microcode update. As some of the attacks exploit data structures shared between hyperthreads, full protection requires to disable hyperthreading. The kernel does not do that by default to avoid breaking unattended updates. The mitigation set comes with documentation for administrators and a deeper technical view" * 'x86-mds-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits) x86/speculation/mds: Fix documentation typo Documentation: Correct the possible MDS sysfs values x86/mds: Add MDSUM variant to the MDS documentation x86/speculation/mds: Add 'mitigations=' support for MDS x86/speculation/mds: Print SMT vulnerable on MSBDS with mitigations off x86/speculation/mds: Fix comment x86/speculation/mds: Add SMT warning message x86/speculation: Move arch_smt_update() call to after mitigation decisions x86/speculation/mds: Add mds=full,nosmt cmdline option Documentation: Add MDS vulnerability documentation Documentation: Move L1TF to separate directory x86/speculation/mds: Add mitigation mode VMWERV x86/speculation/mds: Add sysfs reporting for MDS x86/speculation/mds: Add mitigation control for MDS x86/speculation/mds: Conditionally clear CPU buffers on idle entry x86/kvm/vmx: Add MDS protection when L1D Flush is not active x86/speculation/mds: Clear CPU buffers on exit to user x86/speculation/mds: Add mds_clear_cpu_buffers() x86/kvm: Expose X86_FEATURE_MD_CLEAR to guests x86/speculation/mds: Add BUG_MSBDS_ONLY ...

x86/fpu: Defer FPU state load until return to userspace

2019-04-12T17:34:47+00:00

Defer loading of FPU state until return to userspace. This gives the kernel the potential to skip loading FPU state for tasks that stay in kernel mode, or for tasks that end up with repeated invocations of kernel_fpu_begin() & kernel_fpu_end(). The fpregs_lock/unlock() section ensures that the registers remain unchanged. Otherwise a context switch or a bottom half could save the registers to its FPU context and the processor's FPU registers would became random if modified at the same time. KVM swaps the host/guest registers on entry/exit path. This flow has been kept as is. First it ensures that the registers are loaded and then saves the current (host) state before it loads the guest's registers. The swap is done at the very end with disabled interrupts so it should not change anymore before theg guest is entered. The read/save version seems to be cheaper compared to memcpy() in a micro benchmark. Each thread gets TIF_NEED_FPU_LOAD set as part of fork() / fpu__copy(). For kernel threads, this flag gets never cleared which avoids saving / restoring the FPU state for kernel threads and during in-kernel usage of the FPU registers. [ bp: Correct and update commit message and fix checkpatch warnings. s/register/registers/ where it is used in plural. minor comment corrections. remove unused trace_x86_fpu_activate_state() TP. ] Signed-off-by: Rik van Riel Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Borislav Petkov Reviewed-by: Dave Hansen Reviewed-by: Thomas Gleixner Cc: Andy Lutomirski Cc: Aubrey Li Cc: Babu Moger Cc: "Chang S. Bae" Cc: Dmitry Safonov Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Jann Horn Cc: "Jason A. Donenfeld" Cc: Joerg Roedel Cc: Konrad Rzeszutek Wilk Cc: kvm ML Cc: Nicolai Stange Cc: Paolo Bonzini Cc: "Radim Krčmář" Cc: Tim Chen Cc: Waiman Long Cc: x86-ml Cc: Yi Wang Link: https://lkml.kernel.org/r/20190403164156.19645-24-bigeasy@linutronix.de

x86/speculation/mds: Clear CPU buffers on exit to user

2019-03-06T20:52:13+00:00

Add a static key which controls the invocation of the CPU buffer clear mechanism on exit to user space and add the call into prepare_exit_to_usermode() and do_nmi() right before actually returning. Add documentation which kernel to user space transition this covers and explain why some corner cases are not mitigated. Signed-off-by: Thomas Gleixner Reviewed-by: Greg Kroah-Hartman Reviewed-by: Borislav Petkov Reviewed-by: Frederic Weisbecker Reviewed-by: Jon Masters Tested-by: Jon Masters

x86: Fix various typos in comments

2018-12-03T09:49:13+00:00

Go over arch/x86/ and fix common typos in comments, and a typo in an actual function argument name. No change in functionality intended. Cc: Thomas Gleixner Cc: Borislav Petkov Cc: Peter Zijlstra Cc: Linus Torvalds Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

rseq: Avoid infinite recursion when delivering SIGSEGV

2018-06-22T17:04:22+00:00

When delivering a signal to a task that is using rseq, we call into __rseq_handle_notify_resume() so that the registers pushed in the sigframe are updated to reflect the state of the restartable sequence (for example, ensuring that the signal returns to the abort handler if necessary). However, if the rseq management fails due to an unrecoverable fault when accessing userspace or certain combinations of RSEQ_CS_* flags, then we will attempt to deliver a SIGSEGV. This has the potential for infinite recursion if the rseq code continuously fails on signal delivery. Avoid this problem by using force_sigsegv() instead of force_sig(), which is explicitly designed to reset the SEGV handler to SIG_DFL in the case of a recursive fault. In doing so, remove rseq_signal_deliver() from the internal rseq API and have an optional struct ksignal * parameter to rseq_handle_notify_resume() instead. Signed-off-by: Will Deacon Signed-off-by: Thomas Gleixner Acked-by: Mathieu Desnoyers Cc: peterz@infradead.org Cc: paulmck@linux.vnet.ibm.com Cc: boqun.feng@gmail.com Link: https://lkml.kernel.org/r/1529664307-983-1-git-send-email-will.deacon@arm.com

x86: Add support for restartable sequences

2018-06-06T09:58:32+00:00

Call the rseq_handle_notify_resume() function on return to userspace if TIF_NOTIFY_RESUME thread flag is set. Perform fixup on the pre-signal frame when a signal is delivered on top of a restartable sequence critical section. Check that system calls are not invoked from within rseq critical sections by invoking rseq_signal() from syscall_return_slowpath(). With CONFIG_DEBUG_RSEQ, such behavior results in termination of the process with SIGSEGV. Signed-off-by: Mathieu Desnoyers Signed-off-by: Thomas Gleixner Reviewed-by: Thomas Gleixner Cc: Joel Fernandes Cc: Peter Zijlstra Cc: Catalin Marinas Cc: Dave Watson Cc: Will Deacon Cc: Andi Kleen Cc: "H . Peter Anvin" Cc: Chris Lameter Cc: Russell King Cc: Andrew Hunter Cc: Michael Kerrisk Cc: "Paul E . McKenney" Cc: Paul Turner Cc: Boqun Feng Cc: Josh Triplett Cc: Steven Rostedt Cc: Ben Maurer Cc: linux-api@vger.kernel.org Cc: Andy Lutomirski Cc: Andrew Morton Cc: Linus Torvalds Link: https://lkml.kernel.org/r/20180602124408.8430-7-mathieu.desnoyers@efficios.com

syscalls/x86: Unconditionally enable 'struct pt_regs' based syscalls on x86_64

2018-04-05T14:59:38+00:00

Removing CONFIG_SYSCALL_PTREGS from arch/x86/Kconfig and simply selecting ARCH_HAS_SYSCALL_WRAPPER unconditionally on x86-64 allows us to simplify several codepaths. Signed-off-by: Dominik Brodowski Acked-by: Linus Torvalds Cc: Al Viro Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20180405095307.3730-7-linux@dominikbrodowski.net Signed-off-by: Ingo Molnar

syscalls/x86: Use 'struct pt_regs' based syscall calling for IA32_EMULATION and x32

2018-04-05T14:59:38+00:00

Extend ARCH_HAS_SYSCALL_WRAPPER for i386 emulation and for x32 on 64-bit x86. For x32, all we need to do is to create an additional stub for each compat syscall which decodes the parameters in x86-64 ordering, e.g.: asmlinkage long __compat_sys_x32_xyzzy(struct pt_regs *regs) { return c_SyS_xyzzy(regs->di, regs->si, regs->dx); } For i386 emulation, we need to teach compat_sys_*() to take struct pt_regs as its only argument, e.g.: asmlinkage long __compat_sys_ia32_xyzzy(struct pt_regs *regs) { return c_SyS_xyzzy(regs->bx, regs->cx, regs->dx); } In addition, we need to create additional stubs for common syscalls (that is, for syscalls which have the same parameters on 32-bit and 64-bit), e.g.: asmlinkage long __sys_ia32_xyzzy(struct pt_regs *regs) { return c_sys_xyzzy(regs->bx, regs->cx, regs->dx); } This approach avoids leaking random user-provided register content down the call chain. This patch is based on an original proof-of-concept | From: Linus Torvalds | Signed-off-by: Linus Torvalds and was split up and heavily modified by me, in particular to base it on ARCH_HAS_SYSCALL_WRAPPER. Signed-off-by: Dominik Brodowski Acked-by: Linus Torvalds Cc: Al Viro Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20180405095307.3730-6-linux@dominikbrodowski.net Signed-off-by: Ingo Molnar

syscalls/x86: Use 'struct pt_regs' based syscall calling convention for 64-bit syscalls

2018-04-05T14:59:26+00:00

Let's make use of ARCH_HAS_SYSCALL_WRAPPER=y on pure 64-bit x86-64 systems: Each syscall defines a stub which takes struct pt_regs as its only argument. It decodes just those parameters it needs, e.g: asmlinkage long sys_xyzzy(const struct pt_regs *regs) { return SyS_xyzzy(regs->di, regs->si, regs->dx); } This approach avoids leaking random user-provided register content down the call chain. For example, for sys_recv() which is a 4-parameter syscall, the assembly now is (in slightly reordered fashion): : callq <__fentry__> /* decode regs->di, ->si, ->dx and ->r10 */ mov 0x70(%rdi),%rdi mov 0x68(%rdi),%rsi mov 0x60(%rdi),%rdx mov 0x38(%rdi),%rcx [ SyS_recv() is automatically inlined by the compiler, as it is not [yet] used anywhere else ] /* clear %r9 and %r8, the 5th and 6th args */ xor %r9d,%r9d xor %r8d,%r8d /* do the actual work */ callq __sys_recvfrom /* cleanup and return */ cltq retq The only valid place in an x86-64 kernel which rightfully calls a syscall function on its own -- vsyscall -- needs to be modified to pass struct pt_regs onwards as well. To keep the syscall table generation working independent of SYSCALL_PTREGS being enabled, the stubs are named the same as the "original" syscall stubs, i.e. sys_*(). This patch is based on an original proof-of-concept | From: Linus Torvalds | Signed-off-by: Linus Torvalds and was split up and heavily modified by me, in particular to base it on ARCH_HAS_SYSCALL_WRAPPER, to limit it to 64-bit-only for the time being, and to update the vsyscall to the new calling convention. Signed-off-by: Dominik Brodowski Acked-by: Linus Torvalds Cc: Al Viro Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20180405095307.3730-4-linux@dominikbrodowski.net Signed-off-by: Ingo Molnar