a638b0461b
Top of the kernel thread stack should be reserved for pt_regs. However this is not the case for the idle threads of the secondary boot harts. Their stacks overlap with their pt_regs, so both may get corrupted. Similar issue has been fixed for the primary hart, seec7cdd96eca("riscv: prevent stack corruption by reserving task_pt_regs(p) early"). However that fix was not propagated to the secondary harts. The problem has been noticed in some CPU hotplug tests with V enabled. The function smp_callin stored several registers on stack, corrupting top of pt_regs structure including status field. As a result, kernel attempted to save or restore inexistent V context. Fixes:9a2451f186("RISC-V: Avoid using per cpu array for ordered booting") Fixes:2875fe0561("RISC-V: Add cpu_ops and modify default booting method") Signed-off-by: Sergey Matyukevich <sergey.matyukevich@syntacore.com> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Link: https://lore.kernel.org/r/20240523084327.2013211-1-geomatsi@gmail.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
111 lines
2.5 KiB
C
111 lines
2.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* HSM extension and cpu_ops implementation.
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*
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* Copyright (c) 2020 Western Digital Corporation or its affiliates.
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*/
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#include <linux/init.h>
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#include <linux/mm.h>
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#include <linux/sched/task_stack.h>
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#include <asm/cpu_ops.h>
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#include <asm/cpu_ops_sbi.h>
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#include <asm/sbi.h>
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#include <asm/smp.h>
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extern char secondary_start_sbi[];
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const struct cpu_operations cpu_ops_sbi;
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/*
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* Ordered booting via HSM brings one cpu at a time. However, cpu hotplug can
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* be invoked from multiple threads in parallel. Define a per cpu data
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* to handle that.
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*/
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static DEFINE_PER_CPU(struct sbi_hart_boot_data, boot_data);
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static int sbi_hsm_hart_start(unsigned long hartid, unsigned long saddr,
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unsigned long priv)
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{
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struct sbiret ret;
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ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_START,
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hartid, saddr, priv, 0, 0, 0);
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if (ret.error)
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return sbi_err_map_linux_errno(ret.error);
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else
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return 0;
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}
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#ifdef CONFIG_HOTPLUG_CPU
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static int sbi_hsm_hart_stop(void)
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{
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struct sbiret ret;
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ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_STOP, 0, 0, 0, 0, 0, 0);
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if (ret.error)
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return sbi_err_map_linux_errno(ret.error);
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else
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return 0;
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}
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static int sbi_hsm_hart_get_status(unsigned long hartid)
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{
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struct sbiret ret;
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ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_STATUS,
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hartid, 0, 0, 0, 0, 0);
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if (ret.error)
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return sbi_err_map_linux_errno(ret.error);
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else
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return ret.value;
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}
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#endif
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static int sbi_cpu_start(unsigned int cpuid, struct task_struct *tidle)
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{
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unsigned long boot_addr = __pa_symbol(secondary_start_sbi);
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unsigned long hartid = cpuid_to_hartid_map(cpuid);
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unsigned long hsm_data;
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struct sbi_hart_boot_data *bdata = &per_cpu(boot_data, cpuid);
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/* Make sure tidle is updated */
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smp_mb();
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bdata->task_ptr = tidle;
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bdata->stack_ptr = task_pt_regs(tidle);
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/* Make sure boot data is updated */
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smp_mb();
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hsm_data = __pa(bdata);
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return sbi_hsm_hart_start(hartid, boot_addr, hsm_data);
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}
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#ifdef CONFIG_HOTPLUG_CPU
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static void sbi_cpu_stop(void)
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{
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int ret;
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ret = sbi_hsm_hart_stop();
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pr_crit("Unable to stop the cpu %u (%d)\n", smp_processor_id(), ret);
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}
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static int sbi_cpu_is_stopped(unsigned int cpuid)
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{
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int rc;
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unsigned long hartid = cpuid_to_hartid_map(cpuid);
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rc = sbi_hsm_hart_get_status(hartid);
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if (rc == SBI_HSM_STATE_STOPPED)
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return 0;
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return rc;
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}
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#endif
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const struct cpu_operations cpu_ops_sbi = {
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.cpu_start = sbi_cpu_start,
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#ifdef CONFIG_HOTPLUG_CPU
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.cpu_stop = sbi_cpu_stop,
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.cpu_is_stopped = sbi_cpu_is_stopped,
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#endif
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};
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