MIPS: Add new AUDIT_ARCH token for the N32 ABI on MIPS64

A MIPS64 kernel may support ELF files for all 3 MIPS ABIs
(O32, N32, N64). Furthermore, the AUDIT_ARCH_MIPS{,EL}64 token
does not provide enough information about the ABI for the 64-bit
process. As a result of which, userland needs to use complex
seccomp filters to decide whether a syscall belongs to the o32 or n32
or n64 ABI. Therefore, a new arch token for MIPS64/n32 is added so it
can be used by seccomp to explicitely set syscall filters for this ABI.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Acked-by: Eric Paris <eparis@redhat.com>
Acked-by: Paul Moore <pmoore@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: linux-mips@linux-mips.org
Link: http://sourceforge.net/p/libseccomp/mailman/message/32239040/
Patchwork: https://patchwork.linux-mips.org/patch/6818/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/mips/include/asm/syscall.h b/arch/mips/include/asm/syscall.h
index c6e9cd2bca8d..17960fe7a8ce 100644
--- a/arch/mips/include/asm/syscall.h
+++ b/arch/mips/include/asm/syscall.h
@@ -133,6 +133,8 @@ static inline int syscall_get_arch(void)
 #ifdef CONFIG_64BIT
         if (!test_thread_flag(TIF_32BIT_REGS))
                 arch |= __AUDIT_ARCH_64BIT;
+        if (test_thread_flag(TIF_32BIT_ADDR))
+                arch |= __AUDIT_ARCH_CONVENTION_MIPS64_N32;
 #endif
 #if defined(__LITTLE_ENDIAN)
         arch |=  __AUDIT_ARCH_LE;