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From: Christoffer Dall on 21 Mar 2010 21:10
In addition to doing everything that clone() system call does, the
eclone() system call:

- allows additional clone flags (31 of 32 bits in the flags
parameter to clone() are in use)

- allows user to specify a pid for the child process in its
active and ancestor pid namespaces.

Eclone is needed for restarting a process from a checkpoint. See more
in Documentation/eclone and refer to the original LKML posting:
http://lkml.org/lkml/2009/11/11/361

The new system call for ARM has number 366.

Cc: rmk(a)arm.linux.org.uk
Cc: libc-ports <libc-ports(a)sourceware.org>
Cc: Sukadev Bhattiprolu <sukadev(a)linux.vnet.ibm.com>
Signed-off-by: Christoffer Dall <christofferdall(a)christofferdall.dk>
Acked-by: Oren Laadan <orenl(a)cs.columbia.edu>
---
arch/arm/include/asm/unistd.h | 1 +
arch/arm/kernel/calls.S | 1 +
arch/arm/kernel/entry-common.S | 6 ++++++
arch/arm/kernel/sys_arm.c | 39 +++++++++++++++++++++++++++++++++++++++
4 files changed, 47 insertions(+), 0 deletions(-)

diff --git a/arch/arm/include/asm/unistd.h b/arch/arm/include/asm/unistd.h
index cf9cdaa..f295a6c 100644
--- a/arch/arm/include/asm/unistd.h
+++ b/arch/arm/include/asm/unistd.h
@@ -392,6 +392,7 @@
#define __NR_rt_tgsigqueueinfo (__NR_SYSCALL_BASE+363)
#define __NR_perf_event_open (__NR_SYSCALL_BASE+364)
#define __NR_recvmmsg (__NR_SYSCALL_BASE+365)
+#define __NR_eclone (__NR_SYSCALL_BASE+366)

/*
* The following SWIs are ARM private.
diff --git a/arch/arm/kernel/calls.S b/arch/arm/kernel/calls.S
index 9314a2d..5ef0b03 100644
--- a/arch/arm/kernel/calls.S
+++ b/arch/arm/kernel/calls.S
@@ -375,6 +375,7 @@
CALL(sys_rt_tgsigqueueinfo)
CALL(sys_perf_event_open)
/* 365 */ CALL(sys_recvmmsg)
+ CALL(sys_eclone_wrapper)
#ifndef syscalls_counted
.equ syscalls_padding, ((NR_syscalls + 3) & ~3) - NR_syscalls
#define syscalls_counted
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index f694f4d..9ead15d 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -386,6 +386,12 @@ sys_clone_wrapper:
b sys_clone
ENDPROC(sys_clone_wrapper)

+sys_eclone_wrapper:
+ add ip, sp, #S_OFF
+ str ip, [sp, #0]
+ b sys_eclone
+ENDPROC(sys_eclone_wrapper)
+
sys_sigreturn_wrapper:
add r0, sp, #S_OFF
b sys_sigreturn
diff --git a/arch/arm/kernel/sys_arm.c b/arch/arm/kernel/sys_arm.c
index ae4027b..fd8199d 100644
--- a/arch/arm/kernel/sys_arm.c
+++ b/arch/arm/kernel/sys_arm.c
@@ -183,6 +183,45 @@ asmlinkage int sys_clone(unsigned long clone_flags, unsigned long newsp,
return do_fork(clone_flags, newsp, regs, 0, parent_tidptr, child_tidptr);
}

+asmlinkage int sys_eclone(unsigned flags_low, struct clone_args __user *uca,
+ int args_size, pid_t __user *pids,
+ struct pt_regs *regs)
+{
+ int rc;
+ struct clone_args kca;
+ unsigned long flags;
+ int __user *parent_tidp;
+ int __user *child_tidp;
+ unsigned long __user stack;
+ unsigned long stack_size;
+
+ rc = fetch_clone_args_from_user(uca, args_size, &kca);
+ if (rc)
+ return rc;
+
+ /*
+ * TODO: Convert 'clone-flags' to 64-bits on all architectures.
+ * TODO: When ->clone_flags_high is non-zero, copy it in to the
+ * higher word(s) of 'flags':
+ *
+ * flags = (kca.clone_flags_high << 32) | flags_low;
+ */
+ flags = flags_low;
+ parent_tidp = (int *)(unsigned long)kca.parent_tid_ptr;
+ child_tidp = (int *)(unsigned long)kca.child_tid_ptr;
+
+ stack_size = (unsigned long)kca.child_stack_size;
+ if (stack_size)
+ return -EINVAL;
+
+ stack = (unsigned long)kca.child_stack;
+ if (!stack)
+ stack = regs->ARM_sp;
+
+ return do_fork_with_pids(flags, stack, regs, stack_size, parent_tidp,
+ child_tidp, kca.nr_pids, pids);
+}
+
asmlinkage int sys_vfork(struct pt_regs *regs)
{
return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->ARM_sp, regs, 0, NULL, NULL);
--
1.5.6.5

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