linux/arch/x86/include, branch v3.10.37

x86: fix boot on uniprocessor systems

2014-04-03T19:01:05Z

commit 825600c0f20e595daaa7a6dd8970f84fa2a2ee57 upstream. On x86 uniprocessor systems topology_physical_package_id() returns -1 which causes rapl_cpu_prepare() to leave rapl_pmu variable uninitialized which leads to GPF in rapl_pmu_init(). See arch/x86/kernel/cpu/perf_event_intel_rapl.c. It turns out that physical_package_id and core_id can actually be retreived for uniprocessor systems too. Enabling them also fixes rapl_pmu code. Signed-off-by: Artem Fetishev Cc: Stephane Eranian Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Thomas Gleixner Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

xen/p2m: check MFN is in range before using the m2p table

2014-02-22T20:41:25Z

commit 0160676bba69523e8b0ac83f306cce7d342ed7c8 upstream. On hosts with more than 168 GB of memory, a 32-bit guest may attempt to grant map an MFN that is error cannot lookup in its mapping of the m2p table. There is an m2p lookup as part of m2p_add_override() and m2p_remove_override(). The lookup falls off the end of the mapped portion of the m2p and (because the mapping is at the highest virtual address) wraps around and the lookup causes a fault on what appears to be a user space address. do_page_fault() (thinking it's a fault to a userspace address), tries to lock mm->mmap_sem. If the gntdev device is used for the grant map, m2p_add_override() is called from from gnttab_mmap() with mm->mmap_sem already locked. do_page_fault() then deadlocks. The deadlock would most commonly occur when a 64-bit guest is started and xenconsoled attempts to grant map its console ring. Introduce mfn_to_pfn_no_overrides() which checks the MFN is within the mapped portion of the m2p table before accessing the table and use this in m2p_add_override(), m2p_remove_override(), and mfn_to_pfn() (which already had the correct range check). All faults caused by accessing the non-existant parts of the m2p are thus within the kernel address space and exception_fixup() is called without trying to lock mm->mmap_sem. This means that for MFNs that are outside the mapped range of the m2p then mfn_to_pfn() will always look in the m2p overrides. This is correct because it must be a foreign MFN (and the PFN in the m2p in this case is only relevant for the other domain). v3: check for auto_translated_physmap in mfn_to_pfn_no_overrides() v2: in mfn_to_pfn() look in m2p_overrides if the MFN is out of range as it's probably foreign. Signed-off-by: David Vrabel Cc: Stefano Stabellini Cc: Jan Beulich Signed-off-by: Konrad Rzeszutek Wilk Acked-by: Stefano Stabellini Signed-off-by: Greg Kroah-Hartman

x86, cpu, amd: Add workaround for family 16h, erratum 793

2014-02-06T19:08:18Z

commit 3b56496865f9f7d9bcb2f93b44c63f274f08e3b6 upstream. This adds the workaround for erratum 793 as a precaution in case not every BIOS implements it. This addresses CVE-2013-6885. Erratum text: [Revision Guide for AMD Family 16h Models 00h-0Fh Processors, document 51810 Rev. 3.04 November 2013] 793 Specific Combination of Writes to Write Combined Memory Types and Locked Instructions May Cause Core Hang Description Under a highly specific and detailed set of internal timing conditions, a locked instruction may trigger a timing sequence whereby the write to a write combined memory type is not flushed, causing the locked instruction to stall indefinitely. Potential Effect on System Processor core hang. Suggested Workaround BIOS should set MSR C001_1020[15] = 1b. Fix Planned No fix planned [ hpa: updated description, fixed typo in MSR name ] Signed-off-by: Borislav Petkov Link: http://lkml.kernel.org/r/20140114230711.GS29865@pd.tnic Tested-by: Aravind Gopalakrishnan Signed-off-by: H. Peter Anvin Signed-off-by: Greg Kroah-Hartman

x86, fpu, amd: Clear exceptions in AMD FXSAVE workaround

2014-01-15T23:28:53Z

commit 26bef1318adc1b3a530ecc807ef99346db2aa8b0 upstream. Before we do an EMMS in the AMD FXSAVE information leak workaround we need to clear any pending exceptions, otherwise we trap with a floating-point exception inside this code. Reported-by: halfdog Tested-by: Borislav Petkov Link: http://lkml.kernel.org/r/CA%2B55aFxQnY_PCG_n4=0w-VG=YLXL-yr7oMxyy0WU2gCBAf3ydg@mail.gmail.com Signed-off-by: H. Peter Anvin Signed-off-by: Greg Kroah-Hartman

mm: fix TLB flush race between migration, and change_protection_range

2014-01-09T20:24:23Z

commit 20841405940e7be0617612d521e206e4b6b325db upstream. There are a few subtle races, between change_protection_range (used by mprotect and change_prot_numa) on one side, and NUMA page migration and compaction on the other side. The basic race is that there is a time window between when the PTE gets made non-present (PROT_NONE or NUMA), and the TLB is flushed. During that time, a CPU may continue writing to the page. This is fine most of the time, however compaction or the NUMA migration code may come in, and migrate the page away. When that happens, the CPU may continue writing, through the cached translation, to what is no longer the current memory location of the process. This only affects x86, which has a somewhat optimistic pte_accessible. All other architectures appear to be safe, and will either always flush, or flush whenever there is a valid mapping, even with no permissions (SPARC). The basic race looks like this: CPU A CPU B CPU C load TLB entry make entry PTE/PMD_NUMA fault on entry read/write old page start migrating page change PTE/PMD to new page read/write old page [*] flush TLB reload TLB from new entry read/write new page lose data [*] the old page may belong to a new user at this point! The obvious fix is to flush remote TLB entries, by making sure that pte_accessible aware of the fact that PROT_NONE and PROT_NUMA memory may still be accessible if there is a TLB flush pending for the mm. This should fix both NUMA migration and compaction. [mgorman@suse.de: fix build] Signed-off-by: Rik van Riel Signed-off-by: Mel Gorman Cc: Alex Thorlton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

sched: fix the theoretical signal_wake_up() vs schedule() race

2014-01-09T20:24:23Z

commit e0acd0a68ec7dbf6b7a81a87a867ebd7ac9b76c4 upstream. This is only theoretical, but after try_to_wake_up(p) was changed to check p->state under p->pi_lock the code like __set_current_state(TASK_INTERRUPTIBLE); schedule(); can miss a signal. This is the special case of wait-for-condition, it relies on try_to_wake_up/schedule interaction and thus it does not need mb() between __set_current_state() and if(signal_pending). However, this __set_current_state() can move into the critical section protected by rq->lock, now that try_to_wake_up() takes another lock we need to ensure that it can't be reordered with "if (signal_pending(current))" check inside that section. The patch is actually one-liner, it simply adds smp_wmb() before spin_lock_irq(rq->lock). This is what try_to_wake_up() already does by the same reason. We turn this wmb() into the new helper, smp_mb__before_spinlock(), for better documentation and to allow the architectures to change the default implementation. While at it, kill smp_mb__after_lock(), it has no callers. Perhaps we can also add smp_mb__before/after_spinunlock() for prepare_to_wait(). Signed-off-by: Oleg Nesterov Acked-by: Peter Zijlstra Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

x86: avoid remapping data in parse_setup_data()

2013-10-18T14:45:48Z

commit 30e46b574a1db7d14404e52dca8e1aa5f5155fd2 upstream. Type SETUP_PCI, added by setup_efi_pci(), may advertise a ROM size larger than early_memremap() is able to handle, which is currently limited to 256kB. If this occurs it leads to a NULL dereference in parse_setup_data(). To avoid this, remap the setup_data header and allow parsing functions for individual types to handle their own data remapping. Signed-off-by: Linn Crosetto Link: http://lkml.kernel.org/r/1376430401-67445-1-git-send-email-linn@hp.com Acked-by: Yinghai Lu Reviewed-by: Pekka Enberg Signed-off-by: H. Peter Anvin Cc: Paul Gortmaker Signed-off-by: Greg Kroah-Hartman

compiler/gcc4: Add quirk for 'asm goto' miscompilation bug

2013-10-18T14:45:45Z

commit 3f0116c3238a96bc18ad4b4acefe4e7be32fa861 upstream. Fengguang Wu, Oleg Nesterov and Peter Zijlstra tracked down a kernel crash to a GCC bug: GCC miscompiles certain 'asm goto' constructs, as outlined here: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 Implement a workaround suggested by Jakub Jelinek. Reported-and-tested-by: Fengguang Wu Reported-by: Oleg Nesterov Reported-by: Peter Zijlstra Suggested-by: Jakub Jelinek Reviewed-by: Richard Henderson Cc: Linus Torvalds Cc: Andrew Morton Link: http://lkml.kernel.org/r/20131015062351.GA4666@gmail.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

sched/x86: Optimize switch_mm() for multi-threaded workloads

2013-09-27T00:18:14Z

commit 8f898fbbe5ee5e20a77c4074472a1fd088dc47d1 upstream. Dick Fowles, Don Zickus and Joe Mario have been working on improvements to perf, and noticed heavy cache line contention on the mm_cpumask, running linpack on a 60 core / 120 thread system. The cause turned out to be unnecessary atomic accesses to the mm_cpumask. When in lazy TLB mode, the CPU is only removed from the mm_cpumask if there is a TLB flush event. Most of the time, no such TLB flush happens, and the kernel skips the TLB reload. It can also skip the atomic memory set & test. Here is a summary of Joe's test results: * The __schedule function dropped from 24% of all program cycles down to 5.5%. * The cacheline contention/hotness for accesses to that bitmask went from being the 1st/2nd hottest - down to the 84th hottest (0.3% of all shared misses which is now quite cold) * The average load latency for the bit-test-n-set instruction in __schedule dropped from 10k-15k cycles down to an average of 600 cycles. * The linpack program results improved from 133 GFlops to 144 GFlops. Peak GFlops rose from 133 to 153. Reported-by: Don Zickus Reported-by: Joe Mario Tested-by: Joe Mario Signed-off-by: Rik van Riel Reviewed-by: Paul Turner Acked-by: Linus Torvalds Link: http://lkml.kernel.org/r/20130731221421.616d3d20@annuminas.surriel.com [ Made the comments consistent around the modified code. ] Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

x86/mce: Pay no attention to 'F' bit in MCACOD when parsing 'UC' errors

2013-09-27T00:18:14Z

commit 0ca06c0857aee11911f91621db14498496f2c2cd upstream. The 0x1000 bit of the MCACOD field of machine check MCi_STATUS registers is only defined for corrected errors (where it means that hardware may be filtering errors see SDM section 15.9.2.1). For uncorrected errors it may, or may not be set - so we should mask it out when checking for the architecturaly defined recoverable error signatures (see SDM 15.9.3.1 and 15.9.3.2) Acked-by: Naveen N. Rao Signed-off-by: Tony Luck Signed-off-by: Greg Kroah-Hartman