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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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5c492c3f52
kernel/smp.c has a fancy counter that keeps track of the number of CPUs
it marked as not-present and left in cpu_park_loop(). If there are any
CPUs spinning in here, features like kexec or hibernate may release them
by overwriting this memory.
This problem also occurs on machines using spin-tables to release
secondary cores.
After commit 44dbcc93ab ("arm64: Fix behavior of maxcpus=N")
we bring all known cpus into the secondary holding pen, meaning this
memory can't be re-used by kexec or hibernate.
Add a function cpus_are_stuck_in_kernel() to determine if either of these
cases have occurred.
Signed-off-by: James Morse <james.morse@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
142 lines
3.7 KiB
C
142 lines
3.7 KiB
C
/*
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* Copyright (C) 2012 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __ASM_SMP_H
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#define __ASM_SMP_H
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/* Values for secondary_data.status */
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#define CPU_MMU_OFF (-1)
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#define CPU_BOOT_SUCCESS (0)
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/* The cpu invoked ops->cpu_die, synchronise it with cpu_kill */
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#define CPU_KILL_ME (1)
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/* The cpu couldn't die gracefully and is looping in the kernel */
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#define CPU_STUCK_IN_KERNEL (2)
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/* Fatal system error detected by secondary CPU, crash the system */
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#define CPU_PANIC_KERNEL (3)
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#ifndef __ASSEMBLY__
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#include <linux/threads.h>
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#include <linux/cpumask.h>
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#include <linux/thread_info.h>
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#define raw_smp_processor_id() (current_thread_info()->cpu)
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struct seq_file;
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/*
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* generate IPI list text
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*/
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extern void show_ipi_list(struct seq_file *p, int prec);
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/*
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* Called from C code, this handles an IPI.
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*/
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extern void handle_IPI(int ipinr, struct pt_regs *regs);
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/*
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* Discover the set of possible CPUs and determine their
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* SMP operations.
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*/
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extern void smp_init_cpus(void);
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/*
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* Provide a function to raise an IPI cross call on CPUs in callmap.
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*/
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extern void set_smp_cross_call(void (*)(const struct cpumask *, unsigned int));
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extern void (*__smp_cross_call)(const struct cpumask *, unsigned int);
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/*
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* Called from the secondary holding pen, this is the secondary CPU entry point.
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*/
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asmlinkage void secondary_start_kernel(void);
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/*
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* Initial data for bringing up a secondary CPU.
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* @stack - sp for the secondary CPU
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* @status - Result passed back from the secondary CPU to
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* indicate failure.
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*/
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struct secondary_data {
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void *stack;
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long status;
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};
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extern struct secondary_data secondary_data;
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extern long __early_cpu_boot_status;
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extern void secondary_entry(void);
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extern void arch_send_call_function_single_ipi(int cpu);
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extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);
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#ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
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extern void arch_send_wakeup_ipi_mask(const struct cpumask *mask);
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#else
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static inline void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
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{
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BUILD_BUG();
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}
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#endif
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extern int __cpu_disable(void);
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extern void __cpu_die(unsigned int cpu);
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extern void cpu_die(void);
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extern void cpu_die_early(void);
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static inline void cpu_park_loop(void)
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{
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for (;;) {
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wfe();
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wfi();
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}
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}
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static inline void update_cpu_boot_status(int val)
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{
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WRITE_ONCE(secondary_data.status, val);
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/* Ensure the visibility of the status update */
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dsb(ishst);
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}
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/*
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* The calling secondary CPU has detected serious configuration mismatch,
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* which calls for a kernel panic. Update the boot status and park the calling
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* CPU.
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*/
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static inline void cpu_panic_kernel(void)
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{
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update_cpu_boot_status(CPU_PANIC_KERNEL);
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cpu_park_loop();
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}
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/*
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* If a secondary CPU enters the kernel but fails to come online,
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* (e.g. due to mismatched features), and cannot exit the kernel,
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* we increment cpus_stuck_in_kernel and leave the CPU in a
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* quiesecent loop within the kernel text. The memory containing
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* this loop must not be re-used for anything else as the 'stuck'
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* core is executing it.
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*
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* This function is used to inhibit features like kexec and hibernate.
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*/
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bool cpus_are_stuck_in_kernel(void);
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#endif /* ifndef __ASSEMBLY__ */
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#endif /* ifndef __ASM_SMP_H */
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