Re: [v11][PATCH 8/9] Define clone_with_pids() syscall

Serge E. Hallyn
2009-11-09T20:37:18Z

Here is a stab at the s390 syscall.

>From f710be4f1296d50551210bcc9ff6ba25d288bc46 Mon Sep 17 00:00:00 2001
From: Serge E. Hallyn <serue@us.ibm.com>
Date: Fri, 6 Nov 2009 19:03:43 -0500
Subject: [PATCH 1/1] implement s390 clone_with_pids syscall

This does the s390 hook for v11 of clone-with-pids.

I've got a program using the syscall successfully passing
args to the child function and continuing to run - but I
haven't yet gotten that hooked into user-cr/restart.c
successfully.

The core of my user-space code to use it is:

int do_child(void *arg)
{
int iarg = (int ) arg;

printf("here i am, i was passed %d, my tid is %d\n", iarg, gettid());
return 0;
}

#define do_cwp(flags, pids, args, sz) \
( { \
register unsigned long int __r2 asm ("2") = (unsigned long int)(flags); \
register unsigned long int __r3 asm ("3") = (unsigned long int)(args); \
register unsigned long int __r4 asm ("4") = (unsigned long int)(sz); \
register unsigned long int __r5 asm ("5") = (unsigned long int)(pids); \
register unsigned long int __result asm ("2"); \
__asm__ __volatile__( \
" lghi %%r1,%5\n" /* put __NR_cwp in r1 for svc 0 */ \
" svc 0\n" /* do __NR_cwp syscall */ \
" ltgr %%r2,%%r2\n" /* returned 0? */ \
" jnz 1f\n" /* if not goto label 1 */ \
" lg %%r3,0(%%r15)\n" /* get fnarg off stack into arg 1 */ \
" lg %%r2,8(%%r15)\n" /* get fn off stack into r3 for basr*/ \
" lgr %%r1,%%r15\n" /* tmp store old stack pointer */ \
" aghi %%r15,-160\n" /* move the stack */ \
" stg %%r1,0(%%r15)\n" /* and save old stack pointer */ \
" basr %%r14,%%r3\n" /* call fn(arg) */ \
" svc 1\n" /* call exit */ \
" 1:\n" \
: "=d" (__result) \
: "0" (__r2), "d" (__r3), "d" (__r4), "d" (__r5), \
"i" (__NR_clone_with_pids) \
: "1", "cc", "memory"); \
__result; \
} )

int clone_with_pids(int (*fn)(void *), int flags, int nrpids, int *pids,
void *fnarg)
{
long retval;
struct clone_args clone_args, *ca = &clone_args;
int stacksize;
void *sb;
u64 *s;
int i;

memset(ca, 0, sizeof(struct clone_args));
stacksize = 4*getpagesize();
sb = (void *) malloc(stacksize);
if (!sb) {
perror("malloc");
_exit(1);
}

ca->child_stack_base = (u64) sb;
ca->child_stack_size = stacksize-8;
s = (u64 *)(sb + ca->child_stack_size);
*--s = (u64)fnarg;
*--s = (u64)fn;
ca->child_stack_size -= 16;
ca->nr_pids = nrpids;
retval = do_cwp(flags, pids, ca, sizeof(struct clone_args));

return retval;
}

Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
---
arch/s390/include/asm/unistd.h | 3 +-
arch/s390/kernel/compat_linux.c | 50 ++++++++++++++++++++++++++++++++++++++
arch/s390/kernel/process.c | 51 +++++++++++++++++++++++++++++++++++++++
arch/s390/kernel/syscalls.S | 1 +
4 files changed, 104 insertions(+), 1 deletions(-)

diff --git a/arch/s390/include/asm/unistd.h b/arch/s390/include/asm/unistd.h
index cb5232d..ae9474e 100644
--- a/arch/s390/include/asm/unistd.h
+++ b/arch/s390/include/asm/unistd.h
@@ -269,7 +269,8 @@
#define __NR_pwritev 329
#define __NR_rt_tgsigqueueinfo 330
#define __NR_perf_event_open 331
-#define NR_syscalls 332
+#define __NR_clone_with_pids 332
+#define NR_syscalls 333

/*
* There are some system calls that are not present on 64 bit, some
diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.c
index 0debcec..1750fae 100644
--- a/arch/s390/kernel/compat_linux.c
+++ b/arch/s390/kernel/compat_linux.c
@@ -762,6 +762,56 @@ asmlinkage long sys32_write(unsigned int fd, char __user * buf, size_t count)
return sys_write(fd, buf, count);
}

+asmlinkage long sys32_clone_with_pids(void)
+{
+ int rc;
+ struct pt_regs *regs = task_pt_regs(current);
+ int args_size;
+ struct clone_args kca;
+ unsigned long flags;
+ int __user *parent_tid_ptr;
+ int __user *child_tid_ptr;
+ unsigned long __user child_stack;
+ unsigned long stack_size;
+ unsigned int flags_low;
+ struct clone_args __user *uca;
+ pid_t __user *pids;
+
+ flags_low = regs->gprs[2] & 0xffffffffUL;
+ uca = compat_ptr(regs->gprs[3]);
+ args_size = regs->gprs[4] & 0xffffffffUL;
+ pids = compat_ptr(regs->gprs[5]);
+
+ 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_tid_ptr = (int *)kca.parent_tid_ptr;
+ child_tid_ptr = (int *)kca.child_tid_ptr;
+
+ stack_size = (unsigned long)kca.child_stack_size;
+ child_stack = (unsigned long)kca.child_stack_base + stack_size;
+
+ if (!child_stack)
+ child_stack = regs->gprs[15];
+
+ /*
+ * TODO: On 32-bit systems, clone_flags is passed in as 32-bit value
+ * to several functions. Need to convert clone_flags to 64-bit.
+ */
+ return do_fork_with_pids(flags, child_stack, regs, stack_size,
+ parent_tid_ptr, child_tid_ptr, kca.nr_pids,
+ pids);
+}
+
/*
* 31 bit emulation wrapper functions for sys_fadvise64/fadvise64_64.
* These need to rewrite the advise values for POSIX_FADV_{DONTNEED,NOREUSE}
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 5417eb5..e27a1b4 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -241,6 +241,57 @@ SYSCALL_DEFINE4(clone, unsigned long, newsp, unsigned long, clone_flags,
parent_tidptr, child_tidptr);
}

+SYSCALL_DEFINE0(clone_with_pids)
+{
+ int rc;
+ struct pt_regs *regs = task_pt_regs(current);
+ int args_size;
+ struct clone_args kca;
+ unsigned long flags;
+ int __user *parent_tid_ptr;
+ int __user *child_tid_ptr;
+ unsigned long __user child_stack;
+ unsigned long stack_size;
+ unsigned int flags_low;
+ struct clone_args __user *uca;
+ pid_t __user *pids;
+
+ flags_low = regs->gprs[2];
+ uca = (struct clone_args __user *)regs->gprs[3];
+ args_size = regs->gprs[4];
+ pids = (pid_t __user *)regs->gprs[5];
+
+ 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_tid_ptr = (int *)kca.parent_tid_ptr;
+ child_tid_ptr = (int *)kca.child_tid_ptr;
+
+ stack_size = (unsigned long)kca.child_stack_size;
+ child_stack = (unsigned long)kca.child_stack_base;
+ if (child_stack)
+ child_stack += stack_size;
+ else
+ child_stack = regs->gprs[15];
+
+ /*
+ * TODO: On 32-bit systems, clone_flags is passed in as 32-bit value
+ * to several functions. Need to convert clone_flags to 64-bit.
+ */
+ return do_fork_with_pids(flags, child_stack, regs, stack_size,
+ parent_tid_ptr, child_tid_ptr, kca.nr_pids,
+ pids);
+}
+
/*
* This is trivial, and on the face of it looks like it
* could equally well be done in user mode.
diff --git a/arch/s390/kernel/syscalls.S b/arch/s390/kernel/syscalls.S
index 30eca07..c6dc240 100644
--- a/arch/s390/kernel/syscalls.S
+++ b/arch/s390/kernel/syscalls.S
@@ -340,3 +340,4 @@ SYSCALL(sys_preadv,sys_preadv,compat_sys_preadv_wrapper)
SYSCALL(sys_pwritev,sys_pwritev,compat_sys_pwritev_wrapper)
SYSCALL(sys_rt_tgsigqueueinfo,sys_rt_tgsigqueueinfo,compat_sys_rt_tgsigqueueinfo_wrapper) /* 330 */
SYSCALL(sys_perf_event_open,sys_perf_event_open,sys_perf_event_open_wrapper)
+SYSCALL(sys_clone_with_pids,sys_clone_with_pids,sys_clone_with_pids_wrapper)
--
1.6.1