Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 728 insertions, 0 deletions

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
new file mode 100644
index 000000000..59f71d0f2
--- /dev/null
+++ b/arch/x86/kernel/process_64.c
@@ -0,0 +1,728 @@
+/*
+ *  Copyright (C) 1995  Linus Torvalds
+ *
+ *  Pentium III FXSR, SSE support
+ *	Gareth Hughes <gareth@valinux.com>, May 2000
+ *
+ *  X86-64 port
+ *	Andi Kleen.
+ *
+ *	CPU hotplug support - ashok.raj@intel.com
+ */
+
+/*
+ * This file handles the architecture-dependent parts of process handling..
+ */
+
+#include <linux/cpu.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/sched/task.h>
+#include <linux/sched/task_stack.h>
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/elfcore.h>
+#include <linux/smp.h>
+#include <linux/slab.h>
+#include <linux/user.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/export.h>
+#include <linux/ptrace.h>
+#include <linux/notifier.h>
+#include <linux/kprobes.h>
+#include <linux/kdebug.h>
+#include <linux/prctl.h>
+#include <linux/uaccess.h>
+#include <linux/io.h>
+#include <linux/ftrace.h>
+#include <linux/syscalls.h>
+
+#include <asm/pgtable.h>
+#include <asm/processor.h>
+#include <asm/fpu/internal.h>
+#include <asm/mmu_context.h>
+#include <asm/prctl.h>
+#include <asm/desc.h>
+#include <asm/proto.h>
+#include <asm/ia32.h>
+#include <asm/syscalls.h>
+#include <asm/debugreg.h>
+#include <asm/switch_to.h>
+#include <asm/xen/hypervisor.h>
+#include <asm/vdso.h>
+#include <asm/intel_rdt_sched.h>
+#include <asm/unistd.h>
+#ifdef CONFIG_IA32_EMULATION
+/* Not included via unistd.h */
+#include <asm/unistd_32_ia32.h>
+#endif
+
+#include "process.h"
+
+__visible DEFINE_PER_CPU(unsigned long, rsp_scratch);
+
+/* Prints also some state that isn't saved in the pt_regs */
+void __show_regs(struct pt_regs *regs, enum show_regs_mode mode)
+{
+	unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs;
+	unsigned long d0, d1, d2, d3, d6, d7;
+	unsigned int fsindex, gsindex;
+	unsigned int ds, cs, es;
+
+	show_iret_regs(regs);
+
+	if (regs->orig_ax != -1)
+		pr_cont(" ORIG_RAX: %016lx\n", regs->orig_ax);
+	else
+		pr_cont("\n");
+
+	printk(KERN_DEFAULT "RAX: %016lx RBX: %016lx RCX: %016lx\n",
+	       regs->ax, regs->bx, regs->cx);
+	printk(KERN_DEFAULT "RDX: %016lx RSI: %016lx RDI: %016lx\n",
+	       regs->dx, regs->si, regs->di);
+	printk(KERN_DEFAULT "RBP: %016lx R08: %016lx R09: %016lx\n",
+	       regs->bp, regs->r8, regs->r9);
+	printk(KERN_DEFAULT "R10: %016lx R11: %016lx R12: %016lx\n",
+	       regs->r10, regs->r11, regs->r12);
+	printk(KERN_DEFAULT "R13: %016lx R14: %016lx R15: %016lx\n",
+	       regs->r13, regs->r14, regs->r15);
+
+	if (mode == SHOW_REGS_SHORT)
+		return;
+
+	if (mode == SHOW_REGS_USER) {
+		rdmsrl(MSR_FS_BASE, fs);
+		rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
+		printk(KERN_DEFAULT "FS:  %016lx GS:  %016lx\n",
+		       fs, shadowgs);
+		return;
+	}
+
+	asm("movl %%ds,%0" : "=r" (ds));
+	asm("movl %%cs,%0" : "=r" (cs));
+	asm("movl %%es,%0" : "=r" (es));
+	asm("movl %%fs,%0" : "=r" (fsindex));
+	asm("movl %%gs,%0" : "=r" (gsindex));
+
+	rdmsrl(MSR_FS_BASE, fs);
+	rdmsrl(MSR_GS_BASE, gs);
+	rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
+
+	cr0 = read_cr0();
+	cr2 = read_cr2();
+	cr3 = __read_cr3();
+	cr4 = __read_cr4();
+
+	printk(KERN_DEFAULT "FS:  %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",
+	       fs, fsindex, gs, gsindex, shadowgs);
+	printk(KERN_DEFAULT "CS:  %04x DS: %04x ES: %04x CR0: %016lx\n", cs, ds,
+			es, cr0);
+	printk(KERN_DEFAULT "CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3,
+			cr4);
+
+	get_debugreg(d0, 0);
+	get_debugreg(d1, 1);
+	get_debugreg(d2, 2);
+	get_debugreg(d3, 3);
+	get_debugreg(d6, 6);
+	get_debugreg(d7, 7);
+
+	/* Only print out debug registers if they are in their non-default state. */
+	if (!((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) &&
+	    (d6 == DR6_RESERVED) && (d7 == 0x400))) {
+		printk(KERN_DEFAULT "DR0: %016lx DR1: %016lx DR2: %016lx\n",
+		       d0, d1, d2);
+		printk(KERN_DEFAULT "DR3: %016lx DR6: %016lx DR7: %016lx\n",
+		       d3, d6, d7);
+	}
+
+	if (boot_cpu_has(X86_FEATURE_OSPKE))
+		printk(KERN_DEFAULT "PKRU: %08x\n", read_pkru());
+}
+
+void release_thread(struct task_struct *dead_task)
+{
+	if (dead_task->mm) {
+#ifdef CONFIG_MODIFY_LDT_SYSCALL
+		if (dead_task->mm->context.ldt) {
+			pr_warn("WARNING: dead process %s still has LDT? <%p/%d>\n",
+				dead_task->comm,
+				dead_task->mm->context.ldt->entries,
+				dead_task->mm->context.ldt->nr_entries);
+			BUG();
+		}
+#endif
+	}
+}
+
+enum which_selector {
+	FS,
+	GS
+};
+
+/*
+ * Saves the FS or GS base for an outgoing thread if FSGSBASE extensions are
+ * not available.  The goal is to be reasonably fast on non-FSGSBASE systems.
+ * It's forcibly inlined because it'll generate better code and this function
+ * is hot.
+ */
+static __always_inline void save_base_legacy(struct task_struct *prev_p,
+					     unsigned short selector,
+					     enum which_selector which)
+{
+	if (likely(selector == 0)) {
+		/*
+		 * On Intel (without X86_BUG_NULL_SEG), the segment base could
+		 * be the pre-existing saved base or it could be zero.  On AMD
+		 * (with X86_BUG_NULL_SEG), the segment base could be almost
+		 * anything.
+		 *
+		 * This branch is very hot (it's hit twice on almost every
+		 * context switch between 64-bit programs), and avoiding
+		 * the RDMSR helps a lot, so we just assume that whatever
+		 * value is already saved is correct.  This matches historical
+		 * Linux behavior, so it won't break existing applications.
+		 *
+		 * To avoid leaking state, on non-X86_BUG_NULL_SEG CPUs, if we
+		 * report that the base is zero, it needs to actually be zero:
+		 * see the corresponding logic in load_seg_legacy.
+		 */
+	} else {
+		/*
+		 * If the selector is 1, 2, or 3, then the base is zero on
+		 * !X86_BUG_NULL_SEG CPUs and could be anything on
+		 * X86_BUG_NULL_SEG CPUs.  In the latter case, Linux
+		 * has never attempted to preserve the base across context
+		 * switches.
+		 *
+		 * If selector > 3, then it refers to a real segment, and
+		 * saving the base isn't necessary.
+		 */
+		if (which == FS)
+			prev_p->thread.fsbase = 0;
+		else
+			prev_p->thread.gsbase = 0;
+	}
+}
+
+static __always_inline void save_fsgs(struct task_struct *task)
+{
+	savesegment(fs, task->thread.fsindex);
+	savesegment(gs, task->thread.gsindex);
+	save_base_legacy(task, task->thread.fsindex, FS);
+	save_base_legacy(task, task->thread.gsindex, GS);
+}
+
+#if IS_ENABLED(CONFIG_KVM)
+/*
+ * While a process is running,current->thread.fsbase and current->thread.gsbase
+ * may not match the corresponding CPU registers (see save_base_legacy()). KVM
+ * wants an efficient way to save and restore FSBASE and GSBASE.
+ * When FSGSBASE extensions are enabled, this will have to use RD{FS,GS}BASE.
+ */
+void save_fsgs_for_kvm(void)
+{
+	save_fsgs(current);
+}
+EXPORT_SYMBOL_GPL(save_fsgs_for_kvm);
+#endif
+
+static __always_inline void loadseg(enum which_selector which,
+				    unsigned short sel)
+{
+	if (which == FS)
+		loadsegment(fs, sel);
+	else
+		load_gs_index(sel);
+}
+
+static __always_inline void load_seg_legacy(unsigned short prev_index,
+					    unsigned long prev_base,
+					    unsigned short next_index,
+					    unsigned long next_base,
+					    enum which_selector which)
+{
+	if (likely(next_index <= 3)) {
+		/*
+		 * The next task is using 64-bit TLS, is not using this
+		 * segment at all, or is having fun with arcane CPU features.
+		 */
+		if (next_base == 0) {
+			/*
+			 * Nasty case: on AMD CPUs, we need to forcibly zero
+			 * the base.
+			 */
+			if (static_cpu_has_bug(X86_BUG_NULL_SEG)) {
+				loadseg(which, __USER_DS);
+				loadseg(which, next_index);
+			} else {
+				/*
+				 * We could try to exhaustively detect cases
+				 * under which we can skip the segment load,
+				 * but there's really only one case that matters
+				 * for performance: if both the previous and
+				 * next states are fully zeroed, we can skip
+				 * the load.
+				 *
+				 * (This assumes that prev_base == 0 has no
+				 * false positives.  This is the case on
+				 * Intel-style CPUs.)
+				 */
+				if (likely(prev_index | next_index | prev_base))
+					loadseg(which, next_index);
+			}
+		} else {
+			if (prev_index != next_index)
+				loadseg(which, next_index);
+			wrmsrl(which == FS ? MSR_FS_BASE : MSR_KERNEL_GS_BASE,
+			       next_base);
+		}
+	} else {
+		/*
+		 * The next task is using a real segment.  Loading the selector
+		 * is sufficient.
+		 */
+		loadseg(which, next_index);
+	}
+}
+
+int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
+		unsigned long arg, struct task_struct *p, unsigned long tls)
+{
+	int err;
+	struct pt_regs *childregs;
+	struct fork_frame *fork_frame;
+	struct inactive_task_frame *frame;
+	struct task_struct *me = current;
+
+	childregs = task_pt_regs(p);
+	fork_frame = container_of(childregs, struct fork_frame, regs);
+	frame = &fork_frame->frame;
+
+	/*
+	 * For a new task use the RESET flags value since there is no before.
+	 * All the status flags are zero; DF and all the system flags must also
+	 * be 0, specifically IF must be 0 because we context switch to the new
+	 * task with interrupts disabled.
+	 */
+	frame->flags = X86_EFLAGS_FIXED;
+	frame->bp = 0;
+	frame->ret_addr = (unsigned long) ret_from_fork;
+	p->thread.sp = (unsigned long) fork_frame;
+	p->thread.io_bitmap_ptr = NULL;
+
+	savesegment(gs, p->thread.gsindex);
+	p->thread.gsbase = p->thread.gsindex ? 0 : me->thread.gsbase;
+	savesegment(fs, p->thread.fsindex);
+	p->thread.fsbase = p->thread.fsindex ? 0 : me->thread.fsbase;
+	savesegment(es, p->thread.es);
+	savesegment(ds, p->thread.ds);
+	memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
+
+	if (unlikely(p->flags & PF_KTHREAD)) {
+		/* kernel thread */
+		memset(childregs, 0, sizeof(struct pt_regs));
+		frame->bx = sp;		/* function */
+		frame->r12 = arg;
+		return 0;
+	}
+	frame->bx = 0;
+	*childregs = *current_pt_regs();
+
+	childregs->ax = 0;
+	if (sp)
+		childregs->sp = sp;
+
+	err = -ENOMEM;
+	if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) {
+		p->thread.io_bitmap_ptr = kmemdup(me->thread.io_bitmap_ptr,
+						  IO_BITMAP_BYTES, GFP_KERNEL);
+		if (!p->thread.io_bitmap_ptr) {
+			p->thread.io_bitmap_max = 0;
+			return -ENOMEM;
+		}
+		set_tsk_thread_flag(p, TIF_IO_BITMAP);
+	}
+
+	/*
+	 * Set a new TLS for the child thread?
+	 */
+	if (clone_flags & CLONE_SETTLS) {
+#ifdef CONFIG_IA32_EMULATION
+		if (in_ia32_syscall())
+			err = do_set_thread_area(p, -1,
+				(struct user_desc __user *)tls, 0);
+		else
+#endif
+			err = do_arch_prctl_64(p, ARCH_SET_FS, tls);
+		if (err)
+			goto out;
+	}
+	err = 0;
+out:
+	if (err && p->thread.io_bitmap_ptr) {
+		kfree(p->thread.io_bitmap_ptr);
+		p->thread.io_bitmap_max = 0;
+	}
+
+	return err;
+}
+
+static void
+start_thread_common(struct pt_regs *regs, unsigned long new_ip,
+		    unsigned long new_sp,
+		    unsigned int _cs, unsigned int _ss, unsigned int _ds)
+{
+	WARN_ON_ONCE(regs != current_pt_regs());
+
+	if (static_cpu_has(X86_BUG_NULL_SEG)) {
+		/* Loading zero below won't clear the base. */
+		loadsegment(fs, __USER_DS);
+		load_gs_index(__USER_DS);
+	}
+
+	loadsegment(fs, 0);
+	loadsegment(es, _ds);
+	loadsegment(ds, _ds);
+	load_gs_index(0);
+
+	regs->ip		= new_ip;
+	regs->sp		= new_sp;
+	regs->cs		= _cs;
+	regs->ss		= _ss;
+	regs->flags		= X86_EFLAGS_IF;
+	force_iret();
+}
+
+void
+start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
+{
+	start_thread_common(regs, new_ip, new_sp,
+			    __USER_CS, __USER_DS, 0);
+}
+EXPORT_SYMBOL_GPL(start_thread);
+
+#ifdef CONFIG_COMPAT
+void compat_start_thread(struct pt_regs *regs, u32 new_ip, u32 new_sp)
+{
+	start_thread_common(regs, new_ip, new_sp,
+			    test_thread_flag(TIF_X32)
+			    ? __USER_CS : __USER32_CS,
+			    __USER_DS, __USER_DS);
+}
+#endif
+
+/*
+ *	switch_to(x,y) should switch tasks from x to y.
+ *
+ * This could still be optimized:
+ * - fold all the options into a flag word and test it with a single test.
+ * - could test fs/gs bitsliced
+ *
+ * Kprobes not supported here. Set the probe on schedule instead.
+ * Function graph tracer not supported too.
+ */
+__visible __notrace_funcgraph struct task_struct *
+__switch_to(struct task_struct *prev_p, struct task_struct *next_p)
+{
+	struct thread_struct *prev = &prev_p->thread;
+	struct thread_struct *next = &next_p->thread;
+	struct fpu *prev_fpu = &prev->fpu;
+	struct fpu *next_fpu = &next->fpu;
+	int cpu = smp_processor_id();
+
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ENTRY) &&
+		     this_cpu_read(irq_count) != -1);
+
+	switch_fpu_prepare(prev_fpu, cpu);
+
+	/* We must save %fs and %gs before load_TLS() because
+	 * %fs and %gs may be cleared by load_TLS().
+	 *
+	 * (e.g. xen_load_tls())
+	 */
+	save_fsgs(prev_p);
+
+	/*
+	 * Load TLS before restoring any segments so that segment loads
+	 * reference the correct GDT entries.
+	 */
+	load_TLS(next, cpu);
+
+	/*
+	 * Leave lazy mode, flushing any hypercalls made here.  This
+	 * must be done after loading TLS entries in the GDT but before
+	 * loading segments that might reference them, and and it must
+	 * be done before fpu__restore(), so the TS bit is up to
+	 * date.
+	 */
+	arch_end_context_switch(next_p);
+
+	/* Switch DS and ES.
+	 *
+	 * Reading them only returns the selectors, but writing them (if
+	 * nonzero) loads the full descriptor from the GDT or LDT.  The
+	 * LDT for next is loaded in switch_mm, and the GDT is loaded
+	 * above.
+	 *
+	 * We therefore need to write new values to the segment
+	 * registers on every context switch unless both the new and old
+	 * values are zero.
+	 *
+	 * Note that we don't need to do anything for CS and SS, as
+	 * those are saved and restored as part of pt_regs.
+	 */
+	savesegment(es, prev->es);
+	if (unlikely(next->es | prev->es))
+		loadsegment(es, next->es);
+
+	savesegment(ds, prev->ds);
+	if (unlikely(next->ds | prev->ds))
+		loadsegment(ds, next->ds);
+
+	load_seg_legacy(prev->fsindex, prev->fsbase,
+			next->fsindex, next->fsbase, FS);
+	load_seg_legacy(prev->gsindex, prev->gsbase,
+			next->gsindex, next->gsbase, GS);
+
+	switch_fpu_finish(next_fpu, cpu);
+
+	/*
+	 * Switch the PDA and FPU contexts.
+	 */
+	this_cpu_write(current_task, next_p);
+	this_cpu_write(cpu_current_top_of_stack, task_top_of_stack(next_p));
+
+	/* Reload sp0. */
+	update_task_stack(next_p);
+
+	switch_to_extra(prev_p, next_p);
+
+#ifdef CONFIG_XEN_PV
+	/*
+	 * On Xen PV, IOPL bits in pt_regs->flags have no effect, and
+	 * current_pt_regs()->flags may not match the current task's
+	 * intended IOPL.  We need to switch it manually.
+	 */
+	if (unlikely(static_cpu_has(X86_FEATURE_XENPV) &&
+		     prev->iopl != next->iopl))
+		xen_set_iopl_mask(next->iopl);
+#endif
+
+	if (static_cpu_has_bug(X86_BUG_SYSRET_SS_ATTRS)) {
+		/*
+		 * AMD CPUs have a misfeature: SYSRET sets the SS selector but
+		 * does not update the cached descriptor.  As a result, if we
+		 * do SYSRET while SS is NULL, we'll end up in user mode with
+		 * SS apparently equal to __USER_DS but actually unusable.
+		 *
+		 * The straightforward workaround would be to fix it up just
+		 * before SYSRET, but that would slow down the system call
+		 * fast paths.  Instead, we ensure that SS is never NULL in
+		 * system call context.  We do this by replacing NULL SS
+		 * selectors at every context switch.  SYSCALL sets up a valid
+		 * SS, so the only way to get NULL is to re-enter the kernel
+		 * from CPL 3 through an interrupt.  Since that can't happen
+		 * in the same task as a running syscall, we are guaranteed to
+		 * context switch between every interrupt vector entry and a
+		 * subsequent SYSRET.
+		 *
+		 * We read SS first because SS reads are much faster than
+		 * writes.  Out of caution, we force SS to __KERNEL_DS even if
+		 * it previously had a different non-NULL value.
+		 */
+		unsigned short ss_sel;
+		savesegment(ss, ss_sel);
+		if (ss_sel != __KERNEL_DS)
+			loadsegment(ss, __KERNEL_DS);
+	}
+
+	/* Load the Intel cache allocation PQR MSR. */
+	intel_rdt_sched_in();
+
+	return prev_p;
+}
+
+void set_personality_64bit(void)
+{
+	/* inherit personality from parent */
+
+	/* Make sure to be in 64bit mode */
+	clear_thread_flag(TIF_IA32);
+	clear_thread_flag(TIF_ADDR32);
+	clear_thread_flag(TIF_X32);
+	/* Pretend that this comes from a 64bit execve */
+	task_pt_regs(current)->orig_ax = __NR_execve;
+	current_thread_info()->status &= ~TS_COMPAT;
+
+	/* Ensure the corresponding mm is not marked. */
+	if (current->mm)
+		current->mm->context.ia32_compat = 0;
+
+	/* TBD: overwrites user setup. Should have two bits.
+	   But 64bit processes have always behaved this way,
+	   so it's not too bad. The main problem is just that
+	   32bit childs are affected again. */
+	current->personality &= ~READ_IMPLIES_EXEC;
+}
+
+static void __set_personality_x32(void)
+{
+#ifdef CONFIG_X86_X32
+	clear_thread_flag(TIF_IA32);
+	set_thread_flag(TIF_X32);
+	if (current->mm)
+		current->mm->context.ia32_compat = TIF_X32;
+	current->personality &= ~READ_IMPLIES_EXEC;
+	/*
+	 * in_compat_syscall() uses the presence of the x32 syscall bit
+	 * flag to determine compat status.  The x86 mmap() code relies on
+	 * the syscall bitness so set x32 syscall bit right here to make
+	 * in_compat_syscall() work during exec().
+	 *
+	 * Pretend to come from a x32 execve.
+	 */
+	task_pt_regs(current)->orig_ax = __NR_x32_execve | __X32_SYSCALL_BIT;
+	current_thread_info()->status &= ~TS_COMPAT;
+#endif
+}
+
+static void __set_personality_ia32(void)
+{
+#ifdef CONFIG_IA32_EMULATION
+	set_thread_flag(TIF_IA32);
+	clear_thread_flag(TIF_X32);
+	if (current->mm)
+		current->mm->context.ia32_compat = TIF_IA32;
+	current->personality |= force_personality32;
+	/* Prepare the first "return" to user space */
+	task_pt_regs(current)->orig_ax = __NR_ia32_execve;
+	current_thread_info()->status |= TS_COMPAT;
+#endif
+}
+
+void set_personality_ia32(bool x32)
+{
+	/* Make sure to be in 32bit mode */
+	set_thread_flag(TIF_ADDR32);
+
+	if (x32)
+		__set_personality_x32();
+	else
+		__set_personality_ia32();
+}
+EXPORT_SYMBOL_GPL(set_personality_ia32);
+
+#ifdef CONFIG_CHECKPOINT_RESTORE
+static long prctl_map_vdso(const struct vdso_image *image, unsigned long addr)
+{
+	int ret;
+
+	ret = map_vdso_once(image, addr);
+	if (ret)
+		return ret;
+
+	return (long)image->size;
+}
+#endif
+
+long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2)
+{
+	int ret = 0;
+	int doit = task == current;
+	int cpu;
+
+	switch (option) {
+	case ARCH_SET_GS:
+		if (arg2 >= TASK_SIZE_MAX)
+			return -EPERM;
+		cpu = get_cpu();
+		task->thread.gsindex = 0;
+		task->thread.gsbase = arg2;
+		if (doit) {
+			load_gs_index(0);
+			ret = wrmsrl_safe(MSR_KERNEL_GS_BASE, arg2);
+		}
+		put_cpu();
+		break;
+	case ARCH_SET_FS:
+		/* Not strictly needed for fs, but do it for symmetry
+		   with gs */
+		if (arg2 >= TASK_SIZE_MAX)
+			return -EPERM;
+		cpu = get_cpu();
+		task->thread.fsindex = 0;
+		task->thread.fsbase = arg2;
+		if (doit) {
+			/* set the selector to 0 to not confuse __switch_to */
+			loadsegment(fs, 0);
+			ret = wrmsrl_safe(MSR_FS_BASE, arg2);
+		}
+		put_cpu();
+		break;
+	case ARCH_GET_FS: {
+		unsigned long base;
+
+		if (doit)
+			rdmsrl(MSR_FS_BASE, base);
+		else
+			base = task->thread.fsbase;
+		ret = put_user(base, (unsigned long __user *)arg2);
+		break;
+	}
+	case ARCH_GET_GS: {
+		unsigned long base;
+
+		if (doit)
+			rdmsrl(MSR_KERNEL_GS_BASE, base);
+		else
+			base = task->thread.gsbase;
+		ret = put_user(base, (unsigned long __user *)arg2);
+		break;
+	}
+
+#ifdef CONFIG_CHECKPOINT_RESTORE
+# ifdef CONFIG_X86_X32_ABI
+	case ARCH_MAP_VDSO_X32:
+		return prctl_map_vdso(&vdso_image_x32, arg2);
+# endif
+# if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
+	case ARCH_MAP_VDSO_32:
+		return prctl_map_vdso(&vdso_image_32, arg2);
+# endif
+	case ARCH_MAP_VDSO_64:
+		return prctl_map_vdso(&vdso_image_64, arg2);
+#endif
+
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+}
+
+SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
+{
+	long ret;
+
+	ret = do_arch_prctl_64(current, option, arg2);
+	if (ret == -EINVAL)
+		ret = do_arch_prctl_common(current, option, arg2);
+
+	return ret;
+}
+
+#ifdef CONFIG_IA32_EMULATION
+COMPAT_SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
+{
+	return do_arch_prctl_common(current, option, arg2);
+}
+#endif
+
+unsigned long KSTK_ESP(struct task_struct *task)
+{
+	return task_pt_regs(task)->sp;
+}