Re: [Qemu-devel] [PATCH v10 7/8] generic-loader: Add a generic loader

[Peter Maydell]

On 3 August 2016 at 21:06, Alistair Francis <address@hidden> wrote:
> Add a generic loader to QEMU which can be used to load images or set
> memory values.
>
> Signed-off-by: Alistair Francis <address@hidden>
> ---
> V10:
>  - Split out the PC setting and data loading
> V9:
>  - Fix error messages
>  - Updated some incorrect logic
>  - Add address space loading support for all image types
>  - Explain why the reset is manually registered
> V8:
>  - Code corrections
>  - Rebase
> V7:
>  - Rebase
> V6:
>  - Add error checking
> V5:
>  - Rebase
> V4:
>  - Allow the loader to work with every architecture
>  - Move the file to hw/core
>  - Increase the maximum number of CPUs
>  - Make the CPU operations conditional
>  - Convert the cpu option to cpu-num
>  - Require the user to specify endianess
> V3:
>  - Pass the ram_size to load_image_targphys()
> V2:
>  - Add maintainers entry
>  - Perform bounds checking
>  - Register and unregister the reset in the realise/unrealise
> Changes since RFC:
>  - Add BE support
>
>  MAINTAINERS                      |   6 ++
>  hw/core/Makefile.objs            |   2 +
>  hw/core/generic-loader.c         | 195 
> +++++++++++++++++++++++++++++++++++++++
>  include/hw/core/generic-loader.h |  46 +++++++++
>  4 files changed, 249 insertions(+)
>  create mode 100644 hw/core/generic-loader.c
>  create mode 100644 include/hw/core/generic-loader.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 9c88c44..cc34ae0 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -984,6 +984,12 @@ M: Dmitry Fleytman <address@hidden>
>  S: Maintained
>  F: hw/net/e1000e*
>
> +Generic Loader
> +M: Alistair Francis <address@hidden>
> +S: Maintained
> +F: hw/core/generic-loader.c
> +F: include/hw/core/generic-loader.h
> +
>  Subsystems
>  ----------
>  Audio
> diff --git a/hw/core/Makefile.objs b/hw/core/Makefile.objs
> index cfd4840..939c94e 100644
> --- a/hw/core/Makefile.objs
> +++ b/hw/core/Makefile.objs
> @@ -17,3 +17,5 @@ common-obj-$(CONFIG_SOFTMMU) += loader.o
>  common-obj-$(CONFIG_SOFTMMU) += qdev-properties-system.o
>  common-obj-$(CONFIG_SOFTMMU) += register.o
>  common-obj-$(CONFIG_PLATFORM_BUS) += platform-bus.o
> +
> +obj-$(CONFIG_SOFTMMU) += generic-loader.o
> diff --git a/hw/core/generic-loader.c b/hw/core/generic-loader.c
> new file mode 100644
> index 0000000..4ee71cb
> --- /dev/null
> +++ b/hw/core/generic-loader.c
> @@ -0,0 +1,195 @@
> +/*
> + * Generic Loader
> + *
> + * Copyright (C) 2014 Li Guang
> + * Copyright (C) 2016 Xilinx Inc.
> + * Written by Li Guang <address@hidden>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License as published by the
> + * Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful, but 
> WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
> + * for more details.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qom/cpu.h"
> +#include "hw/sysbus.h"
> +#include "sysemu/dma.h"
> +#include "hw/loader.h"
> +#include "qapi/error.h"
> +#include "hw/core/generic-loader.h"
> +
> +#define CPU_NONE 0xFFFFFFFF
> +
> +static void generic_loader_reset(void *opaque)
> +{
> +    GenericLoaderState *s = GENERIC_LOADER(opaque);
> +
> +    if (s->set_pc && s->cpu) {

This check on s->cpu means that -device loader,file=<...> won't set the
PC to the entry point unless you specifically pass cpu-num=0.
The easiest fix for this is just to remove it (see below).

> +        CPUClass *cc = CPU_GET_CLASS(s->cpu);
> +        cpu_reset(s->cpu);
> +        if (cc) {
> +            cc->set_pc(s->cpu, s->addr);
> +        }
> +    }
> +
> +    if (s->data_len) {
> +        assert(s->data_len < sizeof(s->data));
> +        dma_memory_write((s->cpu ? s->cpu : first_cpu)->as, s->addr, 
> &s->data,
> +                         s->data_len);
> +    }
> +}
> +
> +static void generic_loader_realize(DeviceState *dev, Error **errp)
> +{
> +    GenericLoaderState *s = GENERIC_LOADER(dev);
> +    hwaddr entry;
> +    int big_endian;
> +    int size = 0;
> +
> +    s->set_pc = false;
> +
> +    /* Perform some error checking on the user's options */
> +    if (s->data || s->data_len  || s->data_be) {
> +        /* User is loading memory values */
> +        if (s->file) {
> +            error_setg(errp, "Specifying a file is not supported when 
> loading "
> +                       "memory values");
> +            return;
> +        } else if (s->force_raw) {
> +            error_setg(errp, "Specifying force-raw is not supported when "
> +                       "loading memory values");
> +            return;
> +        } else if (!s->data || !s->data_len) {
> +            error_setg(errp, "Both data and data-len must be specified");
> +            return;
> +        } else if (s->data_len > 8) {
> +            error_setg(errp, "data-len cannot be greater then 8 bytes");
> +            return;
> +        } else if (s->data_len > sizeof(s->data)) {
> +            error_setg(errp, "data-len cannot be more then the data size");

This can't ever happen, because sizeof(s->data) is always 8.

> +            return;
> +        }
> +    } else if (s->file || s->force_raw)  {
> +        /* User is loading an image */
> +        if (s->data || s->data_len || s->data_be) {
> +            error_setg(errp, "data can not be specified when loading an "
> +                       "image");
> +            return;
> +        }
> +        s->set_pc = true;
> +    } else if (s->addr) {
> +        /* User is setting the PC */
> +        if (s->data || s->data_len || s->data_be) {
> +            error_setg(errp, "data can not be specified when setting a "
> +                       "program counter");
> +            return;
> +        }

Failing to specify cpu_num in this case needs to be an error.

> +        s->set_pc = true;
> +    } else {
> +        /* Did the user specify anything? */
> +        error_setg(errp, "please include valid arguments");
> +        return;
> +    }


> +
> +    qemu_register_reset(generic_loader_reset, dev);
> +
> +    if (s->cpu_num != CPU_NONE) {
> +        s->cpu = qemu_get_cpu(s->cpu_num);
> +        if (!s->cpu) {
> +            error_setg(errp, "Specified boot CPU#%d is nonexistent",
> +                       s->cpu_num);
> +            return;
> +        }
> +    }

If you always set s->cpu to be first_cpu in the "cpu_num is CPU_NONE"
case you can avoid all the ?: everywhere you use it, and you don't need
to check for 's->cpu' being non-NULL in the function where you set the PC.

> +
> +#ifdef TARGET_WORDS_BIGENDIAN
> +    big_endian = 1;
> +#else
> +    big_endian = 0;
> +#endif
> +
> +    if (s->file) {
> +        if (!s->force_raw) {
> +            size = load_elf_as(s->file, NULL, NULL, &entry, NULL, NULL,
> +                               big_endian, 0, 0, 0,
> +                               (s->cpu ? s->cpu : first_cpu)->as);
> +
> +            if (size < 0) {
> +                size = load_uimage_as(s->file, &entry, NULL, NULL, NULL, 
> NULL,
> +                                      (s->cpu ? s->cpu : first_cpu)->as);
> +            }
> +        }
> +
> +        if (size < 0 || s->force_raw) {
> +            /* Default to the maximum size being the machine's ram size */
> +            size = load_image_targphys_as(s->file, s->addr, ram_size,
> +                                          (s->cpu ? s->cpu : first_cpu)->as);
> +        } else {
> +            s->addr = entry;
> +        }
> +
> +        if (size < 0) {
> +            error_setg(errp, "Cannot load specified image %s", s->file);
> +            return;
> +        }
> +    }

Otherwise:

Reviewed-by: Peter Maydell <address@hidden>

thanks
-- PMM