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cabe1c81ea
By enabling the MMU early in cpu_resume(), the sleep_save_sp and stack can
be accessed by VA, which avoids the need to convert-addresses and clean to
PoC on the suspend path.
MMU setup is shared with the boot path, meaning the swapper_pg_dir is
restored directly: ttbr1_el1 is no longer saved/restored.
struct sleep_save_sp is removed, replacing it with a single array of
pointers.
cpu_do_{suspend,resume} could be further reduced to not restore: cpacr_el1,
mdscr_el1, tcr_el1, vbar_el1 and sctlr_el1, all of which are set by
__cpu_setup(). However these values all contain res0 bits that may be used
to enable future features.
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
127 lines
3.3 KiB
C
127 lines
3.3 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 void (*hw_breakpoint_restore)(void *);
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void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *))
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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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/*
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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(smp_processor_id()));
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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(NULL);
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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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