Apart from the usual small churn, we have

- initial SMP support (only kernel)
 
  - major vDSO cleanups (and fixes for 32-bit)
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Merge tag 'uml-for-linux-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux

Pull UML updates from Johannes Berg:
 "Apart from the usual small churn, we have

   - initial SMP support (only kernel)

   - major vDSO cleanups (and fixes for 32-bit)"

* tag 'uml-for-linux-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: (33 commits)
  um: Disable KASAN_INLINE when STATIC_LINK is selected
  um: Don't rename vmap to kernel_vmap
  um: drivers: virtio: use string choices helper
  um: Always set up AT_HWCAP and AT_PLATFORM
  x86/um: Remove FIXADDR_USER_START and FIXADDR_USE_END
  um: Remove __access_ok_vsyscall()
  um: Remove redundant range check from __access_ok_vsyscall()
  um: Remove fixaddr_user_init()
  x86/um: Drop gate area handling
  x86/um: Do not inherit vDSO from host
  um: Split out default elf_aux_hwcap
  x86/um: Move ELF_PLATFORM fallback to x86-specific code
  um: Split out default elf_aux_platform
  um: Avoid circular dependency on asm-offsets in pgtable.h
  um: Enable SMP support on x86
  asm-generic: percpu: Add assembly guard
  um: vdso: Remove getcpu support on x86
  um: Add initial SMP support
  um: Define timers on a per-CPU basis
  um: Determine sleep based on need_resched()
  ...

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  |
     -----------------------

arch/um/Kconfig

@@ -5,6 +5,7 @@ menu "UML-specific options"
 config UML
 	bool
 	default y
+	select ARCH_DISABLE_KASAN_INLINE if STATIC_LINK
 	select ARCH_NEEDS_DEFER_KASAN if STATIC_LINK
 	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
 	select ARCH_HAS_CACHE_LINE_SIZE
@@ -28,6 +29,7 @@ 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 +83,48 @@ 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 if !SMP
-	default 1
+	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"
 
@@ -200,12 +240,6 @@ config KERNEL_STACK_ORDER
 	  increase in the size of the state which needs to be saved when handling
 	  signals.
 
-config MMAPPER
-	tristate "iomem emulation driver"
-	help
-	  This driver allows a host file to be used as emulated IO memory inside
-	  UML.
-
 config PGTABLE_LEVELS
 	int
 	default 4 if 64BIT
@@ -260,6 +294,7 @@ source "arch/um/drivers/Kconfig"
 
 config ARCH_SUSPEND_POSSIBLE
 	def_bool y
+	depends on !SMP
 
 menu "Power management options"
 

arch/um/Makefile

@@ -46,19 +46,17 @@ ARCH_INCLUDE	:= -I$(srctree)/$(SHARED_HEADERS)
 ARCH_INCLUDE	+= -I$(srctree)/$(HOST_DIR)/um/shared
 KBUILD_CPPFLAGS += -I$(srctree)/$(HOST_DIR)/um
 
-# -Dvmap=kernel_vmap prevents anything from referencing the libpcap.o symbol so
+# -Dstrrchr=kernel_strrchr (as well as the various in6addr symbols) prevents
-# named - it's a common symbol in libpcap, so we get a binary which crashes.
+#  anything from referencing
-#
+# libc symbols with the same name, which can cause a linker error.
-# Same things for in6addr_loopback and mktime - found in libc. For these two we
-# only get link-time error, luckily.
 #
 # -Dlongjmp=kernel_longjmp prevents anything from referencing the libpthread.a
 # embedded copy of longjmp, same thing for setjmp.
 #
-# These apply to USER_CFLAGS to.
+# These apply to USER_CFLAGS too.
 
 KBUILD_CFLAGS += $(CFLAGS) $(CFLAGS-y) -D__arch_um__ \
-	$(ARCH_INCLUDE) $(MODE_INCLUDE) -Dvmap=kernel_vmap	\
+	$(ARCH_INCLUDE) $(MODE_INCLUDE)	\
 	-Dlongjmp=kernel_longjmp -Dsetjmp=kernel_setjmp \
 	-Din6addr_loopback=kernel_in6addr_loopback \
 	-Din6addr_any=kernel_in6addr_any -Dstrrchr=kernel_strrchr \

arch/um/drivers/Makefile

@@ -29,7 +29,6 @@ obj-$(CONFIG_STDERR_CONSOLE) += stderr_console.o
 
 obj-$(CONFIG_UML_NET_VECTOR) += vector.o
 obj-$(CONFIG_MCONSOLE) += mconsole.o
-obj-$(CONFIG_MMAPPER) += mmapper_kern.o 
 obj-$(CONFIG_BLK_DEV_UBD) += ubd.o 
 obj-$(CONFIG_UML_SOUND) += hostaudio.o
 obj-$(CONFIG_NULL_CHAN) += null.o 

arch/um/drivers/mmapper_kern.c

@@ -1,135 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * arch/um/drivers/mmapper_kern.c
- *
- * BRIEF MODULE DESCRIPTION
- *
- * Copyright (C) 2000 RidgeRun, Inc.
- * Author: RidgeRun, Inc.
- *         Greg Lonnon glonnon@ridgerun.com or info@ridgerun.com
- *
- */
-
-#include <linux/stddef.h>
-#include <linux/types.h>
-#include <linux/fs.h>
-#include <linux/init.h>
-#include <linux/miscdevice.h>
-#include <linux/module.h>
-#include <linux/mm.h>
-
-#include <linux/uaccess.h>
-#include <mem_user.h>
-
-/* These are set in mmapper_init, which is called at boot time */
-static unsigned long mmapper_size;
-static unsigned long p_buf;
-static char *v_buf;
-
-static ssize_t mmapper_read(struct file *file, char __user *buf, size_t count,
-			    loff_t *ppos)
-{
-	return simple_read_from_buffer(buf, count, ppos, v_buf, mmapper_size);
-}
-
-static ssize_t mmapper_write(struct file *file, const char __user *buf,
-			     size_t count, loff_t *ppos)
-{
-	if (*ppos > mmapper_size)
-		return -EINVAL;
-
-	return simple_write_to_buffer(v_buf, mmapper_size, ppos, buf, count);
-}
-
-static long mmapper_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
-{
-	return -ENOIOCTLCMD;
-}
-
-static int mmapper_mmap(struct file *file, struct vm_area_struct *vma)
-{
-	int ret = -EINVAL;
-	int size;
-
-	if (vma->vm_pgoff != 0)
-		goto out;
-
-	size = vma->vm_end - vma->vm_start;
-	if (size > mmapper_size)
-		return -EFAULT;
-
-	/*
-	 * XXX A comment above remap_pfn_range says it should only be
-	 * called when the mm semaphore is held
-	 */
-	if (remap_pfn_range(vma, vma->vm_start, p_buf >> PAGE_SHIFT, size,
-			    vma->vm_page_prot))
-		goto out;
-	ret = 0;
-out:
-	return ret;
-}
-
-static int mmapper_open(struct inode *inode, struct file *file)
-{
-	return 0;
-}
-
-static int mmapper_release(struct inode *inode, struct file *file)
-{
-	return 0;
-}
-
-static const struct file_operations mmapper_fops = {
-	.owner		= THIS_MODULE,
-	.read		= mmapper_read,
-	.write		= mmapper_write,
-	.unlocked_ioctl	= mmapper_ioctl,
-	.mmap		= mmapper_mmap,
-	.open		= mmapper_open,
-	.release	= mmapper_release,
-	.llseek		= default_llseek,
-};
-
-/*
- * No locking needed - only used (and modified) by below initcall and exitcall.
- */
-static struct miscdevice mmapper_dev = {
-	.minor		= MISC_DYNAMIC_MINOR,
-	.name		= "mmapper",
-	.fops		= &mmapper_fops
-};
-
-static int __init mmapper_init(void)
-{
-	int err;
-
-	printk(KERN_INFO "Mapper v0.1\n");
-
-	v_buf = (char *) find_iomem("mmapper", &mmapper_size);
-	if (mmapper_size == 0) {
-		printk(KERN_ERR "mmapper_init - find_iomem failed\n");
-		return -ENODEV;
-	}
-	p_buf = __pa(v_buf);
-
-	err = misc_register(&mmapper_dev);
-	if (err) {
-		printk(KERN_ERR "mmapper - misc_register failed, err = %d\n",
-		       err);
-		return err;
-	}
-	return 0;
-}
-
-static void __exit mmapper_exit(void)
-{
-	misc_deregister(&mmapper_dev);
-}
-
-module_init(mmapper_init);
-module_exit(mmapper_exit);
-
-MODULE_AUTHOR("Greg Lonnon <glonnon@ridgerun.com>");
-MODULE_DESCRIPTION("DSPLinux simulator mmapper driver");
-MODULE_LICENSE("GPL");

arch/um/drivers/virtio_uml.c

@@ -24,6 +24,7 @@
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
+#include <linux/string_choices.h>
 #include <linux/virtio.h>
 #include <linux/virtio_config.h>
 #include <linux/virtio_ring.h>
@@ -1151,8 +1152,7 @@ void virtio_uml_set_no_vq_suspend(struct virtio_device *vdev,
 		return;
 
 	vu_dev->no_vq_suspend = no_vq_suspend;
-	dev_info(&vdev->dev, "%sabled VQ suspend\n",
+	dev_info(&vdev->dev, "%s VQ suspend\n", str_disabled_enabled(no_vq_suspend));
-		 no_vq_suspend ? "dis" : "en");
 }
 
 static void vu_of_conn_broken(struct work_struct *wk)

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__ */

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 */

arch/um/include/asm/irqflags.h

@@ -2,7 +2,7 @@
 #ifndef __UM_IRQFLAGS_H
 #define __UM_IRQFLAGS_H
 
-extern int signals_enabled;
+int um_get_signals(void);
 int um_set_signals(int enable);
 void block_signals(void);
 void unblock_signals(void);
@@ -10,7 +10,7 @@ void unblock_signals(void);
 #define arch_local_save_flags arch_local_save_flags
 static inline unsigned long arch_local_save_flags(void)
 {
-	return signals_enabled;
+	return um_get_signals();
 }
 
 #define arch_local_irq_restore arch_local_irq_restore

arch/um/include/asm/kasan.h

@@ -24,10 +24,6 @@
 
 #ifdef CONFIG_KASAN
 void kasan_init(void);
-
-#if defined(CONFIG_STATIC_LINK) && defined(CONFIG_KASAN_INLINE)
-#error UML does not work in KASAN_INLINE mode with STATIC_LINK enabled!
-#endif
 #else
 static inline void kasan_init(void) { }
 #endif /* CONFIG_KASAN */

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

arch/um/include/asm/page.h

@@ -96,8 +96,4 @@ extern unsigned long uml_physmem;
 
 #endif	/* __ASSEMBLER__ */
 
-#ifdef CONFIG_X86_32
-#define __HAVE_ARCH_GATE_AREA 1
-#endif
-
 #endif	/* __UM_PAGE_H */

arch/um/include/asm/pgtable.h

@@ -45,10 +45,12 @@ extern unsigned long *empty_zero_page;
  * area for the same reason. ;)
  */
 
-extern unsigned long end_iomem;
+#ifndef COMPILE_OFFSETS
+#include <as-layout.h> /* for high_physmem */
+#endif
 
 #define VMALLOC_OFFSET	(__va_space)
-#define VMALLOC_START ((end_iomem + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1))
+#define VMALLOC_START	((high_physmem + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1))
 #define VMALLOC_END	(TASK_SIZE-2*PAGE_SIZE)
 #define MODULES_VADDR	VMALLOC_START
 #define MODULES_END	VMALLOC_END
@@ -225,6 +227,8 @@ 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;

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

arch/um/include/asm/uaccess.h

@@ -15,11 +15,6 @@
 	(((unsigned long) (addr) < TASK_SIZE) && \
 	 (((unsigned long) (addr) + (size)) < TASK_SIZE))
 
-#define __access_ok_vsyscall(addr, size) \
-	  (((unsigned long) (addr) >= FIXADDR_USER_START) && \
-	  ((unsigned long) (addr) + (size) <= FIXADDR_USER_END) && \
-	  ((unsigned long) (addr) + (size) >= (unsigned long)(addr)))
-
 #define __addr_range_nowrap(addr, size) \
 	((unsigned long) (addr) <= ((unsigned long) (addr) + (size)))
 
@@ -40,9 +35,7 @@ static inline int __access_ok(const void __user *ptr, unsigned long size);
 static inline int __access_ok(const void __user *ptr, unsigned long size)
 {
 	unsigned long addr = (unsigned long)ptr;
-	return __addr_range_nowrap(addr, size) &&
+	return __addr_range_nowrap(addr, size) && __under_task_size(addr, size);
-		(__under_task_size(addr, size) ||
-		 __access_ok_vsyscall(addr, size));
 }
 
 #define __get_kernel_nofault(dst, src, type, err_label)			\

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 */

arch/um/include/linux/time-internal.h

@@ -90,4 +90,7 @@ extern unsigned long tt_extra_sched_jiffies;
  * which is intentional since we really shouldn't link it in that case.
  */
 void time_travel_ndelay(unsigned long nsec);
+
+int um_setup_timer(void);
+
 #endif /* __TIMER_INTERNAL_H__ */

arch/um/include/shared/as-layout.h

@@ -44,7 +44,6 @@ extern unsigned long start_vm;
 
 extern unsigned long brk_start;
 
-extern unsigned long host_task_size;
 extern unsigned long stub_start;
 
 extern int linux_main(int argc, char **argv, char **envp);

arch/um/include/shared/common-offsets.h

@@ -1,20 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/* for use by sys-$SUBARCH/kernel-offsets.c */
-
-DEFINE(KERNEL_MADV_REMOVE, MADV_REMOVE);
-
-DEFINE(UM_KERN_PAGE_SIZE, PAGE_SIZE);
-DEFINE(UM_KERN_PAGE_MASK, PAGE_MASK);
-DEFINE(UM_KERN_PAGE_SHIFT, PAGE_SHIFT);
-
-DEFINE(UM_GFP_KERNEL, GFP_KERNEL);
-DEFINE(UM_GFP_ATOMIC, GFP_ATOMIC);
-
-DEFINE(UM_THREAD_SIZE, THREAD_SIZE);
-
-DEFINE(UM_NSEC_PER_SEC, NSEC_PER_SEC);
-DEFINE(UM_NSEC_PER_USEC, NSEC_PER_USEC);
-
-DEFINE(UM_KERN_GDT_ENTRY_TLS_ENTRIES, GDT_ENTRY_TLS_ENTRIES);
-
-DEFINE(UM_SECCOMP_ARCH_NATIVE, SECCOMP_ARCH_NATIVE);

arch/um/include/shared/kern_util.h

@@ -15,9 +15,6 @@ extern int uml_exitcode;
 
 extern int kmalloc_ok;
 
-#define UML_ROUND_UP(addr) \
-	((((unsigned long) addr) + PAGE_SIZE - 1) & PAGE_MASK)
-
 extern unsigned long alloc_stack(int order, int atomic);
 extern void free_stack(unsigned long stack, int order);
 
@@ -42,7 +39,6 @@ extern void uml_pm_wake(void);
 
 extern int start_uml(void);
 extern void paging_init(void);
-extern int parse_iomem(char *str, int *add);
 
 extern void uml_cleanup(void);
 extern void do_uml_exitcalls(void);
@@ -55,6 +51,7 @@ extern int __uml_cant_sleep(void);
 extern int get_current_pid(void);
 extern int copy_from_user_proc(void *to, void *from, int size);
 extern char *uml_strdup(const char *string);
+int uml_need_resched(void);
 
 extern unsigned long to_irq_stack(unsigned long *mask_out);
 extern unsigned long from_irq_stack(int nested);

arch/um/include/shared/longjmp.h

@@ -5,7 +5,6 @@
 #include <sysdep/archsetjmp.h>
 #include <os.h>
 
-extern int signals_enabled;
 extern int setjmp(jmp_buf);
 extern void longjmp(jmp_buf, int);
 
@@ -15,7 +14,7 @@ extern void longjmp(jmp_buf, int);
 
 #define UML_SETJMP(buf) ({				\
 	int n, enable;					\
-	enable = *(volatile int *)&signals_enabled;	\
+	enable = um_get_signals();			\
 	n = setjmp(*buf);				\
 	if(n != 0)					\
 		um_set_signals_trace(enable);		\

arch/um/include/shared/mem_user.h

@@ -32,21 +32,8 @@
 #ifndef _MEM_USER_H
 #define _MEM_USER_H
 
-struct iomem_region {
-	struct iomem_region *next;
-	char *driver;
-	int fd;
-	int size;
-	unsigned long phys;
-	unsigned long virt;
-};
-
-extern struct iomem_region *iomem_regions;
-extern int iomem_size;
-
 #define ROUND_4M(n) ((((unsigned long) (n)) + (1 << 22)) & ~((1 << 22) - 1))
 
-extern unsigned long find_iomem(char *driver, unsigned long *len_out);
 extern void setup_physmem(unsigned long start, unsigned long usable,
 			  unsigned long len);
 extern void map_memory(unsigned long virt, unsigned long phys,

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 */
@@ -243,6 +246,7 @@ extern void send_sigio_to_self(void);
 extern int change_sig(int signal, int on);
 extern void block_signals(void);
 extern void unblock_signals(void);
+extern int um_get_signals(void);
 extern int um_set_signals(int enable);
 extern int um_set_signals_trace(int enable);
 extern void deliver_alarm(void);
@@ -266,11 +270,12 @@ 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(unsigned long long nsecs);
+extern int os_timer_set_interval(int cpu, unsigned long long nsecs);
-extern int os_timer_one_shot(unsigned long long nsecs);
+extern int os_timer_one_shot(int cpu, unsigned long long nsecs);
-extern void os_timer_disable(void);
+extern void os_timer_disable(int cpu);
 extern long long os_persistent_clock_emulation(void);
 extern long long os_nsecs(void);
 
@@ -338,4 +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

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

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

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 */

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
 

arch/um/kernel/asm-offsets.c

@@ -1,3 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #define COMPILE_OFFSETS
+#include <linux/stddef.h>
+#include <linux/sched.h>
+#include <linux/elf.h>
+#include <linux/crypto.h>
+#include <linux/kbuild.h>
+#include <linux/audit.h>
+#include <linux/fs.h>
+#include <asm/mman.h>
+#include <asm/seccomp.h>
 
-#include <sysdep/kernel-offsets.h>
+/* workaround for a warning with -Wmissing-prototypes */
+void foo(void);
+
+void foo(void)
+{
+	DEFINE(KERNEL_MADV_REMOVE, MADV_REMOVE);
+
+	DEFINE(UM_KERN_PAGE_SIZE, PAGE_SIZE);
+	DEFINE(UM_KERN_PAGE_MASK, PAGE_MASK);
+	DEFINE(UM_KERN_PAGE_SHIFT, PAGE_SHIFT);
+
+	DEFINE(UM_GFP_KERNEL, GFP_KERNEL);
+	DEFINE(UM_GFP_ATOMIC, GFP_ATOMIC);
+
+	DEFINE(UM_THREAD_SIZE, THREAD_SIZE);
+
+	DEFINE(UM_NSEC_PER_SEC, NSEC_PER_SEC);
+	DEFINE(UM_NSEC_PER_USEC, NSEC_PER_USEC);
+
+	DEFINE(UM_KERN_GDT_ENTRY_TLS_ENTRIES, GDT_ENTRY_TLS_ENTRIES);
+
+	DEFINE(UM_SECCOMP_ARCH_NATIVE, SECCOMP_ARCH_NATIVE);
+
+	DEFINE(HOSTFS_ATTR_MODE, ATTR_MODE);
+	DEFINE(HOSTFS_ATTR_UID, ATTR_UID);
+	DEFINE(HOSTFS_ATTR_GID, ATTR_GID);
+	DEFINE(HOSTFS_ATTR_SIZE, ATTR_SIZE);
+	DEFINE(HOSTFS_ATTR_ATIME, ATTR_ATIME);
+	DEFINE(HOSTFS_ATTR_MTIME, ATTR_MTIME);
+	DEFINE(HOSTFS_ATTR_CTIME, ATTR_CTIME);
+	DEFINE(HOSTFS_ATTR_ATIME_SET, ATTR_ATIME_SET);
+	DEFINE(HOSTFS_ATTR_MTIME_SET, ATTR_MTIME_SET);
+}

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.
@@ -683,7 +686,7 @@ void __init init_IRQ(void)
 {
 	int i;
 
-	irq_set_chip_and_handler(TIMER_IRQ, &alarm_irq_type, handle_edge_irq);
+	irq_set_chip_and_handler(TIMER_IRQ, &alarm_irq_type, handle_percpu_irq);
 
 	for (i = 1; i < UM_LAST_SIGNAL_IRQ; i++)
 		irq_set_chip_and_handler(i, &normal_irq_type, handle_edge_irq);
@@ -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;
+}

arch/um/kernel/ksyms.c

@@ -6,8 +6,8 @@
 #include <linux/module.h>
 #include <os.h>
 
+EXPORT_SYMBOL(um_get_signals);
 EXPORT_SYMBOL(um_set_signals);
-EXPORT_SYMBOL(signals_enabled);
 
 EXPORT_SYMBOL(os_stat_fd);
 EXPORT_SYMBOL(os_stat_file);

arch/um/kernel/mem.c

@@ -71,7 +71,7 @@ void __init arch_mm_preinit(void)
 	/* Map in the area just after the brk now that kmalloc is about
 	 * to be turned on.
 	 */
-	brk_end = (unsigned long) UML_ROUND_UP(sbrk(0));
+	brk_end = PAGE_ALIGN((unsigned long) sbrk(0));
 	map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1, 0);
 	memblock_free((void *)brk_end, uml_reserved - brk_end);
 	uml_reserved = brk_end;
@@ -84,109 +84,6 @@ void __init mem_init(void)
 	kmalloc_ok = 1;
 }
 
-#if IS_ENABLED(CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA)
-/*
- * Create a page table and place a pointer to it in a middle page
- * directory entry.
- */
-static void __init one_page_table_init(pmd_t *pmd)
-{
-	if (pmd_none(*pmd)) {
-		pte_t *pte = (pte_t *) memblock_alloc_low(PAGE_SIZE,
-							  PAGE_SIZE);
-		if (!pte)
-			panic("%s: Failed to allocate %lu bytes align=%lx\n",
-			      __func__, PAGE_SIZE, PAGE_SIZE);
-
-		set_pmd(pmd, __pmd(_KERNPG_TABLE +
-					   (unsigned long) __pa(pte)));
-		BUG_ON(pte != pte_offset_kernel(pmd, 0));
-	}
-}
-
-static void __init one_md_table_init(pud_t *pud)
-{
-#if CONFIG_PGTABLE_LEVELS > 2
-	pmd_t *pmd_table = (pmd_t *) memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
-	if (!pmd_table)
-		panic("%s: Failed to allocate %lu bytes align=%lx\n",
-		      __func__, PAGE_SIZE, PAGE_SIZE);
-
-	set_pud(pud, __pud(_KERNPG_TABLE + (unsigned long) __pa(pmd_table)));
-	BUG_ON(pmd_table != pmd_offset(pud, 0));
-#endif
-}
-
-static void __init one_ud_table_init(p4d_t *p4d)
-{
-#if CONFIG_PGTABLE_LEVELS > 3
-	pud_t *pud_table = (pud_t *) memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
-	if (!pud_table)
-		panic("%s: Failed to allocate %lu bytes align=%lx\n",
-		      __func__, PAGE_SIZE, PAGE_SIZE);
-
-	set_p4d(p4d, __p4d(_KERNPG_TABLE + (unsigned long) __pa(pud_table)));
-	BUG_ON(pud_table != pud_offset(p4d, 0));
-#endif
-}
-
-static void __init fixrange_init(unsigned long start, unsigned long end,
-				 pgd_t *pgd_base)
-{
-	pgd_t *pgd;
-	p4d_t *p4d;
-	pud_t *pud;
-	pmd_t *pmd;
-	int i, j;
-	unsigned long vaddr;
-
-	vaddr = start;
-	i = pgd_index(vaddr);
-	j = pmd_index(vaddr);
-	pgd = pgd_base + i;
-
-	for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
-		p4d = p4d_offset(pgd, vaddr);
-		if (p4d_none(*p4d))
-			one_ud_table_init(p4d);
-		pud = pud_offset(p4d, vaddr);
-		if (pud_none(*pud))
-			one_md_table_init(pud);
-		pmd = pmd_offset(pud, vaddr);
-		for (; (j < PTRS_PER_PMD) && (vaddr < end); pmd++, j++) {
-			one_page_table_init(pmd);
-			vaddr += PMD_SIZE;
-		}
-		j = 0;
-	}
-}
-
-static void __init fixaddr_user_init( void)
-{
-	long size = FIXADDR_USER_END - FIXADDR_USER_START;
-	pte_t *pte;
-	phys_t p;
-	unsigned long v, vaddr = FIXADDR_USER_START;
-
-	if (!size)
-		return;
-
-	fixrange_init( FIXADDR_USER_START, FIXADDR_USER_END, swapper_pg_dir);
-	v = (unsigned long) memblock_alloc_low(size, PAGE_SIZE);
-	if (!v)
-		panic("%s: Failed to allocate %lu bytes align=%lx\n",
-		      __func__, size, PAGE_SIZE);
-
-	memcpy((void *) v , (void *) FIXADDR_USER_START, size);
-	p = __pa(v);
-	for ( ; size > 0; size -= PAGE_SIZE, vaddr += PAGE_SIZE,
-		      p += PAGE_SIZE) {
-		pte = virt_to_kpte(vaddr);
-		pte_set_val(*pte, p, PAGE_READONLY);
-	}
-}
-#endif
-
 void __init paging_init(void)
 {
 	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
@@ -197,12 +94,8 @@ void __init paging_init(void)
 		panic("%s: Failed to allocate %lu bytes align=%lx\n",
 		      __func__, PAGE_SIZE, PAGE_SIZE);
 
-	max_zone_pfn[ZONE_NORMAL] = end_iomem >> PAGE_SHIFT;
+	max_zone_pfn[ZONE_NORMAL] = high_physmem >> PAGE_SHIFT;
 	free_area_init(max_zone_pfn);
-
-#if IS_ENABLED(CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA)
-	fixaddr_user_init();
-#endif
 }
 
 /*

arch/um/kernel/physmem.c

@@ -105,19 +105,6 @@ int phys_mapping(unsigned long phys, unsigned long long *offset_out)
 		fd = physmem_fd;
 		*offset_out = phys;
 	}
-	else if (phys < __pa(end_iomem)) {
-		struct iomem_region *region = iomem_regions;
-
-		while (region != NULL) {
-			if ((phys >= region->phys) &&
-			    (phys < region->phys + region->size)) {
-				fd = region->fd;
-				*offset_out = phys - region->phys;
-				break;
-			}
-			region = region->next;
-		}
-	}
 
 	return fd;
 }
@@ -140,61 +127,3 @@ __uml_setup("mem=", uml_mem_setup,
 "    be more, and the excess, if it's ever used, will just be swapped out.\n"
 "	Example: mem=64M\n\n"
 );
-
-__uml_setup("iomem=", parse_iomem,
-"iomem=<name>,<file>\n"
-"    Configure <file> as an IO memory region named <name>.\n\n"
-);
-
-/*
- * This list is constructed in parse_iomem and addresses filled in
- * setup_iomem, both of which run during early boot.  Afterwards, it's
- * unchanged.
- */
-struct iomem_region *iomem_regions;
-
-/* Initialized in parse_iomem and unchanged thereafter */
-int iomem_size;
-
-unsigned long find_iomem(char *driver, unsigned long *len_out)
-{
-	struct iomem_region *region = iomem_regions;
-
-	while (region != NULL) {
-		if (!strcmp(region->driver, driver)) {
-			*len_out = region->size;
-			return region->virt;
-		}
-
-		region = region->next;
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL(find_iomem);
-
-static int setup_iomem(void)
-{
-	struct iomem_region *region = iomem_regions;
-	unsigned long iomem_start = high_physmem + PAGE_SIZE;
-	int err;
-
-	while (region != NULL) {
-		err = os_map_memory((void *) iomem_start, region->fd, 0,
-				    region->size, 1, 1, 0);
-		if (err)
-			printk(KERN_ERR "Mapping iomem region for driver '%s' "
-			       "failed, errno = %d\n", region->driver, -err);
-		else {
-			region->virt = iomem_start;
-			region->phys = __pa(region->virt);
-		}
-
-		iomem_start += region->size + PAGE_SIZE;
-		region = region->next;
-	}
-
-	return 0;
-}
-
-__initcall(setup_iomem);

arch/um/kernel/process.c

@@ -43,7 +43,9 @@
  * cares about its entry, so it's OK if another processor is modifying its
  * entry.
  */
-struct task_struct *cpu_tasks[NR_CPUS];
+struct task_struct *cpu_tasks[NR_CPUS] = {
+	[0 ... NR_CPUS - 1] = &init_task,
+};
 EXPORT_SYMBOL(cpu_tasks);
 
 void free_stack(unsigned long stack, int order)
@@ -185,11 +187,7 @@ int copy_thread(struct task_struct * p, const struct kernel_clone_args *args)
 
 void initial_thread_cb(void (*proc)(void *), void *arg)
 {
-	int save_kmalloc_ok = kmalloc_ok;
-
-	kmalloc_ok = 0;
 	initial_thread_cb_skas(proc, arg);
-	kmalloc_ok = save_kmalloc_ok;
 }
 
 int arch_dup_task_struct(struct task_struct *dst,
@@ -220,11 +218,21 @@ 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? */
 }
 
+int uml_need_resched(void)
+{
+	return need_resched();
+}
+
 extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
 
 void do_uml_exitcalls(void)

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

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);
+	stack_protections((unsigned long) &cpu_irqstacks[0]);
-	set_sigstack(cpu0_irqstack, THREAD_SIZE);
+	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);
+}

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, &uml_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);

arch/um/kernel/time.c

@@ -625,9 +625,10 @@ void time_travel_sleep(void)
 	 * controller application.
 	 */
 	unsigned long long next = S64_MAX;
+	int cpu = raw_smp_processor_id();
 
 	if (time_travel_mode == TT_MODE_BASIC)
-		os_timer_disable();
+		os_timer_disable(cpu);
 
 	time_travel_update_time(next, true);
 
@@ -638,9 +639,9 @@ void time_travel_sleep(void)
 			 * This is somewhat wrong - we should get the first
 			 * one sooner like the os_timer_one_shot() below...
 			 */
-			os_timer_set_interval(time_travel_timer_interval);
+			os_timer_set_interval(cpu, time_travel_timer_interval);
 		} else {
-			os_timer_one_shot(time_travel_timer_event.time - next);
+			os_timer_one_shot(cpu, time_travel_timer_event.time - next);
 		}
 	}
 }
@@ -758,6 +759,8 @@ extern u64 time_travel_ext_req(u32 op, u64 time);
 #define time_travel_del_event(e) do { } while (0)
 #endif
 
+static struct clock_event_device timer_clockevent[NR_CPUS];
+
 void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
 {
 	unsigned long flags;
@@ -780,12 +783,14 @@ void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
 
 static int itimer_shutdown(struct clock_event_device *evt)
 {
+	int cpu = evt - &timer_clockevent[0];
+
 	if (time_travel_mode != TT_MODE_OFF)
 		time_travel_del_event(&time_travel_timer_event);
 
 	if (time_travel_mode != TT_MODE_INFCPU &&
 	    time_travel_mode != TT_MODE_EXTERNAL)
-		os_timer_disable();
+		os_timer_disable(cpu);
 
 	return 0;
 }
@@ -793,6 +798,7 @@ static int itimer_shutdown(struct clock_event_device *evt)
 static int itimer_set_periodic(struct clock_event_device *evt)
 {
 	unsigned long long interval = NSEC_PER_SEC / HZ;
+	int cpu = evt - &timer_clockevent[0];
 
 	if (time_travel_mode != TT_MODE_OFF) {
 		time_travel_del_event(&time_travel_timer_event);
@@ -805,7 +811,7 @@ static int itimer_set_periodic(struct clock_event_device *evt)
 
 	if (time_travel_mode != TT_MODE_INFCPU &&
 	    time_travel_mode != TT_MODE_EXTERNAL)
-		os_timer_set_interval(interval);
+		os_timer_set_interval(cpu, interval);
 
 	return 0;
 }
@@ -825,7 +831,7 @@ static int itimer_next_event(unsigned long delta,
 
 	if (time_travel_mode != TT_MODE_INFCPU &&
 	    time_travel_mode != TT_MODE_EXTERNAL)
-		return os_timer_one_shot(delta);
+		return os_timer_one_shot(raw_smp_processor_id(), delta);
 
 	return 0;
 }
@@ -835,10 +841,9 @@ static int itimer_one_shot(struct clock_event_device *evt)
 	return itimer_next_event(0, evt);
 }
 
-static struct clock_event_device timer_clockevent = {
+static struct clock_event_device _timer_clockevent = {
 	.name			= "posix-timer",
 	.rating			= 250,
-	.cpumask		= cpu_possible_mask,
 	.features		= CLOCK_EVT_FEAT_PERIODIC |
 				  CLOCK_EVT_FEAT_ONESHOT,
 	.set_state_shutdown	= itimer_shutdown,
@@ -856,6 +861,9 @@ static struct clock_event_device timer_clockevent = {
 
 static irqreturn_t um_timer(int irq, void *dev)
 {
+	int cpu = raw_smp_processor_id();
+	struct clock_event_device *evt = &timer_clockevent[cpu];
+
 	/*
 	 * Interrupt the (possibly) running userspace process, technically this
 	 * should only happen if userspace is currently executing.
@@ -867,7 +875,7 @@ static irqreturn_t um_timer(int irq, void *dev)
 	    get_current()->mm)
 		os_alarm_process(get_current()->mm->context.id.pid);
 
-	(*timer_clockevent.event_handler)(&timer_clockevent);
+	evt->event_handler(evt);
 
 	return IRQ_HANDLED;
 }
@@ -904,7 +912,24 @@ static struct clocksource timer_clocksource = {
 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
-static void __init um_timer_setup(void)
+int um_setup_timer(void)
+{
+	int cpu = raw_smp_processor_id();
+	struct clock_event_device *evt = &timer_clockevent[cpu];
+	int err;
+
+	err = os_timer_create();
+	if (err)
+		return err;
+
+	memcpy(evt, &_timer_clockevent, sizeof(*evt));
+	evt->cpumask = cpumask_of(cpu);
+	clockevents_register_device(evt);
+
+	return 0;
+}
+
+static void __init um_timer_init(void)
 {
 	int err;
 
@@ -913,8 +938,8 @@ static void __init um_timer_setup(void)
 		printk(KERN_ERR "register_timer : request_irq failed - "
 		       "errno = %d\n", -err);
 
-	err = os_timer_create();
+	err = um_setup_timer();
-	if (err != 0) {
+	if (err) {
 		printk(KERN_ERR "creation of timer failed - errno = %d\n", -err);
 		return;
 	}
@@ -924,7 +949,6 @@ static void __init um_timer_setup(void)
 		printk(KERN_ERR "clocksource_register_hz returned %d\n", err);
 		return;
 	}
-	clockevents_register_device(&timer_clockevent);
 }
 
 void read_persistent_clock64(struct timespec64 *ts)
@@ -945,7 +969,7 @@ void read_persistent_clock64(struct timespec64 *ts)
 void __init time_init(void)
 {
 	timer_set_signal_handler();
-	late_time_init = um_timer_setup;
+	late_time_init = um_timer_init;
 }
 
 #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
@@ -961,21 +985,21 @@ static int setup_time_travel(char *str)
 {
 	if (strcmp(str, "=inf-cpu") == 0) {
 		time_travel_mode = TT_MODE_INFCPU;
-		timer_clockevent.name = "time-travel-timer-infcpu";
+		_timer_clockevent.name = "time-travel-timer-infcpu";
 		timer_clocksource.name = "time-travel-clock";
 		return 1;
 	}
 
 	if (strncmp(str, "=ext:", 5) == 0) {
 		time_travel_mode = TT_MODE_EXTERNAL;
-		timer_clockevent.name = "time-travel-timer-external";
+		_timer_clockevent.name = "time-travel-timer-external";
 		timer_clocksource.name = "time-travel-clock-external";
 		return time_travel_connect_external(str + 5);
 	}
 
 	if (!*str) {
 		time_travel_mode = TT_MODE_BASIC;
-		timer_clockevent.name = "time-travel-timer";
+		_timer_clockevent.name = "time-travel-timer";
 		timer_clocksource.name = "time-travel-clock";
 		return 1;
 	}

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);

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

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)
@@ -239,8 +247,6 @@ static struct notifier_block panic_exit_notifier = {
 
 void uml_finishsetup(void)
 {
-	cpu_tasks[0] = &init_task;
-
 	atomic_notifier_chain_register(&panic_notifier_list,
 				       &panic_exit_notifier);
 
@@ -254,11 +260,7 @@ unsigned long stub_start;
 unsigned long task_size;
 EXPORT_SYMBOL(task_size);
 
-unsigned long host_task_size;
-
 unsigned long brk_start;
-unsigned long end_iomem;
-EXPORT_SYMBOL(end_iomem);
 
 #define MIN_VMALLOC (32 * 1024 * 1024)
 
@@ -298,16 +300,14 @@ static unsigned long __init get_top_address(char **envp)
 			top_addr = (unsigned long) envp[i];
 	}
 
-	top_addr &= ~(UM_KERN_PAGE_SIZE - 1);
+	return PAGE_ALIGN(top_addr + 1);
-	top_addr += UM_KERN_PAGE_SIZE;
-
-	return top_addr;
 }
 
 int __init linux_main(int argc, char **argv, char **envp)
 {
 	unsigned long avail, diff;
 	unsigned long virtmem_size, max_physmem;
+	unsigned long host_task_size;
 	unsigned long stack;
 	unsigned int i;
 	int add;
@@ -354,12 +354,11 @@ int __init linux_main(int argc, char **argv, char **envp)
 	 * so they actually get what they asked for. This should
 	 * add zero for non-exec shield users
 	 */
-
+	diff = PAGE_ALIGN(brk_start) - PAGE_ALIGN((unsigned long) &_end);
-	diff = UML_ROUND_UP(brk_start) - UML_ROUND_UP(&_end);
 	if (diff > 1024 * 1024) {
 		os_info("Adding %ld bytes to physical memory to account for "
 			"exec-shield gap\n", diff);
-		physmem_size += UML_ROUND_UP(brk_start) - UML_ROUND_UP(&_end);
+		physmem_size += diff;
 	}
 
 	uml_physmem = (unsigned long) __binary_start & PAGE_MASK;
@@ -369,10 +368,8 @@ int __init linux_main(int argc, char **argv, char **envp)
 
 	setup_machinename(init_utsname()->machine);
 
-	physmem_size = (physmem_size + PAGE_SIZE - 1) & PAGE_MASK;
+	physmem_size = PAGE_ALIGN(physmem_size);
-	iomem_size = (iomem_size + PAGE_SIZE - 1) & PAGE_MASK;
+	max_physmem = TASK_SIZE - uml_physmem - MIN_VMALLOC;
-
-	max_physmem = TASK_SIZE - uml_physmem - iomem_size - MIN_VMALLOC;
 	if (physmem_size > max_physmem) {
 		physmem_size = max_physmem;
 		os_info("Physical memory size shrunk to %llu bytes\n",
@@ -380,7 +377,6 @@ int __init linux_main(int argc, char **argv, char **envp)
 	}
 
 	high_physmem = uml_physmem + physmem_size;
-	end_iomem = high_physmem + iomem_size;
 
 	start_vm = VMALLOC_START;
 
@@ -421,6 +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));
@@ -455,6 +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)
 {
 	/*

arch/um/os-Linux/Makefile

@@ -6,7 +6,7 @@
 # Don't instrument UML-specific code
 KCOV_INSTRUMENT                := n
 
-obj-y = execvp.o file.o helper.o irq.o main.o mem.o process.o \
+obj-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 user_syms.o util.o skas/
 
@@ -14,10 +14,10 @@ CFLAGS_signal.o += -Wframe-larger-than=4096
 
 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

arch/um/os-Linux/elf_aux.c

@@ -14,37 +14,26 @@
 #include <elf_user.h>
 #include <mem_user.h>
 #include "internal.h"
+#include <linux/swab.h>
 
+#if __BITS_PER_LONG == 64
+typedef Elf64_auxv_t elf_auxv_t;
+#else
 typedef Elf32_auxv_t elf_auxv_t;
+#endif
 
 /* These are initialized very early in boot and never changed */
 char * elf_aux_platform;
-extern long elf_aux_hwcap;
+long elf_aux_hwcap;
-unsigned long vsyscall_ehdr;
-unsigned long vsyscall_end;
-unsigned long __kernel_vsyscall;
 
 __init void scan_elf_aux( char **envp)
 {
-	long page_size = 0;
 	elf_auxv_t * auxv;
 
 	while ( *envp++ != NULL) ;
 
 	for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) {
 		switch ( auxv->a_type ) {
-			case AT_SYSINFO:
-				__kernel_vsyscall = auxv->a_un.a_val;
-				/* See if the page is under TASK_SIZE */
-				if (__kernel_vsyscall < (unsigned long) envp)
-					__kernel_vsyscall = 0;
-				break;
-			case AT_SYSINFO_EHDR:
-				vsyscall_ehdr = auxv->a_un.a_val;
-				/* See if the page is under TASK_SIZE */
-				if (vsyscall_ehdr < (unsigned long) envp)
-					vsyscall_ehdr = 0;
-				break;
 			case AT_HWCAP:
 				elf_aux_hwcap = auxv->a_un.a_val;
 				break;
@@ -56,20 +45,6 @@ __init void scan_elf_aux( char **envp)
 				elf_aux_platform =
 					(char *) (long) auxv->a_un.a_val;
 				break;
-			case AT_PAGESZ:
-				page_size = auxv->a_un.a_val;
-				break;
 		}
 	}
-	if ( ! __kernel_vsyscall || ! vsyscall_ehdr ||
-	     ! elf_aux_hwcap || ! elf_aux_platform ||
-	     ! page_size || (vsyscall_ehdr % page_size) ) {
-		__kernel_vsyscall = 0;
-		vsyscall_ehdr = 0;
-		elf_aux_hwcap = 0;
-		elf_aux_platform = "i586";
-	}
-	else {
-		vsyscall_end = vsyscall_ehdr + page_size;
-	}
 }

arch/um/os-Linux/internal.h

@@ -4,6 +4,7 @@
 
 #include <mm_id.h>
 #include <stub-data.h>
+#include <signal.h>
 
 /*
  * elf_aux.c
@@ -15,9 +16,21 @@ void scan_elf_aux(char **envp);
  */
 void check_tmpexec(void);
 
+/*
+ * signal.c
+ */
+extern __thread int signals_enabled;
+int timer_alarm_pending(void);
+
 /*
  * skas/process.c
  */
 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 */

arch/um/os-Linux/main.c

@@ -21,8 +21,6 @@
 
 #define STACKSIZE (8 * 1024 * 1024)
 
-long elf_aux_hwcap;
-
 static void __init set_stklim(void)
 {
 	struct rlimit lim;
@@ -149,9 +147,7 @@ int __init main(int argc, char **argv, char **envp)
 	install_fatal_handler(SIGINT);
 	install_fatal_handler(SIGTERM);
 
-#ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 	scan_elf_aux(envp);
-#endif
 
 	change_sig(SIGPIPE, 0);
 	ret = linux_main(argc, argv, envp);
@@ -171,7 +167,7 @@ int __init main(int argc, char **argv, char **envp)
 	 */
 
 	/* stop timers and set timer signal to be ignored */
-	os_timer_disable();
+	os_timer_disable(0);
 
 	/* disable SIGIO for the fds and set SIGIO to be ignored */
 	err = deactivate_all_fds();

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;
+}

arch/um/os-Linux/signal.c

@@ -20,6 +20,7 @@
 #include <um_malloc.h>
 #include <sys/ucontext.h>
 #include <timetravel.h>
+#include "internal.h"
 
 void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *, void *mc) = {
 	[SIGTRAP]	= relay_signal,
@@ -68,12 +69,12 @@ static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
 #define SIGCHLD_BIT 2
 #define SIGCHLD_MASK (1 << SIGCHLD_BIT)
 
-int signals_enabled;
+__thread int signals_enabled;
 #if IS_ENABLED(CONFIG_UML_TIME_TRAVEL_SUPPORT)
 static int signals_blocked, signals_blocked_pending;
 #endif
-static unsigned int signals_pending;
+static __thread unsigned int signals_pending;
-static unsigned int signals_active = 0;
+static __thread unsigned int signals_active;
 
 static void sig_handler(int sig, struct siginfo *si, mcontext_t *mc)
 {
@@ -159,6 +160,11 @@ void timer_set_signal_handler(void)
 	set_handler(SIGALRM);
 }
 
+int timer_alarm_pending(void)
+{
+	return !!(signals_pending & SIGALRM_MASK);
+}
+
 void set_sigstack(void *sig_stack, int size)
 {
 	stack_t stack = {
@@ -253,9 +259,29 @@ int change_sig(int signal, int on)
 	return 0;
 }
 
+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)
 {
-	signals_enabled = 0;
+	__block_signals();
 	/*
 	 * This must return with signals disabled, so this barrier
 	 * ensures that writes are flushed out before the return.
@@ -272,7 +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
@@ -306,7 +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();
 
 		/*
@@ -338,10 +365,15 @@ void unblock_signals(void)
 
 		/* Re-enable signals and trace that we're doing so. */
 		um_trace_signals_on();
-		signals_enabled = 1;
+		__unblock_signals();
 	}
 }
 
+int um_get_signals(void)
+{
+	return signals_enabled;
+}
+
 int um_set_signals(int enable)
 {
 	int ret;

arch/um/os-Linux/skas/process.c

@@ -298,7 +298,6 @@ static int userspace_tramp(void *data)
 		.seccomp = using_seccomp,
 		.stub_start = STUB_START,
 	};
-	struct iomem_region *iomem;
 	int ret;
 
 	if (using_seccomp) {
@@ -332,12 +331,6 @@ static int userspace_tramp(void *data)
 
 	fcntl(init_data.stub_data_fd, F_SETFD, 0);
 
-	/* In SECCOMP mode, these FDs are passed when needed */
-	if (!using_seccomp) {
-		for (iomem = iomem_regions; iomem; iomem = iomem->next)
-			fcntl(iomem->fd, F_SETFD, 0);
-	}
-
 	/* dup2 signaling FD/socket to STDIN */
 	if (dup2(tramp_data->sockpair[0], 0) < 0)
 		exit(3);
@@ -553,7 +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;
 
@@ -563,6 +556,13 @@ void userspace(struct uml_pt_regs *regs)
 	while (1) {
 		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
@@ -630,9 +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",
+				panic("%s - Invalid siginfo offset from child", __func__);
-				      __func__);
+
-			si = (void *)&proc_data->sigstack[proc_data->si_offset];
+			si = &si_local;
+			memcpy(si, &proc_data->sigstack[proc_data->si_offset], sizeof(*si));
 
 			regs->is_user = 1;
 
@@ -728,8 +729,8 @@ void userspace(struct uml_pt_regs *regs)
 				case SIGFPE:
 				case SIGWINCH:
 					ptrace(PTRACE_GETSIGINFO, pid, 0,
-					       (struct siginfo *)&si_ptrace);
+					       (struct siginfo *)&si_local);
-					si = &si_ptrace;
+					si = &si_local;
 					break;
 				default:
 					si = NULL;
@@ -740,6 +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) {
@@ -809,10 +812,9 @@ void switch_threads(jmp_buf *me, jmp_buf *you)
 
 static jmp_buf initial_jmpbuf;
 
-/* XXX Make these percpu */
+static __thread void (*cb_proc)(void *arg);
-static void (*cb_proc)(void *arg);
+static __thread void *cb_arg;
-static void *cb_arg;
+static __thread jmp_buf *cb_back;
-static jmp_buf *cb_back;
 
 int start_idle_thread(void *stack, jmp_buf *switch_buf)
 {
@@ -866,10 +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;
@@ -878,8 +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;
@@ -899,6 +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 */
 }

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();
+}

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();
 
@@ -489,53 +493,3 @@ void __init os_early_checks(void)
 		fatal("Failed to initialize default registers");
 	stop_ptraced_child(pid, 1);
 }
-
-int __init parse_iomem(char *str, int *add)
-{
-	struct iomem_region *new;
-	struct stat64 buf;
-	char *file, *driver;
-	int fd, size;
-
-	driver = str;
-	file = strchr(str,',');
-	if (file == NULL) {
-		os_warn("parse_iomem : failed to parse iomem\n");
-		goto out;
-	}
-	*file = '\0';
-	file++;
-	fd = open(file, O_RDWR, 0);
-	if (fd < 0) {
-		perror("parse_iomem - Couldn't open io file");
-		goto out;
-	}
-
-	if (fstat64(fd, &buf) < 0) {
-		perror("parse_iomem - cannot stat_fd file");
-		goto out_close;
-	}
-
-	new = malloc(sizeof(*new));
-	if (new == NULL) {
-		perror("Couldn't allocate iomem_region struct");
-		goto out_close;
-	}
-
-	size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
-
-	*new = ((struct iomem_region) { .next		= iomem_regions,
-					.driver		= driver,
-					.fd		= fd,
-					.size		= size,
-					.phys		= 0,
-					.virt		= 0 });
-	iomem_regions = new;
-	iomem_size += new->size + UM_KERN_PAGE_SIZE;
-
-	return 0;
- out_close:
-	close(fd);
- out:
-	return 1;
-}

arch/um/os-Linux/time.c

@@ -11,12 +11,15 @@
 #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"
 
-static timer_t event_high_res_timer = 0;
+static timer_t event_high_res_timer[CONFIG_NR_CPUS] = { 0 };
 
 static inline long long timespec_to_ns(const struct timespec *ts)
 {
@@ -31,20 +34,31 @@ long long os_persistent_clock_emulation(void)
 	return timespec_to_ns(&realtime_tp);
 }
 
+#ifndef sigev_notify_thread_id
+#define sigev_notify_thread_id _sigev_un._tid
+#endif
+
 /**
  * os_timer_create() - create an new posix (interval) timer
  */
 int os_timer_create(void)
 {
-	timer_t *t = &event_high_res_timer;
+	int cpu = uml_curr_cpu();
+	timer_t *t = &event_high_res_timer[cpu];
+	struct sigevent sev = {
+		.sigev_notify = SIGEV_THREAD_ID,
+		.sigev_signo = SIGALRM,
+		.sigev_value.sival_ptr = t,
+		.sigev_notify_thread_id = gettid(),
+	};
 
-	if (timer_create(CLOCK_MONOTONIC, NULL, t) == -1)
+	if (timer_create(CLOCK_MONOTONIC, &sev, t) == -1)
 		return -1;
 
 	return 0;
 }
 
-int os_timer_set_interval(unsigned long long nsecs)
+int os_timer_set_interval(int cpu, unsigned long long nsecs)
 {
 	struct itimerspec its;
 
@@ -54,13 +68,13 @@ int os_timer_set_interval(unsigned long long nsecs)
 	its.it_interval.tv_sec = nsecs / UM_NSEC_PER_SEC;
 	its.it_interval.tv_nsec = nsecs % UM_NSEC_PER_SEC;
 
-	if (timer_settime(event_high_res_timer, 0, &its, NULL) == -1)
+	if (timer_settime(event_high_res_timer[cpu], 0, &its, NULL) == -1)
 		return -errno;
 
 	return 0;
 }
 
-int os_timer_one_shot(unsigned long long nsecs)
+int os_timer_one_shot(int cpu, unsigned long long nsecs)
 {
 	struct itimerspec its = {
 		.it_value.tv_sec = nsecs / UM_NSEC_PER_SEC,
@@ -70,19 +84,20 @@ int os_timer_one_shot(unsigned long long nsecs)
 		.it_interval.tv_nsec = 0, // we cheat here
 	};
 
-	timer_settime(event_high_res_timer, 0, &its, NULL);
+	timer_settime(event_high_res_timer[cpu], 0, &its, NULL);
 	return 0;
 }
 
 /**
  * os_timer_disable() - disable the posix (interval) timer
+ * @cpu: the CPU for which the timer is to be disabled
  */
-void os_timer_disable(void)
+void os_timer_disable(int cpu)
 {
 	struct itimerspec its;
 
 	memset(&its, 0, sizeof(struct itimerspec));
-	timer_settime(event_high_res_timer, 0, &its, NULL);
+	timer_settime(event_high_res_timer[cpu], 0, &its, NULL);
 }
 
 long long os_nsecs(void)
@@ -93,23 +108,50 @@ 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)
 {
-	struct itimerspec its;
+	sigset_t set;
-	sigset_t set, old;
 
-	/* block SIGALRM while we analyze the timer state */
+	/*
+	 * 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);
 
-	/* check the timer, and if it'll fire then wait for it */
+	/*
-	timer_gettime(event_high_res_timer, &its);
+	 * Because disabling IRQs does not block SIGALRM, it is also
-	if (its.it_value.tv_sec || its.it_value.tv_nsec)
+	 * necessary to check for any pending timer alarms.
-		sigsuspend(&old);
+	 */
-	/* either way, restore the signal mask */
+	if (!uml_need_resched() && !timer_alarm_pending())
+		os_poll(1, &wake_signals);
+
+	/* Restore the signal mask. */
 	sigprocmask(SIG_UNBLOCK, &set, NULL);
 }

arch/um/os-Linux/user_syms.c

@@ -31,12 +31,6 @@ extern void *memset(void *, int, size_t);
 EXPORT_SYMBOL(memset);
 #endif
 
-#ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
-/* needed for __access_ok() */
-EXPORT_SYMBOL(vsyscall_ehdr);
-EXPORT_SYMBOL(vsyscall_end);
-#endif
-
 #ifdef _FORTIFY_SOURCE
 extern int __sprintf_chk(char *str, int flag, size_t len, const char *format);
 EXPORT_SYMBOL(__sprintf_chk);

arch/x86/um/Kconfig

@@ -8,9 +8,11 @@ endmenu
 
 config UML_X86
 	def_bool y
-	select ARCH_BINFMT_ELF_EXTRA_PHDRS if X86_32
+	select ARCH_USE_QUEUED_RWLOCKS
+	select ARCH_USE_QUEUED_SPINLOCKS
 	select DCACHE_WORD_ACCESS
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
+	select UML_SUBARCH_SUPPORTS_SMP if X86_CX8
 
 config 64BIT
 	bool "64-bit kernel" if "$(SUBARCH)" = "x86"
@@ -32,8 +34,5 @@ config X86_64
 config ARCH_HAS_SC_SIGNALS
 	def_bool !64BIT
 
-config ARCH_REUSE_HOST_VSYSCALL_AREA
-	def_bool !64BIT
-
 config GENERIC_HWEIGHT
 	def_bool y

arch/x86/um/Makefile

@@ -13,12 +13,11 @@ obj-y = bugs_$(BITS).o delay.o fault.o \
 	ptrace.o ptrace_$(BITS).o ptrace_user.o setjmp_$(BITS).o signal.o \
 	stub_segv.o \
 	sys_call_table_$(BITS).o sysrq_$(BITS).o tls_$(BITS).o \
-	mem_$(BITS).o subarch.o os-Linux/
+	subarch.o os-Linux/
 
 ifeq ($(CONFIG_X86_32),y)
 
 obj-y += syscalls_32.o
-obj-$(CONFIG_ELF_CORE) += elfcore.o
 
 subarch-y = ../lib/string_32.o ../lib/atomic64_32.o ../lib/atomic64_cx8_32.o
 subarch-y += ../lib/cmpxchg8b_emu.o ../lib/atomic64_386_32.o
@@ -27,7 +26,7 @@ subarch-y += ../kernel/sys_ia32.o
 
 else
 
-obj-y += syscalls_64.o vdso/
+obj-y += mem_64.o syscalls_64.o vdso/
 
 subarch-y = ../lib/csum-partial_64.o ../lib/memcpy_64.o \
 	../lib/memmove_64.o ../lib/memset_64.o

arch/x86/um/asm/elf.h

@@ -68,35 +68,7 @@
 	pr_reg[16] = PT_REGS_SS(regs);		\
 } while (0);
 
-extern char * elf_aux_platform;
+#define ELF_PLATFORM_FALLBACK "i586"
-#define ELF_PLATFORM (elf_aux_platform)
-
-extern unsigned long vsyscall_ehdr;
-extern unsigned long vsyscall_end;
-extern unsigned long __kernel_vsyscall;
-
-/*
- * This is the range that is readable by user mode, and things
- * acting like user mode such as get_user_pages.
- */
-#define FIXADDR_USER_START      vsyscall_ehdr
-#define FIXADDR_USER_END        vsyscall_end
-
-
-/*
- * Architecture-neutral AT_ values in 0-17, leave some room
- * for more of them, start the x86-specific ones at 32.
- */
-#define AT_SYSINFO		32
-#define AT_SYSINFO_EHDR		33
-
-#define ARCH_DLINFO						\
-do {								\
-	if ( vsyscall_ehdr ) {					\
-		NEW_AUX_ENT(AT_SYSINFO,	__kernel_vsyscall);	\
-		NEW_AUX_ENT(AT_SYSINFO_EHDR, vsyscall_ehdr);	\
-	}							\
-} while (0)
 
 #else
 
@@ -177,11 +149,7 @@ do {								\
 	(pr_reg)[25] = 0;					\
 	(pr_reg)[26] = 0;
 
-#define ELF_PLATFORM "x86_64"
+#define ELF_PLATFORM_FALLBACK "x86_64"
-
-/* No user-accessible fixmap addresses, i.e. vsyscall */
-#define FIXADDR_USER_START      0
-#define FIXADDR_USER_END        0
 
 #define ARCH_HAS_SETUP_ADDITIONAL_PAGES 1
 struct linux_binprm;
@@ -210,6 +178,9 @@ struct task_struct;
 extern long elf_aux_hwcap;
 #define ELF_HWCAP (elf_aux_hwcap)
 
+extern char *elf_aux_platform;
+#define ELF_PLATFORM (elf_aux_platform ?: ELF_PLATFORM_FALLBACK)
+
 #define SET_PERSONALITY(ex) do {} while(0)
 
 #endif

arch/x86/um/asm/spinlock.h

@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_UM_SPINLOCK_H
+#define __ASM_UM_SPINLOCK_H
+
+#include <asm/qspinlock.h>
+#include <asm/qrwlock.h>
+
+#endif /* __ASM_UM_SPINLOCK_H */

arch/x86/um/elfcore.c

@@ -1,78 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-#include <linux/elf.h>
-#include <linux/elfcore.h>
-#include <linux/coredump.h>
-#include <linux/fs.h>
-#include <linux/mm.h>
-
-#include <asm/elf.h>
-
-
-Elf32_Half elf_core_extra_phdrs(struct coredump_params *cprm)
-{
-	return vsyscall_ehdr ? (((struct elfhdr *)vsyscall_ehdr)->e_phnum) : 0;
-}
-
-int elf_core_write_extra_phdrs(struct coredump_params *cprm, loff_t offset)
-{
-	if ( vsyscall_ehdr ) {
-		const struct elfhdr *const ehdrp =
-			(struct elfhdr *) vsyscall_ehdr;
-		const struct elf_phdr *const phdrp =
-			(const struct elf_phdr *) (vsyscall_ehdr + ehdrp->e_phoff);
-		int i;
-		Elf32_Off ofs = 0;
-
-		for (i = 0; i < ehdrp->e_phnum; ++i) {
-			struct elf_phdr phdr = phdrp[i];
-
-			if (phdr.p_type == PT_LOAD) {
-				ofs = phdr.p_offset = offset;
-				offset += phdr.p_filesz;
-			} else {
-				phdr.p_offset += ofs;
-			}
-			phdr.p_paddr = 0; /* match other core phdrs */
-			if (!dump_emit(cprm, &phdr, sizeof(phdr)))
-				return 0;
-		}
-	}
-	return 1;
-}
-
-int elf_core_write_extra_data(struct coredump_params *cprm)
-{
-	if ( vsyscall_ehdr ) {
-		const struct elfhdr *const ehdrp =
-			(struct elfhdr *) vsyscall_ehdr;
-		const struct elf_phdr *const phdrp =
-			(const struct elf_phdr *) (vsyscall_ehdr + ehdrp->e_phoff);
-		int i;
-
-		for (i = 0; i < ehdrp->e_phnum; ++i) {
-			if (phdrp[i].p_type == PT_LOAD) {
-				void *addr = (void *) phdrp[i].p_vaddr;
-				size_t filesz = phdrp[i].p_filesz;
-				if (!dump_emit(cprm, addr, filesz))
-					return 0;
-			}
-		}
-	}
-	return 1;
-}
-
-size_t elf_core_extra_data_size(struct coredump_params *cprm)
-{
-	if ( vsyscall_ehdr ) {
-		const struct elfhdr *const ehdrp =
-			(struct elfhdr *)vsyscall_ehdr;
-		const struct elf_phdr *const phdrp =
-			(const struct elf_phdr *) (vsyscall_ehdr + ehdrp->e_phoff);
-		int i;
-
-		for (i = 0; i < ehdrp->e_phnum; ++i)
-			if (phdrp[i].p_type == PT_LOAD)
-				return (size_t) phdrp[i].p_filesz;
-	}
-	return 0;
-}

arch/x86/um/mem_32.c

@@ -1,50 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
- */
-
-#include <linux/mm.h>
-#include <asm/elf.h>
-
-static struct vm_area_struct gate_vma;
-
-static int __init gate_vma_init(void)
-{
-	if (!FIXADDR_USER_START)
-		return 0;
-
-	vma_init(&gate_vma, NULL);
-	gate_vma.vm_start = FIXADDR_USER_START;
-	gate_vma.vm_end = FIXADDR_USER_END;
-	vm_flags_init(&gate_vma, VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC);
-	gate_vma.vm_page_prot = PAGE_READONLY;
-
-	return 0;
-}
-__initcall(gate_vma_init);
-
-struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
-{
-	return FIXADDR_USER_START ? &gate_vma : NULL;
-}
-
-int in_gate_area_no_mm(unsigned long addr)
-{
-	if (!FIXADDR_USER_START)
-		return 0;
-
-	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
-		return 1;
-
-	return 0;
-}
-
-int in_gate_area(struct mm_struct *mm, unsigned long addr)
-{
-	struct vm_area_struct *vma = get_gate_vma(mm);
-
-	if (!vma)
-		return 0;
-
-	return (addr >= vma->vm_start) && (addr < vma->vm_end);
-}

arch/x86/um/shared/sysdep/kernel-offsets.h

@@ -1,17 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#include <linux/stddef.h>
-#include <linux/sched.h>
-#include <linux/elf.h>
-#include <linux/crypto.h>
-#include <linux/kbuild.h>
-#include <linux/audit.h>
-#include <asm/mman.h>
-#include <asm/seccomp.h>
-
-/* workaround for a warning with -Wmissing-prototypes */
-void foo(void);
-
-void foo(void)
-{
-#include <common-offsets.h>
-}

arch/x86/um/vdso/Makefile

@@ -3,16 +3,13 @@
 # Building vDSO images for x86.
 #
 
-VDSO64-y		:= y
+vdso-install-y += vdso.so
-
-vdso-install-$(VDSO64-y)	+= vdso.so
-
 
 # files to link into the vdso
 vobjs-y := vdso-note.o um_vdso.o
 
 # files to link into kernel
-obj-$(VDSO64-y)			+= vdso.o vma.o
+obj-y += vdso.o vma.o
 
 vobjs := $(foreach F,$(vobjs-y),$(obj)/$F)
 

arch/x86/um/vdso/um_vdso.c

@@ -9,17 +9,11 @@
 /* Disable profiling for userspace code */
 #define DISABLE_BRANCH_PROFILING
 
+#include <vdso/gettime.h>
 #include <linux/time.h>
-#include <linux/getcpu.h>
 #include <asm/unistd.h>
 
-/* workaround for -Wmissing-prototypes warnings */
+int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
-int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts);
-int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz);
-__kernel_old_time_t __vdso_time(__kernel_old_time_t *t);
-long __vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused);
-
-int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts)
 {
 	long ret;
 
@@ -30,7 +24,7 @@ int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts)
 
 	return ret;
 }
-int clock_gettime(clockid_t, struct __kernel_old_timespec *)
+int clock_gettime(clockid_t, struct __kernel_timespec *)
 	__attribute__((weak, alias("__vdso_clock_gettime")));
 
 int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
@@ -58,21 +52,3 @@ __kernel_old_time_t __vdso_time(__kernel_old_time_t *t)
 	return secs;
 }
 __kernel_old_time_t time(__kernel_old_time_t *t) __attribute__((weak, alias("__vdso_time")));
-
-long
-__vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused)
-{
-	/*
-	 * UML does not support SMP, we can cheat here. :)
-	 */
-
-	if (cpu)
-		*cpu = 0;
-	if (node)
-		*node = 0;
-
-	return 0;
-}
-
-long getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *tcache)
-	__attribute__((weak, alias("__vdso_getcpu")));

arch/x86/um/vdso/vdso.lds.S

@@ -22,8 +22,6 @@ VERSION {
 		__vdso_clock_gettime;
 		gettimeofday;
 		__vdso_gettimeofday;
-		getcpu;
-		__vdso_getcpu;
 		time;
 		__vdso_time;
 	local: *;

arch/x86/um/vdso/vma.c

@@ -10,7 +10,6 @@
 #include <asm/elf.h>
 #include <linux/init.h>
 
-static unsigned int __read_mostly vdso_enabled = 1;
 unsigned long um_vdso_addr;
 static struct page *um_vdso;
 
@@ -25,17 +24,11 @@ static int __init init_vdso(void)
 
 	um_vdso = alloc_page(GFP_KERNEL);
 	if (!um_vdso)
-		goto oom;
+		panic("Cannot allocate vdso\n");
 
 	copy_page(page_address(um_vdso), vdso_start);
 
 	return 0;
-
-oom:
-	printk(KERN_ERR "Cannot allocate vdso\n");
-	vdso_enabled = 0;
-
-	return -ENOMEM;
 }
 subsys_initcall(init_vdso);
 
@@ -48,9 +41,6 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 		.pages = &um_vdso,
 	};
 
-	if (!vdso_enabled)
-		return 0;
-
 	if (mmap_write_lock_killable(mm))
 		return -EINTR;
 

fs/hostfs/hostfs.h

@@ -3,40 +3,8 @@
 #define __UM_FS_HOSTFS
 
 #include <os.h>
+#include <generated/asm-offsets.h>
 
-/*
- * These are exactly the same definitions as in fs.h, but the names are
- * changed so that this file can be included in both kernel and user files.
- */
-
-#define HOSTFS_ATTR_MODE	1
-#define HOSTFS_ATTR_UID 	2
-#define HOSTFS_ATTR_GID 	4
-#define HOSTFS_ATTR_SIZE	8
-#define HOSTFS_ATTR_ATIME	16
-#define HOSTFS_ATTR_MTIME	32
-#define HOSTFS_ATTR_CTIME	64
-#define HOSTFS_ATTR_ATIME_SET	128
-#define HOSTFS_ATTR_MTIME_SET	256
-
-/* This one is unused by hostfs. */
-#define HOSTFS_ATTR_FORCE	512	/* Not a change, but a change it */
-#define HOSTFS_ATTR_ATTR_FLAG	1024
-
-/*
- * If you are very careful, you'll notice that these two are missing:
- *
- * #define ATTR_KILL_SUID	2048
- * #define ATTR_KILL_SGID	4096
- *
- * and this is because they were added in 2.5 development.
- * Actually, they are not needed by most ->setattr() methods - they are set by
- * callers of notify_change() to notify that the setuid/setgid bits must be
- * dropped.
- * notify_change() will delete those flags, make sure attr->ia_valid & ATTR_MODE
- * is on, and remove the appropriate bits from attr->ia_mode (attr is a
- * "struct iattr *"). -BlaisorBlade
- */
 struct hostfs_timespec {
 	long long tv_sec;
 	long long tv_nsec;

include/asm-generic/percpu.h

@@ -2,6 +2,8 @@
 #ifndef _ASM_GENERIC_PERCPU_H_
 #define _ASM_GENERIC_PERCPU_H_
 
+#ifndef __ASSEMBLER__
+
 #include <linux/compiler.h>
 #include <linux/threads.h>
 #include <linux/percpu-defs.h>
@@ -557,4 +559,5 @@ do {									\
 	this_cpu_generic_cmpxchg(pcp, oval, nval)
 #endif
 
+#endif /* __ASSEMBLER__ */
 #endif /* _ASM_GENERIC_PERCPU_H_ */