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[PATCH v9 0/7] x86/arch_prctl Add ARCH_[GET|SET]_CPUID for controlling the CPUID instruction

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  [PATCH v9 0/7] x86/arch_prctl Add ARCH_[GET|SET]_CPUID for controlling the CPUID instruction Kyle Huey <me@kylehuey.com> - 2016-11-06 22:00 +0100
    [PATCH v9 1/7] x86/arch_prctl/64: Use SYSCALL_DEFINE2 to define sys_arch_prctl Kyle Huey <me@kylehuey.com> - 2016-11-06 22:00 +0100

#1515771 — [PATCH v9 0/7] x86/arch_prctl Add ARCH_[GET|SET]_CPUID for controlling the CPUID instruction

rr (http://rr-project.org/), a userspace record-and-replay reverse-
execution debugger, would like to trap and emulate the CPUID instruction.
This would allow us to a) mask away certain hardware features that rr does
not support (e.g. RDRAND) and b) enable trace portability across machines
by providing constant results.

Newer Intel CPUs (Ivy Bridge and later) can fault when CPUID is executed at
CPL > 0. Expose this capability to userspace as a new pair of arch_prctls,
ARCH_GET_CPUID and ARCH_SET_CPUID, with two values, ARCH_CPUID_ENABLE and
ARCH_CPUID_SIGSEGV.

Since v8:
Patch 7: KVM: x86: virtualize cpuid faulting
- Moved vcpu->arch.cpuid_fault initialization to the '!init_event' block.
- Added support for hypervisors writing to MSR_PLATFORM_INFO to disable the
  cpuid faulting feature.
- Added MSR_MISC_FEATURES_ENABLES to emulated_msrs[] to allow hypervisors
  to save/restore the msr.

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#1515772 — [PATCH v9 1/7] x86/arch_prctl/64: Use SYSCALL_DEFINE2 to define sys_arch_prctl

Signed-off-by: Kyle Huey <khuey@kylehuey.com>
---
 arch/x86/kernel/process_64.c | 3 ++-
 arch/x86/um/syscalls_64.c    | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index b3760b3..2718cf9 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -30,16 +30,17 @@
 #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>
@@ -607,17 +608,17 @@ long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
 	default:
 		ret = -EINVAL;
 		break;
 	}
 
 	return ret;
 }
 
-long sys_arch_prctl(int code, unsigned long addr)
+SYSCALL_DEFINE2(arch_prctl, int, code, unsigned long, addr)
 {
 	return do_arch_prctl(current, code, addr);
 }
 
 unsigned long KSTK_ESP(struct task_struct *task)
 {
 	return task_pt_regs(task)->sp;
 }
diff --git a/arch/x86/um/syscalls_64.c b/arch/x86/um/syscalls_64.c
index e655227..ab3f7f4 100644
--- a/arch/x86/um/syscalls_64.c
+++ b/arch/x86/um/syscalls_64.c
@@ -1,16 +1,17 @@
 /*
  * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Copyright 2003 PathScale, Inc.
  *
  * Licensed under the GPL
  */
 
 #include <linux/sched.h>
+#include <linux/syscalls.h>
 #include <linux/uaccess.h>
 #include <asm/prctl.h> /* XXX This should get the constants from libc */
 #include <os.h>
 
 long arch_prctl(struct task_struct *task, int code, unsigned long __user *addr)
 {
 	unsigned long *ptr = addr, tmp;
 	long ret;
@@ -67,17 +68,17 @@ long arch_prctl(struct task_struct *task, int code, unsigned long __user *addr)
 	case ARCH_GET_GS:
 		ret = put_user(tmp, addr);
 		break;
 	}
 
 	return ret;
 }
 
-long sys_arch_prctl(int code, unsigned long addr)
+SYSCALL_DEFINE2(arch_prctl, int, code, unsigned long, addr)
 {
 	return arch_prctl(current, code, (unsigned long __user *) addr);
 }
 
 void arch_switch_to(struct task_struct *to)
 {
 	if ((to->thread.arch.fs == 0) || (to->mm == NULL))
 		return;

base-commit: bc33b0ca11e3df467777a4fa7639ba488c9d4911
-- 
2.10.2

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