Re: [PATCH v5 12/17] linux-user: Create special-errno.h

[Warner Losh <imp@bsdimp.com>]

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On Wed, Nov 17, 2021 at 9:04 AM Richard Henderson <
richard.henderson@linaro.org> wrote:

> Pull the two internal errno used by qemu internally into their own
> header file.  This includes the one define required by safe-syscall.S.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  linux-user/cpu_loop-common.h           |  1 +
>  linux-user/generic/target_errno_defs.h | 17 --------------
>  linux-user/signal-common.h             |  2 ++
>  linux-user/special-errno.h             | 32 ++++++++++++++++++++++++++
>  linux-user/syscall.c                   |  1 +
>  linux-user/safe-syscall.S              |  2 +-
>  6 files changed, 37 insertions(+), 18 deletions(-)
>  create mode 100644 linux-user/special-errno.h
>

Reviewed-by: Warner Losh <imp@bsdimp.com>


> diff --git a/linux-user/cpu_loop-common.h b/linux-user/cpu_loop-common.h
> index 8828af28a4..dc0042e4de 100644
> --- a/linux-user/cpu_loop-common.h
> +++ b/linux-user/cpu_loop-common.h
> @@ -21,6 +21,7 @@
>  #define CPU_LOOP_COMMON_H
>
>  #include "exec/log.h"
> +#include "special-errno.h"
>
>  #define EXCP_DUMP(env, fmt, ...)                                        \
>  do {                                                                    \
> diff --git a/linux-user/generic/target_errno_defs.h
> b/linux-user/generic/target_errno_defs.h
> index bb37d88be9..c2f9d403e7 100644
> --- a/linux-user/generic/target_errno_defs.h
> +++ b/linux-user/generic/target_errno_defs.h
> @@ -147,21 +147,4 @@
>  #define TARGET_ERFKILL         132     /* Operation not possible due to
> RF-kill */
>  #define TARGET_EHWPOISON       133     /* Memory page has hardware error
> */
>
> -/* QEMU internal, not visible to the guest. This is returned when a
> - * system call should be restarted, to tell the main loop that it
> - * should wind the guest PC backwards so it will re-execute the syscall
> - * after handling any pending signals. They match with the ones the guest
> - * kernel uses for the same purpose.
> - */
> -#define QEMU_ERESTARTSYS     512     /* Restart system call (if
> SA_RESTART) */
> -
> -/* QEMU internal, not visible to the guest. This is returned by the
> - * do_sigreturn() code after a successful sigreturn syscall, to indicate
> - * that it has correctly set the guest registers and so the main loop
> - * should not touch them. We use the value the guest would use for
> - * ERESTART_NOINTR (which is kernel internal) to guarantee that we won't
> - * clash with a valid guest errno now or in the future.
> - */
> -#define QEMU_ESIGRETURN 513     /* Return from signal */
> -
>  #endif
> diff --git a/linux-user/signal-common.h b/linux-user/signal-common.h
> index b9f33bb44f..42aa479080 100644
> --- a/linux-user/signal-common.h
> +++ b/linux-user/signal-common.h
> @@ -20,6 +20,8 @@
>  #ifndef SIGNAL_COMMON_H
>  #define SIGNAL_COMMON_H
>
> +#include "special-errno.h"
> +
>  /* Fallback addresses into sigtramp page. */
>  extern abi_ulong default_sigreturn;
>  extern abi_ulong default_rt_sigreturn;
> diff --git a/linux-user/special-errno.h b/linux-user/special-errno.h
> new file mode 100644
> index 0000000000..4120455baa
> --- /dev/null
> +++ b/linux-user/special-errno.h
> @@ -0,0 +1,32 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * QEMU internal errno values for implementing user-only POSIX.
> + *
> + *  Copyright (c) 2003 Fabrice Bellard
> + *  Copyright (c) 2021 Linaro, Ltd.
> + */
> +
> +#ifndef SPECIAL_ERRNO_H
> +#define SPECIAL_ERRNO_H
> +
> +/*
> + * All of these are QEMU internal, not visible to the guest.
> + * They should be chosen so as to not overlap with any host
> + * or guest errno.
> + */
> +
> +/*
> + * This is returned when a system call should be restarted, to tell the
> + * main loop that it should wind the guest PC backwards so it will
> + * re-execute the syscall after handling any pending signals.
> + */
> +#define QEMU_ERESTARTSYS  512
> +
> +/*
> + * This is returned after a successful sigreturn syscall, to indicate
> + * that it has correctly set the guest registers and so the main loop
> + * should not touch them.
> + */
> +#define QEMU_ESIGRETURN   513
> +
> +#endif /* SPECIAL_ERRNO_H */
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 1ef6abb776..33d342157d 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -136,6 +136,7 @@
>  #include "qemu/guest-random.h"
>  #include "qemu/selfmap.h"
>  #include "user/syscall-trace.h"
> +#include "special-errno.h"
>  #include "qapi/error.h"
>  #include "fd-trans.h"
>  #include "tcg/tcg.h"
> diff --git a/linux-user/safe-syscall.S b/linux-user/safe-syscall.S
> index 7ddc997801..74f7e35694 100644
> --- a/linux-user/safe-syscall.S
> +++ b/linux-user/safe-syscall.S
> @@ -10,7 +10,7 @@
>   * See the COPYING file in the top-level directory.
>   */
>
> -#include "target_errno_defs.h"
> +#include "special-errno.h"
>
>  /* We have the correct host directory on our include path
>   * so that this will pull in the right fragment for the architecture.
> --
> 2.25.1
>
>

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