[RFC][PATCH] x86, syscalls: use SYSCALL_DEFINE() macros for sys_modify_ldt()

[Dave Hansen]

I noticed that we don't have tracepoints for sys_modify_ldt().  I
think that's because we define it directly instead of using the
normal SYSCALL_DEFINEx() macros.

Is there a reason for that, or were they just missed when the
macros were created?

Cc: x86@xxxxxxxxxx
Cc: Andy Lutomirski <luto@xxxxxxxxxx>

---

 b/arch/x86/include/asm/syscalls.h |    2 +-
 b/arch/x86/kernel/ldt.c           |    5 +++--
 b/arch/x86/um/ldt.c               |    3 ++-
 3 files changed, 6 insertions(+), 4 deletions(-)

diff -puN arch/x86/kernel/ldt.c~x86-syscall-macros-modify_ldt arch/x86/kernel/ldt.c
--- a/arch/x86/kernel/ldt.c~x86-syscall-macros-modify_ldt	2017-10-13 13:30:12.802553391 -0700
+++ b/arch/x86/kernel/ldt.c	2017-10-13 13:30:12.817553391 -0700
@@ -12,6 +12,7 @@
 #include <linux/string.h>
 #include <linux/mm.h>
 #include <linux/smp.h>
+#include <linux/syscalls.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/uaccess.h>
@@ -294,8 +295,8 @@ out:
 	return error;
 }
 
-asmlinkage int sys_modify_ldt(int func, void __user *ptr,
-			      unsigned long bytecount)
+SYSCALL_DEFINE3(modify_ldt, int , func , void __user * , ptr ,
+		unsigned long , bytecount)
 {
 	int ret = -ENOSYS;
 
diff -puN arch/x86/include/asm/syscalls.h~x86-syscall-macros-modify_ldt arch/x86/include/asm/syscalls.h
--- a/arch/x86/include/asm/syscalls.h~x86-syscall-macros-modify_ldt	2017-10-13 13:30:12.812553391 -0700
+++ b/arch/x86/include/asm/syscalls.h	2017-10-13 13:30:12.818553391 -0700
@@ -21,7 +21,7 @@ asmlinkage long sys_ioperm(unsigned long
 asmlinkage long sys_iopl(unsigned int);
 
 /* kernel/ldt.c */
-asmlinkage int sys_modify_ldt(int, void __user *, unsigned long);
+asmlinkage long sys_modify_ldt(int, void __user *, unsigned long);
 
 /* kernel/signal.c */
 asmlinkage long sys_rt_sigreturn(void);
diff -puN arch/x86/um/ldt.c~x86-syscall-macros-modify_ldt arch/x86/um/ldt.c
--- a/arch/x86/um/ldt.c~x86-syscall-macros-modify_ldt	2017-10-13 13:30:12.814553391 -0700
+++ b/arch/x86/um/ldt.c	2017-10-13 13:30:12.818553391 -0700
@@ -369,7 +369,8 @@ void free_ldt(struct mm_context *mm)
 	mm->arch.ldt.entry_count = 0;
 }
 
-int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount)
+SYSCALL_DEFINE3(modify_ldt, int , func , void __user * , ptr ,
+		unsigned long , bytecount)
 {
 	return do_modify_ldt_skas(func, ptr, bytecount);
 }
_