0001-Add-an-uptime-system-call.patch

From a48de0703be228ffadc465f91cbf228b565a24b9 Mon Sep 17 00:00:00 2001
From: Guillaume Gelin <contact@ramnes.eu>
Date: Sun, 19 Oct 2014 15:47:07 +0200
Subject: [PATCH] Add an uptime system call.

Signed-off-by: Guillaume Gelin <contact@ramnes.eu>
---
 arch/x86/syscalls/syscall_32.tbl  |  1 +
 arch/x86/syscalls/syscall_64.tbl  |  1 +
 fs/proc/uptime.c                  | 13 +++++++++++++
 include/linux/syscalls.h          |  1 +
 include/uapi/asm-generic/unistd.h |  6 +++++-
 5 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/arch/x86/syscalls/syscall_32.tbl b/arch/x86/syscalls/syscall_32.tbl
index 9fe1b5d..73733a1 100644
--- a/arch/x86/syscalls/syscall_32.tbl
+++ b/arch/x86/syscalls/syscall_32.tbl
@@ -364,3 +364,4 @@
 355	i386	getrandom		sys_getrandom
 356	i386	memfd_create		sys_memfd_create
 357	i386	bpf			sys_bpf
+358	i386	uptime			sys_uptime
diff --git a/arch/x86/syscalls/syscall_64.tbl b/arch/x86/syscalls/syscall_64.tbl
index 281150b..a5d9e57 100644
--- a/arch/x86/syscalls/syscall_64.tbl
+++ b/arch/x86/syscalls/syscall_64.tbl
@@ -328,6 +328,7 @@
 319	common	memfd_create		sys_memfd_create
 320	common	kexec_file_load		sys_kexec_file_load
 321	common	bpf			sys_bpf
+322	common 	uptime			sys_uptime
 
 #
 # x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/proc/uptime.c b/fs/proc/uptime.c
index 33de567..ef0ec65 100644
--- a/fs/proc/uptime.c
+++ b/fs/proc/uptime.c
@@ -6,6 +6,19 @@
 #include <linux/time.h>
 #include <linux/kernel_stat.h>
 #include <linux/cputime.h>
+#include <linux/syscalls.h>
+
+#include <asm/uaccess.h>
+
+SYSCALL_DEFINE1(uptime, struct timespec __user *, uptime_uptr)
+{
+	struct timespec uptime;
+
+	get_monotonic_boottime(&uptime);
+	if (uptime_uptr)
+		return copy_to_user(uptime_uptr, &uptime, sizeof(uptime));
+	return uptime.tv_sec;
+}
 
 static int uptime_proc_show(struct seq_file *m, void *v)
 {
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index bda9b81..ae6cedb 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -877,4 +877,5 @@ asmlinkage long sys_seccomp(unsigned int op, unsigned int flags,
 asmlinkage long sys_getrandom(char __user *buf, size_t count,
 			      unsigned int flags);
 asmlinkage long sys_bpf(int cmd, union bpf_attr *attr, unsigned int size);
+asmlinkage long sys_uptime(struct timespec __user *uptime_uptr);
 #endif
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 22749c1..3b1a42b 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -656,11 +656,15 @@ __SYSCALL(__NR_accept4, sys_accept4)
 #define __NR_recvmmsg 243
 __SC_COMP(__NR_recvmmsg, sys_recvmmsg, compat_sys_recvmmsg)
 
+/* fs/uptime.c */
+#define __NR_uptime 244
+__SYSCALL(__NR_uptime, sys_uptime)
+
 /*
  * Architectures may provide up to 16 syscalls of their own
  * starting with this value.
  */
-#define __NR_arch_specific_syscall 244
+#define __NR_arch_specific_syscall 245
 
 #define __NR_wait4 260
 __SC_COMP(__NR_wait4, sys_wait4, compat_sys_wait4)
-- 
2.0.2