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2021-02-07x86: __always_inline __{rd,wr}msr()Peter Zijlstra1-2/+2
[ Upstream commit 66a425011c61e71560c234492d204e83cfb73d1d ] When the compiler choses to not inline the trivial MSR helpers: vmlinux.o: warning: objtool: __sev_es_nmi_complete()+0xce: call to __wrmsr.constprop.14() leaves .noinstr.text section Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested Link: https://lore.kernel.org/r/X/bf3gV+BW7kGEsB@hirez.programming.kicks-ass.net Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-02-07arm64: Do not pass tagged addresses to __is_lm_address()Catalin Marinas2-2/+2
commit 91cb2c8b072e00632adf463b78b44f123d46a0fa upstream. Commit 519ea6f1c82f ("arm64: Fix kernel address detection of __is_lm_address()") fixed the incorrect validation of addresses below PAGE_OFFSET. However, it no longer allowed tagged addresses to be passed to virt_addr_valid(). Fix this by explicitly resetting the pointer tag prior to invoking __is_lm_address(). This is consistent with the __lm_to_phys() macro. Fixes: 519ea6f1c82f ("arm64: Fix kernel address detection of __is_lm_address()") Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Ard Biesheuvel <ardb@kernel.org> Cc: <stable@vger.kernel.org> # 5.4.x Cc: Will Deacon <will@kernel.org> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Link: https://lore.kernel.org/r/20210201190634.22942-2-catalin.marinas@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-07arm64: Fix kernel address detection of __is_lm_address()Vincenzo Frascino1-4/+4
commit 519ea6f1c82fcdc9842908155ae379de47818778 upstream. Currently, the __is_lm_address() check just masks out the top 12 bits of the address, but if they are 0, it still yields a true result. This has as a side effect that virt_addr_valid() returns true even for invalid virtual addresses (e.g. 0x0). Fix the detection checking that it's actually a kernel address starting at PAGE_OFFSET. Fixes: 68dd8ef32162 ("arm64: memory: Fix virt_addr_valid() using __is_lm_address()") Cc: <stable@vger.kernel.org> # 5.4.x Cc: Will Deacon <will@kernel.org> Suggested-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Link: https://lore.kernel.org/r/20210126134056.45747-1-vincenzo.frascino@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-03ARM: dts: imx6qdl-kontron-samx6i: fix i2c_lcd/cam default statusMarco Felsch1-2/+2
[ Upstream commit 70b6ff4c549a62b59b286445f66cfec6c5327ac8 ] Fix typo so the gpio i2c busses are really disabled. Fixes: 2125212785c9 ("ARM: dts: imx6qdl-kontron-samx6i: add Kontron SMARC SoM Support") Signed-off-by: Marco Felsch <m.felsch@pengutronix.de> Signed-off-by: Shawn Guo <shawnguo@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-02-03arm64: dts: ls1028a: fix the offset of the reset registerMichael Walle1-1/+1
[ Upstream commit 1653e3d470629d25c64cd8a2f84adb20a9348b0c ] The offset of the reset request register is 0, the absolute address is 0x1e60000. Boards without PSCI support will fail to perform a reset: [ 26.734700] reboot: Restarting system [ 27.743259] Unable to restart system [ 27.746845] Reboot failed -- System halted Fixes: 8897f3255c9c ("arm64: dts: Add support for NXP LS1028A SoC") Signed-off-by: Michael Walle <michael@walle.cc> Signed-off-by: Shawn Guo <shawnguo@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-02-03ARM: imx: build suspend-imx6.S with arm instruction setMax Krummenacher1-0/+1
commit a88afa46b86ff461c89cc33fc3a45267fff053e8 upstream. When the kernel is configured to use the Thumb-2 instruction set "suspend-to-memory" fails to resume. Observed on a Colibri iMX6ULL (i.MX 6ULL) and Apalis iMX6 (i.MX 6Q). It looks like the CPU resumes unconditionally in ARM instruction mode and then chokes on the presented Thumb-2 code it should execute. Fix this by using the arm instruction set for all code in suspend-imx6.S. Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com> Fixes: df595746fa69 ("ARM: imx: add suspend in ocram support for i.mx6q") Acked-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com> Signed-off-by: Shawn Guo <shawnguo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-03arm64: dts: broadcom: Fix USB DMA address translation for StingrayBharat Gooty1-1/+6
commit da8ee66f56071aef0b5b0de41d2c2a97fa30c8a1 upstream. Add a non-empty dma-ranges so that DMA address translation happens. Fixes: 2013a4b684b6 ("arm64: dts: broadcom: clear the warnings caused by empty dma-ranges") Signed-off-by: Bharat Gooty <bharat.gooty@broadcom.com> Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Ray Jui <ray.jui@broadcom.com> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-03KVM: x86: get smi pending status correctlyJay Zhou1-0/+5
commit 1f7becf1b7e21794fc9d460765fe09679bc9b9e0 upstream. The injection process of smi has two steps: Qemu KVM Step1: cpu->interrupt_request &= \ ~CPU_INTERRUPT_SMI; kvm_vcpu_ioctl(cpu, KVM_SMI) call kvm_vcpu_ioctl_smi() and kvm_make_request(KVM_REQ_SMI, vcpu); Step2: kvm_vcpu_ioctl(cpu, KVM_RUN, 0) call process_smi() if kvm_check_request(KVM_REQ_SMI, vcpu) is true, mark vcpu->arch.smi_pending = true; The vcpu->arch.smi_pending will be set true in step2, unfortunately if vcpu paused between step1 and step2, the kvm_run->immediate_exit will be set and vcpu has to exit to Qemu immediately during step2 before mark vcpu->arch.smi_pending true. During VM migration, Qemu will get the smi pending status from KVM using KVM_GET_VCPU_EVENTS ioctl at the downtime, then the smi pending status will be lost. Signed-off-by: Jay Zhou <jianjay.zhou@huawei.com> Signed-off-by: Shengen Zhuang <zhuangshengen@huawei.com> Message-Id: <20210118084720.1585-1-jianjay.zhou@huawei.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-03KVM: nVMX: Sync unsync'd vmcs02 state to vmcs12 on migrationMaxim Levitsky1-5/+8
commit d51e1d3f6b4236e0352407d8a63f5c5f71ce193d upstream. Even when we are outside the nested guest, some vmcs02 fields may not be in sync vs vmcs12. This is intentional, even across nested VM-exit, because the sync can be delayed until the nested hypervisor performs a VMCLEAR or a VMREAD/VMWRITE that affects those rarely accessed fields. However, during KVM_GET_NESTED_STATE, the vmcs12 has to be up to date to be able to restore it. To fix that, call copy_vmcs02_to_vmcs12_rare() before the vmcs12 contents are copied to userspace. Fixes: 7952d769c29ca ("KVM: nVMX: Sync rarely accessed guest fields only when needed") Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210114205449.8715-2-mlevitsk@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-03KVM: x86/pmu: Fix UBSAN shift-out-of-bounds warning in intel_pmu_refresh()Like Xu1-0/+4
commit e61ab2a320c3dfd6209efe18a575979e07470597 upstream. Since we know vPMU will not work properly when (1) the guest bit_width(s) of the [gp|fixed] counters are greater than the host ones, or (2) guest requested architectural events exceeds the range supported by the host, so we can setup a smaller left shift value and refresh the guest cpuid entry, thus fixing the following UBSAN shift-out-of-bounds warning: shift exponent 197 is too large for 64-bit type 'long long unsigned int' Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:120 ubsan_epilogue+0xb/0x5a lib/ubsan.c:148 __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:395 intel_pmu_refresh.cold+0x75/0x99 arch/x86/kvm/vmx/pmu_intel.c:348 kvm_vcpu_after_set_cpuid+0x65a/0xf80 arch/x86/kvm/cpuid.c:177 kvm_vcpu_ioctl_set_cpuid2+0x160/0x440 arch/x86/kvm/cpuid.c:308 kvm_arch_vcpu_ioctl+0x11b6/0x2d70 arch/x86/kvm/x86.c:4709 kvm_vcpu_ioctl+0x7b9/0xdb0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3386 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Reported-by: syzbot+ae488dc136a4cc6ba32b@syzkaller.appspotmail.com Signed-off-by: Like Xu <like.xu@linux.intel.com> Message-Id: <20210118025800.34620-1-like.xu@linux.intel.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-03KVM: x86/pmu: Fix HW_REF_CPU_CYCLES event pseudo-encoding in intel_arch_events[]Like Xu1-1/+1
commit 98dd2f108e448988d91e296173e773b06fb978b8 upstream. The HW_REF_CPU_CYCLES event on the fixed counter 2 is pseudo-encoded as 0x0300 in the intel_perfmon_event_map[]. Correct its usage. Fixes: 62079d8a4312 ("KVM: PMU: add proper support for fixed counter 2") Signed-off-by: Like Xu <like.xu@linux.intel.com> Message-Id: <20201230081916.63417-1-like.xu@linux.intel.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-03ARM: dts: imx6qdl-gw52xx: fix duplicate regulator namingKoen Vandeputte1-1/+1
commit 5a22747b76ca2384057d8e783265404439d31d7f upstream. 2 regulator descriptions carry identical naming. This leads to following boot warning: [ 0.173138] debugfs: Directory 'vdd1p8' with parent 'regulator' already present! Fix this by renaming the one used for audio. Fixes: 5051bff33102 ("ARM: dts: imx: ventana: add LTC3676 PMIC support") Signed-off-by: Tim Harvey <tharvey@gateworks.com> Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com> Cc: stable@vger.kernel.org # v4.11 Signed-off-by: Shawn Guo <shawnguo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-30arm64: mm: use single quantity to represent the PA to VA translationArd Biesheuvel3-25/+14
commit 7bc1a0f9e1765830e945669c99c59c35cf9bca82 upstream. On arm64, the global variable memstart_addr represents the physical address of PAGE_OFFSET, and so physical to virtual translations or vice versa used to come down to simple additions or subtractions involving the values of PAGE_OFFSET and memstart_addr. When support for 52-bit virtual addressing was introduced, we had to deal with PAGE_OFFSET potentially being outside of the region that can be covered by the virtual range (as the 52-bit VA capable build needs to be able to run on systems that are only 48-bit VA capable), and for this reason, another translation was introduced, and recorded in the global variable physvirt_offset. However, if we go back to the original definition of memstart_addr, i.e., the physical address of PAGE_OFFSET, it turns out that there is no need for two separate translations: instead, we can simply subtract the size of the unaddressable VA space from memstart_addr to make the available physical memory appear in the 48-bit addressable VA region. This simplifies things, but also fixes a bug on KASLR builds, which may update memstart_addr later on in arm64_memblock_init(), but fails to update vmemmap and physvirt_offset accordingly. Fixes: 5383cc6efed1 ("arm64: mm: Introduce vabits_actual") Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Steve Capper <steve.capper@arm.com> Link: https://lore.kernel.org/r/20201008153602.9467-2-ardb@kernel.org Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-27sh: dma: fix kconfig dependency for G2_DMANecip Fazil Yildiran1-2/+1
commit f477a538c14d07f8c45e554c8c5208d588514e98 upstream. When G2_DMA is enabled and SH_DMA is disabled, it results in the following Kbuild warning: WARNING: unmet direct dependencies detected for SH_DMA_API Depends on [n]: SH_DMA [=n] Selected by [y]: - G2_DMA [=y] && SH_DREAMCAST [=y] The reason is that G2_DMA selects SH_DMA_API without depending on or selecting SH_DMA while SH_DMA_API depends on SH_DMA. When G2_DMA was first introduced with commit 40f49e7ed77f ("sh: dma: Make G2 DMA configurable."), this wasn't an issue since SH_DMA_API didn't have such dependency, and this way was the only way to enable it since SH_DMA_API was non-visible. However, later SH_DMA_API was made visible and dependent on SH_DMA with commit d8902adcc1a9 ("dmaengine: sh: Add Support SuperH DMA Engine driver"). Let G2_DMA depend on SH_DMA_API instead to avoid Kbuild issues. Fixes: d8902adcc1a9 ("dmaengine: sh: Add Support SuperH DMA Engine driver") Signed-off-by: Necip Fazil Yildiran <fazilyildiran@gmail.com> Signed-off-by: Rich Felker <dalias@libc.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-27x86/cpu/amd: Set __max_die_per_package on AMDYazen Ghannam1-2/+2
commit 76e2fc63ca40977af893b724b00cc2f8e9ce47a4 upstream. Set the maximum DIE per package variable on AMD using the NodesPerProcessor topology value. This will be used by RAPL, among others, to determine the maximum number of DIEs on the system in order to do per-DIE manipulations. [ bp: Productize into a proper patch. ] Fixes: 028c221ed190 ("x86/CPU/AMD: Save AMD NodeId as cpu_die_id") Reported-by: Johnathan Smithinovic <johnathan.smithinovic@gmx.at> Reported-by: Rafael Kitover <rkitover@gmail.com> Signed-off-by: Yazen Ghannam <Yazen.Ghannam@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Tested-by: Johnathan Smithinovic <johnathan.smithinovic@gmx.at> Tested-by: Rafael Kitover <rkitover@gmail.com> Link: https://bugzilla.kernel.org/show_bug.cgi?id=210939 Link: https://lkml.kernel.org/r/20210106112106.GE5729@zn.tnic Link: https://lkml.kernel.org/r/20210111101455.1194-1-bp@alien8.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-27x86/mmx: Use KFPU_387 for MMX string operationsAndy Lutomirski1-5/+15
commit 67de8dca50c027ca0fa3b62a488ee5035036a0da upstream. The default kernel_fpu_begin() doesn't work on systems that support XMM but haven't yet enabled CR4.OSFXSR. This causes crashes when _mmx_memcpy() is called too early because LDMXCSR generates #UD when the aforementioned bit is clear. Fix it by using kernel_fpu_begin_mask(KFPU_387) explicitly. Fixes: 7ad816762f9b ("x86/fpu: Reset MXCSR to default in kernel_fpu_begin()") Reported-by: Krzysztof Mazur <krzysiek@podlesie.net> Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Tested-by: Krzysztof Piotr Olędzki <ole@ans.pl> Tested-by: Krzysztof Mazur <krzysiek@podlesie.net> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/e7bf21855fe99e5f3baa27446e32623358f69e8d.1611205691.git.luto@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-27x86/topology: Make __max_die_per_package available unconditionallyBorislav Petkov2-3/+3
commit 1eb8f690bcb565a6600f8b6dcc78f7b239ceba17 upstream. Move it outside of CONFIG_SMP in order to avoid ifdeffery at the usage sites. Fixes: 76e2fc63ca40 ("x86/cpu/amd: Set __max_die_per_package on AMD") Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210114111814.5346-1-bp@alien8.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-27x86/fpu: Add kernel_fpu_begin_mask() to selectively initialize stateAndy Lutomirski2-6/+18
commit e45122893a9870813f9bd7b4add4f613e6f29008 upstream. Currently, requesting kernel FPU access doesn't distinguish which parts of the extended ("FPU") state are needed. This is nice for simplicity, but there are a few cases in which it's suboptimal: - The vast majority of in-kernel FPU users want XMM/YMM/ZMM state but do not use legacy 387 state. These users want MXCSR initialized but don't care about the FPU control word. Skipping FNINIT would save time. (Empirically, FNINIT is several times slower than LDMXCSR.) - Code that wants MMX doesn't want or need MXCSR initialized. _mmx_memcpy(), for example, can run before CR4.OSFXSR gets set, and initializing MXCSR will fail because LDMXCSR generates an #UD when the aforementioned CR4 bit is not set. - Any future in-kernel users of XFD (eXtended Feature Disable)-capable dynamic states will need special handling. Add a more specific API that allows callers to specify exactly what they want. Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Tested-by: Krzysztof Piotr Olędzki <ole@ans.pl> Link: https://lkml.kernel.org/r/aff1cac8b8fc7ee900cf73e8f2369966621b053f.1611205691.git.luto@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-27powerpc: Fix alignment bug within the init sectionsAriel Marcovitch1-0/+8
[ Upstream commit 2225a8dda263edc35a0e8b858fe2945cf6240fde ] This is a bug that causes early crashes in builds with an .exit.text section smaller than a page and an .init.text section that ends in the beginning of a physical page (this is kinda random, which might explain why this wasn't really encountered before). The init sections are ordered like this: .init.text .exit.text .init.data Currently, these sections aren't page aligned. Because the init code might become read-only at runtime and because the .init.text section can potentially reside on the same physical page as .init.data, the beginning of .init.data might be mapped read-only along with .init.text. Then when the kernel tries to modify a variable in .init.data (like kthreadd_done, used in kernel_init()) the kernel panics. To avoid this, make _einittext page aligned and also align .exit.text to make sure .init.data is always seperated from the text segments. Fixes: 060ef9d89d18 ("powerpc32: PAGE_EXEC required for inittext") Signed-off-by: Ariel Marcovitch <ariel.marcovitch@gmail.com> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210102201156.10805-1-ariel.marcovitch@gmail.com Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-27powerpc: Use the common INIT_DATA_SECTION macro in vmlinux.lds.SYouling Tang1-18/+1
[ Upstream commit fdcfeaba38e5b183045f5b079af94f97658eabe6 ] Use the common INIT_DATA_SECTION rule for the linker script in an effort to regularize the linker script. Signed-off-by: Youling Tang <tangyouling@loongson.cn> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/1604487550-20040-1-git-send-email-tangyouling@loongson.cn Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-27riscv: defconfig: enable gpio support for HiFive UnleashedSagar Shrikant Kadam1-0/+2
[ Upstream commit 0983834a83931606a647c275e5d4165ce4e7b49f ] Ethernet phy VSC8541-01 on HiFive Unleashed has its reset line connected to a gpio, so enable GPIO driver's required to reset the phy. Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-27dts: phy: fix missing mdio device and probe failure of vsc8541-01 deviceSagar Shrikant Kadam1-0/+1
[ Upstream commit be969b7cfbcfa8a835a528f1dc467f0975c6d883 ] HiFive unleashed A00 board has VSC8541-01 ethernet phy, this device is identified as a Revision B device as described in device identification registers. In order to use this phy in the unmanaged mode, it requires a specific reset sequence of logical 0-1-0-1 transition on the NRESET pin as documented here [1]. Currently, the bootloader (fsbl or u-boot-spl) takes care of the phy reset. If due to some reason the phy device hasn't received the reset by the prior stages before the linux macb driver comes into the picture, the MACB mii bus gets probed but the mdio scan fails and is not even able to read the phy ID registers. It gives an error message: "libphy: MACB_mii_bus: probed mdio_bus 10090000.ethernet-ffffffff: MDIO device at address 0 is missing." Thus adding the device OUI (Organizationally Unique Identifier) to the phy device node helps to probe the phy device. [1]: VSC8541-01 datasheet: https://www.mouser.com/ds/2/523/Microsemi_VSC8541-01_Datasheet_10496_V40-1148034.pdf Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-27x86/xen: Add xen_no_vector_callback option to test PCI INTX deliveryDavid Woodhouse1-1/+10
[ Upstream commit b36b0fe96af13460278bf9b173beced1bd15f85d ] It's useful to be able to test non-vector event channel delivery, to make sure Linux will work properly on older Xen which doesn't have it. It's also useful for those working on Xen and Xen-compatible hypervisors, because there are guest kernels still in active use which use PCI INTX even when vector delivery is available. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: https://lore.kernel.org/r/20210106153958.584169-4-dwmw2@infradead.org Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-27xen: Fix event channel callback via INTX/GSIDavid Woodhouse1-1/+1
[ Upstream commit 3499ba8198cad47b731792e5e56b9ec2a78a83a2 ] For a while, event channel notification via the PCI platform device has been broken, because we attempt to communicate with xenstore before we even have notifications working, with the xs_reset_watches() call in xs_init(). We tend to get away with this on Xen versions below 4.0 because we avoid calling xs_reset_watches() anyway, because xenstore might not cope with reading a non-existent key. And newer Xen *does* have the vector callback support, so we rarely fall back to INTX/GSI delivery. To fix it, clean up a bit of the mess of xs_init() and xenbus_probe() startup. Call xs_init() directly from xenbus_init() only in the !XS_HVM case, deferring it to be called from xenbus_probe() in the XS_HVM case instead. Then fix up the invocation of xenbus_probe() to happen either from its device_initcall if the callback is available early enough, or when the callback is finally set up. This means that the hack of calling xenbus_probe() from a workqueue after the first interrupt, or directly from the PCI platform device setup, is no longer needed. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Link: https://lore.kernel.org/r/20210113132606.422794-2-dwmw2@infradead.org Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-27arm64: make atomic helpers __always_inlineArnd Bergmann1-5/+5
[ Upstream commit c35a824c31834d947fb99b0c608c1b9f922b4ba0 ] With UBSAN enabled and building with clang, there are occasionally warnings like WARNING: modpost: vmlinux.o(.text+0xc533ec): Section mismatch in reference from the function arch_atomic64_or() to the variable .init.data:numa_nodes_parsed The function arch_atomic64_or() references the variable __initdata numa_nodes_parsed. This is often because arch_atomic64_or lacks a __initdata annotation or the annotation of numa_nodes_parsed is wrong. for functions that end up not being inlined as intended but operating on __initdata variables. Mark these as __always_inline, along with the corresponding asm-generic wrappers. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20210108092024.4034860-1-arnd@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-27riscv: Fix kernel time_init()Damien Le Moal1-0/+3
[ Upstream commit 11f4c2e940e2f317c9d8fb5a79702f2a4a02ff98 ] If of_clk_init() is not called in time_init(), clock providers defined in the system device tree are not initialized, resulting in failures for other devices to initialize due to missing clocks. Similarly to other architectures and to the default kernel time_init() implementation, call of_clk_init() before executing timer_probe() in time_init(). Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Acked-by: Stephen Boyd <sboyd@kernel.org> Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-19ARM: picoxcell: fix missing interrupt-parent propertiesArnd Bergmann1-0/+4
[ Upstream commit bac717171971176b78c72d15a8b6961764ab197f ] dtc points out that the interrupts for some devices are not parsable: picoxcell-pc3x2.dtsi:45.19-49.5: Warning (interrupts_property): /paxi/gem@30000: Missing interrupt-parent picoxcell-pc3x2.dtsi:51.21-55.5: Warning (interrupts_property): /paxi/dmac@40000: Missing interrupt-parent picoxcell-pc3x2.dtsi:57.21-61.5: Warning (interrupts_property): /paxi/dmac@50000: Missing interrupt-parent picoxcell-pc3x2.dtsi:233.21-237.5: Warning (interrupts_property): /rwid-axi/axi2pico@c0000000: Missing interrupt-parent There are two VIC instances, so it's not clear which one needs to be used. I found the BSP sources that reference VIC0, so use that: https://github.com/r1mikey/meta-picoxcell/blob/master/recipes-kernel/linux/linux-picochip-3.0/0001-picoxcell-support-for-Picochip-picoXcell-SoC.patch Acked-by: Jamie Iles <jamie@jamieiles.com> Link: https://lore.kernel.org/r/20201230152010.3914962-1-arnd@kernel.org' Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-19arch/arc: add copy_user_page() to <asm/page.h> to fix build error on ARCRandy Dunlap1-0/+1
[ Upstream commit 8a48c0a3360bf2bf4f40c980d0ec216e770e58ee ] fs/dax.c uses copy_user_page() but ARC does not provide that interface, resulting in a build error. Provide copy_user_page() in <asm/page.h>. ../fs/dax.c: In function 'copy_cow_page_dax': ../fs/dax.c:702:2: error: implicit declaration of function 'copy_user_page'; did you mean 'copy_to_user_page'? [-Werror=implicit-function-declaration] Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: linux-snps-arc@lists.infradead.org Cc: Dan Williams <dan.j.williams@intel.com> #Acked-by: Vineet Gupta <vgupta@synopsys.com> # v1 Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Jan Kara <jack@suse.cz> Cc: linux-fsdevel@vger.kernel.org Cc: linux-nvdimm@lists.01.org #Reviewed-by: Ira Weiny <ira.weiny@intel.com> # v2 Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-19ARC: build: move symlink creation to arch/arc/Makefile to avoid raceMasahiro Yamada2-11/+13
[ Upstream commit c5e6ae563c802c4d828d42e134af64004db2e58c ] If you run 'make uImage uImage.gz' with the parallel option, uImage.gz will be created by two threads simultaneously. This is because arch/arc/Makefile does not specify the dependency between uImage and uImage.gz. Hence, GNU Make assumes they can be built in parallel. One thread descends into arch/arc/boot/ to create uImage, and another to create uImage.gz. Please notice the same log is displayed twice in the following steps: $ export CROSS_COMPILE=<your-arc-compiler-prefix> $ make -s ARCH=arc defconfig $ make -j$(nproc) ARCH=arc uImage uImage.gz [ snip ] LD vmlinux SORTTAB vmlinux SYSMAP System.map OBJCOPY arch/arc/boot/vmlinux.bin OBJCOPY arch/arc/boot/vmlinux.bin GZIP arch/arc/boot/vmlinux.bin.gz GZIP arch/arc/boot/vmlinux.bin.gz UIMAGE arch/arc/boot/uImage.gz UIMAGE arch/arc/boot/uImage.gz Image Name: Linux-5.10.0-rc4-00003-g62f23044 Created: Sun Nov 22 02:52:26 2020 Image Type: ARC Linux Kernel Image (gzip compressed) Data Size: 2109376 Bytes = 2059.94 KiB = 2.01 MiB Load Address: 80000000 Entry Point: 80004000 Image arch/arc/boot/uImage is ready Image Name: Linux-5.10.0-rc4-00003-g62f23044 Created: Sun Nov 22 02:52:26 2020 Image Type: ARC Linux Kernel Image (gzip compressed) Data Size: 2815455 Bytes = 2749.47 KiB = 2.69 MiB Load Address: 80000000 Entry Point: 80004000 This is a race between the two threads trying to write to the same file arch/arc/boot/uImage.gz. This is a potential problem that can generate a broken file. I fixed a similar problem for ARM by commit 3939f3345050 ("ARM: 8418/1: add boot image dependencies to not generate invalid images"). I highly recommend to avoid such build rules that cause a race condition. Move the uImage rule to arch/arc/Makefile. Another strangeness is that arch/arc/boot/Makefile compares the timestamps between $(obj)/uImage and $(obj)/uImage.*: $(obj)/uImage: $(obj)/uImage.$(suffix-y) @ln -sf $(notdir $<) $@ @echo ' Image $@ is ready' This does not work as expected since $(obj)/uImage is a symlink. The symlink should be created in a phony target rule. I used $(kecho) instead of echo to suppress the message 'Image arch/arc/boot/uImage is ready' when the -s option is given. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-19ARC: build: add boot_targets to PHONYMasahiro Yamada1-0/+1
[ Upstream commit 0cfccb3c04934cdef42ae26042139f16e805b5f7 ] The top-level boot_targets (uImage and uImage.*) should be phony targets. They just let Kbuild descend into arch/arc/boot/ and create files there. If a file exists in the top directory with the same name, the boot image will not be created. You can confirm it by the following steps: $ export CROSS_COMPILE=<your-arc-compiler-prefix> $ make -s ARCH=arc defconfig all # vmlinux will be built $ touch uImage.gz $ make ARCH=arc uImage.gz CALL scripts/atomic/check-atomics.sh CALL scripts/checksyscalls.sh CHK include/generated/compile.h # arch/arc/boot/uImage.gz is not created Specify the targets as PHONY to fix this. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-19ARC: build: add uImage.lzma to the top-level targetMasahiro Yamada1-1/+1
[ Upstream commit f2712ec76a5433e5ec9def2bd52a95df1f96d050 ] arch/arc/boot/Makefile supports uImage.lzma, but you cannot do 'make uImage.lzma' because the corresponding target is missing in arch/arc/Makefile. Add it. I also changed the assignment operator '+=' to ':=' since this is the only place where we expect this variable to be set. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-19ARC: build: remove non-existing bootpImage from KBUILD_IMAGEMasahiro Yamada1-6/+0
[ Upstream commit 9836720911cfec25d3fbdead1c438bf87e0f2841 ] The deb-pkg builds for ARCH=arc fail. $ export CROSS_COMPILE=<your-arc-compiler-prefix> $ make -s ARCH=arc defconfig $ make ARCH=arc bindeb-pkg SORTTAB vmlinux SYSMAP System.map MODPOST Module.symvers make KERNELRELEASE=5.10.0-rc4 ARCH=arc KBUILD_BUILD_VERSION=2 -f ./Makefile intdeb-pkg sh ./scripts/package/builddeb cp: cannot stat 'arch/arc/boot/bootpImage': No such file or directory make[4]: *** [scripts/Makefile.package:87: intdeb-pkg] Error 1 make[3]: *** [Makefile:1527: intdeb-pkg] Error 2 make[2]: *** [debian/rules:13: binary-arch] Error 2 dpkg-buildpackage: error: debian/rules binary subprocess returned exit status 2 make[1]: *** [scripts/Makefile.package:83: bindeb-pkg] Error 2 make: *** [Makefile:1527: bindeb-pkg] Error 2 The reason is obvious; arch/arc/Makefile sets $(boot)/bootpImage as the default image, but there is no rule to build it. Remove the meaningless KBUILD_IMAGE assignment so it will fallback to the default vmlinux. With this change, you can build the deb package. I removed the 'bootpImage' target as well. At best, it provides 'make bootpImage' as an alias of 'make vmlinux', but I do not see much sense in doing so. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-01-19MIPS: relocatable: fix possible boot hangup with KASLR enabledAlexander Lobakin1-2/+8
commit 69e976831cd53f9ba304fd20305b2025ecc78eab upstream. LLVM-built Linux triggered a boot hangup with KASLR enabled. arch/mips/kernel/relocate.c:get_random_boot() uses linux_banner, which is a string constant, as a random seed, but accesses it as an array of unsigned long (in rotate_xor()). When the address of linux_banner is not aligned to sizeof(long), such access emits unaligned access exception and hangs the kernel. Use PTR_ALIGN() to align input address to sizeof(long) and also align down the input length to prevent possible access-beyond-end. Fixes: 405bc8fd12f5 ("MIPS: Kernel: Implement KASLR using CONFIG_RELOCATABLE") Cc: stable@vger.kernel.org # 4.7+ Signed-off-by: Alexander Lobakin <alobakin@pm.me> Tested-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-19MIPS: boot: Fix unaligned access with CONFIG_MIPS_RAW_APPENDED_DTBPaul Cercueil1-1/+2
commit 4d4f9c1a17a3480f8fe523673f7232b254d724b7 upstream. The compressed payload is not necesarily 4-byte aligned, at least when compiling with Clang. In that case, the 4-byte value appended to the compressed payload that corresponds to the uncompressed kernel image size must be read using get_unaligned_le32(). This fixes Clang-built kernels not booting on MIPS (tested on a Ingenic JZ4770 board). Fixes: b8f54f2cde78 ("MIPS: ZBOOT: copy appended dtb to the end of the kernel") Cc: <stable@vger.kernel.org> # v4.7 Signed-off-by: Paul Cercueil <paul@crapouillou.net> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-19mips: lib: uncached: fix non-standard usage of variable 'sp'Anders Roxell1-1/+3
commit 5b058973d3205578aa6c9a71392e072a11ca44ef upstream. When building mips tinyconfig with clang the following warning show up: arch/mips/lib/uncached.c:45:6: warning: variable 'sp' is uninitialized when used here [-Wuninitialized] if (sp >= (long)CKSEG0 && sp < (long)CKSEG2) ^~ arch/mips/lib/uncached.c:40:18: note: initialize the variable 'sp' to silence this warning register long sp __asm__("$sp"); ^ = 0 1 warning generated. Rework to make an explicit inline move, instead of the non-standard use of specifying registers for local variables. This is what's written from the gcc-10 manual [1] about specifying registers for local variables: "6.47.5.2 Specifying Registers for Local Variables ................................................. [...] "The only supported use for this feature is to specify registers for input and output operands when calling Extended 'asm' (*note Extended Asm::). [...]". [1] https://docs.w3cub.com/gcc~10/local-register-variables Signed-off-by: Anders Roxell <anders.roxell@linaro.org> Reported-by: Nathan Chancellor <natechancellor@gmail.com> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-19mips: fix Section mismatch in referenceAnders Roxell2-3/+3
commit ad4fddef5f2345aa9214e979febe2f47639c10d9 upstream. When building mips tinyconfig with clang the following error show up: WARNING: modpost: vmlinux.o(.text+0x1940c): Section mismatch in reference from the function r4k_cache_init() to the function .init.text:loongson3_sc_init() The function r4k_cache_init() references the function __init loongson3_sc_init(). This is often because r4k_cache_init lacks a __init annotation or the annotation of loongson3_sc_init is wrong. Remove marked __init from function loongson3_sc_init(), mips_sc_probe_cm3(), and mips_sc_probe(). Signed-off-by: Anders Roxell <anders.roxell@linaro.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-19x86/hyperv: check cpu mask after interrupt has been disabledWei Liu1-3/+9
commit ad0a6bad44758afa3b440c254a24999a0c7e35d5 upstream. We've observed crashes due to an empty cpu mask in hyperv_flush_tlb_others. Obviously the cpu mask in question is changed between the cpumask_empty call at the beginning of the function and when it is actually used later. One theory is that an interrupt comes in between and a code path ends up changing the mask. Move the check after interrupt has been disabled to see if it fixes the issue. Signed-off-by: Wei Liu <wei.liu@kernel.org> Cc: stable@kernel.org Link: https://lore.kernel.org/r/20210105175043.28325-1-wei.liu@kernel.org Reviewed-by: Michael Kelley <mikelley@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-17KVM: arm64: Don't access PMCR_EL0 when no PMU is availableMarc Zyngier1-0/+4
commit 2a5f1b67ec577fb1544b563086e0377f095f88e2 upstream. We reset the guest's view of PMCR_EL0 unconditionally, based on the host's view of this register. It is however legal for an implementation not to provide any PMU, resulting in an UNDEF. The obvious fix is to skip the reset of this shadow register when no PMU is available, sidestepping the issue entirely. If no PMU is available, the guest is not able to request a virtual PMU anyway, so not doing nothing is the right thing to do! It is unlikely that this bug can hit any HW implementation though, as they all provide a PMU. It has been found using nested virt with the host KVM not implementing the PMU itself. Fixes: ab9468340d2bc ("arm64: KVM: Add access handler for PMCR register") Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20201210083059.1277162-1-maz@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-17ARM: OMAP2+: omap_device: fix idling of devices during probeAndreas Kemnade1-3/+5
commit ec76c2eea903947202098090bbe07a739b5246e9 upstream. On the GTA04A5 od->_driver_status was not set to BUS_NOTIFY_BIND_DRIVER during probe of the second mmc used for wifi. Therefore omap_device_late_idle idled the device during probing causing oopses when accessing the registers. It was not set because od->_state was set to OMAP_DEVICE_STATE_IDLE in the notifier callback. Therefore set od->_driver_status also in that case. This came apparent after commit 21b2cec61c04 ("mmc: Set PROBE_PREFER_ASYNCHRONOUS for drivers that existed in v4.4") causing this oops: omap_hsmmc 480b4000.mmc: omap_device_late_idle: enabled but no driver. Idling 8<--- cut here --- Unhandled fault: external abort on non-linefetch (0x1028) at 0xfa0b402c ... (omap_hsmmc_set_bus_width) from [<c07996bc>] (omap_hsmmc_set_ios+0x11c/0x258) (omap_hsmmc_set_ios) from [<c077b2b0>] (mmc_power_up.part.8+0x3c/0xd0) (mmc_power_up.part.8) from [<c077c14c>] (mmc_start_host+0x88/0x9c) (mmc_start_host) from [<c077d284>] (mmc_add_host+0x58/0x84) (mmc_add_host) from [<c0799190>] (omap_hsmmc_probe+0x5fc/0x8c0) (omap_hsmmc_probe) from [<c0666728>] (platform_drv_probe+0x48/0x98) (platform_drv_probe) from [<c066457c>] (really_probe+0x1dc/0x3b4) Fixes: 04abaf07f6d5 ("ARM: OMAP2+: omap_device: Sync omap_device and pm_runtime after probe defer") Fixes: 21b2cec61c04 ("mmc: Set PROBE_PREFER_ASYNCHRONOUS for drivers that existed in v4.4") Acked-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Andreas Kemnade <andreas@kemnade.info> [tony@atomide.com: left out extra parens, trimmed description stack trace] Signed-off-by: Tony Lindgren <tony@atomide.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-17x86/resctrl: Don't move a task to the same resource groupFenghua Yu1-0/+7
commit a0195f314a25582b38993bf30db11c300f4f4611 upstream Shakeel Butt reported in [1] that a user can request a task to be moved to a resource group even if the task is already in the group. It just wastes time to do the move operation which could be costly to send IPI to a different CPU. Add a sanity check to ensure that the move operation only happens when the task is not already in the resource group. [1] https://lore.kernel.org/lkml/CALvZod7E9zzHwenzf7objzGKsdBmVwTgEJ0nPgs0LUFU3SN5Pw@mail.gmail.com/ Fixes: e02737d5b826 ("x86/intel_rdt: Add tasks files") Reported-by: Shakeel Butt <shakeelb@google.com> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Tony Luck <tony.luck@intel.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/962ede65d8e95be793cb61102cca37f7bb018e66.1608243147.git.reinette.chatre@intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-17x86/resctrl: Use an IPI instead of task_work_add() to update PQR_ASSOC MSRFenghua Yu1-65/+43
commit ae28d1aae48a1258bd09a6f707ebb4231d79a761 upstream Currently, when moving a task to a resource group the PQR_ASSOC MSR is updated with the new closid and rmid in an added task callback. If the task is running, the work is run as soon as possible. If the task is not running, the work is executed later in the kernel exit path when the kernel returns to the task again. Updating the PQR_ASSOC MSR as soon as possible on the CPU a moved task is running is the right thing to do. Queueing work for a task that is not running is unnecessary (the PQR_ASSOC MSR is already updated when the task is scheduled in) and causing system resource waste with the way in which it is implemented: Work to update the PQR_ASSOC register is queued every time the user writes a task id to the "tasks" file, even if the task already belongs to the resource group. This could result in multiple pending work items associated with a single task even if they are all identical and even though only a single update with most recent values is needed. Specifically, even if a task is moved between different resource groups while it is sleeping then it is only the last move that is relevant but yet a work item is queued during each move. This unnecessary queueing of work items could result in significant system resource waste, especially on tasks sleeping for a long time. For example, as demonstrated by Shakeel Butt in [1] writing the same task id to the "tasks" file can quickly consume significant memory. The same problem (wasted system resources) occurs when moving a task between different resource groups. As pointed out by Valentin Schneider in [2] there is an additional issue with the way in which the queueing of work is done in that the task_struct update is currently done after the work is queued, resulting in a race with the register update possibly done before th