From a3310c0397e21df8f47cde3e55736104b9584d2d Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Mon, 15 Nov 2021 14:08:52 +0100 Subject: linux-user: Move syscall error detection into safe_syscall_base The current api from safe_syscall_base() is to return -errno, which is the interface provided by *some* linux kernel abis. The wrapper macro, safe_syscall(), detects error, stores into errno, and returns -1, to match the api of the system syscall(). For those kernel abis that do not return -errno natively, this leads to double syscall error detection. E.g. Linux ppc64, which sets the SO flag for error. Simplify the usage from C by moving the error detection into assembly, and usage from assembly by providing a C helper with which to set errno. Reviewed-by: Warner Losh Signed-off-by: Richard Henderson --- linux-user/safe-syscall-error.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 linux-user/safe-syscall-error.c (limited to 'linux-user/safe-syscall-error.c') diff --git a/linux-user/safe-syscall-error.c b/linux-user/safe-syscall-error.c new file mode 100644 index 0000000000..d7e2700f81 --- /dev/null +++ b/linux-user/safe-syscall-error.c @@ -0,0 +1,28 @@ +/* + * safe-syscall-error.c: errno setting fragment + * This is intended to be invoked by safe-syscall.S + * + * Written by Richard Henderson + * Copyright (C) 2021 Red Hat, Inc. + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + */ + +#include "qemu/osdep.h" +#include "hostdep.h" +#include "safe-syscall.h" + +#ifdef HAVE_SAFE_SYSCALL +/* + * This is intended to be invoked via tail-call on the error path + * from the assembly in host/arch/safe-syscall.inc.S. This takes + * care of the host specific addressing of errno. + * Return -1 to finalize the return value for safe_syscall_base. + */ +long safe_syscall_set_errno_tail(int value) +{ + errno = value; + return -1; +} +#endif -- cgit 1.4.1