[PATCH v3 3/4] um: Add full asm/syscall.h support

From: MickaÃl SalaÃn
Date: Tue Dec 29 2015 - 15:45:57 EST


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: MickaÃl SalaÃn <mic@xxxxxxxxxxx>
Cc: Jeff Dike <jdike@xxxxxxxxxxx>
Cc: Richard Weinberger <richard@xxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Will Drewry <wad@xxxxxxxxxxxx>
Cc: Meredydd Luff <meredydd@xxxxxxxxxxxxxxx>
Cc: David Drysdale <drysdale@xxxxxxxxxx>
---
arch/um/include/asm/syscall-generic.h | 138 ++++++++++++++++++++++++++++++++++
arch/x86/um/asm/syscall.h | 1 +
2 files changed, 139 insertions(+)
create mode 100644 arch/um/include/asm/syscall-generic.h

diff --git a/arch/um/include/asm/syscall-generic.h b/arch/um/include/asm/syscall-generic.h
new file mode 100644
index 000000000000..9fb9cf8cd39a
--- /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 MickaÃl SalaÃn <mic@xxxxxxxxxxx>
+ *
+ * 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 81d6562ce01d..11ab90dc5f14 100644
--- 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,
--
2.6.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/