mirror of
https://github.com/torvalds/linux.git
synced 2024-11-22 20:22:09 +00:00
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
|
|
/*
|
|
* HSM extension and cpu_ops implementation.
|
|
*
|
|
* Copyright (c) 2020 Western Digital Corporation or its affiliates.
|
|
*/
|
|
|
|
#include <linux/init.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/sched/task_stack.h>
|
|
#include <asm/cpu_ops.h>
|
|
#include <asm/cpu_ops_sbi.h>
|
|
#include <asm/sbi.h>
|
|
#include <asm/smp.h>
|
|
|
|
extern char secondary_start_sbi[];
|
|
const struct cpu_operations cpu_ops_sbi;
|
|
|
|
/*
|
|
* Ordered booting via HSM brings one cpu at a time. However, cpu hotplug can
|
|
* be invoked from multiple threads in parallel. Define a per cpu data
|
|
* to handle that.
|
|
*/
|
|
static DEFINE_PER_CPU(struct sbi_hart_boot_data, boot_data);
|
|
|
|
static int sbi_hsm_hart_start(unsigned long hartid, unsigned long saddr,
|
|
unsigned long priv)
|
|
{
|
|
struct sbiret ret;
|
|
|
|
ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_START,
|
|
hartid, saddr, priv, 0, 0, 0);
|
|
if (ret.error)
|
|
return sbi_err_map_linux_errno(ret.error);
|
|
else
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
static int sbi_hsm_hart_stop(void)
|
|
{
|
|
struct sbiret ret;
|
|
|
|
ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_STOP, 0, 0, 0, 0, 0, 0);
|
|
|
|
if (ret.error)
|
|
return sbi_err_map_linux_errno(ret.error);
|
|
else
|
|
return 0;
|
|
}
|
|
|
|
static int sbi_hsm_hart_get_status(unsigned long hartid)
|
|
{
|
|
struct sbiret ret;
|
|
|
|
ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_STATUS,
|
|
hartid, 0, 0, 0, 0, 0);
|
|
if (ret.error)
|
|
return sbi_err_map_linux_errno(ret.error);
|
|
else
|
|
return ret.value;
|
|
}
|
|
#endif
|
|
|
|
static int sbi_cpu_start(unsigned int cpuid, struct task_struct *tidle)
|
|
{
|
|
unsigned long boot_addr = __pa_symbol(secondary_start_sbi);
|
|
unsigned long hartid = cpuid_to_hartid_map(cpuid);
|
|
unsigned long hsm_data;
|
|
struct sbi_hart_boot_data *bdata = &per_cpu(boot_data, cpuid);
|
|
|
|
/* Make sure tidle is updated */
|
|
smp_mb();
|
|
bdata->task_ptr = tidle;
|
|
bdata->stack_ptr = task_pt_regs(tidle);
|
|
/* Make sure boot data is updated */
|
|
smp_mb();
|
|
hsm_data = __pa(bdata);
|
|
return sbi_hsm_hart_start(hartid, boot_addr, hsm_data);
|
|
}
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
static void sbi_cpu_stop(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = sbi_hsm_hart_stop();
|
|
pr_crit("Unable to stop the cpu %u (%d)\n", smp_processor_id(), ret);
|
|
}
|
|
|
|
static int sbi_cpu_is_stopped(unsigned int cpuid)
|
|
{
|
|
int rc;
|
|
unsigned long hartid = cpuid_to_hartid_map(cpuid);
|
|
|
|
rc = sbi_hsm_hart_get_status(hartid);
|
|
|
|
if (rc == SBI_HSM_STATE_STOPPED)
|
|
return 0;
|
|
return rc;
|
|
}
|
|
#endif
|
|
|
|
const struct cpu_operations cpu_ops_sbi = {
|
|
.cpu_start = sbi_cpu_start,
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
.cpu_stop = sbi_cpu_stop,
|
|
.cpu_is_stopped = sbi_cpu_is_stopped,
|
|
#endif
|
|
};
|