um: Add full asm/syscall.h support

Add subarchitecture-independent implementation of asm-generic/syscall.h
allowing access to user system call parameters and results:
* syscall_get_nr()
* syscall_rollback()
* syscall_get_error()
* syscall_get_return_value()
* syscall_set_return_value()
* syscall_get_arguments()
* syscall_set_arguments()
* syscall_get_arch() provided by arch/x86/um/asm/syscall.h

This provides the necessary syscall helpers needed by
HAVE_ARCH_SECCOMP_FILTER plus syscall_get_error().

This is inspired from Meredydd Luff's patch
(https://gerrit.chromium.org/gerrit/21425).

Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will Drewry <wad@chromium.org>
Cc: Meredydd Luff <meredydd@senatehouse.org>
Cc: David Drysdale <drysdale@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Acked-by: Kees Cook <keescook@chromium.org>

diff --git a/arch/um/include/asm/syscall-generic.h b/arch/um/include/asm/syscall-generic.h
new file mode 100644 (file)
index 0000000..9fb9cf8
--- /dev/null
+++ b/arch/um/include/asm/syscall-generic.h
@@ -0,0 +1,138 @@
+/*
+ * Access to user system call parameters and results
+ *
+ * See asm-generic/syscall.h for function descriptions.
+ *
+ * Copyright (C) 2015 Mickaël Salaün <mic@digikod.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __UM_SYSCALL_GENERIC_H
+#define __UM_SYSCALL_GENERIC_H
+
+#include <asm/ptrace.h>
+#include <linux/err.h>
+#include <linux/sched.h>
+#include <sysdep/ptrace.h>
+
+static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
+{
+
+       return PT_REGS_SYSCALL_NR(regs);
+}
+
+static inline void syscall_rollback(struct task_struct *task,
+                                   struct pt_regs *regs)
+{
+       /* do nothing */
+}
+
+static inline long syscall_get_error(struct task_struct *task,
+                                    struct pt_regs *regs)
+{
+       const long error = regs_return_value(regs);
+
+       return IS_ERR_VALUE(error) ? error : 0;
+}
+
+static inline long syscall_get_return_value(struct task_struct *task,
+                                           struct pt_regs *regs)
+{
+       return regs_return_value(regs);
+}
+
+static inline void syscall_set_return_value(struct task_struct *task,
+                                           struct pt_regs *regs,
+                                           int error, long val)
+{
+       PT_REGS_SET_SYSCALL_RETURN(regs, (long) error ?: val);
+}
+
+static inline void syscall_get_arguments(struct task_struct *task,
+                                        struct pt_regs *regs,
+                                        unsigned int i, unsigned int n,
+                                        unsigned long *args)
+{
+       const struct uml_pt_regs *r = &regs->regs;
+
+       switch (i) {
+       case 0:
+               if (!n--)
+                       break;
+               *args++ = UPT_SYSCALL_ARG1(r);
+       case 1:
+               if (!n--)
+                       break;
+               *args++ = UPT_SYSCALL_ARG2(r);
+       case 2:
+               if (!n--)
+                       break;
+               *args++ = UPT_SYSCALL_ARG3(r);
+       case 3:
+               if (!n--)
+                       break;
+               *args++ = UPT_SYSCALL_ARG4(r);
+       case 4:
+               if (!n--)
+                       break;
+               *args++ = UPT_SYSCALL_ARG5(r);
+       case 5:
+               if (!n--)
+                       break;
+               *args++ = UPT_SYSCALL_ARG6(r);
+       case 6:
+               if (!n--)
+                       break;
+       default:
+               BUG();
+               break;
+       }
+}
+
+static inline void syscall_set_arguments(struct task_struct *task,
+                                        struct pt_regs *regs,
+                                        unsigned int i, unsigned int n,
+                                        const unsigned long *args)
+{
+       struct uml_pt_regs *r = &regs->regs;
+
+       switch (i) {
+       case 0:
+               if (!n--)
+                       break;
+               UPT_SYSCALL_ARG1(r) = *args++;
+       case 1:
+               if (!n--)
+                       break;
+               UPT_SYSCALL_ARG2(r) = *args++;
+       case 2:
+               if (!n--)
+                       break;
+               UPT_SYSCALL_ARG3(r) = *args++;
+       case 3:
+               if (!n--)
+                       break;
+               UPT_SYSCALL_ARG4(r) = *args++;
+       case 4:
+               if (!n--)
+                       break;
+               UPT_SYSCALL_ARG5(r) = *args++;
+       case 5:
+               if (!n--)
+                       break;
+               UPT_SYSCALL_ARG6(r) = *args++;
+       case 6:
+               if (!n--)
+                       break;
+       default:
+               BUG();
+               break;
+       }
+}
+
+/* See arch/x86/um/asm/syscall.h for syscall_get_arch() definition. */
+
+#endif /* __UM_SYSCALL_GENERIC_H */

diff --git a/arch/x86/um/asm/syscall.h b/arch/x86/um/asm/syscall.h
index 81d6562ce01d5ce52294691e03555c1b4cf3e10f..11ab90dc5f14e95b521ee389e800f8abcfba0ca6 100644 (file)
--- a/arch/x86/um/asm/syscall.h
+++ b/arch/x86/um/asm/syscall.h
@@ -1,6 +1,7 @@
 #ifndef __UM_ASM_SYSCALL_H
 #define __UM_ASM_SYSCALL_H
 
+#include <asm/syscall-generic.h>
 #include <uapi/linux/audit.h>
 
 typedef asmlinkage long (*sys_call_ptr_t)(unsigned long, unsigned long,