linux/arch/powerpc/include/uapi/asm/errno.h
Michael Ellerman c3525940cc powerpc/kernel: Switch to using MAX_ERRNO
Currently on powerpc we have our own #define for the highest (negative)
errno value, called _LAST_ERRNO. This is defined to be 516, for reasons
which are not clear.

The generic code, and x86, use MAX_ERRNO, which is defined to be 4095.

In particular seccomp uses MAX_ERRNO to restrict the value that a
seccomp filter can return.

Currently with the mismatch between _LAST_ERRNO and MAX_ERRNO, a seccomp
tracer wanting to return 600, expecting it to be seen as an error, would
instead find on powerpc that userspace sees a successful syscall with a
return value of 600.

To avoid this inconsistency, switch powerpc to use MAX_ERRNO.

We are somewhat confident that generic syscalls that can return a
non-error value above negative MAX_ERRNO have already been updated to
use force_successful_syscall_return().

I have also checked all the powerpc specific syscalls, and believe that
none of them expect to return a non-error value between -MAX_ERRNO and
-516. So this change should be safe ...

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Kees Cook <keescook@chromium.org>
2015-07-29 11:56:11 +10:00

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C

#ifndef _ASM_POWERPC_ERRNO_H
#define _ASM_POWERPC_ERRNO_H
#include <asm-generic/errno.h>
#undef EDEADLOCK
#define EDEADLOCK 58 /* File locking deadlock error */
#endif /* _ASM_POWERPC_ERRNO_H */