- Nov 30, 2020
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Mark Rutland authored
In debug_exception_enter() and debug_exception_exit() we trace hardirqs on/off while RCU isn't guaranteed to be watching, and we don't save and restore the hardirq state, and so may return with this having changed. Handle this appropriately with new entry/exit helpers which do the bare minimum to ensure this is appropriately maintained, without marking debug exceptions as NMIs. These are placed in entry-common.c with the other entry/exit helpers. In future we'll want to reconsider whether some debug exceptions should be NMIs, but this will require a significant refactoring, and for now this should prevent issues with lockdep and RCU. Signed-off-by:
Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marins <catalin.marinas@arm.com> Cc: James Morse <james.morse@arm.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20201130115950.22492-12-mark.rutland@arm.com Signed-off-by:
Will Deacon <will@kernel.org>
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Mark Rutland authored
Exceptions which can be taken at (almost) any time are consdiered to be NMIs. On arm64 that includes: * SDEI events * GICv3 Pseudo-NMIs * Kernel stack overflows * Unexpected/unhandled exceptions ... but currently debug exceptions (BRKs, breakpoints, watchpoints, single-step) are not considered NMIs. As these can be taken at any time, kernel features (lockdep, RCU, ftrace) may not be in a consistent kernel state. For example, we may take an NMI from the idle code or partway through an entry/exit path. While nmi_enter() and nmi_exit() handle most of this state, notably they don't save/restore the lockdep state across an NMI being taken and handled. When interrupts are enabled and an NMI is taken, lockdep may see interrupts become disabled within the NMI code, but not see interrupts become enabled when returning from the NMI, leaving lockdep believing interrupts are disabled when they are actually disabled. The x86 code handles this in idtentry_{enter,exit}_nmi(), which will shortly be moved to the generic entry code. As we can't use either yet, we copy the x86 approach in arm64-specific helpers. All the NMI entrypoints are marked as noinstr to prevent any instrumentation handling code being invoked before the state has been corrected. Signed-off-by: -
Mark Rutland authored
There are periods in kernel mode when RCU is not watching and/or the scheduler tick is disabled, but we can still take exceptions such as interrupts. The arm64 exception handlers do not account for this, and it's possible that RCU is not watching while an exception handler runs. The x86/generic entry code handles this by ensuring that all (non-NMI) kernel exception handlers call irqentry_enter() and irqentry_exit(), which handle RCU, lockdep, and IRQ flag tracing. We can't yet move to the generic entry code, and already hadnle the user<->kernel transitions elsewhere, so we add new kernel<->kernel transition helpers alog the lines of the generic entry code. Since we now track interrupts becoming masked when an exception is taken, local_daif_inherit() is modified to track interrupts becoming re-enabled when the original context is inherited. To balance the entry/exit paths, each handler masks all DAIF exceptions before exit_to_kernel_mode(). Signed-off-by:
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Mark Rutland authored
When built with PROVE_LOCKING, NO_HZ_FULL, and CONTEXT_TRACKING_FORCE will WARN() at boot time that interrupts are enabled when we call context_tracking_user_enter(), despite the DAIF flags indicating that IRQs are masked. The problem is that we're not tracking IRQ flag changes accurately, and so lockdep believes interrupts are enabled when they are not (and vice-versa). We can shuffle things so to make this more accurate. For kernel->user transitions there are a number of constraints we need to consider: 1) When we call __context_tracking_user_enter() HW IRQs must be disabled and lockdep must be up-to-date with this. 2) Userspace should be treated as having IRQs enabled from the PoV of both lockdep and tracing. 3) As context_tracking_user_enter() stops RCU from watching, we cannot use RCU after calling it. 4) IRQ flag tracing and lockdep have state that must be manipulated before RCU is disabled. ... with similar constraints applying for user->kernel transitions, with the ordering reversed. The generic entry code has enter_from_user_mode() and exit_to_user_mode() helpers to handle this. We can't use those directly, so we add arm64 copies for now (without the instrumentation markers which aren't used on arm64). These replace the existing user_exit() and user_exit_irqoff() calls spread throughout handlers, and the exception unmasking is left as-is. Note that: * The accounting for debug exceptions from userspace now happens in el0_dbg() and ret_to_user(), so this is removed from debug_exception_enter() and debug_exception_exit(). As user_exit_irqoff() wakes RCU, the userspace-specific check is removed. * The accounting for syscalls now happens in el0_svc(), el0_svc_compat(), and ret_to_user(), so this is removed from el0_svc_common(). This does not adversely affect the workaround for erratum 1463225, as this does not depend on any of the state tracking. * In ret_to_user() we mask interrupts with local_daif_mask(), and so we need to inform lockdep and tracing. Here a trace_hardirqs_off() is sufficient and safe as we have not yet exited kernel context and RCU is usable. * As PROVE_LOCKING selects TRACE_IRQFLAGS, the ifdeferry in entry.S only needs to check for the latter. * EL0 SError handling will be dealt with in a subsequent patch, as this needs to be treated as an NMI. Prior to this patch, booting an appropriately-configured kernel would result in spats as below: | DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled()) | WARNING: CPU: 2 PID: 1 at kernel/locking/lockdep.c:5280 check_flags.part.54+0x1dc/0x1f0 | Modules linked in: | CPU: 2 PID: 1 Comm: init Not tainted 5.10.0-rc3 #3 | Hardware name: linux,dummy-virt (DT) | pstate: 804003c5 (Nzcv DAIF +PAN -UAO -TCO BTYPE=--) | pc : check_flags.part.54+0x1dc/0x1f0 | lr : check_flags.part.54+0x1dc/0x1f0 | sp : ffff80001003bd80 | x29: ffff80001003bd80 x28: ffff66ce801e0000 | x27: 00000000ffffffff x26: 00000000000003c0 | x25: 0000000000000000 x24: ffffc31842527258 | x23: ffffc31842491368 x22: ffffc3184282d000 | x21: 0000000000000000 x20: 0000000000000001 | x19: ffffc318432ce000 x18: 0080000000000000 | x17: 0000000000000000 x16: ffffc31840f18a78 | x15: 0000000000000001 x14: ffffc3184285c810 | x13: 0000000000000001 x12: 0000000000000000 | x11: ffffc318415857a0 x10: ffffc318406614c0 | x9 : ffffc318415857a0 x8 : ffffc31841f1d000 | x7 : 647261685f706564 x6 : ffffc3183ff7c66c | x5 : ffff66ce801e0000 x4 : 0000000000000000 | x3 : ffffc3183fe00000 x2 : ffffc31841500000 | x1 : e956dc24146b3500 x0 : 0000000000000000 | Call trace: | check_flags.part.54+0x1dc/0x1f0 | lock_is_held_type+0x10c/0x188 | rcu_read_lock_sched_held+0x70/0x98 | __context_tracking_enter+0x310/0x350 | context_tracking_enter.part.3+0x5c/0xc8 | context_tracking_user_enter+0x6c/0x80 | finish_ret_to_user+0x2c/0x13cr Signed-off-by:
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Mark Rutland authored
In preparation for reworking the EL1 irq/nmi entry code, move the existing logic to C. We no longer need the asm_nmi_enter() and asm_nmi_exit() wrappers, so these are removed. The new C functions are marked noinstr, which prevents compiler instrumentation and runtime probing. In subsequent patches we'll want the new C helpers to be called in all cases, so we don't bother wrapping the calls with ifdeferry. Even when the new C functions are stubs the trivial calls are unlikely to have a measurable impact on the IRQ or NMI paths anyway. Prototypes are added to <asm/exception.h> as otherwise (in some configurations) GCC will complain about the lack of a forward declaration. We already do this for existing function, e.g. enter_from_user_mode(). The new helpers are marked as noinstr (which prevents all instrumentation, tracing, and kprobes). Otherwise, there should be no functional change as a result of this patch. Signed-off-by:
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Mark Rutland authored
In a subsequent patch ret_to_user will need to make a C function call (in some configurations) which may clobber x0-x18 at the start of the finish_ret_to_user block, before enable_step_tsk consumes the flags loaded into x1. In preparation for this, let's load the flags into x19, which is preserved across C function calls. This avoids a redundant reload of the flags and ensures we operate on a consistent shapshot regardless. There should be no functional change as a result of this patch. At this point of the entry/exit paths we only need to preserve x28 (tsk) and the sp, and x19 is free for this use. Signed-off-by:
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Mark Rutland authored
In later patches we'll want to extend enter_from_user_mode() and add a corresponding exit_to_user_mode(). As these will be common for all entries/exits from userspace, it'd be better for these to live in entry-common.c with the rest of the entry logic. This patch moves enter_from_user_mode() into entry-common.c. As with other functions in entry-common.c it is marked as noinstr (which prevents all instrumentation, tracing, and kprobes) but there are no other functional changes. Signed-off-by:
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Mark Rutland authored
Functions in entry-common.c are marked as notrace and NOKPROBE_SYMBOL(), but they're still subject to other instrumentation which may rely on lockdep/rcu/context-tracking being up-to-date, and may cause nested exceptions (e.g. for WARN/BUG or KASAN's use of BRK) which will corrupt exceptions registers which have not yet been read. Prevent this by marking all functions in entry-common.c as noinstr to prevent compiler instrumentation. This also blacklists the functions for tracing and kprobes, so we don't need to handle that separately. Functions elsewhere will be dealt with in subsequent patches. Signed-off-by:
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Mark Rutland authored
Core code disables RCU when calling arch_cpu_idle(), so it's not safe for arch_cpu_idle() or its calees to be instrumented, as the instrumentation callbacks may attempt to use RCU or other features which are unsafe to use in this context. Mark them noinstr to prevent issues. The use of local_irq_enable() in arch_cpu_idle() is similarly problematic, and the "sched/idle: Fix arch_cpu_idle() vs tracing" patch queued in the tip tree addresses that case. Reported-by:
Marco Elver <elver@google.com> Signed-off-by:
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Mark Rutland authored
In el0_svc_common() we unmask exceptions before we call user_exit(), and so there's a window where an IRQ or debug exception can be taken while RCU is not watching. In do_debug_exception() we account for this in via debug_exception_{enter,exit}(), but in the el1_irq asm we do not and we call trace functions which rely on RCU before we have a guarantee that RCU is watching. Let's avoid this by having el0_svc_common() exit userspace before unmasking exceptions, matching what we do for all other EL0 entry paths. We can use user_exit_irqoff() to avoid the pointless save/restore of IRQ flags while we're sure exceptions are masked in DAIF. The workaround for Cortex-A76 erratum 1463225 may trigger a debug exception before this point, but the debug code invoked in this case is safe even when RCU is not watching. Signed-off-by:
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- Nov 13, 2020
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Konrad Dybcio authored
QCOM KRYO2XX Silver cores are Cortex-A53 based and are susceptible to the 845719 erratum. Add them to the lookup list to apply the erratum. Signed-off-by:
Konrad Dybcio <konrad.dybcio@somainline.org> Link: https://lore.kernel.org/r/20201104232218.198800-5-konrad.dybcio@somainline.org Signed-off-by:
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Konrad Dybcio authored
KRYO2XX silver (LITTLE) CPUs are based on Cortex-A53 and they are not affected by spectre-v2. Signed-off-by:
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Konrad Dybcio authored
QCOM KRYO2XX gold (big) silver (LITTLE) CPU cores are based on Cortex-A73 and Cortex-A53 respectively and are meltdown safe, hence add them to kpti_safe_list[]. Signed-off-by:
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- Nov 10, 2020
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Will Deacon authored
Commit ce3d31ad ("arm64/smp: Move rcu_cpu_starting() earlier") ensured that RCU is informed early about incoming CPUs that might end up calling into printk() before they are online. However, if such a CPU fails the early CPU feature compatibility checks in check_local_cpu_capabilities(), then it will be powered off or parked without informing RCU, leading to an endless stream of stalls: | rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: | rcu: 2-O...: (0 ticks this GP) idle=002/1/0x4000000000000000 softirq=0/0 fqs=2593 | (detected by 0, t=5252 jiffies, g=9317, q=136) | Task dump for CPU 2: | task:swapper/2 state:R running task stack: 0 pid: 0 ppid: 1 flags:0x00000028 | Call trace: | ret_from_fork+0x0/0x30 Ensure that the dying CPU invokes rcu_report_dead() prior to being powered off or parked. Cc: Qian Cai <cai@redhat.com> Cc: "Paul E. McKenney" <paulmck@kernel.org> Reviewed-by:
Paul E. McKenney <paulmck@kernel.org> Suggested-by:
Qian Cai <cai@redhat.com> Link: https://lore.kernel.org/r/20201105222242.GA8842@willie-the-truck Link: https://lore.kernel.org/r/20201106103602.9849-3-will@kernel.org Signed-off-by:
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Will Deacon authored
cpu_psci_cpu_die() is called in the context of the dying CPU, which will no longer be online or tracked by RCU. It is therefore not generally safe to call printk() if the PSCI "cpu off" request fails, so remove the pr_crit() invocation. Cc: Qian Cai <cai@redhat.com> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20201106103602.9849-2-will@kernel.org Signed-off-by:
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Will Deacon authored
Sparse gets cross about us returning 0 from image_load(), which has a return type of 'void *': >> arch/arm64/kernel/kexec_image.c:130:16: sparse: sparse: Using plain integer as NULL pointer Return NULL instead, as we don't use the return value for anything if it does not indicate an error. Cc: Benjamin Gwin <bgwin@google.com> Reported-by:
kernel test robot <lkp@intel.com> Fixes: 108aa503 ("arm64: kexec_file: try more regions if loading segments fails") Link: https://lore.kernel.org/r/202011091736.T0zH8kaC-lkp@intel.com Signed-off-by:
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Will Deacon authored
In a surprising turn of events, it transpires that CPU capabilities configured as ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE are never set as the result of late-onlining. Therefore our handling of erratum 1418040 does not get activated if it is not required by any of the boot CPUs, even though we allow late-onlining of an affected CPU. In order to get things working again, replace the cpus_have_const_cap() invocation with an explicit check for the current CPU using this_cpu_has_cap(). Cc: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Reviewed-by:
Suzuki K Poulose <suzuki.poulose@arm.com> Acked-by:
Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20201106114952.10032-1-will@kernel.org Signed-off-by:
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- Nov 05, 2020
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Benjamin Gwin authored
It's possible that the first region picked for the new kernel will make it impossible to fit the other segments in the required 32GB window, especially if we have a very large initrd. Instead of giving up, we can keep testing other regions for the kernel until we find one that works. Suggested-by:
Ryan O'Leary <ryanoleary@google.com> Signed-off-by:
Benjamin Gwin <bgwin@google.com> Link: https://lore.kernel.org/r/20201103201106.2397844-1-bgwin@google.com Signed-off-by:
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- Nov 03, 2020
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Jean-Philippe Brucker authored
Commit 36dadef2 ("kprobes: Init kprobes in early_initcall") enabled using kprobes from early_initcall. Unfortunately at this point the hardware debug infrastructure is not operational. The OS lock may still be locked, and the hardware watchpoints may have unknown values when kprobe enables debug monitors to single-step instructions. Rather than using hardware single-step, append a BRK instruction after the instruction to be executed out-of-line. Fixes: 36dadef2 ("kprobes: Init kprobes in early_initcall") Suggested-by:
Jean-Philippe Brucker <jean-philippe@linaro.org> Acked-by:
Masami Hiramatsu <mhiramat@kernel.org> Link: https://lore.kernel.org/r/20201103134900.337243-1-jean-philippe@linaro.org Signed-off-by:
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- Oct 30, 2020
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Qian Cai authored
The call to rcu_cpu_starting() in secondary_start_kernel() is not early enough in the CPU-hotplug onlining process, which results in lockdep splats as follows: WARNING: suspicious RCU usage ----------------------------- kernel/locking/lockdep.c:3497 RCU-list traversed in non-reader section!! other info that might help us debug this: RCU used illegally from offline CPU! rcu_scheduler_active = 1, debug_locks = 1 no locks held by swapper/1/0. Call trace: dump_backtrace+0x0/0x3c8 show_stack+0x14/0x60 dump_stack+0x14c/0x1c4 lockdep_rcu_suspicious+0x134/0x14c __lock_acquire+0x1c30/0x2600 lock_acquire+0x274/0xc48 _raw_spin_lock+0xc8/0x140 vprintk_emit+0x90/0x3d0 vprintk_default+0x34/0x40 vprintk_func+0x378/0x590 printk+0xa8/0xd4 __cpuinfo_store_cpu+0x71c/0x868 cpuinfo_store_cpu+0x2c/0xc8 secondary_start_kernel+0x244/0x318 This is avoided by moving the call to rcu_cpu_starting up near the beginning of the secondary_start_kernel() function. Signed-off-by:
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- Oct 29, 2020
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Rob Herring authored
On Cortex-A77 r0p0 and r1p0, a sequence of a non-cacheable or device load and a store exclusive or PAR_EL1 read can cause a deadlock. The workaround requires a DMB SY before and after a PAR_EL1 register read. In addition, it's possible an interrupt (doing a device read) or KVM guest exit could be taken between the DMB and PAR read, so we also need a DMB before returning from interrupt and before returning to a guest. A deadlock is still possible with the workaround as KVM guests must also have the workaround. IOW, a malicious guest can deadlock an affected systems. This workaround also depends on a firmware counterpart to enable the h/w to insert DMB SY after load and store exclusive instructions. See the errata document SDEN-1152370 v10 [1] for more information. [1] https://static.docs.arm.com/101992/0010/Arm_Cortex_A77_MP074_Software_Developer_Errata_Notice_v10.pdf Signed-off-by:
Rob Herring <robh@kernel.org> Reviewed-by:
Catalin Marinas <catalin.marinas@arm.com> Acked-by:
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- Oct 28, 2020
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Ard Biesheuvel authored
Commit 76085aff ("efi/libstub/arm64: align PE/COFF sections to segment alignment") increased the PE/COFF section alignment to match the minimum segment alignment of the kernel image, which ensures that the kernel does not need to be moved around in memory by the EFI stub if it was built as relocatable. However, the first PE/COFF section starts at _stext, which is only 4 KB aligned, and so the section layout is inconsistent. Existing EFI loaders seem to care little about this, but it is better to clean this up. So let's pad the header to 64 KB to match the PE/COFF section alignment. Fixes: 76085aff ("efi/libstub/arm64: align PE/COFF sections to segment alignment") Signed-off-by:
Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20201027073209.2897-2-ardb@kernel.org Signed-off-by:
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Ard Biesheuvel authored
Now that we started making the linker warn about orphan sections (input sections that are not explicitly consumed by an output section), some configurations produce the following warning: aarch64-linux-gnu-ld: warning: orphan section `.igot.plt' from `arch/arm64/kernel/head.o' being placed in section `.igot.plt' It could be any file that triggers this - head.o is simply the first input file in the link - and the resulting .igot.plt section never actually appears in vmlinux as it turns out to be empty. So let's add .igot.plt to our collection of input sections to disregard unless they are empty. Signed-off-by: -
Arnd Bergmann authored
The icache_policy_str[] definition causes a warning when extra warning flags are enabled: arch/arm64/kernel/cpuinfo.c:38:26: warning: initialized field overwritten [-Woverride-init] 38 | [ICACHE_POLICY_VIPT] = "VIPT", | ^~~~~~ arch/arm64/kernel/cpuinfo.c:38:26: note: (near initialization for 'icache_policy_str[2]') arch/arm64/kernel/cpuinfo.c:39:26: warning: initialized field overwritten [-Woverride-init] 39 | [ICACHE_POLICY_PIPT] = "PIPT", | ^~~~~~ arch/arm64/kernel/cpuinfo.c:39:26: note: (near initialization for 'icache_policy_str[3]') arch/arm64/kernel/cpuinfo.c:40:27: warning: initialized field overwritten [-Woverride-init] 40 | [ICACHE_POLICY_VPIPT] = "VPIPT", | ^~~~~~~ arch/arm64/kernel/cpuinfo.c:40:27: note: (near initialization for 'icache_policy_str[0]') There is no real need for the default initializer here, as printing a NULL string is harmless. Rewrite the logic to have an explicit reserved value for the only one that uses the default value. This partially reverts the commit that removed ICACHE_POLICY_AIVIVT. Fixes: 155433cb ("arm64: cache: Remove support for ASID-tagged VIVT I-caches") Signed-off-by:Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20201026193807.3816388-1-arnd@kernel.org Signed-off-by:
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Stephen Boyd authored
According to the SMCCC spec[1](7.5.2 Discovery) the ARM_SMCCC_ARCH_WORKAROUND_1 function id only returns 0, 1, and SMCCC_RET_NOT_SUPPORTED. 0 is "workaround required and safe to call this function" 1 is "workaround not required but safe to call this function" SMCCC_RET_NOT_SUPPORTED is "might be vulnerable or might not be, who knows, I give up!" SMCCC_RET_NOT_SUPPORTED might as well mean "workaround required, except calling this function may not work because it isn't implemented in some cases". Wonderful. We map this SMC call to 0 is SPECTRE_MITIGATED 1 is SPECTRE_UNAFFECTED SMCCC_RET_NOT_SUPPORTED is SPECTRE_VULNERABLE For KVM hypercalls (hvc), we've implemented this function id to return SMCCC_RET_NOT_SUPPORTED, 0, and SMCCC_RET_NOT_REQUIRED. One of those isn't supposed to be there. Per the code we call arm64_get_spectre_v2_state() to figure out what to return for this feature discovery call. 0 is SPECTRE_MITIGATED SMCCC_RET_NOT_REQUIRED is SPECTRE_UNAFFECTED SMCCC_RET_NOT_SUPPORTED is SPECTRE_VULNERABLE Let's clean this up so that KVM tells the guest this mapping: 0 is SPECTRE_MITIGATED 1 is SPECTRE_UNAFFECTED SMCCC_RET_NOT_SUPPORTED is SPECTRE_VULNERABLE Note: SMCCC_RET_NOT_AFFECTED is 1 but isn't part of the SMCCC spec Fixes: c118bbb5 ("arm64: KVM: Propagate full Spectre v2 workaround state to KVM guests") Signed-off-by:
Stephen Boyd <swboyd@chromium.org> Acked-by:
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- Oct 26, 2020
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Nathan Chancellor authored
As it stands now, the vdso32 Makefile hardcodes the linker to ld.bfd using -fuse-ld=bfd with $(CC). This was taken from the arm vDSO Makefile, as the comment notes, done in commit d2b30cd4 ("ARM: 8384/1: VDSO: force use of BFD linker"). Commit fe00e50b ("ARM: 8858/1: vdso: use $(LD) instead of $(CC) to link VDSO") changed that Makefile to use $(LD) directly instead of through $(CC), which matches how the rest of the kernel operates. Since then, LD=ld.lld means that the arm vDSO will be linked with ld.lld, which has shown no problems so far. Allow ld.lld to link this vDSO as we do the regular arm vDSO. To do this, we need to do a few things: * Add a LD_COMPAT variable, which defaults to $(CROSS_COMPILE_COMPAT)ld with gcc and $(LD) if LLVM is 1, which will be ld.lld, or $(CROSS_COMPILE_COMPAT)ld if not, which matches the logic of the main Makefile. It is overrideable for further customization and avoiding breakage. * Eliminate cc32-ldoption, which matches commit 055efab3 ("kbuild: drop support for cc-ldoption"). With those, we can use $(LD_COMPAT) in cmd_ldvdso and change the flags from compiler linker flags to linker flags directly. We eliminate -mfloat-abi=soft because it is not handled by the linker. Reported-by:
Nick Desaulniers <ndesaulniers@google.com> Signed-off-by:
Nathan Chancellor <natechancellor@gmail.com> Tested-by:
Vincenzo Frascino <vincenzo.frascino@arm.com> Link: https://github.com/ClangBuiltLinux/linux/issues/1033 Link: https://lore.kernel.org/r/20201020011406.1818918-1-natechancellor@gmail.com Signed-off-by:
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- Oct 25, 2020
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Joe Perches authored
Use a more generic form for __section that requires quotes to avoid complications with clang and gcc differences. Remove the quote operator # from compiler_attributes.h __section macro. Convert all unquoted __section(foo) uses to quoted __section("foo"). Also convert __attribute__((section("foo"))) uses to __section("foo") even if the __attribute__ has multiple list entry forms. Conversion done using the script at: https://lore.kernel.org/lkml/75393e5ddc272dc7403de74d645e6c6e0f4e70eb.camel@perches.com/2-convert_section.pl Signed-off-by:Joe Perches <joe@perches.com> Reviewed-by:
Nick Desaulniers <ndesaulniers@gooogle.com> Reviewed-by:
Miguel Ojeda <ojeda@kernel.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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- Oct 21, 2020
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Stephen Boyd authored
The function detect_harden_bp_fw() is gone after commit d4647f0a ("arm64: Rewrite Spectre-v2 mitigation code"). Update this comment to reflect the new state of affairs. Fixes: d4647f0a ("arm64: Rewrite Spectre-v2 mitigation code") Signed-off-by:
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- Oct 20, 2020
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Sami Tolvanen authored
This change removes all instances of DISABLE_LTO from Makefiles, as they are currently unused, and the preferred method of disabling LTO is to filter out the flags instead. Note added by Masahiro Yamada: DISABLE_LTO was added as preparation for GCC LTO, but GCC LTO was not pulled into the mainline. (https://lkml.org/lkml/2014/4/8/272 ) Suggested-by:
Kees Cook <keescook@chromium.org> Signed-off-by:
Sami Tolvanen <samitolvanen@google.com> Reviewed-by:
Masahiro Yamada <masahiroy@kernel.org>
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Will Deacon authored
Spectre-v2 can be mitigated on Falkor CPUs either by calling into firmware or by issuing a magic, CPU-specific sequence of branches. Although the latter is faster, the size of the code sequence means that it cannot be used in the EL2 vectors, and so there is a need for both mitigations to co-exist in order to achieve optimal performance. Change the mitigation selection logic for Spectre-v2 so that the CPU-specific mitigation is used only when the firmware mitigation is also available, rather than when a firmware mitigation is unavailable. Cc: Marc Zyngier <maz@kernel.org> Signed-off-by: -
Palmer Dabbelt authored
I was going to copy this but I didn't want to chase around the build system stuff so I did it a different way. Signed-off-by:
Palmer Dabbelt <palmerdabbelt@google.com> Link: https://lore.kernel.org/r/20201017002637.503579-1-palmer@dabbelt.com Signed-off-by:
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- Oct 17, 2020
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Jens Axboe authored
All the callers currently do this, clean it up and move the clearing into tracehook_notify_resume() instead. Reviewed-by:
Oleg Nesterov <oleg@redhat.com> Reviewed-by:
Thomas Gleixner <tglx@linutronix.de> Signed-off-by:
Jens Axboe <axboe@kernel.dk>
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- Oct 15, 2020
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Peter Collingbourne authored
It doesn't make sense to issue prctl(PR_PAC_RESET_KEYS) on a compat task because the 32-bit instruction set does not offer PAuth instructions. For consistency with other 64-bit only prctls such as {SET,GET}_TAGGED_ADDR_CTRL, reject the prctl on compat tasks. Although this is a userspace-visible change, maybe it isn't too late to make this change given that the hardware isn't available yet and it's very unlikely that anyone has 32-bit software that actually depends on this succeeding. Signed-off-by:Peter Collingbourne <pcc@google.com> Link: https://linux-review.googlesource.com/id/Ie885a1ff84ab498cc9f62d6451e9f2cfd4b1d06a Link: https://lore.kernel.org/r/20201014052430.11630-1-pcc@google.com [will: Do the same for the SVE prctl()s] Signed-off-by:
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- Oct 14, 2020
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Mike Rapoport authored
for_each_memblock() is used to iterate over memblock.memory in a few places that use data from memblock_region rather than the memory ranges. Introduce separate for_each_mem_region() and for_each_reserved_mem_region() to improve encapsulation of memblock internals from its users. Signed-off-by:
Mike Rapoport <rppt@linux.ibm.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Reviewed-by:
Baoquan He <bhe@redhat.com> Acked-by: Ingo Molnar <mingo@kernel.org> [x86] Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> [MIPS] Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> [.clang-format] Cc: Andy Lutomirski <luto@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Daniel Axtens <dja@axtens.net> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Emil Renner Berthing <kernel@esmil.dk> Cc: Hari Bathini <hbathini@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will@kernel.org> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Link: https://lkml.kernel.org/r/20200818151634.14343-18-rppt@kernel.org Signed-off-by:
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Mike Rapoport authored
Iteration over memblock.reserved with for_each_reserved_mem_region() used __next_reserved_mem_region() that implemented a subset of __next_mem_region(). Use __for_each_mem_range() and, essentially, __next_mem_region() with appropriate parameters to reduce code duplication. While on it, rename for_each_reserved_mem_region() to for_each_reserved_mem_range() for consistency. Signed-off-by:
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Mike Rapoport authored
Currently for_each_mem_range() and for_each_mem_range_rev() iterators are the most generic way to traverse memblock regions. As such, they have 8 parameters and they are hardly convenient to users. Most users choose to utilize one of their wrappers and the only user that actually needs most of the parameters is memblock itself. To avoid yet another naming for memblock iterators, rename the existing for_each_mem_range[_rev]() to __for_each_mem_range[_rev]() and add a new for_each_mem_range[_rev]() wrappers with only index, start and end parameters. The new wrapper nicely fits into init_unavailable_mem() and will be used in upcoming changes to simplify memblock traversals. Signed-off-by:
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Nick Desaulniers authored
This reverts commit 3acf4be2. The minimum supported version of clang is clang 10.0.1. Suggested-by:
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- Oct 09, 2020
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Bill Wendling authored
ld's --build-id defaults to "sha1" style, while lld defaults to "fast". The build IDs are very different between the two, which may confuse programs that reference them. Signed-off-by:
Bill Wendling <morbo@google.com> Acked-by:
David S. Miller <davem@davemloft.net> Signed-off-by:
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Will Deacon authored
This reverts commit 353e228e. Qian Cai reports that TX2 no longer boots with his .config as it appears that task_cpu() gets instrumented and used before KASAN has been initialised. Although Mark has a proposed fix, let's take the safe option of reverting this for now and sorting it out properly later. Link: https://lore.kernel.org/r/711bc57a314d8d646b41307008db2845b7537b3d.camel@redhat.com Reported-by:
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- Oct 05, 2020
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Mark Rutland authored
The current initialization of the per-cpu offset register is difficult to follow and this initialization is not always early enough for upcoming instrumentation with KCSAN, where the instrumentation callbacks use the per-cpu offset. To make it possible to support KCSAN, and to simplify reasoning about early bringup code, let's initialize the per-cpu offset earlier, before we run any C code that may consume it. To do so, this patch adds a new init_this_cpu_offset() helper that's called before the usual primary/secondary start functions. For consistency, this is also used to re-initialize the per-cpu offset after the runtime per-cpu areas have been allocated (which can change CPU0's offset). So that init_this_cpu_offset() isn't subject to any instrumentation that might consume the per-cpu offset, it is marked with noinstr, preventing instrumentation. Signed-off-by:
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