[PATCHv4 1/6] actual sys_indirect code

[PATCHv4 1/6] actual sys_indirect code

[Ulrich Drepper]

This is the actual architecture-independent part of the system call
implementation.

 include/linux/indirect.h |    6 ++++++
 include/linux/sched.h    |    4 ++++
 include/linux/syscalls.h |    4 ++++
 kernel/Makefile          |    2 +-
 kernel/indirect.c        |   36 ++++++++++++++++++++++++++++++++++++
 5 files changed, 51 insertions(+), 1 deletion(-)

--- /dev/null
+++ include/linux/indirect.h
@@ -0,0 +1,6 @@
+#ifndef _LINUX_INDIRECT_H
+#define _LINUX_INDIRECT_H
+
+#include <asm/indirect.h>
+
+#endif
--- include/linux/sched.h
+++ include/linux/sched.h
@@ -80,6 +80,7 @@ struct sched_param {
 #include <linux/rcupdate.h>
 #include <linux/futex.h>
 #include <linux/rtmutex.h>
+#include <linux/indirect.h>
 
 #include <linux/time.h>
 #include <linux/param.h>
@@ -1174,6 +1175,9 @@ struct task_struct {
 	int make_it_fail;
 #endif
 	struct prop_local_single dirties;
+
+	/* Additional system call parameters.  */
+	union indirect_params indirect_params;
 };
 
 /*
--- include/linux/syscalls.h
+++ include/linux/syscalls.h
@@ -54,6 +54,7 @@ struct compat_stat;
 struct compat_timeval;
 struct robust_list_head;
 struct getcpu_cache;
+struct indirect_registers;
 
 #include <linux/types.h>
 #include <linux/aio_abi.h>
@@ -611,6 +612,9 @@ asmlinkage long sys_timerfd(int ufd, int clockid, int flags,
 			    const struct itimerspec __user *utmr);
 asmlinkage long sys_eventfd(unsigned int count);
 asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len);
+asmlinkage long sys_indirect(struct indirect_registers __user *userregs,
+			     void __user *userparams, size_t paramslen,
+			     int flags);
 
 int kernel_execve(const char *filename, char *const argv[], char *const envp[]);
 
--- /dev/null
+++ kernel/indirect.c
@@ -0,0 +1,36 @@
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include <linux/unistd.h>
+#include <asm/asm-offsets.h>
+
+
+asmlinkage long sys_indirect(struct indirect_registers __user *userregs,
+			     void __user *userparams, size_t paramslen,
+			     int flags)
+{
+	struct indirect_registers regs;
+	long result;
+
+	if (unlikely(flags != 0))
+		return -EINVAL;
+
+	if (copy_from_user(&regs, userregs, sizeof(regs)))
+		return -EFAULT;
+
+	switch (INDIRECT_SYSCALL (&regs))
+	{
+	default:
+		return -EINVAL;
+	}
+
+	if (paramslen > sizeof(union indirect_params))
+		return -EINVAL;
+
+	result = -EFAULT;
+	if (!copy_from_user(&current->indirect_params, userparams, paramslen))
+		result = CALL_INDIRECT(&regs);
+
+	memset(&current->indirect_params, '\0', paramslen);
+
+	return result;
+}
--- kernel/Makefile
+++ kernel/Makefile
@@ -9,7 +9,7 @@ obj-y     = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
 	    rcupdate.o extable.o params.o posix-timers.o \
 	    kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
 	    hrtimer.o rwsem.o latency.o nsproxy.o srcu.o \
-	    utsname.o notifier.o
+	    utsname.o notifier.o indirect.o
 
 obj-$(CONFIG_SYSCTL) += sysctl_check.o
 obj-$(CONFIG_STACKTRACE) += stacktrace.o

Re: [PATCHv4 1/6] actual sys_indirect code

[Ingo Molnar]

cool patchset. Small nit, the series is not bisectable:

> +#include <asm/indirect.h>

> --- kernel/Makefile
> +++ kernel/Makefile
> @@ -9,7 +9,7 @@ obj-y     = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
>  	    rcupdate.o extable.o params.o posix-timers.o \
>  	    kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
>  	    hrtimer.o rwsem.o latency.o nsproxy.o srcu.o \
> -	    utsname.o notifier.o
> +	    utsname.o notifier.o indirect.o

indirect.o is built unconditionally, but it wont build at this stage 
because asm/indirect.h is only introduced in later patches. I suspect a 
CONFIG_ARCH_SUPPORTS_INDIRECT_SYSCALLS Kconfig flag, and its use in the 
Makefile ought to do the trick. (it also reduces object size on 
architectures that have no support for indirect syscalls (yet))

	Ingo

Re: [PATCHv4 1/6] actual sys_indirect code

[Zach Brown]

Ingo Molnar wrote:
> cool patchset. Small nit, the series is not bisectable:

Yeah, in a few places.

Uli, this is super easy to test if you maintain the patches with guilt.
 With some easy scripting around guilt push you can verify that the
series builds as each patch is applied.

- z