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* MIPS: Move 'gic_present' to common location.Steven J. Hill2013-05-09
| | | | | | | | | Move the global variable 'gic_present' to be defined in the file 'arch/mips/kernel/irq-gic.c' instead of defining it individually for each platform making use of the GIC. Also change the type to be an unsigned integer instead of signed. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: MIPS16e: Add unaligned access support.Steven J. Hill2013-05-09
| | | | | | | Add logic needed to handle unaligned accesses in MIPS16e mode. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com> Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
* MIPS: MIPS16e: Support handling of delay slots.Steven J. Hill2013-05-09
| | | | | | | Add logic needed to properly calculate exceptions for delay slots when in MIPS16e mode. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: MIPS16e: Add instruction formats.Steven J. Hill2013-05-09
| | | | | | | Add structures for all the MIPS16e instructions. Also add the enumerations for all the bit fields for opcodes, functions, etc. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: microMIPS: Optimise 'strnlen' core library function.Steven J. Hill2013-05-09
| | | | | | | | Optimise 'strnlen' to use microMIPS instructions and/or optimisations for binary size reduction. When the microMIPS ISA is not being used, the library function compiles to the original binary code. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: microMIPS: Optimise 'strlen' core library function.Steven J. Hill2013-05-09
| | | | | | | | Optimise 'strlen' to use microMIPS instructions and/or optimisations for binary size reduction. When the microMIPS ISA is not being used, the library function compiles to the original binary code. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: microMIPS: Optimise 'strncpy' core library function.Steven J. Hill2013-05-09
| | | | | | | | Optimise 'strncpy' to use microMIPS instructions and/or optimisations for binary size reduction. When the microMIPS ISA is not being used, the library function compiles to the original binary code. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: microMIPS: Optimise 'memset' core library function.Steven J. Hill2013-05-09
| | | | | | | | Optimise 'memset' to use microMIPS instructions and/or optimisations for binary size reduction. When the microMIPS ISA is not being used, the library function compiles to the original binary code. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: microMIPS: Add configuration option for microMIPS kernel.Steven J. Hill2013-05-09
| | | | | | | | This adds the option to build the Linux kernel using only the microMIPS ISA. The resulting kernel binary is, at a minimum, 20% smaller than using the MIPS32R2 ISA. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: microMIPS: Disable LL/SC and fix linker bug.Steven J. Hill2013-05-09
| | | | | | | | | | | | | Partially revert commit e0c14a260d66ba35935600d6435940a566fe806b and turn off LL/SC when building a pure microMIPS kernel. This is a temporary fix until the cmpxchg assembly macro functions are re-written to not use the HI/LO registers in address calculations. Also add .insn in selected user access functions which would otherwise produce ISA mode jump incompatibilities. This is also a temporary fix. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: microMIPS: Add vdso support.Douglas Leung2013-05-09
| | | | | | | Support vdso in microMIPS mode. Signed-off-by: Douglas Leung <Douglas.Leung@imgtec.com> Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: microMIPS: Add unaligned access support.Leonid Yegoshin2013-05-09
| | | | | | | Add logic needed to handle unaligned accesses in microMIPS mode. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com> Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
* MIPS: microMIPS: Support handling of delay slots.Leonid Yegoshin2013-05-09
| | | | | | | | Add logic needed to properly calculate exceptions for delay slots when in microMIPS mode. Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: microMIPS: Add support for exception handling.Steven J. Hill2013-05-09
| | | | | | | | | All exceptions must be taken in microMIPS mode, never in classic MIPS mode or the kernel falls apart. A few NOP instructions are used to maintain the correct alignment of microMIPS versions of the exception vectors. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: microMIPS: Floating point support.Leonid Yegoshin2013-05-09
| | | | | | | Add logic needed to do floating point emulation in microMIPS mode. Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> Signed-off-by: Steven J. Hill <Steven. Hill@imgtec.com>
* MIPS: microMIPS: Fix macro naming in micro-assembler.Steven J. Hill2013-05-09
| | | | | | | | | | | The macros did not properly take into account the ISA that the kernel was being compiled with. A classic MIPS kernel will have the standard 'uasm_i_##op' macro functions with 'MM_uasm_i_##op' macro functions for the microMIPS version. A pure microMIPS kernel will have the standard macros with 'CL_uasm_i_##op' macro functions for the classic version. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: microMIPS: Fix incorrect mask for jump immediate.Steven J. Hill2013-05-09
| | | | | | | | | Jump or branch target addresses have the first bit set. The original mask did not take this into account and will cause a field overflow warning for the target address when a jump immediate instruction is built. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: microMIPS: Support dynamic ASID sizing.Steven J. Hill2013-05-08
| | | | | | | | | | Changes for pure microMIPS cores to dynamically determine the ASID size at boot time. Includes bug fix https://patchwork.linux-mips.org/patch/5230/ Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com> Signed-off-by: Jonas Gorski <jogo@openwrt.org>
* MIPS: Allow ASID size to be determined at boot time.Steven J. Hill2013-05-08
| | | | | | | | | | | | | | | Original patch by Ralf Baechle and removed by Harold Koerfgen with commit f67e4ffc79905482c3b9b8c8dd65197bac7eb508. This allows for more generic kernels since the size of the ASID and corresponding masks can be determined at run-time. This patch is also required for the new Aptiv cores and has been tested on Malta and Malta Aptiv platforms. [ralf@linux-mips.org: Added relevant part of fix https://patchwork.linux-mips.org/patch/5213/] Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
* MIPS: FW: malta: Code formatting clean-ups.Steven J. Hill2013-05-08
| | | | | | Clean-up code according to the 'checkpatch.pl' script. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: FW: Remove obsolete header file for MTI platforms.Steven J. Hill2013-05-08
| | | | | | | | | | | | | | | Remove 'arch/mips/include/asm/mips-boards/prom.h' and get rid of all inclusions of it by Malta and SEAD-3 platforms. [ralf@linux-mips.org: Fold in John Crispin <blogic@openwrt.org>'s "MIPS: ar7 powertv build"]. [ralf@linux-mips.org: Fold in John Crispin <blogic@openwrt.org>'s "MIPS: unbreak powertv build"]. [ralf@linux-mips.org: Test. Build. Your. Fscking. Code. Or...] Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: FW: malta: Use new common FW library variable processing.Steven J. Hill2013-05-08
| | | | | | Remove old YAMON prom code and use common firmware library code. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: FW: sead3: Use new common FW library variable processing.Steven J. Hill2013-05-08
| | | | | | Remove old YAMON prom code and use common firmware library code. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: FW: Add environment variable processing.Steven J. Hill2013-05-08
| | | | | | | Add parsing of the environment and command line variables passed to the kernel to the firmware library. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: Add declarations to MIPS Technologies Inc. generic header.Steven J. Hill2013-05-08
| | | | | | | | Add declaration of 'mips_scroll_message' and 'mips_display_message' to the common generic header file for the MIPS Technologies Inc. development boards. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: sead3: Use generic suspend/resume for LEDs.Lars-Peter Clausen2013-05-08
| | | | | | | | | | Setting the LED_CORE_SUSPENDRESUME flag causes the LED driver core to call led_classdev_suspend/led_classdev_resume during suspend/resume. Since this is exactly what the driver's custom suspend/resume callbacks do we can replace them by setting the LED_CORE_SUSPENDRESUME flag. Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: Add option to disable software I/O coherency.Steven J. Hill2013-05-01
| | | | | | | | | Some MIPS controllers have hardware I/O coherency. This patch detects those and turns off software coherency. A new kernel command line option also allows the user to manually turn software coherency on or off. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: malta: Add new Malta config files.Steven J. Hill2013-05-01
| | | | | | | Add in new Malta config files for SMVP, SMTC, and APRP. Also update the original 'malta_defconfig' config file. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
* MIPS: microMIPS: Add instruction utility macros.Steven J. Hill2013-05-01
| | | | | | | | | | | | | | | | | | | Add two new macros for microMIPS. One checks if an exception was taken in either microMIPS or classic MIPS mode. The other checks if a microMIPS instruction is 16-bit or 32-bit in length. [ralf@linux-mips.org: Removed unnecessary parenthesis as noted by Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>] Signed-off-by: Steven J. Hill <sjhill@mips.com> Cc: linux-mips@linux-mips.org Cc: cernekee@gmail.com Cc: kevink@paralogos.com Cc: ddaney.cavm@gmail.com Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Patchwork: https://patchwork.linux-mips.org/patch/4924/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org> (cherry picked from commit 49df26472338b935fd5781bf94a77a88b148a716)
* MIPS: microMIPS: uasm: Add microMIPS micro assembler support.Steven J. Hill2013-05-01
| | | | | | | | | | | | | | | | Add new file 'uasm-micromips.c' that allows the micro assembler to generate microMIPS ISA code. It can be included in the kernel alongside the classic ISA as long as the platform supports the microMIPS ISA. Signed-off-by: Steven J. Hill <sjhill@mips.com> Cc: linux-mips@linux-mips.org Cc: cernekee@gmail.com Cc: kevink@paralogos.com Cc: ddaney.cavm@gmail.com Patchwork: https://patchwork.linux-mips.org/patch/4923/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org> (cherry picked from commit 5f011a866afbd03a5379f67f4e70e5efbdfc16e9)
* MIPS: microMIPS: uasm: Split 'uasm.c' into two files.Steven J. Hill2013-05-01
| | | | | | | | | | | | | | | | Split 'uasm.c' into two files. The new file 'uasm-mips.c' has the functions specific to the classic MIPS ISA. The 'uasm.c' file contains common code that can be used by classic or other ISAs that could be supported by the kernel. Signed-off-by: Steven J. Hill <sjhill@mips.com> Cc: linux-mips@linux-mips.org Cc: cernekee@gmail.com Cc: kevink@paralogos.com Cc: ddaney.cavm@gmail.com Patchwork: https://patchwork.linux-mips.org/patch/4922/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org> (cherry picked from commit 0961103562ab958fa74f35043bf4f72e51ed6155)
* MIPS: microMIPS: Add instruction formats.Steven J. Hill2013-05-01
| | | | | | | | | | | | | | Add structures for all the microMIPS instructions. Also add the enumerations for all the bit fields for opcodes, functions, etc. Signed-off-by: Steven J. Hill <sjhill@mips.com> Cc: linux-mips@linux-mips.org Cc: cernekee@gmail.com Cc: kevink@paralogos.com Cc: ddaney.cavm@gmail.com Patchwork: https://patchwork.linux-mips.org/patch/4921/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org> (cherry picked from commit d7f19e43a4337d4d40ff5e241172912130d06a4c)
* Linux 3.9-rc7Linus Torvalds2013-04-14
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* Merge branch 'x86-urgent-for-linus' of ↵Linus Torvalds2013-04-14
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fixes from Ingo Molnar: "Misc fixes" * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/mm: Flush lazy MMU when DEBUG_PAGEALLOC is set x86/mm/cpa/selftest: Fix false positive in CPA self test x86/mm/cpa: Convert noop to functional fix x86, mm: Patch out arch_flush_lazy_mmu_mode() when running on bare metal x86, mm, paravirt: Fix vmalloc_fault oops during lazy MMU updates
| * x86/mm: Flush lazy MMU when DEBUG_PAGEALLOC is setBoris Ostrovsky2013-04-12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | When CONFIG_DEBUG_PAGEALLOC is set page table updates made by kernel_map_pages() are not made visible (via TLB flush) immediately if lazy MMU is on. In environments that support lazy MMU (e.g. Xen) this may lead to fatal page faults, for example, when zap_pte_range() needs to allocate pages in __tlb_remove_page() -> tlb_next_batch(). Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: konrad.wilk@oracle.com Link: http://lkml.kernel.org/r/1365703192-2089-1-git-send-email-boris.ostrovsky@oracle.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * x86/mm/cpa/selftest: Fix false positive in CPA self testAndrea Arcangeli2013-04-12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | If the pmd is not present, _PAGE_PSE will not be set anymore. Fix the false positive. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Stefan Bader <stefan.bader@canonical.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Borislav Petkov <bp@alien8.de> Link: http://lkml.kernel.org/r/1365687369-30802-1-git-send-email-aarcange@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * x86/mm/cpa: Convert noop to functional fixAndrea Arcangeli2013-04-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit: a8aed3e0752b ("x86/mm/pageattr: Prevent PSE and GLOABL leftovers to confuse pmd/pte_present and pmd_huge") introduced a valid fix but one location that didn't trigger the bug that lead to finding those (small) problems, wasn't updated using the right variable. The wrong variable was also initialized for no good reason, that may have been the source of the confusion. Remove the noop initialization accordingly. Commit a8aed3e0752b also erroneously removed one canon_pgprot pass meant to clear pmd bitflags not supported in hardware by older CPUs, that automatically gets corrected by this patch too by applying it to the right variable in the new location. Reported-by: Stefan Bader <stefan.bader@canonical.com> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Borislav Petkov <bp@alien8.de> Cc: Andy Whitcroft <apw@canonical.com> Cc: Mel Gorman <mgorman@suse.de> Link: http://lkml.kernel.org/r/1365600505-19314-1-git-send-email-aarcange@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * x86, mm: Patch out arch_flush_lazy_mmu_mode() when running on bare metalBoris Ostrovsky2013-04-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Invoking arch_flush_lazy_mmu_mode() results in calls to preempt_enable()/disable() which may have performance impact. Since lazy MMU is not used on bare metal we can patch away arch_flush_lazy_mmu_mode() so that it is never called in such environment. [ hpa: the previous patch "Fix vmalloc_fault oops during lazy MMU updates" may cause a minor performance regression on bare metal. This patch resolves that performance regression. It is somewhat unclear to me if this is a good -stable candidate. ] Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: http://lkml.kernel.org/r/1364045796-10720-2-git-send-email-konrad.wilk@oracle.com Tested-by: Josh Boyer <jwboyer@redhat.com> Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: Borislav Petkov <bp@suse.de> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: <stable@vger.kernel.org> SEE NOTE ABOVE
| * x86, mm, paravirt: Fix vmalloc_fault oops during lazy MMU updatesSamu Kallio2013-04-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In paravirtualized x86_64 kernels, vmalloc_fault may cause an oops when lazy MMU updates are enabled, because set_pgd effects are being deferred. One instance of this problem is during process mm cleanup with memory cgroups enabled. The chain of events is as follows: - zap_pte_range enables lazy MMU updates - zap_pte_range eventually calls mem_cgroup_charge_statistics, which accesses the vmalloc'd mem_cgroup per-cpu stat area - vmalloc_fault is triggered which tries to sync the corresponding PGD entry with set_pgd, but the update is deferred - vmalloc_fault oopses due to a mismatch in the PUD entries The OOPs usually looks as so: ------------[ cut here ]------------ kernel BUG at arch/x86/mm/fault.c:396! invalid opcode: 0000 [#1] SMP .. snip .. CPU 1 Pid: 10866, comm: httpd Not tainted 3.6.10-4.fc18.x86_64 #1 RIP: e030:[<ffffffff816271bf>] [<ffffffff816271bf>] vmalloc_fault+0x11f/0x208 .. snip .. Call Trace: [<ffffffff81627759>] do_page_fault+0x399/0x4b0 [<ffffffff81004f4c>] ? xen_mc_extend_args+0xec/0x110 [<ffffffff81624065>] page_fault+0x25/0x30 [<ffffffff81184d03>] ? mem_cgroup_charge_statistics.isra.13+0x13/0x50 [<ffffffff81186f78>] __mem_cgroup_uncharge_common+0xd8/0x350 [<ffffffff8118aac7>] mem_cgroup_uncharge_page+0x57/0x60 [<ffffffff8115fbc0>] page_remove_rmap+0xe0/0x150 [<ffffffff8115311a>] ? vm_normal_page+0x1a/0x80 [<ffffffff81153e61>] unmap_single_vma+0x531/0x870 [<ffffffff81154962>] unmap_vmas+0x52/0xa0 [<ffffffff81007442>] ? pte_mfn_to_pfn+0x72/0x100 [<ffffffff8115c8f8>] exit_mmap+0x98/0x170 [<ffffffff810050d9>] ? __raw_callee_save_xen_pmd_val+0x11/0x1e [<ffffffff81059ce3>] mmput+0x83/0xf0 [<ffffffff810624c4>] exit_mm+0x104/0x130 [<ffffffff8106264a>] do_exit+0x15a/0x8c0 [<ffffffff810630ff>] do_group_exit+0x3f/0xa0 [<ffffffff81063177>] sys_exit_group+0x17/0x20 [<ffffffff8162bae9>] system_call_fastpath+0x16/0x1b Calling arch_flush_lazy_mmu_mode immediately after set_pgd makes the changes visible to the consistency checks. Cc: <stable@vger.kernel.org> RedHat-Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=914737 Tested-by: Josh Boyer <jwboyer@redhat.com> Reported-and-Tested-by: Krishna Raman <kraman@redhat.com> Signed-off-by: Samu Kallio <samu.kallio@aberdeencloud.com> Link: http://lkml.kernel.org/r/1364045796-10720-1-git-send-email-konrad.wilk@oracle.com Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
* | Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds2013-04-14
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Ingo Molnar: "Misc fixlets" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/cputime: Fix accounting on multi-threaded processes sched/debug: Fix sd->*_idx limit range avoiding overflow sched_clock: Prevent 64bit inatomicity on 32bit systems sched: Convert BUG_ON()s in try_to_wake_up_local() to WARN_ON_ONCE()s
| * | sched/cputime: Fix accounting on multi-threaded processesStanislaw Gruszka2013-04-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Recent commit 6fac4829 ("cputime: Use accessors to read task cputime stats") introduced a bug, where we account many times the cputime of the first thread, instead of cputimes of all the different threads. Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20130404085740.GA2495@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/debug: Fix sd->*_idx limit range avoiding overflowlibin2013-04-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 201c373e8e ("sched/debug: Limit sd->*_idx range on sysctl") was an incomplete bug fix. This patch fixes sd->*_idx limit range to [0 ~ CPU_LOAD_IDX_MAX-1] avoiding array overflow caused by setting sd->*_idx to CPU_LOAD_IDX_MAX on sysctl. Signed-off-by: Libin <huawei.libin@huawei.com> Cc: <jiang.liu@huawei.com> Cc: <guohanjun@huawei.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/51626610.2040607@huawei.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched_clock: Prevent 64bit inatomicity on 32bit systemsThomas Gleixner2013-04-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The sched_clock_remote() implementation has the following inatomicity problem on 32bit systems when accessing the remote scd->clock, which is a 64bit value. CPU0 CPU1 sched_clock_local() sched_clock_remote(CPU0) ... remote_clock = scd[CPU0]->clock read_low32bit(scd[CPU0]->clock) cmpxchg64(scd->clock,...) read_high32bit(scd[CPU0]->clock) While the update of scd->clock is using an atomic64 mechanism, the readout on the remote cpu is not, which can cause completely bogus readouts. It is a quite rare problem, because it requires the update to hit the narrow race window between the low/high readout and the update must go across the 32bit boundary. The resulting misbehaviour is, that CPU1 will see the sched_clock on CPU1 ~4 seconds ahead of it's own and update CPU1s sched_clock value to this bogus timestamp. This stays that way due to the clamping implementation for about 4 seconds until the synchronization with CLOCK_MONOTONIC undoes the problem. The issue is hard to observe, because it might only result in a less accurate SCHED_OTHER timeslicing behaviour. To create observable damage on realtime scheduling classes, it is necessary that the bogus update of CPU1 sched_clock happens in the context of an realtime thread, which then gets charged 4 seconds of RT runtime, which results in the RT throttler mechanism to trigger and prevent scheduling of RT tasks for a little less than 4 seconds. So this is quite unlikely as well. The issue was quite hard to decode as the reproduction time is between 2 days and 3 weeks and intrusive tracing makes it less likely, but the following trace recorded with trace_clock=global, which uses sched_clock_local(), gave the final hint: <idle>-0 0d..30 400269.477150: hrtimer_cancel: hrtimer=0xf7061e80 <idle>-0 0d..30 400269.477151: hrtimer_start: hrtimer=0xf7061e80 ... irq/20-S-587 1d..32 400273.772118: sched_wakeup: comm= ... target_cpu=0 <idle>-0 0dN.30 400273.772118: hrtimer_cancel: hrtimer=0xf7061e80 What happens is that CPU0 goes idle and invokes sched_clock_idle_sleep_event() which invokes sched_clock_local() and CPU1 runs a remote wakeup for CPU0 at the same time, which invokes sched_remote_clock(). The time jump gets propagated to CPU0 via sched_remote_clock() and stays stale on both cores for ~4 seconds. There are only two other possibilities, which could cause a stale sched clock: 1) ktime_get() which reads out CLOCK_MONOTONIC returns a sporadic wrong value. 2) sched_clock() which reads the TSC returns a sporadic wrong value. #1 can be excluded because sched_clock would continue to increase for one jiffy and then go stale. #2 can be excluded because it would not make the clock jump forward. It would just result in a stale sched_clock for one jiffy. After quite some brain twisting and finding the same pattern on other traces, sched_clock_remote() remained the only place which could cause such a problem and as explained above it's indeed racy on 32bit systems. So while on 64bit systems the readout is atomic, we need to verify the remote readout on 32bit machines. We need to protect the local->clock readout in sched_clock_remote() on 32bit as well because an NMI could hit between the low and the high readout, call sched_clock_local() and modify local->clock. Thanks to Siegfried Wulsch for bearing with my debug requests and going through the tedious tasks of running a bunch of reproducer systems to generate the debug information which let me decode the issue. Reported-by: Siegfried Wulsch <Siegfried.Wulsch@rovema.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1304051544160.21884@ionos Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org
| * | sched: Convert BUG_ON()s in try_to_wake_up_local() to WARN_ON_ONCE()sTejun Heo2013-03-21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | try_to_wake_up_local() should only be invoked to wake up another task in the same runqueue and BUG_ON()s are used to enforce the rule. Missing try_to_wake_up_local() can stall workqueue execution but such stalls are likely to be finite either by another work item being queued or the one blocked getting unblocked. There's no reason to trigger BUG while holding rq lock crashing the whole system. Convert BUG_ON()s in try_to_wake_up_local() to WARN_ON_ONCE()s. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Steven Rostedt <rostedt@goodmis.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20130318192234.GD3042@htj.dyndns.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | | Merge branch 'perf-urgent-for-linus' of ↵Linus Torvalds2013-04-14
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf fixes from Ingo Molnar: "Misc fixlets" * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf: Fix error return code ftrace: Fix strncpy() use, use strlcpy() instead of strncpy() perf: Fix strncpy() use, use strlcpy() instead of strncpy() perf: Fix strncpy() use, always make sure it's NUL terminated perf: Fix ring_buffer perf_output_space() boundary calculation perf/x86: Fix uninitialized pt_regs in intel_pmu_drain_bts_buffer()
| * | | perf: Fix error return codeWei Yongjun2013-04-12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix to return -ENOMEM in the allocation error case instead of 0 (if pmu_bus_running == 1), as done elsewhere in this function. Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Cc: a.p.zijlstra@chello.nl Cc: paulus@samba.org Cc: acme@ghostprotocols.net Link: http://lkml.kernel.org/r/CAPgLHd8j_fWcgqe%3DKLWjpBj%2B%3Do0Pw6Z-SEq%3DNTPU08c2w1tngQ@mail.gmail.com [ Tweaked the error code setting placement and the changelog. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | ftrace: Fix strncpy() use, use strlcpy() instead of strncpy()Chen Gang2013-04-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For NUL terminated string we always need to set '\0' at the end. Signed-off-by: Chen Gang <gang.chen@asianux.com> Cc: rostedt@goodmis.org Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/516243B7.9020405@asianux.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | perf: Fix strncpy() use, use strlcpy() instead of strncpy()Chen Gang2013-04-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For NUL terminated string we always need to set '\0' at the end. Signed-off-by: Chen Gang <gang.chen@asianux.com> Cc: rostedt@goodmis.org Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/51624254.30301@asianux.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | perf: Fix strncpy() use, always make sure it's NUL terminatedChen Gang2013-04-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For NUL terminated string, always make sure that there's '\0' at the end. In our case we need a return value, so still use strncpy() and fix up the tail explicitly. (strlcpy() returns the size, not the pointer) Signed-off-by: Chen Gang <gang.chen@asianux.com> Cc: a.p.zijlstra@chello.nl <a.p.zijlstra@chello.nl> Cc: paulus@samba.org <paulus@samba.org> Cc: acme@ghostprotocols.net <acme@ghostprotocols.net> Link: http://lkml.kernel.org/r/51623E0B.7070101@asianux.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | perf: Fix ring_buffer perf_output_space() boundary calculationStephane Eranian2013-03-21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch fixes a flaw in perf_output_space(). In case the size of the space needed is bigger than the actual buffer size, there may be situations where the function would return true (i.e., there is space) when it should not. head > offset due to rounding of the masking logic. The problem can be tested by activating BTS on Intel processors. A BTS record can be as big as 16 pages. The following command fails: $ perf record -m 4 -c 1 -e branches:u my_test_program You will get a buffer corruption with this. Perf report won't be able to parse the perf.data. The fix is to first check that the requested space is smaller than the buffer size. If so, then the masking logic will work fine. If not, then there is no chance the record can be saved and it will be gracefully handled by upper code layers. [ In v2, we also make the logic for the writable more explicit by renaming it to rb->overwrite because it tells whether or not the buffer can overwrite its tail (suggested by PeterZ). ] Signed-off-by: Stephane Eranian <eranian@google.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: peterz@infradead.org Cc: jolsa@redhat.com Cc: fweisbec@gmail.com Link: http://lkml.kernel.org/r/20130318133327.GA3056@quad Signed-off-by: Ingo Molnar <mingo@kernel.org>
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