linux/arch/riscv/kernel/smp.c
Samuel Holland 6514f81e1b
riscv: Fix CPU feature detection with SMP disabled
commit 914d6f44fc ("RISC-V: only iterate over possible CPUs in ISA
string parser") changed riscv_fill_hwcap() from iterating over CPU DT
nodes to iterating over logical CPU IDs. Since this function runs long
before cpu_dev_init() creates CPU devices, it hits the fallback path in
of_cpu_device_node_get(), which itself iterates over the DT nodes,
searching for a node with the requested CPU ID. (Incidentally, this
makes riscv_fill_hwcap() now take quadratic time.)

riscv_fill_hwcap() passes a logical CPU ID to of_cpu_device_node_get(),
which uses the arch_match_cpu_phys_id() hook to translate the logical ID
to a physical ID as found in the DT.

arch_match_cpu_phys_id() has a generic weak definition, and RISC-V
provides a strong definition using cpuid_to_hartid_map(). However, the
RISC-V specific implementation is located in arch/riscv/kernel/smp.c,
and that file is only compiled when SMP is enabled.

As a result, when SMP is disabled, the generic definition is used, and
riscv_isa gets initialized based on the ISA string of hart 0, not the
boot hart. On FU740, this means has_fpu() returns false, and userspace
crashes when trying to use floating-point instructions.

Fix this by moving arch_match_cpu_phys_id() to a file which is always
compiled.

Fixes: 70114560b2 ("RISC-V: Add RISC-V specific arch_match_cpu_phys_id")
Fixes: 914d6f44fc ("RISC-V: only iterate over possible CPUs in ISA string parser")
Reported-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230803012608.3540081-1-samuel.holland@sifive.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-08-08 15:28:25 -07:00

335 lines
7.1 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* SMP initialisation and IPI support
* Based on arch/arm64/kernel/smp.c
*
* Copyright (C) 2012 ARM Ltd.
* Copyright (C) 2015 Regents of the University of California
* Copyright (C) 2017 SiFive
*/
#include <linux/cpu.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/kexec.h>
#include <linux/percpu.h>
#include <linux/profile.h>
#include <linux/smp.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/irq_work.h>
#include <asm/tlbflush.h>
#include <asm/cacheflush.h>
#include <asm/cpu_ops.h>
enum ipi_message_type {
IPI_RESCHEDULE,
IPI_CALL_FUNC,
IPI_CPU_STOP,
IPI_CPU_CRASH_STOP,
IPI_IRQ_WORK,
IPI_TIMER,
IPI_MAX
};
unsigned long __cpuid_to_hartid_map[NR_CPUS] __ro_after_init = {
[0 ... NR_CPUS-1] = INVALID_HARTID
};
void __init smp_setup_processor_id(void)
{
cpuid_to_hartid_map(0) = boot_cpu_hartid;
}
static DEFINE_PER_CPU_READ_MOSTLY(int, ipi_dummy_dev);
static int ipi_virq_base __ro_after_init;
static int nr_ipi __ro_after_init = IPI_MAX;
static struct irq_desc *ipi_desc[IPI_MAX] __read_mostly;
int riscv_hartid_to_cpuid(unsigned long hartid)
{
int i;
for (i = 0; i < NR_CPUS; i++)
if (cpuid_to_hartid_map(i) == hartid)
return i;
return -ENOENT;
}
static void ipi_stop(void)
{
set_cpu_online(smp_processor_id(), false);
while (1)
wait_for_interrupt();
}
#ifdef CONFIG_KEXEC_CORE
static atomic_t waiting_for_crash_ipi = ATOMIC_INIT(0);
static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
{
crash_save_cpu(regs, cpu);
atomic_dec(&waiting_for_crash_ipi);
local_irq_disable();
#ifdef CONFIG_HOTPLUG_CPU
if (cpu_has_hotplug(cpu))
cpu_ops[cpu]->cpu_stop();
#endif
for(;;)
wait_for_interrupt();
}
#else
static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
{
unreachable();
}
#endif
static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op)
{
__ipi_send_mask(ipi_desc[op], mask);
}
static void send_ipi_single(int cpu, enum ipi_message_type op)
{
__ipi_send_mask(ipi_desc[op], cpumask_of(cpu));
}
#ifdef CONFIG_IRQ_WORK
void arch_irq_work_raise(void)
{
send_ipi_single(smp_processor_id(), IPI_IRQ_WORK);
}
#endif
static irqreturn_t handle_IPI(int irq, void *data)
{
int ipi = irq - ipi_virq_base;
switch (ipi) {
case IPI_RESCHEDULE:
scheduler_ipi();
break;
case IPI_CALL_FUNC:
generic_smp_call_function_interrupt();
break;
case IPI_CPU_STOP:
ipi_stop();
break;
case IPI_CPU_CRASH_STOP:
ipi_cpu_crash_stop(smp_processor_id(), get_irq_regs());
break;
case IPI_IRQ_WORK:
irq_work_run();
break;
#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
case IPI_TIMER:
tick_receive_broadcast();
break;
#endif
default:
pr_warn("CPU%d: unhandled IPI%d\n", smp_processor_id(), ipi);
break;
}
return IRQ_HANDLED;
}
void riscv_ipi_enable(void)
{
int i;
if (WARN_ON_ONCE(!ipi_virq_base))
return;
for (i = 0; i < nr_ipi; i++)
enable_percpu_irq(ipi_virq_base + i, 0);
}
void riscv_ipi_disable(void)
{
int i;
if (WARN_ON_ONCE(!ipi_virq_base))
return;
for (i = 0; i < nr_ipi; i++)
disable_percpu_irq(ipi_virq_base + i);
}
bool riscv_ipi_have_virq_range(void)
{
return (ipi_virq_base) ? true : false;
}
DEFINE_STATIC_KEY_FALSE(riscv_ipi_for_rfence);
EXPORT_SYMBOL_GPL(riscv_ipi_for_rfence);
void riscv_ipi_set_virq_range(int virq, int nr, bool use_for_rfence)
{
int i, err;
if (WARN_ON(ipi_virq_base))
return;
WARN_ON(nr < IPI_MAX);
nr_ipi = min(nr, IPI_MAX);
ipi_virq_base = virq;
/* Request IPIs */
for (i = 0; i < nr_ipi; i++) {
err = request_percpu_irq(ipi_virq_base + i, handle_IPI,
"IPI", &ipi_dummy_dev);
WARN_ON(err);
ipi_desc[i] = irq_to_desc(ipi_virq_base + i);
irq_set_status_flags(ipi_virq_base + i, IRQ_HIDDEN);
}
/* Enabled IPIs for boot CPU immediately */
riscv_ipi_enable();
/* Update RFENCE static key */
if (use_for_rfence)
static_branch_enable(&riscv_ipi_for_rfence);
else
static_branch_disable(&riscv_ipi_for_rfence);
}
static const char * const ipi_names[] = {
[IPI_RESCHEDULE] = "Rescheduling interrupts",
[IPI_CALL_FUNC] = "Function call interrupts",
[IPI_CPU_STOP] = "CPU stop interrupts",
[IPI_CPU_CRASH_STOP] = "CPU stop (for crash dump) interrupts",
[IPI_IRQ_WORK] = "IRQ work interrupts",
[IPI_TIMER] = "Timer broadcast interrupts",
};
void show_ipi_stats(struct seq_file *p, int prec)
{
unsigned int cpu, i;
for (i = 0; i < IPI_MAX; i++) {
seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
prec >= 4 ? " " : "");
for_each_online_cpu(cpu)
seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu));
seq_printf(p, " %s\n", ipi_names[i]);
}
}
void arch_send_call_function_ipi_mask(struct cpumask *mask)
{
send_ipi_mask(mask, IPI_CALL_FUNC);
}
void arch_send_call_function_single_ipi(int cpu)
{
send_ipi_single(cpu, IPI_CALL_FUNC);
}
#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
void tick_broadcast(const struct cpumask *mask)
{
send_ipi_mask(mask, IPI_TIMER);
}
#endif
void smp_send_stop(void)
{
unsigned long timeout;
if (num_online_cpus() > 1) {
cpumask_t mask;
cpumask_copy(&mask, cpu_online_mask);
cpumask_clear_cpu(smp_processor_id(), &mask);
if (system_state <= SYSTEM_RUNNING)
pr_crit("SMP: stopping secondary CPUs\n");
send_ipi_mask(&mask, IPI_CPU_STOP);
}
/* Wait up to one second for other CPUs to stop */
timeout = USEC_PER_SEC;
while (num_online_cpus() > 1 && timeout--)
udelay(1);
if (num_online_cpus() > 1)
pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
cpumask_pr_args(cpu_online_mask));
}
#ifdef CONFIG_KEXEC_CORE
/*
* The number of CPUs online, not counting this CPU (which may not be
* fully online and so not counted in num_online_cpus()).
*/
static inline unsigned int num_other_online_cpus(void)
{
unsigned int this_cpu_online = cpu_online(smp_processor_id());
return num_online_cpus() - this_cpu_online;
}
void crash_smp_send_stop(void)
{
static int cpus_stopped;
cpumask_t mask;
unsigned long timeout;
/*
* This function can be called twice in panic path, but obviously
* we execute this only once.
*/
if (cpus_stopped)
return;
cpus_stopped = 1;
/*
* If this cpu is the only one alive at this point in time, online or
* not, there are no stop messages to be sent around, so just back out.
*/
if (num_other_online_cpus() == 0)
return;
cpumask_copy(&mask, cpu_online_mask);
cpumask_clear_cpu(smp_processor_id(), &mask);
atomic_set(&waiting_for_crash_ipi, num_other_online_cpus());
pr_crit("SMP: stopping secondary CPUs\n");
send_ipi_mask(&mask, IPI_CPU_CRASH_STOP);
/* Wait up to one second for other CPUs to stop */
timeout = USEC_PER_SEC;
while ((atomic_read(&waiting_for_crash_ipi) > 0) && timeout--)
udelay(1);
if (atomic_read(&waiting_for_crash_ipi) > 0)
pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
cpumask_pr_args(&mask));
}
bool smp_crash_stop_failed(void)
{
return (atomic_read(&waiting_for_crash_ipi) > 0);
}
#endif
void arch_smp_send_reschedule(int cpu)
{
send_ipi_single(cpu, IPI_RESCHEDULE);
}
EXPORT_SYMBOL_GPL(arch_smp_send_reschedule);