[v10,3/7] x86/arch_prctl: Add do_arch_prctl_common

Commit Message

Kyle Huey Nov. 8, 2016, 6:39 p.m. UTC

Add do_arch_prctl_common to handle arch_prctls that are not specific to 64
bits. Call it from the syscall entry point, but not any of the other
callsites in the kernel, which all want one of the existing 64 bit only
arch_prctls.

Signed-off-by: Kyle Huey <[e-mail]>
---
 arch/x86/include/asm/proto.h | 1 +
 arch/x86/kernel/process.c    | 5 +++++
 arch/x86/kernel/process_64.c | 8 +++++++-
 3 files changed, 13 insertions(+), 1 deletion(-)

Comments

Borislav Petkov Nov. 9, 2016, 10:31 a.m. UTC | #1

On Tue, Nov 08, 2016 at 10:39:52AM -0800, Kyle Huey wrote:
> Add do_arch_prctl_common to handle arch_prctls that are not specific to 64

      do_arch_prctl_common()

> bits. Call it from the syscall entry point, but not any of the other

"... to 64-bit mode." Or something like that...

> callsites in the kernel, which all want one of the existing 64 bit only

							      64-bit

> arch_prctls.
> 
> Signed-off-by: Kyle Huey <[e-mail]>

...

Patch

diff --git a/arch/x86/include/asm/proto.h b/arch/x86/include/asm/proto.h
index 95c3e51..f72b551 100644
--- a/arch/x86/include/asm/proto.h
+++ b/arch/x86/include/asm/proto.h
@@ -25,13 +25,14 @@  void entry_SYSCALL_compat(void);
 void entry_INT80_compat(void);
 #endif
 
 void x86_configure_nx(void);
 void x86_report_nx(void);
 
 extern int reboot_force;
 
+long do_arch_prctl_common(struct task_struct *task, int code, unsigned long arg2);
 #ifdef CONFIG_X86_64
 long do_arch_prctl_64(struct task_struct *task, int code, unsigned long arg2);
 #endif
 
 #endif /* _ASM_X86_PROTO_H */
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 0888a87..d0126b2 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -579,8 +579,13 @@  unsigned long get_wchan(struct task_struct *p)
 		}
 		fp = READ_ONCE_NOCHECK(*(unsigned long *)fp);
 	} while (count++ < 16 && p->state != TASK_RUNNING);
 
 out:
 	put_task_stack(p);
 	return ret;
 }
+
+long do_arch_prctl_common(struct task_struct *task, int code, unsigned long arg2)
+{
+	return -EINVAL;
+}
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 611df20..bf75d26 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -612,15 +612,21 @@  long do_arch_prctl_64(struct task_struct *task, int code, unsigned long arg2)
 		break;
 	}
 
 	return ret;
 }
 
 SYSCALL_DEFINE2(arch_prctl, int, code, unsigned long, arg2)
 {
-	return do_arch_prctl_64(current, code, arg2);
+	long ret;
+
+	ret = do_arch_prctl_64(current, code, arg2);
+	if (ret == -EINVAL)
+		ret = do_arch_prctl_common(current, code, arg2);
+
+	return ret;
 }
 
 unsigned long KSTK_ESP(struct task_struct *task)
 {
 	return task_pt_regs(task)->sp;
 }