[PATCH v12 04/13] asm/syscall.h: add syscall_get_arch

[Will Drewry <wad@chromium.org>]

Adds a stub for a function that will return the AUDIT_ARCH_*
value appropriate to the supplied task based on the system
call convention.

For audit's use, the value can generally be hard-coded at the
audit-site.  However, for other functionality not inlined into
syscall entry/exit, this makes that information available.
seccomp_filter is the first planned consumer and, as such,
the comment indicates a tie to HAVE_ARCH_SECCOMP_FILTER.  That
is probably an unneeded detail.

Suggested-by: Roland McGrath <mcgrathr@chromium.org>
Signed-off-by: Will Drewry <wad@chromium.org>

v11: fixed improper return type
v10: introduced
---
 include/asm-generic/syscall.h |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h
index 5c122ae..a2c13dc 100644
--- a/include/asm-generic/syscall.h
+++ b/include/asm-generic/syscall.h
@@ -142,4 +142,18 @@ void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
 			   unsigned int i, unsigned int n,
 			   const unsigned long *args);
 
+/**
+ * syscall_get_arch - return the AUDIT_ARCH for the current system call
+ * @task:	task of interest, must be in system call entry tracing
+ * @regs:	task_pt_regs() of @task
+ *
+ * Returns the AUDIT_ARCH_* based on the system call convention in use.
+ *
+ * It's only valid to call this when @task is stopped on entry to a system
+ * call, due to %TIF_SYSCALL_TRACE, %TIF_SYSCALL_AUDIT, or %TIF_SECCOMP.
+ *
+ * Note, at present this function is only required with
+ * CONFIG_HAVE_ARCH_SECCOMP_FILTER.
+ */
+int syscall_get_arch(struct task_struct *task, struct pt_regs *regs);
 #endif	/* _ASM_SYSCALL_H */
-- 
1.7.5.4