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77345ef704
Use cpuidle context helpers to switch to using DAIF.IF instead of PMR to mask interrupts, ensuring that we suspend with interrupts being able to reach the CPU interface. Signed-off-by: Marc Zyngier <maz@kernel.org> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com> Link: https://lore.kernel.org/r/20210615111227.2454465-5-maz@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
163 lines
4.3 KiB
C
163 lines
4.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/ftrace.h>
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#include <linux/percpu.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include <linux/pgtable.h>
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#include <asm/alternative.h>
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#include <asm/cacheflush.h>
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#include <asm/cpufeature.h>
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#include <asm/cpuidle.h>
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#include <asm/daifflags.h>
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#include <asm/debug-monitors.h>
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#include <asm/exec.h>
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#include <asm/mte.h>
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#include <asm/memory.h>
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#include <asm/mmu_context.h>
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#include <asm/smp_plat.h>
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#include <asm/suspend.h>
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/*
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* This is allocated by cpu_suspend_init(), and used to store a pointer to
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* the 'struct sleep_stack_data' the contains a particular CPUs state.
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*/
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unsigned long *sleep_save_stash;
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/*
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* This hook is provided so that cpu_suspend code can restore HW
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* breakpoints as early as possible in the resume path, before reenabling
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* debug exceptions. Code cannot be run from a CPU PM notifier since by the
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* time the notifier runs debug exceptions might have been enabled already,
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* with HW breakpoints registers content still in an unknown state.
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*/
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static int (*hw_breakpoint_restore)(unsigned int);
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void __init cpu_suspend_set_dbg_restorer(int (*hw_bp_restore)(unsigned int))
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{
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/* Prevent multiple restore hook initializations */
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if (WARN_ON(hw_breakpoint_restore))
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return;
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hw_breakpoint_restore = hw_bp_restore;
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}
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void notrace __cpu_suspend_exit(void)
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{
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unsigned int cpu = smp_processor_id();
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/*
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* We are resuming from reset with the idmap active in TTBR0_EL1.
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* We must uninstall the idmap and restore the expected MMU
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* state before we can possibly return to userspace.
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*/
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cpu_uninstall_idmap();
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/* Restore CnP bit in TTBR1_EL1 */
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if (system_supports_cnp())
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cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
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/*
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* PSTATE was not saved over suspend/resume, re-enable any detected
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* features that might not have been set correctly.
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*/
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__uaccess_enable_hw_pan();
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/*
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* Restore HW breakpoint registers to sane values
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* before debug exceptions are possibly reenabled
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* by cpu_suspend()s local_daif_restore() call.
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*/
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if (hw_breakpoint_restore)
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hw_breakpoint_restore(cpu);
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/*
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* On resume, firmware implementing dynamic mitigation will
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* have turned the mitigation on. If the user has forcefully
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* disabled it, make sure their wishes are obeyed.
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*/
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spectre_v4_enable_mitigation(NULL);
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/* Restore additional feature-specific configuration */
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mte_suspend_exit();
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ptrauth_suspend_exit();
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}
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/*
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* cpu_suspend
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*
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* arg: argument to pass to the finisher function
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* fn: finisher function pointer
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*
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*/
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int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
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{
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int ret = 0;
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unsigned long flags;
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struct sleep_stack_data state;
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struct arm_cpuidle_irq_context context;
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/* Report any MTE async fault before going to suspend */
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mte_suspend_enter();
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/*
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* From this point debug exceptions are disabled to prevent
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* updates to mdscr register (saved and restored along with
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* general purpose registers) from kernel debuggers.
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*/
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flags = local_daif_save();
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/*
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* Function graph tracer state gets inconsistent when the kernel
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* calls functions that never return (aka suspend finishers) hence
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* disable graph tracing during their execution.
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*/
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pause_graph_tracing();
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/*
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* Switch to using DAIF.IF instead of PMR in order to reliably
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* resume if we're using pseudo-NMIs.
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*/
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arm_cpuidle_save_irq_context(&context);
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if (__cpu_suspend_enter(&state)) {
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/* Call the suspend finisher */
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ret = fn(arg);
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/*
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* Never gets here, unless the suspend finisher fails.
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* Successful cpu_suspend() should return from cpu_resume(),
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* returning through this code path is considered an error
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* If the return value is set to 0 force ret = -EOPNOTSUPP
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* to make sure a proper error condition is propagated
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*/
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if (!ret)
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ret = -EOPNOTSUPP;
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} else {
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RCU_NONIDLE(__cpu_suspend_exit());
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}
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arm_cpuidle_restore_irq_context(&context);
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unpause_graph_tracing();
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/*
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* Restore pstate flags. OS lock and mdscr have been already
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* restored, so from this point onwards, debugging is fully
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* renabled if it was enabled when core started shutdown.
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*/
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local_daif_restore(flags);
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return ret;
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}
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static int __init cpu_suspend_init(void)
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{
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/* ctx_ptr is an array of physical addresses */
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sleep_save_stash = kcalloc(mpidr_hash_size(), sizeof(*sleep_save_stash),
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GFP_KERNEL);
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if (WARN_ON(!sleep_save_stash))
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return -ENOMEM;
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return 0;
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}
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early_initcall(cpu_suspend_init);
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