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d7a83d127a
The arm64 hw_breakpoint implementation uses a CPU hotplug notifier to
reset the {break,watch}point registers when CPUs come online.
This patch converts the code to the new hotplug mechanism, whilst moving
the invocation earlier to remove the need to disable IRQs explicitly in
the driver (which could cause havok if we trip a watchpoint in an IRQ
handler whilst restoring the debug register state).
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
129 lines
3.4 KiB
C
129 lines
3.4 KiB
C
#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 <asm/cacheflush.h>
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#include <asm/debug-monitors.h>
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#include <asm/pgtable.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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#include <asm/tlbflush.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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/*
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* Restore per-cpu offset before any kernel
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* subsystem relying on it has a chance to run.
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*/
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set_my_cpu_offset(per_cpu_offset(cpu));
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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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* through local_dbg_restore.
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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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/*
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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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/*
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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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local_dbg_save(flags);
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/*
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* Function graph tracer state gets incosistent 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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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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__cpu_suspend_exit();
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}
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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_dbg_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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