Re: [PATCH v13 1/2] generic-loader: Add a generic loader

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Hi,

[very old patch merged as commit e481a1f63c93]

On 30/9/16 02:25, Alistair Francis wrote:
> Add a generic loader to QEMU which can be used to load images or set
> memory values.
> 
> Internally inside QEMU this is a device. It is a strange device that
> provides no hardware interface but allows QEMU to monkey patch memory
> specified when it is created. To be able to do this it has a reset
> callback that does the memory operations.
> 
> This device allows the user to monkey patch memory. To be able to do
> this it needs a backend to manage the datas, the same as other
> memory-related devices. In this case as the backend is so trivial we
> have merged it with the frontend instead of creating and maintaining a
> seperate backend.
> 
> Signed-off-by: Alistair Francis <alistair.francis@xilinx.com>
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
> Acked-by: Markus Armbruster <armbru@redhat.com>
> ---

> diff --git a/hw/core/generic-loader.c b/hw/core/generic-loader.c
> new file mode 100644
> index 0000000..79ab6df
> --- /dev/null
> +++ b/hw/core/generic-loader.c
> @@ -0,0 +1,211 @@
> +/*
> + * Generic Loader
> + *
> + * Copyright (C) 2014 Li Guang
> + * Copyright (C) 2016 Xilinx Inc.
> + * Written by Li Guang <lig.fnst@cn.fujitsu.com>
> + *
> + * 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.
> + *
> + */
> +
> +/*
> + * Internally inside QEMU this is a device. It is a strange device that
> + * provides no hardware interface but allows QEMU to monkey patch memory
> + * specified when it is created. To be able to do this it has a reset
> + * callback that does the memory operations.
> +
> + * This device allows the user to monkey patch memory. To be able to do
> + * this it needs a backend to manage the datas, the same as other
> + * memory-related devices. In this case as the backend is so trivial we
> + * have merged it with the frontend instead of creating and maintaining a
> + * seperate backend.
> + */
> +
> +#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) {
> +        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->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_len) {
> +            /* We cant' check for !data here as a value of 0 is still valid. */
> +            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");

If s->data_len < 8 (like 4 or 2) ...

> +            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;
> +        } else if (!s->cpu_num) {
> +            error_setg(errp, "cpu_num must be specified when setting a "
> +                       "program counter");
> +            return;
> +        }
> +        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;
> +        }
> +    } else {
> +        s->cpu = first_cpu;
> +    }
> +
> +#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->as);
> +
> +            if (size < 0) {
> +                size = load_uimage_as(s->file, &entry, NULL, NULL, NULL, NULL,
> +                                      s->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->as);
> +        } else {
> +            s->addr = entry;
> +        }
> +
> +        if (size < 0) {
> +            error_setg(errp, "Cannot load specified image %s", s->file);
> +            return;
> +        }
> +    }
> +
> +    /* Convert the data endiannes */
> +    if (s->data_be) {
> +        s->data = cpu_to_be64(s->data);
> +    } else {
> +        s->data = cpu_to_le64(s->data);

... and if we swap, we ignore the data-len and swap 64-bit
regardless, returning invalid data.

I.e. data=0x1122, data-len=2, once swapped we get data=0x0000.

Is that expected?

> +    }
> +}
> +
> +static void generic_loader_unrealize(DeviceState *dev, Error **errp)
> +{
> +    qemu_unregister_reset(generic_loader_reset, dev);
> +}
> +
> +static Property generic_loader_props[] = {
> +    DEFINE_PROP_UINT64("addr", GenericLoaderState, addr, 0),
> +    DEFINE_PROP_UINT64("data", GenericLoaderState, data, 0),
> +    DEFINE_PROP_UINT8("data-len", GenericLoaderState, data_len, 0),
> +    DEFINE_PROP_BOOL("data-be", GenericLoaderState, data_be, false),
> +    DEFINE_PROP_UINT32("cpu-num", GenericLoaderState, cpu_num, CPU_NONE),
> +    DEFINE_PROP_BOOL("force-raw", GenericLoaderState, force_raw, false),
> +    DEFINE_PROP_STRING("file", GenericLoaderState, file),
> +    DEFINE_PROP_END_OF_LIST(),
> +};