diff options
29 files changed, 766 insertions, 48 deletions
diff --git a/Documentation/features/core/generic-idle-thread/arch-support.txt b/Documentation/features/core/generic-idle-thread/arch-support.txt index 0735cb5367b4..425442e31fa2 100644 --- a/Documentation/features/core/generic-idle-thread/arch-support.txt +++ b/Documentation/features/core/generic-idle-thread/arch-support.txt @@ -24,7 +24,7 @@ | s390: | ok | | sh: | ok | | sparc: | ok | - | um: | TODO | + | um: | ok | | x86: | ok | | xtensa: | ok | ----------------------- diff --git a/arch/um/Kconfig b/arch/um/Kconfig index 0b4d00596a8c..097c6a6265ef 100644 --- a/arch/um/Kconfig +++ b/arch/um/Kconfig @@ -28,6 +28,7 @@ config UML select OF_EARLY_FLATTREE if OF select GENERIC_IRQ_SHOW select GENERIC_CPU_DEVICES + select GENERIC_SMP_IDLE_THREAD select HAVE_GCC_PLUGINS select ARCH_SUPPORTS_LTO_CLANG select ARCH_SUPPORTS_LTO_CLANG_THIN @@ -81,10 +82,48 @@ config HZ int default 100 -config NR_CPUS +config UML_SUBARCH_SUPPORTS_SMP + bool + +config SMP + bool "Symmetric multi-processing support" + default n + depends on UML_SUBARCH_SUPPORTS_SMP + help + This option enables UML SMP support. + + With this enabled, users can tell UML to start multiple virtual + processors. Each virtual processor is represented as a separate + host thread. + + In UML, kthreads and normal threads (when running in kernel mode) + can be scheduled and executed simultaneously on different virtual + processors. However, the userspace code of normal threads still + runs within their respective single-threaded stubs. + + That is, SMP support is available both within the kernel and + across different processes, but remains limited within threads + of the same process in userspace. + +config NR_CPUS_RANGE_BEGIN int - range 1 1 - default 1 + default 1 if !SMP + default 2 + +config NR_CPUS_RANGE_END + int + default 1 if !SMP + default 64 + +config NR_CPUS_DEFAULT + int + default 1 if !SMP + default 2 + +config NR_CPUS + int "Maximum number of CPUs" if SMP + range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END + default NR_CPUS_DEFAULT source "arch/$(HEADER_ARCH)/um/Kconfig" @@ -254,6 +293,7 @@ source "arch/um/drivers/Kconfig" config ARCH_SUSPEND_POSSIBLE def_bool y + depends on !SMP menu "Power management options" diff --git a/arch/um/include/asm/current.h b/arch/um/include/asm/current.h index 8accc6d6f502..159a29b3d4cc 100644 --- a/arch/um/include/asm/current.h +++ b/arch/um/include/asm/current.h @@ -7,15 +7,16 @@ #ifndef __ASSEMBLER__ +#include <shared/smp.h> + struct task_struct; extern struct task_struct *cpu_tasks[NR_CPUS]; static __always_inline struct task_struct *get_current(void) { - return cpu_tasks[0]; + return cpu_tasks[uml_curr_cpu()]; } - #define current get_current() #endif /* __ASSEMBLER__ */ diff --git a/arch/um/include/asm/hardirq.h b/arch/um/include/asm/hardirq.h index 52e2c36267a9..8de71752a9b8 100644 --- a/arch/um/include/asm/hardirq.h +++ b/arch/um/include/asm/hardirq.h @@ -2,8 +2,30 @@ #ifndef __ASM_UM_HARDIRQ_H #define __ASM_UM_HARDIRQ_H -#include <asm-generic/hardirq.h> +#include <linux/cache.h> +#include <linux/threads.h> #define __ARCH_IRQ_EXIT_IRQS_DISABLED 1 +typedef struct { + unsigned int __softirq_pending; +#if IS_ENABLED(CONFIG_SMP) + unsigned int irq_resched_count; + unsigned int irq_call_count; +#endif +} ____cacheline_aligned irq_cpustat_t; + +DECLARE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat); + +#define __ARCH_IRQ_STAT + +#define inc_irq_stat(member) this_cpu_inc(irq_stat.member) + +#include <linux/irq.h> + +static inline void ack_bad_irq(unsigned int irq) +{ + pr_crit("unexpected IRQ trap at vector %02x\n", irq); +} + #endif /* __ASM_UM_HARDIRQ_H */ diff --git a/arch/um/include/asm/mmu.h b/arch/um/include/asm/mmu.h index 4d0e4239f3cc..07d48738b402 100644 --- a/arch/um/include/asm/mmu.h +++ b/arch/um/include/asm/mmu.h @@ -7,16 +7,26 @@ #define __ARCH_UM_MMU_H #include "linux/types.h" +#include <linux/mutex.h> +#include <linux/spinlock.h> #include <mm_id.h> typedef struct mm_context { struct mm_id id; + struct mutex turnstile; struct list_head list; /* Address range in need of a TLB sync */ + spinlock_t sync_tlb_lock; unsigned long sync_tlb_range_from; unsigned long sync_tlb_range_to; } mm_context_t; +#define INIT_MM_CONTEXT(mm) \ + .context = { \ + .turnstile = __MUTEX_INITIALIZER(mm.context.turnstile), \ + .sync_tlb_lock = __SPIN_LOCK_INITIALIZER(mm.context.sync_tlb_lock), \ + } + #endif diff --git a/arch/um/include/asm/pgtable.h b/arch/um/include/asm/pgtable.h index 6ca7583003cd..1a0d7405e97c 100644 --- a/arch/um/include/asm/pgtable.h +++ b/arch/um/include/asm/pgtable.h @@ -225,6 +225,8 @@ static inline void set_pte(pte_t *pteptr, pte_t pteval) static inline void um_tlb_mark_sync(struct mm_struct *mm, unsigned long start, unsigned long end) { + guard(spinlock_irqsave)(&mm->context.sync_tlb_lock); + if (!mm->context.sync_tlb_range_to) { mm->context.sync_tlb_range_from = start; mm->context.sync_tlb_range_to = end; diff --git a/arch/um/include/asm/smp.h b/arch/um/include/asm/smp.h index a8cc1d46ddcb..be1743a6ff3c 100644 --- a/arch/um/include/asm/smp.h +++ b/arch/um/include/asm/smp.h @@ -2,6 +2,19 @@ #ifndef __UM_SMP_H #define __UM_SMP_H -#define hard_smp_processor_id() 0 +#if IS_ENABLED(CONFIG_SMP) + +#include <linux/cpumask.h> +#include <shared/smp.h> + +#define raw_smp_processor_id() uml_curr_cpu() + +void arch_smp_send_reschedule(int cpu); + +void arch_send_call_function_single_ipi(int cpu); + +void arch_send_call_function_ipi_mask(const struct cpumask *mask); + +#endif /* CONFIG_SMP */ #endif diff --git a/arch/um/include/linux/smp-internal.h b/arch/um/include/linux/smp-internal.h new file mode 100644 index 000000000000..1dbcbc23f9c9 --- /dev/null +++ b/arch/um/include/linux/smp-internal.h @@ -0,0 +1,17 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __UM_SMP_INTERNAL_H +#define __UM_SMP_INTERNAL_H + +#if IS_ENABLED(CONFIG_SMP) + +void prefill_possible_map(void); + +#else /* !CONFIG_SMP */ + +static inline void prefill_possible_map(void) { } + +#endif /* CONFIG_SMP */ + +extern char cpu_irqstacks[NR_CPUS][THREAD_SIZE] __aligned(THREAD_SIZE); + +#endif /* __UM_SMP_INTERNAL_H */ diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h index 0ca6e4548671..b26e94292fc1 100644 --- a/arch/um/include/shared/os.h +++ b/arch/um/include/shared/os.h @@ -216,6 +216,9 @@ extern int can_drop_memory(void); void os_set_pdeathsig(void); +int os_futex_wait(void *uaddr, unsigned int val); +int os_futex_wake(void *uaddr); + /* execvp.c */ extern int execvp_noalloc(char *buf, const char *file, char *const argv[]); /* helper.c */ @@ -267,6 +270,7 @@ extern void os_warn(const char *fmt, ...) __attribute__ ((format (printf, 1, 2))); /* time.c */ +void os_idle_prepare(void); extern void os_idle_sleep(void); extern int os_timer_create(void); extern int os_timer_set_interval(int cpu, unsigned long long nsecs); @@ -339,4 +343,17 @@ extern void um_trace_signals_off(void); /* time-travel */ extern void deliver_time_travel_irqs(void); +/* smp.c */ +#if IS_ENABLED(CONFIG_SMP) +void os_init_smp(void); +int os_start_cpu_thread(int cpu); +void os_start_secondary(void *arg, jmp_buf *switch_buf); +int os_send_ipi(int cpu, int vector); +void os_local_ipi_enable(void); +void os_local_ipi_disable(void); +#else /* !CONFIG_SMP */ +static inline void os_local_ipi_enable(void) { } +static inline void os_local_ipi_disable(void) { } +#endif /* CONFIG_SMP */ + #endif diff --git a/arch/um/include/shared/skas/mm_id.h b/arch/um/include/shared/skas/mm_id.h index 4f977ef5dda5..fb96c0bd8222 100644 --- a/arch/um/include/shared/skas/mm_id.h +++ b/arch/um/include/shared/skas/mm_id.h @@ -6,6 +6,8 @@ #ifndef __MM_ID_H #define __MM_ID_H +#include <linux/compiler_types.h> + #define STUB_MAX_FDS 4 struct mm_id { @@ -19,6 +21,9 @@ struct mm_id { int syscall_fd_map[STUB_MAX_FDS]; }; +void enter_turnstile(struct mm_id *mm_id) __acquires(turnstile); +void exit_turnstile(struct mm_id *mm_id) __releases(turnstile); + void notify_mm_kill(int pid); #endif diff --git a/arch/um/include/shared/skas/skas.h b/arch/um/include/shared/skas/skas.h index 807514e10538..2237ffedec75 100644 --- a/arch/um/include/shared/skas/skas.h +++ b/arch/um/include/shared/skas/skas.h @@ -15,5 +15,7 @@ extern void handle_syscall(struct uml_pt_regs *regs); extern unsigned long current_stub_stack(void); extern struct mm_id *current_mm_id(void); extern void current_mm_sync(void); +void initial_jmpbuf_lock(void); +void initial_jmpbuf_unlock(void); #endif diff --git a/arch/um/include/shared/smp.h b/arch/um/include/shared/smp.h new file mode 100644 index 000000000000..06e3faa95091 --- /dev/null +++ b/arch/um/include/shared/smp.h @@ -0,0 +1,20 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __UM_SHARED_SMP_H +#define __UM_SHARED_SMP_H + +#if IS_ENABLED(CONFIG_SMP) + +extern int uml_ncpus; + +int uml_curr_cpu(void); +void uml_start_secondary(void *opaque); +void uml_ipi_handler(int vector); + +#else /* !CONFIG_SMP */ + +#define uml_ncpus 1 +#define uml_curr_cpu() 0 + +#endif /* CONFIG_SMP */ + +#endif /* __UM_SHARED_SMP_H */ diff --git a/arch/um/kernel/Makefile b/arch/um/kernel/Makefile index b8f4e9281599..be60bc451b3f 100644 --- a/arch/um/kernel/Makefile +++ b/arch/um/kernel/Makefile @@ -25,6 +25,7 @@ obj-$(CONFIG_GPROF) += gprof_syms.o obj-$(CONFIG_OF) += dtb.o obj-$(CONFIG_EARLY_PRINTK) += early_printk.o obj-$(CONFIG_STACKTRACE) += stacktrace.o +obj-$(CONFIG_SMP) += smp.o USER_OBJS := config.o diff --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c index e95f6c5a259d..f4b13f15a9c1 100644 --- a/arch/um/kernel/irq.c +++ b/arch/um/kernel/irq.c @@ -22,6 +22,9 @@ #include <irq_kern.h> #include <linux/time-internal.h> +DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat); + +#define irq_stats(x) (&per_cpu(irq_stat, x)) /* When epoll triggers we do not know why it did so * we can also have different IRQs for read and write. @@ -701,3 +704,25 @@ void sigchld_handler(int sig, struct siginfo *unused_si, { do_IRQ(SIGCHLD_IRQ, regs); } + +/* + * /proc/interrupts printing for arch specific interrupts + */ +int arch_show_interrupts(struct seq_file *p, int prec) +{ +#if IS_ENABLED(CONFIG_SMP) + int cpu; + + seq_printf(p, "%*s: ", prec, "RES"); + for_each_online_cpu(cpu) + seq_printf(p, "%10u ", irq_stats(cpu)->irq_resched_count); + seq_puts(p, " Rescheduling interrupts\n"); + + seq_printf(p, "%*s: ", prec, "CAL"); + for_each_online_cpu(cpu) + seq_printf(p, "%10u ", irq_stats(cpu)->irq_call_count); + seq_puts(p, " Function call interrupts\n"); +#endif + + return 0; +} diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c index 3b28048f269c..63b38a3f73f7 100644 --- a/arch/um/kernel/process.c +++ b/arch/um/kernel/process.c @@ -218,6 +218,11 @@ void arch_cpu_idle(void) um_idle_sleep(); } +void arch_cpu_idle_prepare(void) +{ + os_idle_prepare(); +} + int __uml_cant_sleep(void) { return in_atomic() || irqs_disabled() || in_interrupt(); /* Is in_interrupt() really needed? */ diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c index afe9a2f251ef..00957788591b 100644 --- a/arch/um/kernel/skas/mmu.c +++ b/arch/um/kernel/skas/mmu.c @@ -23,17 +23,36 @@ static_assert(sizeof(struct stub_data) == STUB_DATA_PAGES * UM_KERN_PAGE_SIZE); static spinlock_t mm_list_lock; static struct list_head mm_list; +void enter_turnstile(struct mm_id *mm_id) __acquires(turnstile) +{ + struct mm_context *ctx = container_of(mm_id, struct mm_context, id); + + mutex_lock(&ctx->turnstile); +} + +void exit_turnstile(struct mm_id *mm_id) __releases(turnstile) +{ + struct mm_context *ctx = container_of(mm_id, struct mm_context, id); + + mutex_unlock(&ctx->turnstile); +} + int init_new_context(struct task_struct *task, struct mm_struct *mm) { struct mm_id *new_id = &mm->context.id; unsigned long stack = 0; int ret = -ENOMEM; + mutex_init(&mm->context.turnstile); + spin_lock_init(&mm->context.sync_tlb_lock); + stack = __get_free_pages(GFP_KERNEL | __GFP_ZERO, ilog2(STUB_DATA_PAGES)); if (stack == 0) goto out; new_id->stack = stack; + new_id->syscall_data_len = 0; + new_id->syscall_fd_num = 0; scoped_guard(spinlock_irqsave, &mm_list_lock) { /* Insert into list, used for lookups when the child dies */ @@ -73,6 +92,9 @@ void destroy_context(struct mm_struct *mm) return; } + scoped_guard(spinlock_irqsave, &mm_list_lock) + list_del(&mm->context.list); + if (mmu->id.pid > 0) { os_kill_ptraced_process(mmu->id.pid, 1); mmu->id.pid = -1; @@ -82,10 +104,6 @@ void destroy_context(struct mm_struct *mm) os_close_file(mmu->id.sock); free_pages(mmu->id.stack, ilog2(STUB_DATA_PAGES)); - - guard(spinlock_irqsave)(&mm_list_lock); - - list_del(&mm->context.list); } static irqreturn_t mm_sigchld_irq(int irq, void* dev) @@ -110,12 +128,11 @@ static irqreturn_t mm_sigchld_irq(int irq, void* dev) /* Marks the MM as dead */ mm_context->id.pid = -1; - /* - * NOTE: If SMP is implemented, a futex_wake - * needs to be added here. - */ stub_data = (void *)mm_context->id.stack; stub_data->futex = FUTEX_IN_KERN; +#if IS_ENABLED(CONFIG_SMP) + os_futex_wake(&stub_data->futex); +#endif /* * NOTE: Currently executing syscalls by diff --git a/arch/um/kernel/skas/process.c b/arch/um/kernel/skas/process.c index 5881b17eb987..4a7673b0261a 100644 --- a/arch/um/kernel/skas/process.c +++ b/arch/um/kernel/skas/process.c @@ -7,6 +7,7 @@ #include <linux/sched/mm.h> #include <linux/sched/task_stack.h> #include <linux/sched/task.h> +#include <linux/smp-internal.h> #include <asm/tlbflush.h> @@ -26,12 +27,12 @@ static int __init start_kernel_proc(void *unused) return 0; } -static char cpu0_irqstack[THREAD_SIZE] __aligned(THREAD_SIZE); +char cpu_irqstacks[NR_CPUS][THREAD_SIZE] __aligned(THREAD_SIZE); int __init start_uml(void) { - stack_protections((unsigned long) &cpu0_irqstack); - set_sigstack(cpu0_irqstack, THREAD_SIZE); + stack_protections((unsigned long) &cpu_irqstacks[0]); + set_sigstack(cpu_irqstacks[0], THREAD_SIZE); init_new_thread_signals(); @@ -64,3 +65,15 @@ void current_mm_sync(void) um_tlb_sync(current->mm); } + +static DEFINE_SPINLOCK(initial_jmpbuf_spinlock); + +void initial_jmpbuf_lock(void) +{ + spin_lock_irq(&initial_jmpbuf_spinlock); +} + +void initial_jmpbuf_unlock(void) +{ + spin_unlock_irq(&initial_jmpbuf_spinlock); +} diff --git a/arch/um/kernel/smp.c b/arch/um/kernel/smp.c new file mode 100644 index 000000000000..f1e52b7348fb --- /dev/null +++ b/arch/um/kernel/smp.c @@ -0,0 +1,242 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2025 Ant Group + * Author: Tiwei Bie <tiwei.btw@antgroup.com> + * + * Based on the previous implementation in TT mode + * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) + */ + +#include <linux/sched.h> +#include <linux/sched/task.h> +#include <linux/sched/task_stack.h> +#include <linux/module.h> +#include <linux/processor.h> +#include <linux/threads.h> +#include <linux/cpu.h> +#include <linux/hardirq.h> +#include <linux/smp.h> +#include <linux/smp-internal.h> +#include <init.h> +#include <kern.h> +#include <os.h> +#include <smp.h> + +enum { + UML_IPI_RES = 0, + UML_IPI_CALL_SINGLE, + UML_IPI_CALL, + UML_IPI_STOP, +}; + +void arch_smp_send_reschedule(int cpu) +{ + os_send_ipi(cpu, UML_IPI_RES); +} + +void arch_send_call_function_single_ipi(int cpu) +{ + os_send_ipi(cpu, UML_IPI_CALL_SINGLE); +} + +void arch_send_call_function_ipi_mask(const struct cpumask *mask) +{ + int cpu; + + for_each_cpu(cpu, mask) + os_send_ipi(cpu, UML_IPI_CALL); +} + +void smp_send_stop(void) +{ + int cpu, me = smp_processor_id(); + + for_each_online_cpu(cpu) { + if (cpu == me) + continue; + os_send_ipi(cpu, UML_IPI_STOP); + } +} + +static void ipi_handler(int vector, struct uml_pt_regs *regs) +{ + struct pt_regs *old_regs = set_irq_regs((struct pt_regs *)regs); + int cpu = raw_smp_processor_id(); + + irq_enter(); + + if (current->mm) + os_alarm_process(current->mm->context.id.pid); + + switch (vector) { + case UML_IPI_RES: + inc_irq_stat(irq_resched_count); + scheduler_ipi(); + break; + + case UML_IPI_CALL_SINGLE: + inc_irq_stat(irq_call_count); + generic_smp_call_function_single_interrupt(); + break; + + case UML_IPI_CALL: + inc_irq_stat(irq_call_count); + generic_smp_call_function_interrupt(); + break; + + case UML_IPI_STOP: + set_cpu_online(cpu, false); + while (1) + pause(); + break; + + default: + pr_err("CPU#%d received unknown IPI (vector=%d)!\n", cpu, vector); + break; + } + + irq_exit(); + set_irq_regs(old_regs); +} + +void uml_ipi_handler(int vector) +{ + struct uml_pt_regs r = { .is_user = 0 }; + + preempt_disable(); + ipi_handler(vector, &r); + preempt_enable(); +} + +/* AP states used only during CPU startup */ +enum { + UML_CPU_PAUSED = 0, + UML_CPU_RUNNING, +}; + +static int cpu_states[NR_CPUS]; + +static int start_secondary(void *unused) +{ + int err, cpu = raw_smp_processor_id(); + + notify_cpu_starting(cpu); + set_cpu_online(cpu, true); + + err = um_setup_timer(); + if (err) + panic("CPU#%d failed to setup timer, err = %d", cpu, err); + + local_irq_enable(); + + cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); + + return 0; +} + +void uml_start_secondary(void *opaque) +{ + int cpu = raw_smp_processor_id(); + struct mm_struct *mm = &init_mm; + struct task_struct *idle; + + stack_protections((unsigned long) &cpu_irqstacks[cpu]); + set_sigstack(&cpu_irqstacks[cpu], THREAD_SIZE); + + set_cpu_present(cpu, true); + os_futex_wait(&cpu_states[cpu], UML_CPU_PAUSED); + + smp_rmb(); /* paired with smp_wmb() in __cpu_up() */ + + idle = cpu_tasks[cpu]; + idle->thread_info.cpu = cpu; + + mmgrab(mm); + idle->active_mm = mm; + + idle->thread.request.thread.proc = start_secondary; + idle->thread.request.thread.arg = NULL; + + new_thread(task_stack_page(idle), &idle->thread.switch_buf, + new_thread_handler); + os_start_secondary(opaque, &idle->thread.switch_buf); +} + +void __init smp_prepare_cpus(unsigned int max_cpus) +{ + int err, cpu, me = smp_processor_id(); + unsigned long deadline; + + os_init_smp(); + + for_each_possible_cpu(cpu) { + if (cpu == me) + continue; + + pr_debug("Booting processor %d...\n", cpu); + err = os_start_cpu_thread(cpu); + if (err) { + pr_crit("CPU#%d failed to start cpu thread, err = %d", + cpu, err); + continue; + } + + deadline = jiffies + msecs_to_jiffies(1000); + spin_until_cond(cpu_present(cpu) || + time_is_before_jiffies(deadline)); + + if (!cpu_present(cpu)) + pr_crit("CPU#%d failed to boot\n", cpu); + } +} + +int __cpu_up(unsigned int cpu, struct task_struct *tidle) +{ + cpu_tasks[cpu] = tidle; + smp_wmb(); /* paired with smp_rmb() in uml_start_secondary() */ + cpu_states[cpu] = UML_CPU_RUNNING; + os_futex_wake(&cpu_states[cpu]); + spin_until_cond(cpu_online(cpu)); + + return 0; +} + +void __init smp_cpus_done(unsigned int max_cpus) +{ +} + +/* Set in uml_ncpus_setup */ +int uml_ncpus = 1; + +void __init prefill_possible_map(void) +{ + int cpu; + + for (cpu = 0; cpu < uml_ncpus; cpu++) + set_cpu_possible(cpu, true); + for (; cpu < NR_CPUS; cpu++) + set_cpu_possible(cpu, false); +} + +static int __init uml_ncpus_setup(char *line, int *add) +{ + *add = 0; + + if (kstrtoint(line, 10, ¨_ncpus)) { + os_warn("%s: Couldn't parse '%s'\n", __func__, line); + return -1; + } + + uml_ncpus = clamp(uml_ncpus, 1, NR_CPUS); + + return 0; +} + +__uml_setup("ncpus=", uml_ncpus_setup, +"ncpus=<# of desired CPUs>\n" +" This tells UML how many virtual processors to start. The maximum\n" +" number of supported virtual processors can be obtained by querying\n" +" the CONFIG_NR_CPUS option using --showconfig.\n\n" +); + +EXPORT_SYMBOL(uml_curr_cpu); diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c index cf7e0d4407f2..39608cccf2c6 100644 --- a/arch/um/kernel/tlb.c +++ b/arch/um/kernel/tlb.c @@ -162,9 +162,11 @@ int um_tlb_sync(struct mm_struct *mm) { pgd_t *pgd; struct vm_ops ops; - unsigned long addr = mm->context.sync_tlb_range_from, next; + unsigned long addr, next; int ret = 0; + guard(spinlock_irqsave)(&mm->context.sync_tlb_lock); + if (mm->context.sync_tlb_range_to == 0) return 0; @@ -177,6 +179,7 @@ int um_tlb_sync(struct mm_struct *mm) ops.unmap = unmap; } + addr = mm->context.sync_tlb_range_from; pgd = pgd_offset(mm, addr); do { next = pgd_addr_end(addr, mm->context.sync_tlb_range_to); diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c index 5b80a3a89c20..177615820a4c 100644 --- a/arch/um/kernel/trap.c +++ b/arch/um/kernel/trap.c @@ -316,7 +316,7 @@ unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, if (!is_user && regs) current->thread.segv_regs = container_of(regs, struct pt_regs, regs); - if (!is_user && init_mm.context.sync_tlb_range_to) { + if (!is_user && address >= start_vm && address < end_vm) { /* * Kernel has pending updates from set_ptes that were not * flushed yet. Syncing them should fix the pagefault (if not diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c index cf06bb732ed8..e2b24e1ecfa6 100644 --- a/arch/um/kernel/um_arch.c +++ b/arch/um/kernel/um_arch.c @@ -19,6 +19,7 @@ #include <linux/kmsg_dump.h> #include <linux/suspend.h> #include <linux/random.h> +#include <linux/smp-internal.h> #include <asm/processor.h> #include <asm/cpufeature.h> @@ -71,6 +72,12 @@ static int show_cpuinfo(struct seq_file *m, void *v) { int i = 0; +#if IS_ENABLED(CONFIG_SMP) + i = (uintptr_t) v - 1; + if (!cpu_online(i)) + return 0; +#endif + seq_printf(m, "processor\t: %d\n", i); seq_printf(m, "vendor_id\t: User Mode Linux\n"); seq_printf(m, "model name\t: UML\n"); @@ -87,13 +94,14 @@ static int show_cpuinfo(struct seq_file *m, void *v) loops_per_jiffy/(500000/HZ), (loops_per_jiffy/(5000/HZ)) % 100); - return 0; } static void *c_start(struct seq_file *m, loff_t *pos) { - return *pos < nr_cpu_ids ? &boot_cpu_data + *pos : NULL; + if (*pos < nr_cpu_ids) + return (void *)(uintptr_t)(*pos + 1); + return NULL; } static void *c_next(struct seq_file *m, void *v, loff_t *pos) @@ -409,6 +417,7 @@ void __init setup_arch(char **cmdline_p) strscpy(boot_command_line, command_line, COMMAND_LINE_SIZE); *cmdline_p = command_line; setup_hostinfo(host_info, sizeof host_info); + prefill_possible_map(); if (os_getrandom(rng_seed, sizeof(rng_seed), 0) == sizeof(rng_seed)) { add_bootloader_randomness(rng_seed, sizeof(rng_seed)); @@ -443,6 +452,18 @@ void apply_alternatives(struct alt_instr *start, struct alt_instr *end) { } +#if IS_ENABLED(CONFIG_SMP) +void alternatives_smp_module_add(struct module *mod, char *name, + void *locks, void *locks_end, + void *text, void *text_end) +{ +} + +void alternatives_smp_module_del(struct module *mod) +{ +} +#endif + void *text_poke(void *addr, const void *opcode, size_t len) { /* diff --git a/arch/um/os-Linux/Makefile b/arch/um/os-Linux/Makefile index fae836713487..70c73c22f715 100644 --- a/arch/um/os-Linux/Makefile +++ b/arch/um/os-Linux/Makefile @@ -16,8 +16,10 @@ CFLAGS_main.o += -Wno-frame-larger-than obj-$(CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA) += elf_aux.o +obj-$(CONFIG_SMP) += smp.o + USER_OBJS := $(user-objs-y) elf_aux.o execvp.o file.o helper.o irq.o \ main.o mem.o process.o registers.o sigio.o signal.o start_up.o time.o \ - tty.o umid.o util.o + tty.o umid.o util.o smp.o include $(srctree)/arch/um/scripts/Makefile.rules diff --git a/arch/um/os-Linux/internal.h b/arch/um/os-Linux/internal.h index c2c7a0dc673c..bac9fcc8c14c 100644 --- a/arch/um/os-Linux/internal.h +++ b/arch/um/os-Linux/internal.h @@ -4,6 +4,7 @@ #include <mm_id.h> #include <stub-data.h> +#include <signal.h> /* * elf_aux.c @@ -18,6 +19,7 @@ void check_tmpexec(void); /* * signal.c */ +extern __thread int signals_enabled; int timer_alarm_pending(void); /* @@ -25,4 +27,10 @@ int timer_alarm_pending(void); */ void wait_stub_done(int pid); void wait_stub_done_seccomp(struct mm_id *mm_idp, int running, int wait_sigsys); + +/* + * smp.c + */ +#define IPI_SIGNAL SIGRTMIN + #endif /* __UM_OS_LINUX_INTERNAL_H */ diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c index 00b49e90d05f..3a2a84ab9325 100644 --- a/arch/um/os-Linux/process.c +++ b/arch/um/os-Linux/process.c @@ -10,6 +10,8 @@ #include <errno.h> #include <signal.h> #include <fcntl.h> +#include <limits.h> +#include <linux/futex.h> #include <sys/mman.h> #include <sys/ptrace.h> #include <sys/prctl.h> @@ -189,3 +191,21 @@ void os_set_pdeathsig(void) { prctl(PR_SET_PDEATHSIG, SIGKILL); } + +int os_futex_wait(void *uaddr, unsigned int val) +{ + int r; + + CATCH_EINTR(r = syscall(__NR_futex, uaddr, FUTEX_WAIT, val, + NULL, NULL, 0)); + return r < 0 ? -errno : r; +} + +int os_futex_wake(void *uaddr) +{ + int r; + + CATCH_EINTR(r = syscall(__NR_futex, uaddr, FUTEX_WAKE, INT_MAX, + NULL, NULL, 0)); + return r < 0 ? -errno : r; +} diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c index 554a87dd32cc..327fb3c52fc7 100644 --- a/arch/um/os-Linux/signal.c +++ b/arch/um/os-Linux/signal.c @@ -69,7 +69,7 @@ static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc) #define SIGCHLD_BIT 2 #define SIGCHLD_MASK (1 << SIGCHLD_BIT) -static __thread int signals_enabled; +__thread int signals_enabled; #if IS_ENABLED(CONFIG_UML_TIME_TRAVEL_SUPPORT) static int signals_blocked, signals_blocked_pending; #endif @@ -259,9 +259,29 @@ int change_sig(int signal, int on) return 0; } -void block_signals(void) +static inline void __block_signals(void) { + if (!signals_enabled) + return; + + os_local_ipi_disable(); + barrier(); signals_enabled = 0; +} + +static inline void __unblock_signals(void) +{ + if (signals_enabled) + return; + + signals_enabled = 1; + barrier(); + os_local_ipi_enable(); +} + +void block_signals(void) +{ + __block_signals(); /* * This must return with signals disabled, so this barrier * ensures that writes are flushed out before the return. @@ -278,7 +298,8 @@ void unblock_signals(void) if (signals_enabled == 1) return; - signals_enabled = 1; + __unblock_signals(); + #if IS_ENABLED(CONFIG_UML_TIME_TRAVEL_SUPPORT) deliver_time_travel_irqs(); #endif @@ -312,7 +333,7 @@ void unblock_signals(void) * tracing that happens inside the handlers we call for the * pending signals will mess up the tracing state. */ - signals_enabled = 0; + __block_signals(); um_trace_signals_off(); /* @@ -344,7 +365,7 @@ void unblock_signals(void) /* Re-enable signals and trace that we're doing so. */ um_trace_signals_on(); - signals_enabled = 1; + __unblock_signals(); } } diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c index 820846ff7179..d6c22f8aa06d 100644 --- a/arch/um/os-Linux/skas/process.c +++ b/arch/um/os-Linux/skas/process.c @@ -546,7 +546,7 @@ extern unsigned long tt_extra_sched_jiffies; void userspace(struct uml_pt_regs *regs) { int err, status, op; - siginfo_t si_ptrace; + siginfo_t si_local; siginfo_t *si; int sig; @@ -557,6 +557,13 @@ void userspace(struct uml_pt_regs *regs) struct mm_id *mm_id = current_mm_id(); /* + * At any given time, only one CPU thread can enter the + * turnstile to operate on the same stub process, including + * executing stub system calls (mmap and munmap). + */ + enter_turnstile(mm_id); + + /* * When we are in time-travel mode, userspace can theoretically * do a *lot* of work without being scheduled. The problem with * this is that it will prevent kernel bookkeeping (primarily @@ -623,9 +630,10 @@ void userspace(struct uml_pt_regs *regs) } if (proc_data->si_offset > sizeof(proc_data->sigstack) - sizeof(*si)) - panic("%s - Invalid siginfo offset from child", - __func__); - si = (void *)&proc_data->sigstack[proc_data->si_offset]; + panic("%s - Invalid siginfo offset from child", __func__); + + si = &si_local; + memcpy(si, &proc_data->sigstack[proc_data->si_offset], sizeof(*si)); regs->is_user = 1; @@ -721,8 +729,8 @@ void userspace(struct uml_pt_regs *regs) case SIGFPE: case SIGWINCH: ptrace(PTRACE_GETSIGINFO, pid, 0, - (struct siginfo *)&si_ptrace); - si = &si_ptrace; + (struct siginfo *)&si_local); + si = &si_local; break; default: si = NULL; @@ -733,6 +741,8 @@ void userspace(struct uml_pt_regs *regs) } } + exit_turnstile(mm_id); + UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */ if (sig) { @@ -802,10 +812,9 @@ void switch_threads(jmp_buf *me, jmp_buf *you) static jmp_buf initial_jmpbuf; -/* XXX Make these percpu */ -static void (*cb_proc)(void *arg); -static void *cb_arg; -static jmp_buf *cb_back; +static __thread void (*cb_proc)(void *arg); +static __thread void *cb_arg; +static __thread jmp_buf *cb_back; int start_idle_thread(void *stack, jmp_buf *switch_buf) { @@ -859,10 +868,10 @@ void initial_thread_cb_skas(void (*proc)(void *), void *arg) cb_arg = arg; cb_back = &here; - block_signals_trace(); + initial_jmpbuf_lock(); if (UML_SETJMP(&here) == 0) UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK); - unblock_signals_trace(); + initial_jmpbuf_unlock(); cb_proc = NULL; cb_arg = NULL; @@ -871,8 +880,9 @@ void initial_thread_cb_skas(void (*proc)(void *), void *arg) void halt_skas(void) { - block_signals_trace(); + initial_jmpbuf_lock(); UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT); + /* unreachable */ } static bool noreboot; @@ -892,6 +902,7 @@ __uml_setup("noreboot", noreboot_cmd_param, void reboot_skas(void) { - block_signals_trace(); + initial_jmpbuf_lock(); UML_LONGJMP(&initial_jmpbuf, noreboot ? INIT_JMP_HALT : INIT_JMP_REBOOT); + /* unreachable */ } diff --git a/arch/um/os-Linux/smp.c b/arch/um/os-Linux/smp.c new file mode 100644 index 000000000000..18d3858a7cd2 --- /dev/null +++ b/arch/um/os-Linux/smp.c @@ -0,0 +1,148 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2025 Ant Group + * Author: Tiwei Bie <tiwei.btw@antgroup.com> + */ + +#include <errno.h> +#include <pthread.h> +#include <signal.h> +#include <kern_util.h> +#include <um_malloc.h> +#include <init.h> +#include <os.h> +#include <smp.h> +#include "internal.h" + +struct cpu_thread_data { + int cpu; + sigset_t sigset; +}; + +static __thread int __curr_cpu; + +int uml_curr_cpu(void) +{ + return __curr_cpu; +} + +static pthread_t cpu_threads[CONFIG_NR_CPUS]; + +static void *cpu_thread(void *arg) +{ + struct cpu_thread_data *data = arg; + + __curr_cpu = data->cpu; + + uml_start_secondary(data); + + return NULL; +} + +int os_start_cpu_thread(int cpu) +{ + struct cpu_thread_data *data; + sigset_t sigset, oset; + int err; + + data = uml_kmalloc(sizeof(*data), UM_GFP_ATOMIC); + if (!data) + return -ENOMEM; + + sigfillset(&sigset); + if (sigprocmask(SIG_SETMASK, &sigset, &oset) < 0) { + err = errno; + goto err; + } + + data->cpu = cpu; + data->sigset = oset; + + err = pthread_create(&cpu_threads[cpu], NULL, cpu_thread, data); + if (sigprocmask(SIG_SETMASK, &oset, NULL) < 0) + panic("Failed to restore the signal mask, errno = %d", errno); + if (err != 0) + goto err; + + return 0; + +err: + kfree(data); + return -err; +} + +void os_start_secondary(void *arg, jmp_buf *switch_buf) +{ + struct cpu_thread_data *data = arg; + + sigaddset(&data->sigset, IPI_SIGNAL); + sigaddset(&data->sigset, SIGIO); + + if (sigprocmask(SIG_SETMASK, &data->sigset, NULL) < 0) + panic("Failed to restore the signal mask, errno = %d", errno); + + kfree(data); + longjmp(*switch_buf, 1); + + /* unreachable */ + printk(UM_KERN_ERR "impossible long jump!"); + fatal_sigsegv(); +} + +int os_send_ipi(int cpu, int vector) +{ + union sigval value = { .sival_int = vector }; + + return pthread_sigqueue(cpu_threads[cpu], IPI_SIGNAL, value); +} + +static void __local_ipi_set(int enable) +{ + sigset_t sigset; + + sigemptyset(&sigset); + sigaddset(&sigset, IPI_SIGNAL); + + if (sigprocmask(enable ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0) + panic("%s: sigprocmask failed, errno = %d", __func__, errno); +} + +void os_local_ipi_enable(void) +{ + __local_ipi_set(1); +} + +void os_local_ipi_disable(void) +{ + __local_ipi_set(0); +} + +static void ipi_sig_handler(int sig, siginfo_t *si, void *uc) +{ + int save_errno = errno; + + signals_enabled = 0; + um_trace_signals_off(); + + uml_ipi_handler(si->si_value.sival_int); + + um_trace_signals_on(); + signals_enabled = 1; + + errno = save_errno; +} + +void __init os_init_smp(void) +{ + struct sigaction action = { + .sa_sigaction = ipi_sig_handler, + .sa_flags = SA_SIGINFO | SA_ONSTACK | SA_RESTART, + }; + + sigfillset(&action.sa_mask); + + if (sigaction(IPI_SIGNAL, &action, NULL) < 0) + panic("%s: sigaction failed, errno = %d", __func__, errno); + + cpu_threads[0] = pthread_self(); +} diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c index 8b19dca83f71..054ac03bbf5e 100644 --- a/arch/um/os-Linux/start_up.c +++ b/arch/um/os-Linux/start_up.c @@ -22,6 +22,7 @@ #include <asm/unistd.h> #include <init.h> #include <os.h> +#include <smp.h> #include <kern_util.h> #include <mem_user.h> #include <ptrace_user.h> @@ -481,6 +482,9 @@ void __init os_early_checks(void) fatal("SECCOMP userspace requested but not functional!\n"); } + if (uml_ncpus > 1) + fatal("SMP is not supported with PTRACE userspace.\n"); + using_seccomp = 0; check_ptrace(); diff --git a/arch/um/os-Linux/time.c b/arch/um/os-Linux/time.c index e0197bfe4ac9..13ebc86918d4 100644 --- a/arch/um/os-Linux/time.c +++ b/arch/um/os-Linux/time.c @@ -11,9 +11,11 @@ #include <errno.h> #include <signal.h> #include <time.h> +#include <sys/signalfd.h> #include <sys/time.h> #include <kern_util.h> #include <os.h> +#include <smp.h> #include <string.h> #include "internal.h" @@ -41,7 +43,8 @@ long long os_persistent_clock_emulation(void) */ int os_timer_create(void) { - timer_t *t = &event_high_res_timer[0]; + int cpu = uml_curr_cpu(); + timer_t *t = &event_high_res_timer[cpu]; struct sigevent sev = { .sigev_notify = SIGEV_THREAD_ID, .sigev_signo = SIGALRM, @@ -105,24 +108,49 @@ long long os_nsecs(void) return timespec_to_ns(&ts); } +static __thread int wake_signals; + +void os_idle_prepare(void) +{ + sigset_t set; + + sigemptyset(&set); + sigaddset(&set, SIGALRM); + sigaddset(&set, IPI_SIGNAL); + + /* + * We need to use signalfd rather than sigsuspend in idle sleep + * because the IPI signal is a real-time signal that carries data, + * and unlike handling SIGALRM, we cannot simply flag it in + * signals_pending. + */ + wake_signals = signalfd(-1, &set, SFD_CLOEXEC); + if (wake_signals < 0) + panic("Failed to create signal FD, errno = %d", errno); +} + /** * os_idle_sleep() - sleep until interrupted */ void os_idle_sleep(void) { - sigset_t set, old; + sigset_t set; - /* Block SIGALRM while performing the need_resched check. */ + /* + * Block SIGALRM while performing the need_resched check. + * Note that, because IRQs are disabled, the IPI signal is + * already blocked. + */ sigemptyset(&set); sigaddset(&set, SIGALRM); - sigprocmask(SIG_BLOCK, &set, &old); + sigprocmask(SIG_BLOCK, &set, NULL); /* * Because disabling IRQs does not block SIGALRM, it is also * necessary to check for any pending timer alarms. */ if (!uml_need_resched() && !timer_alarm_pending()) - sigsuspend(&old); + os_poll(1, &wake_signals); /* Restore the signal mask. */ sigprocmask(SIG_UNBLOCK, &set, NULL); |