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* x86: irq: Define a global vector for nested posted interruptsWincy Van2017-07-261-0/+1
| | | | | | | | | | | | We are using the same vector for nested/non-nested posted interrupts delivery, this may cause interrupts latency in L1 since we can't kick the L2 vcpu out of vmx-nonroot mode. This patch introduces a new vector which is only for nested posted interrupts to solve the problems above. Signed-off-by: Wincy Van <fanwenyi0529@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* x86/asm: Fix comment in return_from_SYSCALL_64()Kirill A. Shutemov2017-06-131-1/+2
| | | | | | | | | | | | | | | | | | | | | | On x86-64 __VIRTUAL_MASK_SHIFT depends on paging mode now. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20170606113133.22974-3-kirill.shutemov@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* Revert "x86/entry: Fix the end of the stack for newly forked tasks"Josh Poimboeuf2017-05-241-7/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Petr Mladek reported the following warning when loading the livepatch sample module: WARNING: CPU: 1 PID: 3699 at arch/x86/kernel/stacktrace.c:132 save_stack_trace_tsk_reliable+0x133/0x1a0 ... Call Trace: __schedule+0x273/0x820 schedule+0x36/0x80 kthreadd+0x305/0x310 ? kthread_create_on_cpu+0x80/0x80 ? icmp_echo.part.32+0x50/0x50 ret_from_fork+0x2c/0x40 That warning means the end of the stack is no longer recognized as such for newly forked tasks. The problem was introduced with the following commit: ff3f7e2475bb ("x86/entry: Fix the end of the stack for newly forked tasks") ... which was completely misguided. It only partially fixed the reported issue, and it introduced another bug in the process. None of the other entry code saves the frame pointer before calling into C code, so it doesn't make sense for ret_from_fork to do so either. Contrary to what I originally thought, the original issue wasn't related to newly forked tasks. It was actually related to ftrace. When entry code calls into a function which then calls into an ftrace handler, the stack frame looks different than normal. The original issue will be fixed in the unwinder, in a subsequent patch. Reported-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Dave Jones <davej@codemonkey.org.uk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: live-patching@vger.kernel.org Fixes: ff3f7e2475bb ("x86/entry: Fix the end of the stack for newly forked tasks") Link: http://lkml.kernel.org/r/f350760f7e82f0750c8d1dd093456eb212751caa.1495553739.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* Merge branch 'x86-mm-for-linus' of ↵Linus Torvalds2017-05-011-5/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 mm updates from Ingo Molnar: "The main x86 MM changes in this cycle were: - continued native kernel PCID support preparation patches to the TLB flushing code (Andy Lutomirski) - various fixes related to 32-bit compat syscall returning address over 4Gb in applications, launched from 64-bit binaries - motivated by C/R frameworks such as Virtuozzo. (Dmitry Safonov) - continued Intel 5-level paging enablement: in particular the conversion of x86 GUP to the generic GUP code. (Kirill A. Shutemov) - x86/mpx ABI corner case fixes/enhancements (Joerg Roedel) - ... plus misc updates, fixes and cleanups" * 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (62 commits) mm, zone_device: Replace {get, put}_zone_device_page() with a single reference to fix pmem crash x86/mm: Fix flush_tlb_page() on Xen x86/mm: Make flush_tlb_mm_range() more predictable x86/mm: Remove flush_tlb() and flush_tlb_current_task() x86/vm86/32: Switch to flush_tlb_mm_range() in mark_screen_rdonly() x86/mm/64: Fix crash in remove_pagetable() Revert "x86/mm/gup: Switch GUP to the generic get_user_page_fast() implementation" x86/boot/e820: Remove a redundant self assignment x86/mm: Fix dump pagetables for 4 levels of page tables x86/mpx, selftests: Only check bounds-vs-shadow when we keep shadow x86/mpx: Correctly report do_mpx_bt_fault() failures to user-space Revert "x86/mm/numa: Remove numa_nodemask_from_meminfo()" x86/espfix: Add support for 5-level paging x86/kasan: Extend KASAN to support 5-level paging x86/mm: Add basic defines/helpers for CONFIG_X86_5LEVEL=y x86/paravirt: Add 5-level support to the paravirt code x86/mm: Define virtual memory map for 5-level paging x86/asm: Remove __VIRTUAL_MASK_SHIFT==47 assert x86/boot: Detect 5-level paging support x86/mm/numa: Remove numa_nodemask_from_meminfo() ...
| * x86/asm: Remove __VIRTUAL_MASK_SHIFT==47 assertKirill A. Shutemov2017-04-041-5/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We don't need the assert anymore, as: 17be0aec74fb ("x86/asm/entry/64: Implement better check for canonical addresses") made canonical address checks generic wrt. address width. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20170330080731.65421-3-kirill.shutemov@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | x86/entry/64: Relax pvops stub clobber specificationsJan Beulich2017-03-011-8/+7
|/ | | | | | | | | | | | | | | | | | | | | Except for the error_exit case, none of the code paths following the {DIS,EN}ABLE_INTERRUPTS() invocations being modified here make any assumptions on register values, so all registers can be clobbered there. In the error_exit case a minor adjustment to register usage (at once eliminating an instruction) also allows for this to be true. Signed-off-by: Jan Beulich <jbeulich@suse.com> Cc: Andy Lutomirski <luto@kernel.org> 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: Josh Poimboeuf <jpoimboe@redhat.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/5894556D02000078001366D3@prv-mh.provo.novell.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry: Fix the end of the stack for newly forked tasksJosh Poimboeuf2017-01-121-4/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When unwinding a task, the end of the stack is always at the same offset right below the saved pt_regs, regardless of which syscall was used to enter the kernel. That convention allows the unwinder to verify that a stack is sane. However, newly forked tasks don't always follow that convention, as reported by the following unwinder warning seen by Dave Jones: WARNING: kernel stack frame pointer at ffffc90001443f30 in kworker/u8:8:30468 has bad value (null) The warning was due to the following call chain: (ftrace handler) call_usermodehelper_exec_async+0x5/0x140 ret_from_fork+0x22/0x30 The problem is that ret_from_fork() doesn't create a stack frame before calling other functions. Fix that by carefully using the frame pointer macros. In addition to conforming to the end of stack convention, this also makes related stack traces more sensible by making it clear to the user that ret_from_fork() was involved. Reported-by: Dave Jones <davej@codemonkey.org.uk> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Miroslav Benes <mbenes@suse.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/8854cdaab980e9700a81e9ebf0d4238e4bbb68ef.1483978430.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry64: Remove unused audit related macrosAlexander Kuleshov2016-10-251-6/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | These macros were added in the following commit: 86a1c34a929f ("x86_64 syscall audit fast-path") They were used in two-phase sycalls entry tracing, but this functionality was then moved to the arch/x86/entry/common.c:syscall_trace_enter() function, in the following commit: 1f484aa69046 ("x86/entry: Move C entry and exit code to arch/x86/entry/common.c") syscall_trace_enter() now uses the defines from <linux/audit.h>, so these defines entry_64.S are no longer used anywhere. Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com> Reviewed-by: Borislav Petkov <bp@suse.de> Cc: Andy Lutomirski <luto@kernel.org> 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: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20161023135646.4453-1-kuleshovmail@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry/unwind: Create stack frames for saved interrupt registersJosh Poimboeuf2016-10-211-3/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With frame pointers, when a task is interrupted, its stack is no longer completely reliable because the function could have been interrupted before it had a chance to save the previous frame pointer on the stack. So the caller of the interrupted function could get skipped by a stack trace. This is problematic for live patching, which needs to know whether a stack trace of a sleeping task can be relied upon. There's currently no way to detect if a sleeping task was interrupted by a page fault exception or preemption before it went to sleep. Another issue is that when dumping the stack of an interrupted task, the unwinder has no way of knowing where the saved pt_regs registers are, so it can't print them. This solves those issues by encoding the pt_regs pointer in the frame pointer on entry from an interrupt or an exception. This patch also updates the unwinder to be able to decode it, because otherwise the unwinder would be broken by this change. Note that this causes a change in the behavior of the unwinder: each instance of a pt_regs on the stack is now considered a "frame". So callers of unwind_get_return_address() will now get an occasional 'regs->ip' address that would have previously been skipped over. Suggested-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> 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/8b9f84a21e39d249049e0547b559ff8da0df0988.1476973742.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* Merge branch 'kbuild' of ↵Linus Torvalds2016-10-141-0/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild Pull kbuild updates from Michal Marek: - EXPORT_SYMBOL for asm source by Al Viro. This does bring a regression, because genksyms no longer generates checksums for these symbols (CONFIG_MODVERSIONS). Nick Piggin is working on a patch to fix this. Plus, we are talking about functions like strcpy(), which rarely change prototypes. - Fixes for PPC fallout of the above by Stephen Rothwell and Nick Piggin - fixdep speedup by Alexey Dobriyan. - preparatory work by Nick Piggin to allow architectures to build with -ffunction-sections, -fdata-sections and --gc-sections - CONFIG_THIN_ARCHIVES support by Stephen Rothwell - fix for filenames with colons in the initramfs source by me. * 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild: (22 commits) initramfs: Escape colons in depfile ppc: there is no clear_pages to export powerpc/64: whitelist unresolved modversions CRCs kbuild: -ffunction-sections fix for archs with conflicting sections kbuild: add arch specific post-link Makefile kbuild: allow archs to select link dead code/data elimination kbuild: allow architectures to use thin archives instead of ld -r kbuild: Regenerate genksyms lexer kbuild: genksyms fix for typeof handling fixdep: faster CONFIG_ search ia64: move exports to definitions sparc32: debride memcpy.S a bit [sparc] unify 32bit and 64bit string.h sparc: move exports to definitions ppc: move exports to definitions arm: move exports to definitions s390: move exports to definitions m68k: move exports to definitions alpha: move exports to actual definitions x86: move exports to actual definitions ...
| * x86: move exports to actual definitionsAl Viro2016-08-071-0/+2
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | Merge branch 'for-linus' of ↵Linus Torvalds2016-10-071-1/+1
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial Pull trivial updates from Jiri Kosina: "The usual rocket science from the trivial tree" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: tracing/syscalls: fix multiline in error message text lib/Kconfig.debug: fix DEBUG_SECTION_MISMATCH description doc: vfs: fix fadvise() sycall name x86/entry: spell EBX register correctly in documentation securityfs: fix securityfs_create_dir comment irq: Fix typo in tracepoint.xml
| * | x86/entry: spell EBX register correctly in documentationNicolas Iooss2016-09-291-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | As EBS does not mean anything reasonable in the context it is used, it seems like a misspelling for EBX. Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org> Acked-by: Borislav Petkov <bp@suse.de> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* | | Merge branch 'x86-asm-for-linus' of ↵Linus Torvalds2016-10-031-38/+113
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull low-level x86 updates from Ingo Molnar: "In this cycle this topic tree has become one of those 'super topics' that accumulated a lot of changes: - Add CONFIG_VMAP_STACK=y support to the core kernel and enable it on x86 - preceded by an array of changes. v4.8 saw preparatory changes in this area already - this is the rest of the work. Includes the thread stack caching performance optimization. (Andy Lutomirski) - switch_to() cleanups and all around enhancements. (Brian Gerst) - A large number of dumpstack infrastructure enhancements and an unwinder abstraction. The secret long term plan is safe(r) live patching plus maybe another attempt at debuginfo based unwinding - but all these current bits are standalone enhancements in a frame pointer based debug environment as well. (Josh Poimboeuf) - More __ro_after_init and const annotations. (Kees Cook) - Enable KASLR for the vmemmap memory region. (Thomas Garnier)" [ The virtually mapped stack changes are pretty fundamental, and not x86-specific per se, even if they are only used on x86 right now. ] * 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (70 commits) x86/asm: Get rid of __read_cr4_safe() thread_info: Use unsigned long for flags x86/alternatives: Add stack frame dependency to alternative_call_2() x86/dumpstack: Fix show_stack() task pointer regression x86/dumpstack: Remove dump_trace() and related callbacks x86/dumpstack: Convert show_trace_log_lvl() to use the new unwinder oprofile/x86: Convert x86_backtrace() to use the new unwinder x86/stacktrace: Convert save_stack_trace_*() to use the new unwinder perf/x86: Convert perf_callchain_kernel() to use the new unwinder x86/unwind: Add new unwind interface and implementations x86/dumpstack: Remove NULL task pointer convention fork: Optimize task creation by caching two thread stacks per CPU if CONFIG_VMAP_STACK=y sched/core: Free the stack early if CONFIG_THREAD_INFO_IN_TASK lib/syscall: Pin the task stack in collect_syscall() x86/process: Pin the target stack in get_wchan() x86/dumpstack: Pin the target stack when dumping it kthread: Pin the stack via try_get_task_stack()/put_task_stack() in to_live_kthread() function sched/core: Add try_get_task_stack() and put_task_stack() x86/entry/64: Fix a minor comment rebase error iommu/amd: Don't put completion-wait semaphore on stack ...
| * | | x86/entry/64: Fix a minor comment rebase errorAndy Lutomirski2016-09-161-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When I rebased my thread_info changes onto Brian's switch_to() changes, I carefully checked that I fixed up all the code correctly, but I missed a comment :( Signed-off-by: Andy Lutomirski <luto@kernel.org> 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: Jann Horn <jann@thejh.net> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 15f4eae70d36 ("x86: Move thread_info into task_struct") Link: http://lkml.kernel.org/r/089fe1e1cbe8b258b064fccbb1a5a5fd23861031.1474003868.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | x86: Move thread_info into task_structAndy Lutomirski2016-09-151-2/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now that most of the thread_info users have been cleaned up, this is straightforward. Most of this code was written by Linus. Originally-from: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Andy Lutomirski <luto@kernel.org> 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: Jann Horn <jann@thejh.net> Cc: Josh Poimboeuf <jpoimboe@redhat.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/a50eab40abeaec9cb9a9e3cbdeafd32190206654.1473801993.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | x86/entry/64: Clean up and document espfix64 stack setupAndy Lutomirski2016-09-131-11/+53
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The espfix64 setup code was a bit inscrutible and contained an unnecessary push of RAX. Remove that push, update all the stack offsets to match, and document the whole mess. Reported-By: Borislav Petkov <bp@alien8.de> Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Borislav Petkov <bp@suse.de> 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: Josh Poimboeuf <jpoimboe@redhat.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/e5459eb10cf1175c8b36b840bc425f210d045f35.1473717910.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | sched/x86: Pass kernel thread parameters in 'struct fork_frame'Brian Gerst2016-08-241-20/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Instead of setting up a fake pt_regs context, put the kernel thread function pointer and arg into the unused callee-restored registers of 'struct fork_frame'. Signed-off-by: Brian Gerst <brgerst@gmail.com> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> 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/1471106302-10159-6-git-send-email-brgerst@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | sched/x86: Rewrite the switch_to() codeBrian Gerst2016-08-241-3/+38
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Move the low-level context switch code to an out-of-line asm stub instead of using complex inline asm. This allows constructing a new stack frame for the child process to make it seamlessly flow to ret_from_fork without an extra test and branch in __switch_to(). It also improves code generation for __schedule() by using the C calling convention instead of clobbering all registers. Signed-off-by: Brian Gerst <brgerst@gmail.com> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> 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/1471106302-10159-5-git-send-email-brgerst@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | Merge branch 'x86/urgent' into x86/asm, to pick up fixesIngo Molnar2016-08-181-5/+20
| |\ \ \ | | | | | | | | | | | | | | | Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | | x86/entry: Remove duplicated commentBorislav Petkov2016-08-011-2/+1
| | |_|/ | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Ok, ok, we see it is called from C :-) Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> 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: Josh Poimboeuf <jpoimboe@redhat.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/20160801100502.29796-1-bp@alien8.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | | | x86/entry/64: Fix context tracking state warning when load_gs_index failsWanpeng Li2016-09-301-2/+2
| |/ / |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This warning: WARNING: CPU: 0 PID: 3331 at arch/x86/entry/common.c:45 enter_from_user_mode+0x32/0x50 CPU: 0 PID: 3331 Comm: ldt_gdt_64 Not tainted 4.8.0-rc7+ #13 Call Trace: dump_stack+0x99/0xd0 __warn+0xd1/0xf0 warn_slowpath_null+0x1d/0x20 enter_from_user_mode+0x32/0x50 error_entry+0x6d/0xc0 ? general_protection+0x12/0x30 ? native_load_gs_index+0xd/0x20 ? do_set_thread_area+0x19c/0x1f0 SyS_set_thread_area+0x24/0x30 do_int80_syscall_32+0x7c/0x220 entry_INT80_compat+0x38/0x50 ... can be reproduced by running the GS testcase of the ldt_gdt test unit in the x86 selftests. do_int80_syscall_32() will call enter_form_user_mode() to convert context tracking state from user state to kernel state. The load_gs_index() call can fail with user gsbase, gsbase will be fixed up and proceed if this happen. However, enter_from_user_mode() will be called again in the fixed up path though it is context tracking kernel state currently. This patch fixes it by just fixing up gsbase and telling lockdep that IRQs are off once load_gs_index() failed with user gsbase. Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Acked-by: Andy Lutomirski <luto@kernel.org> 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: Josh Poimboeuf <jpoimboe@redhat.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/1475197266-3440-1-git-send-email-wanpeng.li@hotmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | | x86/entry: Clarify the RF saving/restoring situation with SYSCALL/SYSRETBorislav Petkov2016-08-101-5/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Clarify why exactly RF cannot be restored properly by SYSRET to avoid confusion. No functionality change. Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> 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: Josh Poimboeuf <jpoimboe@redhat.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/20160803171429.GA2590@nazgul.tnic Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | | x86, kasan, ftrace: Put APIC interrupt handlers into .irqentry.textAlexander Potapenko2016-08-101-0/+11
|/ / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Dmitry Vyukov has reported unexpected KASAN stackdepot growth: https://github.com/google/kasan/issues/36 ... which is caused by the APIC handlers not being present in .irqentry.text: When building with CONFIG_FUNCTION_GRAPH_TRACER=y or CONFIG_KASAN=y, put the APIC interrupt handlers into the .irqentry.text section. This is needed because both KASAN and function graph tracer use __irqentry_text_start and __irqentry_text_end to determine whether a function is an IRQ entry point. Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Alexander Potapenko <glider@google.com> Cc: Andy Lutomirski <luto@kernel.org> 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: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: aryabinin@virtuozzo.com Cc: kasan-dev@googlegroups.com Cc: kcc@google.com Cc: rostedt@goodmis.org Link: http://lkml.kernel.org/r/1468575763-144889-1-git-send-email-glider@google.com [ Minor edits. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | x86/dumpstack: When OOPSing, rewind the stack before do_exit()Andy Lutomirski2016-07-151-0/+11
|/ | | | | | | | | | | | | | | | | | | | If we call do_exit() with a clean stack, we greatly reduce the risk of recursive oopses due to stack overflow in do_exit, and we allow do_exit to work even if we OOPS from an IST stack. The latter gives us a much better chance of surviving long enough after we detect a stack overflow to write out our logs. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> 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/32f73ceb372ec61889598da5e5b145889b9f2e19.1468527351.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry, sched/x86: Don't save/restore EFLAGS on task switchBrian Gerst2016-05-051-3/+0
| | | | | | | | | | | | | | | | | | | Now that NT is filtered by the SYSENTER entry code, it is safe to skip saving and restoring flags on task switch. Also remove a leftover reset of flags on 64-bit fork. Signed-off-by: Brian Gerst <brgerst@gmail.com> Acked-by: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bp@suse.de> 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/1462416278-11974-2-git-send-email-brgerst@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/segments/64: When load_gs_index fails, clear the baseAndy Lutomirski2016-04-291-0/+6
| | | | | | | | | | | | | | | | | On AMD CPUs, a failed load_gs_base currently may not clear the FS base. Fix it. 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/1a6c4d3a8a4e7be79ba448b42685e0321d50c14c.1461698311.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry/64: Make gs_change a local labelBorislav Petkov2016-04-131-5/+5
| | | | | | | | | | | | | | | | | | ... so that it doesn't appear in objdump output. Signed-off-by: Borislav Petkov <bp@suse.de> 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: Rudolf Marek <r.marek@assembler.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/b9c532a0e5f8d56dede2bd59767d40024d5a75e2.1460075211.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/cpu: Add Erratum 88 detection on AMDBorislav Petkov2016-04-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | Erratum 88 affects old AMD K8s, where a SWAPGS fails to cause an input dependency on GS. Therefore, we need to MFENCE before it. But that MFENCE is expensive and unnecessary on the remaining x86 CPUs out there so patch it out on the CPUs which don't require it. Signed-off-by: Borislav Petkov <bp@suse.de> 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: Rudolf Marek <r.marek@assembler.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/aec6b2df1bfc56101d4e9e2e5d5d570bf41663c6.1460075211.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry: Improve system call entry commentsAndy Lutomirski2016-03-101-0/+10
| | | | | | | | | | | | | | | | | | | | Ingo suggested that the comments should explain when the various entries are used. This adds these explanations and improves other parts of the comments. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Andrew Cooper <andrew.cooper3@citrix.com> 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: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/9524ecef7a295347294300045d08354d6a57c6e7.1457578375.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry/64: Fix fast-path syscall return register stateAndy Lutomirski2016-02-011-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | I was fishing RIP (i.e. RCX) out of pt_regs->cx and RFLAGS (i.e. R11) out of pt_regs->r11. While it usually worked (pt_regs started out with CX == IP and R11 == FLAGS), it was very fragile. In particular, it broke sys_iopl() because sys_iopl() forgot to mark itself as using ptregs. Undo that part of the syscall rework. There was no compelling reason to do it this way. While I'm at it, load RCX and R11 before the other regs to be a little friendlier to the CPU, as they will be the first of the reloaded registers to be used. Reported-and-tested-by: Borislav Petkov <bp@suse.de> 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> Fixes: 1e423bff959e x86/entry/64: ("Migrate the 64-bit syscall slow path to C") Link: http://lkml.kernel.org/r/a85f8360c397e48186a9bc3e565ad74307a7b011.1454261517.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry/64: Fix an IRQ state error on ptregs-using syscallsAndy Lutomirski2016-02-011-6/+13
| | | | | | | | | | | | | | | | | | | | | I messed up the IRQ state when jumping off the fast path due to invocation of a ptregs-using syscall. This bug shouldn't have had any impact yet, but it would have caused problems with subsequent context tracking cleanups. Reported-and-tested-by: Borislav Petkov <bp@suse.de> 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> Fixes: 1e423bff959e x86/entry/64: ("Migrate the 64-bit syscall slow path to C") Link: http://lkml.kernel.org/r/ab92cd365fb7b0a56869e920017790d96610fdca.1454261517.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry/64: Migrate the 64-bit syscall slow path to CAndy Lutomirski2016-01-291-78/+39
| | | | | | | | | | | | | | | | | | | | | | | This is more complicated than the 32-bit and compat cases because it preserves an asm fast path for the case where the callee-saved regs aren't needed in pt_regs and no entry or exit work needs to be done. This appears to slow down fastpath syscalls by no more than one cycle on my Skylake laptop. 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: Frederic Weisbecker <fweisbec@gmail.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/ce2335a4d42dc164b24132ee5e8c7716061f947b.1454022279.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry/64: Stop using int_ret_from_sys_call in ret_from_forkAndy Lutomirski2016-01-291-16/+19
| | | | | | | | | | | | | | | | | | | ret_from_fork is now open-coded and is no longer tangled up with the syscall code. This isn't so bad -- this adds very little code, and IMO the result is much easier to understand. 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: Frederic Weisbecker <fweisbec@gmail.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/a0747e2a5e47084655a1e96351c545b755c41fa7.1454022279.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry/64: Call all native slow-path syscalls with full pt-regsAndy Lutomirski2016-01-291-78/+1
| | | | | | | | | | | | | | | | | | | | | | | This removes all of the remaining asm syscall stubs except for stub_ptregs_64. Entries in the main syscall table are now all callable from C. The resulting asm is every bit as ridiculous as it looks. The next few patches will clean it up. This patch is here to let reviewers rest their brains and for bisection. 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: Frederic Weisbecker <fweisbec@gmail.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/a6b3801be0d505d50aefabda02d3b93efbfc9c73.1454022279.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry/64: Always run ptregs-using syscalls on the slow pathAndy Lutomirski2016-01-291-14/+42
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 64-bit syscalls currently have an optimization in which they are called with partial pt_regs. A small handful require full pt_regs. In the 32-bit and compat cases, I cleaned this up by forcing full pt_regs for all syscalls. The performance hit doesn't really matter as the affected system calls are fundamentally heavy and this is the 32-bit compat case. I want to clean up the 64-bit case as well, but I don't want to hurt fast path performance. To do that, I want to force the syscalls that use pt_regs onto the slow path. This will enable us to make slow path syscalls be real ABI-compliant C functions. Use the new syscall entry qualification machinery for this. 'stub_clone' is now 'stub_clone/ptregs'. The next patch will eliminate the stubs, and we'll just have 'sys_clone/ptregs'. As of this patch, two-phase entry tracing is no longer used. It has served its purpose (namely a huge speedup on some workloads prior to more general opportunistic SYSRET support), and once the dust settles I'll send patches to back it out. The implementation is heavily based on a patch from Brian Gerst: http://lkml.kernel.org/g/1449666173-15366-1-git-send-email-brgerst@gmail.com Originally-From: Brian Gerst <brgerst@gmail.com> Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Frédéric Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/b9beda88460bcefec6e7d792bd44eca9b760b0c4.1454022279.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry/64: Bypass enter_from_user_mode on non-context-tracking bootsAndy Lutomirski2015-11-241-6/+2
| | | | | | | | | | | | | | | | | | | | | | | On CONFIG_CONTEXT_TRACKING kernels that have context tracking disabled at runtime (which includes most distro kernels), we still have the overhead of a call to enter_from_user_mode in interrupt and exception entries. If jump labels are available, this uses the jump label infrastructure to skip the call. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> 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: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/73ee804fff48cd8c66b65b724f9f728a11a8c686.1447361906.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry/64: Fix irqflag tracing wrt context trackingAndy Lutomirski2015-11-241-1/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Paolo pointed out that enter_from_user_mode could be called while irqflags were traced as though IRQs were on. In principle, this could confuse lockdep. It doesn't cause any problems that I've seen in any configuration, but if I build with CONFIG_DEBUG_LOCKDEP=y, enable a nohz_full CPU, and add code like: if (irqs_disabled()) { spin_lock(&something); spin_unlock(&something); } to the top of enter_from_user_mode, then lockdep will complain without this fix. It seems that lockdep's irqflags sanity checks are too weak to detect this bug without forcing the issue. This patch adds one byte to normal kernels, and it's IMO a bit ugly. I haven't spotted a better way to do this yet, though. The issue is that we can't do TRACE_IRQS_OFF until after SWAPGS (if needed), but we're also supposed to do it before calling C code. An alternative approach would be to call trace_hardirqs_off in enter_from_user_mode. That would be less code and would not bloat normal kernels at all, but it would be harder to see how the code worked. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> 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: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/86237e362390dfa6fec12de4d75a238acb0ae787.1447361906.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry/64/compat: Migrate the body of the syscall entry to CAndy Lutomirski2015-10-091-1/+1
| | | | | | | | | | | | | | | 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> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/a2f0fce68feeba798a24339b5a7ec1ec2dd9eaf7.1444091585.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry/64/compat: Set up full pt_regs for all compat syscallsAndy Lutomirski2015-10-091-5/+1
| | | | | | | | | | | | | | | | | | | | | | | | | This is conceptually simpler. More importantly, it eliminates the PTREGSCALL and execve stubs, which were not compatible with the C ABI. This means that C code can call through the compat syscall table. The execve stubs are a bit subtle. They did two things: they cleared some registers and they forced slow-path return. Neither is necessary any more: elf_common_init clears the extra registers and start_thread calls force_iret(). 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> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/f95b7f7dfaacf88a8cae85bb06226cae53769287.1444091584.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/entry, locking/lockdep: Move lockdep_sys_exit() to ↵Andy Lutomirski2015-10-071-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | prepare_exit_to_usermode() Rather than worrying about exactly where LOCKDEP_SYS_EXIT should go in the asm code, add it to prepare_exit_from_usermode() and remove all of the asm calls that are followed by prepare_exit_to_usermode(). LOCKDEP_SYS_EXIT now appears only in the syscall fast paths. 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> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1736ebe948b845e68120b86b89091f3ec27f5e8e.1444091584.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* x86/nmi/64: Fix a paravirt stack-clobbering bug in the NMI codeAndy Lutomirski2015-09-221-1/+4
| | | | | | | | | | | | | | | | | The NMI entry code that switches to the normal kernel stack needs to be very careful not to clobber any extra stack slots on the NMI stack. The code is fine under the assumption that SWAPGS is just a normal instruction, but that assumption isn't really true. Use SWAPGS_UNSAFE_STACK instead. This is part of a fix for some random crashes that Sasha saw. Fixes: 9b6e6a8334d5 ("x86/nmi/64: Switch stacks on userspace NMI entry") Reported-and-tested-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/974bc40edffdb5c2950a5c4977f821a446b76178.1442791737.git.luto@kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* x86/paravirt: Replace the paravirt nop with a bona fide empty functionAndy Lutomirski2015-09-221-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | PARAVIRT_ADJUST_EXCEPTION_FRAME generates this code (using nmi as an example, trimmed for readability): ff 15 00 00 00 00 callq *0x0(%rip) # 2796 <nmi+0x6> 2792: R_X86_64_PC32 pv_irq_ops+0x2c That's a call through a function pointer to regular C function that does nothing on native boots, but that function isn't protected against kprobes, isn't marked notrace, and is certainly not guaranteed to preserve any registers if the compiler is feeling perverse. This is bad news for a CLBR_NONE operation. Of course, if everything works correctly, once paravirt ops are patched, it gets nopped out, but what if we hit this code before paravirt ops are patched in? This can potentially cause breakage that is very difficult to debug. A more subtle failure is possible here, too: if _paravirt_nop uses the stack at all (even just to push RBP), it will overwrite the "NMI executing" variable if it's called in the NMI prologue. The Xen case, perhaps surprisingly, is fine, because it's already written in asm. Fix all of the cases that default to paravirt_nop (including adjust_exception_frame) with a big hammer: replace paravirt_nop with an asm function that is just a ret instruction. The Xen case may have other problems, so document them. This is part of a fix for some random crashes that Sasha saw. Reported-and-tested-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/8f5d2ba295f9d73751c33d97fda03e0495d9ade0.1442791737.git.luto@kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* Merge branch 'x86/urgent' into x86/asm, before applying dependent patchesIngo Molnar2015-07-311-100/+199
|\ | | | | | | Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * x86/entry/64, x86/nmi/64: Add CONFIG_DEBUG_ENTRY NMI testing codeAndy Lutomirski2015-07-171-0/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It turns out to be rather tedious to test the NMI nesting code. Make it easier: add a new CONFIG_DEBUG_ENTRY option that causes the NMI handler to pre-emptively unmask NMIs. With this option set, errors in the repeat_nmi logic or failures to detect that we're in a nested NMI will result in quick panics under perf (especially if multiple counters are running at high frequency) instead of requiring an unusual workload that generates page faults or breakpoints inside NMIs. I called it CONFIG_DEBUG_ENTRY instead of CONFIG_DEBUG_NMI_ENTRY because I want to add new non-NMI checks elsewhere in the entry code in the future, and I'd rather not add too many new config options or add this option and then immediately rename it. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Cc: Borislav Petkov <bp@suse.de> 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>
| * x86/nmi/64: Make the "NMI executing" variable more consistentAndy Lutomirski2015-07-171-6/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, "NMI executing" is one the first time an outermost NMI hits repeat_nmi and zero thereafter. Change it to be zero each time for consistency. This is intended to help NMI handling fail harder if it's buggy. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Cc: Borislav Petkov <bp@suse.de> 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>
| * x86/nmi/64: Minor asm simplificationAndy Lutomirski2015-07-171-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Replace LEA; MOV with an equivalent SUB. This saves one instruction. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Cc: Borislav Petkov <bp@suse.de> 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>
| * x86/nmi/64: Use DF to avoid userspace RSP confusing nested NMI detectionAndy Lutomirski2015-07-171-4/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We have a tricky bug in the nested NMI code: if we see RSP pointing to the NMI stack on NMI entry from kernel mode, we assume that we are executing a nested NMI. This isn't quite true. A malicious userspace program can point RSP at the NMI stack, issue SYSCALL, and arrange for an NMI to happen while RSP is still pointing at the NMI stack. Fix it with a sneaky trick. Set DF in the region of code that the RSP check is intended to detect. IRET will clear DF atomically. ( Note: other than paravirt, there's little need for all this complexity. We could check RIP instead of RSP. ) Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Cc: Borislav Petkov <bp@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * x86/nmi/64: Reorder nested NMI checksAndy Lutomirski2015-07-171-16/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Check the repeat_nmi .. end_repeat_nmi special case first. The next patch will rework the RSP check and, as a side effect, the RSP check will no longer detect repeat_nmi .. end_repeat_nmi, so we'll need this ordering of the checks. Note: this is more subtle than it appears. The check for repeat_nmi .. end_repeat_nmi jumps straight out of the NMI code instead of adjusting the "iret" frame to force a repeat. This is necessary, because the code between repeat_nmi and end_repeat_nmi sets "NMI executing" and then writes to the "iret" frame itself. If a nested NMI comes in and modifies the "iret" frame while repeat_nmi is also modifying it, we'll end up with garbage. The old code got this right, as does the new code, but the new code is a bit more explicit. If we were to move the check right after the "NMI executing" check, then we'd get it wrong and have random crashes. ( Because the "NMI executing" check would jump to the code that would modify the "iret" frame without checking if the interrupted NMI was currently modifying it. ) Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Cc: Borislav Petkov <bp@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * x86/nmi/64: Improve nested NMI commentsAndy Lutomirski2015-07-171-66/+92
| | | | | | | | | | | | | | | | | | | | | | | | | | | | I found the nested NMI documentation to be difficult to follow. Improve the comments. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Cc: Borislav Petkov <bp@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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