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2021-11-18x86: Increase exception stack sizesPeter Zijlstra1-1/+1
[ Upstream commit 7fae4c24a2b84a66c7be399727aca11e7a888462 ] It turns out that a single page of stack is trivial to overflow with all the tracing gunk enabled. Raise the exception stacks to 2 pages, which is still half the interrupt stacks, which are at 4 pages. Reported-by: Michael Wang <yun.wang@linux.alibaba.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/YUIO9Ye98S5Eb68w@hirez.programming.kicks-ass.net Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-11-18MIPS: lantiq: dma: reset correct number of channelAleksander Jan Bajkowski1-5/+6
[ Upstream commit 5ca9ce2ba4d5884cd94d1a856c675ab1242cd242 ] Different SoCs have a different number of channels, e.g .: * amazon-se has 10 channels, * danube+ar9 have 20 channels, * vr9 has 28 channels, * ar10 has 24 channels. We can read the ID register and, depending on the reported number of channels, reset the appropriate number of channels. Signed-off-by: Aleksander Jan Bajkowski <olek2@wp.pl> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-11-18MIPS: lantiq: dma: add small delay after resetAleksander Jan Bajkowski1-0/+3
[ Upstream commit c12aa581f6d5e80c3c3675ab26a52c2b3b62f76e ] Reading the DMA registers immediately after the reset causes Data Bus Error. Adding a small delay fixes this issue. Signed-off-by: Aleksander Jan Bajkowski <olek2@wp.pl> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-11-18powerpc/85xx: Fix oops when mpc85xx_smp_guts_ids node cannot be foundXiaoming Ni1-2/+1
commit 3c2172c1c47b4079c29f0e6637d764a99355ebcd upstream. When the field described in mpc85xx_smp_guts_ids[] is not configured in dtb, the mpc85xx_setup_pmc() does not assign a value to the "guts" variable. As a result, the oops is triggered when mpc85xx_freeze_time_base() is executed. Fixes: 56f1ba280719 ("powerpc/mpc85xx: refactor the PM operations") Cc: stable@vger.kernel.org # v4.6+ Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210929033646.39630-2-nixiaoming@huawei.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-18KVM: nVMX: Query current VMCS when determining if MSR bitmaps are in useSean Christopherson1-4/+4
commit 7dfbc624eb5726367900c8d86deff50836240361 upstream. Check the current VMCS controls to determine if an MSR write will be intercepted due to MSR bitmaps being disabled. In the nested VMX case, KVM will disable MSR bitmaps in vmcs02 if they're disabled in vmcs12 or if KVM can't map L1's bitmaps for whatever reason. Note, the bad behavior is relatively benign in the current code base as KVM sets all bits in vmcs02's MSR bitmap by default, clears bits if and only if L0 KVM also disables interception of an MSR, and only uses the buggy helper for MSR_IA32_SPEC_CTRL. Because KVM explicitly tests WRMSR before disabling interception of MSR_IA32_SPEC_CTRL, the flawed check will only result in KVM reading MSR_IA32_SPEC_CTRL from hardware when it isn't strictly necessary. Tag the fix for stable in case a future fix wants to use msr_write_intercepted(), in which case a buggy implementation in older kernels could prove subtly problematic. Fixes: d28b387fb74d ("KVM/VMX: Allow direct access to MSR_IA32_SPEC_CTRL") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20211109013047.2041518-2-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-18KVM: arm64: Extract ESR_ELx.EC onlyMark Rutland3-2/+3
commit 8bb084119f1acc2ec55ea085a97231e3ddb30782 upstream. Since ARMv8.0 the upper 32 bits of ESR_ELx have been RES0, and recently some of the upper bits gained a meaning and can be non-zero. For example, when FEAT_LS64 is implemented, ESR_ELx[36:32] contain ISS2, which for an ST64BV or ST64BV0 can be non-zero. This can be seen in ARM DDI 0487G.b, page D13-3145, section D13.2.37. Generally, we must not rely on RES0 bit remaining zero in future, and when extracting ESR_ELx.EC we must mask out all other bits. All C code uses the ESR_ELx_EC() macro, which masks out the irrelevant bits, and therefore no alterations are required to C code to avoid consuming irrelevant bits. In a couple of places the KVM assembly extracts ESR_ELx.EC using LSR on an X register, and so could in theory consume previously RES0 bits. In both cases this is for comparison with EC values ESR_ELx_EC_HVC32 and ESR_ELx_EC_HVC64, for which the upper bits of ESR_ELx must currently be zero, but this could change in future. This patch adjusts the KVM vectors to use UBFX rather than LSR to extract ESR_ELx.EC, ensuring these are robust to future additions to ESR_ELx. Cc: stable@vger.kernel.org Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Alexandru Elisei <alexandru.elisei@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: James Morse <james.morse@arm.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Will Deacon <will@kernel.org> Acked-by: Will Deacon <will@kernel.org> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20211103110545.4613-1-mark.rutland@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-18signal/mips: Update (_save|_restore)_fp_context to fail with -EFAULTEric W. Biederman2-11/+2
commit 95bf9d646c3c3f95cb0be7e703b371db8da5be68 upstream. When an instruction to save or restore a register from the stack fails in _save_fp_context or _restore_fp_context return with -EFAULT. This change was made to r2300_fpu.S[1] but it looks like it got lost with the introduction of EX2[2]. This is also what the other implementation of _save_fp_context and _restore_fp_context in r4k_fpu.S does, and what is needed for the callers to be able to handle the error. Furthermore calling do_exit(SIGSEGV) from bad_stack is wrong because it does not terminate the entire process it just terminates a single thread. As the changed code was the only caller of arch/mips/kernel/syscall.c:bad_stack remove the problematic and now unused helper function. Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Maciej Rozycki <macro@orcam.me.uk> Cc: linux-mips@vger.kernel.org [1] 35938a00ba86 ("MIPS: Fix ISA I FP sigcontext access violation handling") [2] f92722dc4545 ("MIPS: Correct MIPS I FP sigcontext layout") Cc: stable@vger.kernel.org Fixes: f92722dc4545 ("MIPS: Correct MIPS I FP sigcontext layout") Acked-by: Maciej W. Rozycki <macro@orcam.me.uk> Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Link: https://lkml.kernel.org/r/20211020174406.17889-5-ebiederm@xmission.com Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-18perf/x86/intel/uncore: Fix Intel ICX IIO event constraintsKan Liang1-0/+2
commit f42e8a603c88f72bf047a710b9fc1d3579f31e71 upstream. According to the latest uncore document, both NUM_OUTSTANDING_REQ_OF_CPU (0x88) event and COMP_BUF_OCCUPANCY(0xd5) event also have constraints. Add them into the event constraints table. Fixes: 2b3b76b5ec67 ("perf/x86/intel/uncore: Add Ice Lake server uncore support") Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/1629991963-102621-4-git-send-email-kan.liang@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-18perf/x86/intel/uncore: Support extra IMC channel on Ice Lake serverKan Liang1-2/+2
commit 496a18f09374ad89b3ab4366019bc3975db90234 upstream. There are three channels on a Ice Lake server, but only two channels will ever be active. Current perf only enables two channels. Support the extra IMC channel, which may be activated on some Ice Lake machines. For a non-activated channel, the SW can still access it. The write will be ignored by the HW. 0 is always returned for the reading. Fixes: 2b3b76b5ec67 ("perf/x86/intel/uncore: Add Ice Lake server uncore support") Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Andi Kleen <ak@linux.intel.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/1629991963-102621-2-git-send-email-kan.liang@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-18ia64: kprobes: Fix to pass correct trampoline address to the handlerMasami Hiramatsu1-4/+5
commit a7fe2378454cf46cd5e2776d05e72bbe8f0a468c upstream. The following commit: Commit e792ff804f49 ("ia64: kprobes: Use generic kretprobe trampoline handler") Passed the wrong trampoline address to __kretprobe_trampoline_handler(): it passes the descriptor address instead of function entry address. Pass the right parameter. Also use correct symbol dereference function to get the function address from 'kretprobe_trampoline' - an IA64 special. Link: https://lkml.kernel.org/r/163163042696.489837.12551102356265354730.stgit@devnote2 Fixes: e792ff804f49 ("ia64: kprobes: Use generic kretprobe trampoline handler") Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: X86 ML <x86@kernel.org> Cc: Daniel Xu <dxu@dxuuu.xyz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Abhishek Sagar <sagar.abhishek@gmail.com> Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com> Cc: Paul McKenney <paulmck@kernel.org> Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-18KVM: VMX: Unregister posted interrupt wakeup handler on hardware unsetupSean Christopherson1-2/+5
commit ec5a4919fa7b7d8c7a2af1c7e799b1fe4be84343 upstream. Unregister KVM's posted interrupt wakeup handler during unsetup so that a spurious interrupt that arrives after kvm_intel.ko is unloaded doesn't call into freed memory. Fixes: bf9f6ac8d749 ("KVM: Update Posted-Interrupts Descriptor when vCPU is blocked") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20211009001107.3936588-3-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-18bpf: Define bpf_jit_alloc_exec_limit for arm64 JITLorenz Bauer1-0/+5
[ Upstream commit 5d63ae908242f028bd10860cba98450d11c079b8 ] Expose the maximum amount of useable memory from the arm64 JIT. Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211014142554.53120-3-lmb@cloudflare.com Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-11-18ARM: dts: sun7i: A20-olinuxino-lime2: Fix ethernet phy-modeBastien Roucariès1-1/+1
[ Upstream commit 55dd7e059098ce4bd0a55c251cb78e74604abb57 ] Commit bbc4d71d6354 ("net: phy: realtek: fix rtl8211e rx/tx delay config") sets the RX/TX delay according to the phy-mode property in the device tree. For the A20-olinuxino-lime2 board this is "rgmii", which is the wrong setting. Following the example of a900cac3750b ("ARM: dts: sun7i: a20: bananapro: Fix ethernet phy-mode") the phy-mode is changed to "rgmii-id" which gets the Ethernet working again on this board. Signed-off-by: Bastien Roucariès <rouca@debian.org> Signed-off-by: Maxime Ripard <maxime@cerno.tech> Link: https://lore.kernel.org/r/20210916081721.237137-1-rouca@debian.org Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-11-18x86/irq: Ensure PI wakeup handler is unregistered before module unloadSean Christopherson1-1/+3
commit 6ff53f6a438f72998f56e82e76694a1df9d1ea2c upstream. Add a synchronize_rcu() after clearing the posted interrupt wakeup handler to ensure all readers, i.e. in-flight IRQ handlers, see the new handler before returning to the caller. If the caller is an exiting module and is unregistering its handler, failure to wait could result in the IRQ handler jumping into an unloaded module. The registration path doesn't require synchronization, as it's the caller's responsibility to not generate interrupts it cares about until after its handler is registered. Fixes: f6b3c72c2366 ("x86/irq: Define a global vector for VT-d Posted-Interrupts") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20211009001107.3936588-2-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-18x86/cpu: Fix migration safety with X86_BUG_NULL_SELJane Malalane4-7/+42
commit 415de44076640483648d6c0f6d645a9ee61328ad upstream. Currently, Linux probes for X86_BUG_NULL_SEL unconditionally which makes it unsafe to migrate in a virtualised environment as the properties across the migration pool might differ. To be specific, the case which goes wrong is: 1. Zen1 (or earlier) and Zen2 (or later) in a migration pool 2. Linux boots on Zen2, probes and finds the absence of X86_BUG_NULL_SEL 3. Linux is then migrated to Zen1 Linux is now running on a X86_BUG_NULL_SEL-impacted CPU while believing that the bug is fixed. The only way to address the problem is to fully trust the "no longer affected" CPUID bit when virtualised, because in the above case it would be clear deliberately to indicate the fact "you might migrate to somewhere which has this behaviour". Zen3 adds the NullSelectorClearsBase CPUID bit to indicate that loading a NULL segment selector zeroes the base and limit fields, as well as just attributes. Zen2 also has this behaviour but doesn't have the NSCB bit. [ bp: Minor touchups. ] Signed-off-by: Jane Malalane <jane.malalane@citrix.com> Signed-off-by: Borislav Petkov <bp@suse.de> CC: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/20211021104744.24126-1-jane.malalane@citrix.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-18x86/sme: Use #define USE_EARLY_PGTABLE_L5 in mem_encrypt_identity.cTom Lendacky1-0/+9
commit e7d445ab26db833d6640d4c9a08bee176777cc82 upstream. When runtime support for converting between 4-level and 5-level pagetables was added to the kernel, the SME code that built pagetables was updated to use the pagetable functions, e.g. p4d_offset(), etc., in order to simplify the code. However, the use of the pagetable functions in early boot code requires the use of the USE_EARLY_PGTABLE_L5 #define in order to ensure that the proper definition of pgtable_l5_enabled() is used. Without the #define, pgtable_l5_enabled() is #defined as cpu_feature_enabled(X86_FEATURE_LA57). In early boot, the CPU features have not yet been discovered and populated, so pgtable_l5_enabled() will return false even when 5-level paging is enabled. This causes the SME code to always build 4-level pagetables to perform the in-place encryption. If 5-level paging is enabled, switching to the SME pagetables results in a page-fault that kills the boot. Adding the #define results in pgtable_l5_enabled() using the __pgtable_l5_enabled variable set in early boot and the SME code building pagetables for the proper paging level. Fixes: aad983913d77 ("x86/mm/encrypt: Simplify sme_populate_pgd() and sme_populate_pgd_large()") Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: <stable@vger.kernel.org> # 4.18.x Link: https://lkml.kernel.org/r/2cb8329655f5c753905812d951e212022a480475.1634318656.git.thomas.lendacky@amd.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-18parisc: Fix ptrace check on syscall returnHelge Deller1-1/+1
commit 8779e05ba8aaffec1829872ef9774a71f44f6580 upstream. The TIF_XXX flags are stored in the flags field in the thread_info struct (TI_FLAGS), not in the flags field of the task_struct structure (TASK_FLAGS). It seems this bug didn't generate any important side-effects, otherwise it wouldn't have went unnoticed for 12 years (since v2.6.32). Signed-off-by: Helge Deller <deller@gmx.de> Fixes: ecd3d4bc06e48 ("parisc: stop using task->ptrace for {single,block}step flags") Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-18parisc: Fix set_fixmap() on PA1.x CPUsHelge Deller1-4/+1
commit 6e866a462867b60841202e900f10936a0478608c upstream. Fix a kernel crash which happens on PA1.x CPUs while initializing the FTRACE/KPROBE breakpoints. The PTE table entries for the fixmap area were not created correctly. Signed-off-by: Helge Deller <deller@gmx.de> Fixes: ccfbc68d41c2 ("parisc: add set_fixmap()/clear_fixmap()") Cc: stable@vger.kernel.org # v5.2+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-12Revert "x86/kvm: fix vcpu-id indexed array sizes"Juergen Gross2-3/+3
commit 1e254d0d86a0f2efd4190a89d5204b37c18c6381 upstream. This reverts commit 76b4f357d0e7d8f6f0013c733e6cba1773c266d3. The commit has the wrong reasoning, as KVM_MAX_VCPU_ID is not defining the maximum allowed vcpu-id as its name suggests, but the number of vcpu-ids. So revert this patch again. Suggested-by: Eduardo Habkost <ehabkost@redhat.com> Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20210913135745.13944-2-jgross@suse.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-12KVM: x86: avoid warning with -Wbitwise-instead-of-logicalPaolo Bonzini1-1/+1
commit 3d5e7a28b1ea2d603dea478e58e37ce75b9597ab upstream. This is a new warning in clang top-of-tree (will be clang 14): In file included from arch/x86/kvm/mmu/mmu.c:27: arch/x86/kvm/mmu/spte.h:318:9: error: use of bitwise '|' with boolean operands [-Werror,-Wbitwise-instead-of-logical] return __is_bad_mt_xwr(rsvd_check, spte) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ || arch/x86/kvm/mmu/spte.h:318:9: note: cast one or both operands to int to silence this warning The code is fine, but change it anyway to shut up this clever clogs of a compiler. Reported-by: torvic9@mailbox.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> [nathan: Backport to 5.10, which does not have 961f84457cd4] Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-02riscv: Fix asan-stack clang buildAlexandre Ghiti3-2/+10
commit 54c5639d8f507ebefa814f574cb6f763033a72a5 upstream. Nathan reported that because KASAN_SHADOW_OFFSET was not defined in Kconfig, it prevents asan-stack from getting disabled with clang even when CONFIG_KASAN_STACK is disabled: fix this by defining the corresponding config. Reported-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Alexandre Ghiti <alexandre.ghiti@canonical.com> Fixes: 8ad8b72721d0 ("riscv: Add KASAN support") Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-02riscv: fix misalgned trap vector base addressChen Lu1-0/+1
commit 64a19591a2938b170aa736443d5d3bf4c51e1388 upstream. The trap vector marked by label .Lsecondary_park must align on a 4-byte boundary, as the {m,s}tvec is defined to require 4-byte alignment. Signed-off-by: Chen Lu <181250012@smail.nju.edu.cn> Reviewed-by: Anup Patel <anup.patel@wdc.com> Fixes: e011995e826f ("RISC-V: Move relocate and few other functions out of __init") Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-02KVM: s390: preserve deliverable_mask in __airqs_kick_single_vcpuHalil Pasic1-2/+3
[ Upstream commit 0e9ff65f455dfd0a8aea5e7843678ab6fe097e21 ] Changing the deliverable mask in __airqs_kick_single_vcpu() is a bug. If one idle vcpu can't take the interrupts we want to deliver, we should look for another vcpu that can, instead of saying that we don't want to deliver these interrupts by clearing the bits from the deliverable_mask. Fixes: 9f30f6216378 ("KVM: s390: add gib_alert_irq_handler()") Signed-off-by: Halil Pasic <pasic@linux.ibm.com> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: Michael Mueller <mimu@linux.ibm.com> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Link: https://lore.kernel.org/r/20211019175401.3757927-3-pasic@linux.ibm.com Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-11-02KVM: s390: clear kicked_mask before sleeping againHalil Pasic1-0/+1
[ Upstream commit 9b57e9d5010bbed7c0d9d445085840f7025e6f9a ] The idea behind kicked mask is that we should not re-kick a vcpu that is already in the "kick" process, i.e. that was kicked and is is about to be dispatched if certain conditions are met. The problem with the current implementation is, that it assumes the kicked vcpu is going to enter SIE shortly. But under certain circumstances, the vcpu we just kicked will be deemed non-runnable and will remain in wait state. This can happen, if the interrupt(s) this vcpu got kicked to deal with got already cleared (because the interrupts got delivered to another vcpu). In this case kvm_arch_vcpu_runnable() would return false, and the vcpu would remain in kvm_vcpu_block(), but this time with its kicked_mask bit set. So next time around we wouldn't kick the vcpu form __airqs_kick_single_vcpu(), but would assume that we just kicked it. Let us make sure the kicked_mask is cleared before we give up on re-dispatching the vcpu. Fixes: 9f30f6216378 ("KVM: s390: add gib_alert_irq_handler()") Reported-by: Matthew Rosato <mjrosato@linux.ibm.com> Signed-off-by: Halil Pasic <pasic@linux.ibm.com> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: Michael Mueller <mimu@linux.ibm.com> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Link: https://lore.kernel.org/r/20211019175401.3757927-2-pasic@linux.ibm.com Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-11-02nios2: Make NIOS2_DTB_SOURCE_BOOL depend on !COMPILE_TESTGuenter Roeck1-0/+1
commit 4a089e95b4d6bb625044d47aed0c442a8f7bd093 upstream. nios2:allmodconfig builds fail with make[1]: *** No rule to make target 'arch/nios2/boot/dts/""', needed by 'arch/nios2/boot/dts/built-in.a'. Stop. make: [Makefile:1868: arch/nios2/boot/dts] Error 2 (ignored) This is seen with compile tests since those enable NIOS2_DTB_SOURCE_BOOL, which in turn enables NIOS2_DTB_SOURCE. This causes the build error because the default value for NIOS2_DTB_SOURCE is an empty string. Disable NIOS2_DTB_SOURCE_BOOL for compile tests to avoid the error. Fixes: 2fc8483fdcde ("nios2: Build infrastructure") Signed-off-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Dinh Nguyen <dinguyen@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-02arm64: dts: allwinner: h5: NanoPI Neo 2: Fix ethernet nodeClément Bœsch1-1/+1
commit 0764e365dacd0b8f75c1736f9236be280649bd18 upstream. RX and TX delay are provided by ethernet PHY. Reflect that in ethernet node. Fixes: 44a94c7ef989 ("arm64: dts: allwinner: H5: Restore EMAC changes") Signed-off-by: Clément Bœsch <u@pkh.me> Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: Maxime Ripard <maxime@cerno.tech> Link: https://lore.kernel.org/r/20210905002027.171984-1-u@pkh.me Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-02riscv, bpf: Fix potential NULL dereferenceBjörn Töpel1-1/+2
commit 27de809a3d83a6199664479ebb19712533d6fd9b upstream. The bpf_jit_binary_free() function requires a non-NULL argument. When the RISC-V BPF JIT fails to converge in NR_JIT_ITERATIONS steps, jit_data->header will be NULL, which triggers a NULL dereference. Avoid this by checking the argument, prior calling the function. Fixes: ca6cb5447cec ("riscv, bpf: Factor common RISC-V JIT code") Signed-off-by: Björn Töpel <bjorn@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20211028125115.514587-1-bjorn@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-02arm64: Avoid premature usercopy failureRobin Murphy3-13/+35
commit 295cf156231ca3f9e3a66bde7fab5e09c41835e0 upstream. Al reminds us that the usercopy API must only return complete failure if absolutely nothing could be copied. Currently, if userspace does something silly like giving us an unaligned pointer to Device memory, or a size which overruns MTE tag bounds, we may fail to honour that requirement when faulting on a multi-byte access even though a smaller access could have succeeded. Add a mitigation to the fixup routines to fall back to a single-byte copy if we faulted on a larger access before anything has been written to the destination, to guarantee making *some* forward progress. We needn't be too concerned about the overall performance since this should only occur when callers are doing something a bit dodgy in the first place. Particularly broken userspace might still be able to trick generic_perform_write() into an infinite loop by targeting write() at an mmap() of some read-only device register where the fault-in load succeeds but any store synchronously aborts such that copy_to_user() is genuinely unable to make progress, but, well, don't do that... CC: stable@vger.kernel.org Reported-by: Chen Huang <chenhuang5@huawei.com> Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Robin Murphy <robin.murphy@arm.com> Link: https://lore.kernel.org/r/dc03d5c675731a1f24a62417dba5429ad744234e.1626098433.git.robin.murphy@arm.com Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Chen Huang <chenhuang5@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-02powerpc/bpf: Fix BPF_MOD when imm == 1Naveen N. Rao1-2/+8
commit 8bbc9d822421d9ac8ff9ed26a3713c9afc69d6c8 upstream. Only ignore the operation if dividing by 1. Fixes: 156d0e290e969c ("powerpc/ebpf/jit: Implement JIT compiler for extended BPF") Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Tested-by: Johan Almbladh <johan.almbladh@anyfinetworks.com> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Song Liu <songliubraving@fb.com> Acked-by: Johan Almbladh <johan.almbladh@anyfinetworks.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/c674ca18c3046885602caebb326213731c675d06.1633464148.git.naveen.n.rao@linux.vnet.ibm.com Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-02ARM: 9141/1: only warn about XIP address when not compile testingArnd Bergmann1-1/+1
commit 48ccc8edf5b90622cdc4f8878e0042ab5883e2ca upstream. In randconfig builds, we sometimes come across this warning: arm-linux-gnueabi-ld: XIP start address may cause MPU programming issues While this is helpful for actual systems to figure out why it fails, the warning does not provide any benefit for build testing, so guard it in a check for CONFIG_COMPILE_TEST, which is usually set on randconfig builds. Fixes: 216218308cfb ("ARM: 8713/1: NOMMU: Support MPU in XIP configuration") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-02ARM: 9139/1: kprobes: fix arch_init_kprobes() prototypeArnd Bergmann1-1/+1
commit 1f323127cab086e4fd618981b1e5edc396eaf0f4 upstream. With extra warnings enabled, gcc complains about this function definition: arch/arm/probes/kprobes/core.c: In function 'arch_init_kprobes': arch/arm/probes/kprobes/core.c:465:12: warning: old-style function definition [-Wold-style-definition] 465 | int __init arch_init_kprobes() Link: https://lore.kernel.org/all/20201027093057.c685a14b386acacb3c449e3d@kernel.org/ Fixes: 24ba613c9d6c ("ARM kprobes: core code") Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-02ARM: 9138/1: fix link warning with XIP + frame-pointerArnd Bergmann1-0/+4
commit 44cc6412e66b2b84544eaf2e14cf1764301e2a80 upstream. When frame pointers are used instead of the ARM unwinder, and the kernel is built using clang with an external assembler and CONFIG_XIP_KERNEL, every file produces two warnings like: arm-linux-gnueabi-ld: warning: orphan section `.ARM.extab' from `net/mac802154/util.o' being placed in section `.ARM.extab' arm-linux-gnueabi-ld: warning: orphan section `.ARM.exidx' from `net/mac802154/util.o' being placed in section `.ARM.exidx' The same fix was already merged for the normal (non-XIP) linker script, with a longer description. Fixes: c39866f268f8 ("arm/build: Always handle .ARM.exidx and .ARM.extab sections") Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-02ARM: 9134/1: remove duplicate memcpy() definitionArnd Bergmann1-0/+3
commit eaf6cc7165c9c5aa3c2f9faa03a98598123d0afb upstream. Both the decompressor code and the kasan logic try to override the memcpy() and memmove() definitions, which leading to a clash in a KASAN-enabled kernel with XZ decompression: arch/arm/boot/compressed/decompress.c:50:9: error: 'memmove' macro redefined [-Werror,-Wmacro-redefined] #define memmove memmove ^ arch/arm/include/asm/string.h:59:9: note: previous definition is here #define memmove(dst, src, len) __memmove(dst, src, len) ^ arch/arm/boot/compressed/decompress.c:51:9: error: 'memcpy' macro redefined [-Werror,-Wmacro-redefined] #define memcpy memcpy ^ arch/arm/include/asm/string.h:58:9: note: previous definition is here #define memcpy(dst, src, len) __memcpy(dst, src, len) ^ Here we want the set of functions from the decompressor, so undefine the other macros before the override. Link: https://lore.kernel.org/linux-arm-kernel/CACRpkdZYJogU_SN3H9oeVq=zJkRgRT1gDz3xp59gdqWXxw-B=w@mail.gmail.com/ Link: https://lore.kernel.org/lkml/202105091112.F5rmd4By-lkp@intel.com/ Fixes: d6d51a96c7d6 ("ARM: 9014/2: Replace string mem* functions for KASan") Fixes: a7f464f3db93 ("ARM: 7001/2: Wire up support for the XZ decompressor") Reported-by: kernel test robot <lkp@intel.com> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-02ARM: 9133/1: mm: proc-macros: ensure *_tlb_fns are 4B alignedNick Desaulniers1-0/+1
commit e6a0c958bdf9b2e1b57501fc9433a461f0a6aadd upstream. A kernel built with CONFIG_THUMB2_KERNEL=y and using clang as the assembler could generate non-naturally-aligned v7wbi_tlb_fns which results in a boot failure. The original commit adding the macro missed the .align directive on this data. Link: https://github.com/ClangBuiltLinux/linux/issues/1447 Link: https://lore.kernel.org/all/0699da7b-354f-aecc-a62f-e25693209af4@linaro.org/ Debugged-by: Ard Biesheuvel <ardb@kernel.org> Debugged-by: Nathan Chancellor <nathan@kernel.org> Debugged-by: Richard Henderson <richard.henderson@linaro.org> Fixes: 66a625a88174 ("ARM: mm: proc-macros: Add generic proc/cache/tlb struct definition macros") Suggested-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-02ARM: 9132/1: Fix __get_user_check failure with ARM KASAN imagesLexi Shao1-1/+3
commit df909df0770779f1a5560c2bb641a2809655ef28 upstream. ARM: kasan: Fix __get_user_check failure with kasan In macro __get_user_check defined in arch/arm/include/asm/uaccess.h, error code is store in register int __e(r0). When kasan is enabled, assigning value to kernel address might trigger kasan check, which unexpectedly overwrites r0 and causes undefined behavior on arm kasan images. One example is failure in do_futex and results in process soft lockup. Log: watchdog: BUG: soft lockup - CPU#0 stuck for 62946ms! [rs:main Q:Reg:1151] ... (__asan_store4) from (futex_wait_setup+0xf8/0x2b4) (futex_wait_setup) from (futex_wait+0x138/0x394) (futex_wait) from (do_futex+0x164/0xe40) (do_futex) from (sys_futex_time32+0x178/0x230) (sys_futex_time32) from (ret_fast_syscall+0x0/0x50) The soft lockup happens in function futex_wait_setup. The reason is function get_futex_value_locked always return EINVAL, thus pc jump back to retry label and causes looping. This line in function get_futex_value_locked ret = __get_user(*dest, from); is expanded to *dest = (typeof(*(p))) __r2; , in macro __get_user_check. Writing to pointer dest triggers kasan check and overwrites the return value of __get_user_x function. The assembly code of get_futex_value_locked in kernel/futex.c: ... c01f6dc8: eb0b020e bl c04b7608 <__get_user_4> // "x = (typeof(*(p))) __r2;" triggers kasan check and r0 is overwritten c01f6dCc: e1a00007 mov r0, r7 c01f6dd0: e1a05002 mov r5, r2 c01f6dd4: eb04f1e6 bl c0333574 <__asan_store4> c01f6dd8: e5875000 str r5, [r7] // save ret value of __get_user(*dest, from), which is dest address now c01f6ddc: e1a05000 mov r5, r0 ... // checking return value of __get_user failed c01f6e00: e3550000 cmp r5, #0 ... c01f6e0c: 01a00005 moveq r0, r5 // assign return value to EINVAL c01f6e10: 13e0000d mvnne r0, #13 Return value is the destination address of get_user thus certainly non-zero, so get_futex_value_locked always return EINVAL. Fix it by using a tmp vairable to store the error code before the assignment. This fix has no effects to non-kasan images thanks to compiler optimization. It only affects cases that overwrite r0 due to kasan check. This should fix bug discussed in Link: [1] https://lore.kernel.org/linux-arm-kernel/0ef7c2a5-5d8b-c5e0-63fa-31693fd4495c@gmail.com/ Fixes: 421015713b30 ("ARM: 9017/2: Enable KASan for ARM") Signed-off-by: Lexi Shao <shaolexi@huawei.com> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-27ARM: 9122/1: select HAVE_FUTEX_CMPXCHGNick Desaulniers1-0/+1
commit 9d417cbe36eee7afdd85c2e871685f8dab7c2dba upstream. tglx notes: This function [futex_detect_cmpxchg] is only needed when an architecture has to runtime discover whether the CPU supports it or not. ARM has unconditional support for this, so the obvious thing to do is the below. Fixes linkage failure from Clang randconfigs: kernel/futex.o:(.text.fixup+0x5c): relocation truncated to fit: R_ARM_JUMP24 against `.init.text' and boot failures for CONFIG_THUMB2_KERNEL. Link: https://github.com/ClangBuiltLinux/linux/issues/325 Comments from Nick Desaulniers: See-also: 03b8c7b623c8 ("futex: Allow architectures to skip futex_atomic_cmpxchg_inatomic() test") Reported-by: Arnd Bergmann <arnd@arndb.de> Reported-by: Nathan Chancellor <nathan@kernel.org> Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Cc: stable@vger.kernel.org # v3.14+ Reviewed-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-27s390/pci: fix zpci_zdev_put() on reserveNiklas Schnelle3-7/+45
commit a46044a92add6a400f4dada7b943b30221f7cc80 upstream. Since commit 2a671f77ee49 ("s390/pci: fix use after free of zpci_dev") the reference count of a zpci_dev is incremented between pcibios_add_device() and pcibios_release_device() which was supposed to prevent the zpci_dev from being freed while the common PCI code has access to it. It was missed however that the handling of zPCI availability events assumed that once zpci_zdev_put() was called no later availability event would still see the device. With the previously mentioned commit however this assumption no longer holds and we must make sure that we only drop the initial long-lived reference the zPCI subsystem holds exactly once. Do so by introducing a zpci_device_reserved() function that handles when a device is reserved. Here we make sure the zpci_dev will not be considered for further events by removing it from the zpci_list. This also means that the device actually stays in the ZPCI_FN_STATE_RESERVED state between the time we know it has been reserved and the final reference going away. We thus need to consider it a real state instead of just a conceptual state after the removal. The final cleanup of PCI resources, removal from zbus, and destruction of the IOMMU stays in zpci_release_device() to make sure holders of the reference do see valid data until the release. Fixes: 2a671f77ee49 ("s390/pci: fix use after free of zpci_dev") Cc: stable@vger.kernel.org Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-27perf/x86/msr: Add Sapphire Rapids CPU supportKan Liang1-0/+1
[ Upstream commit 71920ea97d6d1d800ee8b51951dc3fda3f5dc698 ] SMI_COUNT MSR is supported on Sapphire Rapids CPU. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/1633551137-192083-1-git-send-email-kan.liang@linux.intel.com Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-10-27ARM: dts: spear3xx: Fix gmac nodeHerve Codina1-1/+1
[ Upstream commit 6636fec29cdf6665bd219564609e8651f6ddc142 ] On SPEAr3xx, ethernet driver is not compatible with the SPEAr600 one. Indeed, SPEAr3xx uses an earlier version of this IP (v3.40) and needs some driver tuning compare to SPEAr600. The v3.40 IP support was added to stmmac driver and this patch fixes this issue and use the correct compatible string for SPEAr3xx Signed-off-by: Herve Codina <herve.codina@bootlin.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-10-27KVM: nVMX: promptly process interrupts delivered while in guest modePaolo Bonzini1-11/+6
commit 3a25dfa67fe40f3a2690af2c562e0947a78bd6a0 upstream. Since commit c300ab9f08df ("KVM: x86: Replace late check_nested_events() hack with more precise fix") there is no longer the certainty that check_nested_events() tries to inject an external interrupt vmexit to L1 on every call to vcpu_enter_guest. Therefore, even in that case we need to set KVM_REQ_EVENT. This ensures that inject_pending_event() is called, and from there kvm_check_nested_events(). Fixes: c300ab9f08df ("KVM: x86: Replace late check_nested_events() hack with more precise fix") Cc: stable@vger.kernel.org Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-27powerpc/idle: Don't corrupt back chain when going idleMichael Ellerman1-4/+6
commit 496c5fe25c377ddb7815c4ce8ecfb676f051e9b6 upstream. In isa206_idle_insn_mayloss() we store various registers into the stack red zone, which is allowed. However inside the IDLE_STATE_ENTER_SEQ_NORET macro we save r2 again, to 0(r1), which corrupts the stack back chain. We used to do the same in isa206_idle_insn_mayloss() itself, but we fixed that in 73287caa9210 ("powerpc64/idle: Fix SP offsets when saving GPRs"), however we missed that the macro also corrupts the back chain. Corrupting the back chain is bad for debuggability but doesn't necessarily cause a bug. However we recently changed the stack handling in some KVM code, and it now relies on the stack back chain being valid when it returns. The corruption causes that code to return with r1 pointing somewhere in kernel data, at some point LR is restored from the stack and we branch to NULL or somewhere else invalid. Only affects Power8 hosts running KVM guests, with dynamic_mt_modes enabled (which it is by default). The fixes tag below points to the commit that changed the KVM stack handling, exposing this bug. The actual corruption of the back chain has always existed since 948cf67c4726 ("powerpc: Add NAP mode support on Power7 in HV mode"). Fixes: 9b4416c5095c ("KVM: PPC: Book3S HV: Fix stack handling in idle_kvm_start_guest()") Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211020094826.3222052-1-mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-27KVM: PPC: Book3S HV: Make idle_kvm_start_guest() return 0 if it went to guestMichael Ellerman1-2/+7
commit cdeb5d7d890e14f3b70e8087e745c4a6a7d9f337 upstream. We call idle_kvm_start_guest() from power7_offline() if the thread has been requested to enter KVM. We pass it the SRR1 value that was returned from power7_idle_insn() which tells us what sort of wakeup we're processing. Depending on the SRR1 value we pass in, the KVM code might enter the guest, or it might return to us to do some host action if the wakeup requires it. If idle_kvm_start_guest() is able to handle the wakeup, and enter the guest it is supposed to indicate that by returning a zero SRR1 value to us. That was the behaviour prior to commit 10d91611f426 ("powerpc/64s: Reimplement book3s idle code in C"), however in that commit the handling of SRR1 was reworked, and the zeroing behaviour was lost. Returning from idle_kvm_start_guest() without zeroing the SRR1 value can confuse the host offline code, causing the guest to crash and other weirdness. Fixes: 10d91611f426 ("powerpc/64s: Reimplement book3s idle code in C") Cc: stable@vger.kernel.org # v5.2+ Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211015133929.832061-2-mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-27KVM: PPC: Book3S HV: Fix stack handling in idle_kvm_start_guest()Michael Ellerman1-9/+10
commit 9b4416c5095c20e110c82ae602c254099b83b72f upstream. In commit 10d91611f426 ("powerpc/64s: Reimplement book3s idle code in C") kvm_start_guest() became idle_kvm_start_guest(). The old code allocated a stack frame on the emergency stack, but didn't use the frame to store anything, and also didn't store anything in its caller's frame. idle_kvm_start_guest() on the other hand is written more like a normal C function, it creates a frame on entry, and also stores CR/LR into its callers frame (per the ABI). The problem is that there is no caller frame on the emergency stack. The emergency stack for a given CPU is allocated with: paca_ptrs[i]->emergency_sp = alloc_stack(limit, i) + THREAD_SIZE; So emergency_sp actually points to the first address above the emergency stack allocation for a given CPU, we must not store above it without first decrementing it to create a frame. This is different to the regular kernel stack, paca->kstack, which is initialised to point at an initial frame that is ready to use.