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Re: [Qemu-devel] [RFC v3] monitor: add memory search commands s, sp


From: Claudio Fontana
Subject: Re: [Qemu-devel] [RFC v3] monitor: add memory search commands s, sp
Date: Wed, 18 Mar 2015 14:30:50 +0100
User-agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.0.1

Tested with kvm on aarch64 LE host with aarch64 LE guest,
tested with tcg on aarch64 LE host with aarch64 LE/sparc BE/x86 LE guests.
Would be interesting to test this also on a big endian host with different 
guest combinations..

Claudio

On 16.03.2015 11:31, address@hidden wrote:
> From: Claudio Fontana <address@hidden>
> 
> usage is similar to the commands x, xp.
> 
> Example with string: looking for "ELF" header in memory:
> 
> (qemu) s/1000000cb 0x40001000 "ELF"
> searching memory area [0000000040001000-00000000400f5240]
> 0000000040090001
> (qemu) x/20b 0x40090000
> 0000000040090000: '\x7f' 'E' 'L' 'F' '\x02' '\x01' '\x01' '\x03'
> 0000000040090008: '\x00' '\x00' '\x00' '\x00' '\x00' '\x00' '\x00' '\x00'
> 0000000040090010: '\x02' '\x00' '\xb7' '\x00'
> 
> Example with value: looking for 64bit variable value 0x990088
> 
> (qemu) s/1000000xg 0xffff900042000000 0x990088
> searching memory area [ffff900042000000-ffff9000427a1200]
> ffff9000424b3000
> ffff9000424c1000
> 
> Signed-off-by: Claudio Fontana <address@hidden>
> ---
>  hmp-commands.hx |  28 ++++++++++++
>  monitor.c       | 140 
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 168 insertions(+)
> 
> Hello, looking for some comments on whether the addition of this
> command is welcome, and whether the syntax chosen is acceptable,
> or how it can made better.
> 
> Thanks!
> 
> Claudio
> 
> changes from v2:
> move value_raw array outside of the inner block.
> Hopefully this will also make patchew tool happy.
> Weird that I didn't get that warning/error.
> 
> changes from v1:
> make checkpatch happy by adding braces here and there.
> 
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index d5022d8..2bf5737 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -432,6 +432,34 @@ Start gdbserver session (default @var{port}=1234)
>  ETEXI
>  
>      {
> +        .name       = "s",
> +        .args_type  = "fmt:/,addr:l,data:s",
> +        .params     = "/fmt addr data",
> +        .help       = "search virtual memory starting at 'addr' for 'data'",
> +        .mhandler.cmd = hmp_memory_search,
> +    },
> +
> +STEXI
> address@hidden s/fmt @var{addr} @var{data}
> address@hidden s
> +Virtual memory search starting at @var{addr} for data described by 
> @var{data}.
> +ETEXI
> +
> +    {
> +        .name       = "sp",
> +        .args_type  = "fmt:/,addr:l,data:s",
> +        .params     = "/fmt addr data",
> +        .help       = "search physical memory starting at 'addr' for 'data'",
> +        .mhandler.cmd = hmp_physical_memory_search,
> +    },
> +
> +STEXI
> address@hidden sp/fmt @var{addr} @var{data}
> address@hidden sp
> +Physical memory search starting at @var{addr} for data described by 
> @var{data}.
> +ETEXI
> +
> +    {
>          .name       = "x",
>          .args_type  = "fmt:/,addr:l",
>          .params     = "/fmt addr",
> diff --git a/monitor.c b/monitor.c
> index c86a89e..7495d7e 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -1208,6 +1208,124 @@ static void monitor_printc(Monitor *mon, int c)
>      monitor_printf(mon, "'");
>  }
>  
> +static void monitor_print_addr(Monitor *mon, hwaddr addr, bool is_physical)
> +{
> +    if (is_physical) {
> +        monitor_printf(mon, TARGET_FMT_plx "\n", addr);
> +    } else {
> +        monitor_printf(mon, TARGET_FMT_lx "\n", (target_ulong)addr);
> +    }
> +}
> +
> +/* simple memory search for a byte sequence. The sequence is generated from
> + * a numeric value to look for in guest memory, or from a string.
> + */
> +static void memory_search(Monitor *mon, int count, int format, int wsize,
> +                          hwaddr addr, const char *data_str, bool 
> is_physical)
> +{
> +    int pos, len;           /* pos in the search area, len of area */
> +    char *hay;              /* buffer for haystack */
> +    int hay_size;           /* haystack size. Needle size is wsize. */
> +    const char *needle;     /* needle to search in the haystack */
> +    const char *format_str; /* numeric input format string */
> +    char value_raw[8];      /* numeric input converted to raw data */
> +#define MONITOR_S_CHUNK_SIZE 16000
> +
> +    len = wsize * count;
> +    if (len < 1) {
> +        monitor_printf(mon, "invalid search area length.\n");
> +        return;
> +    }
> +    switch (format) {
> +    case 'i':
> +        monitor_printf(mon, "format '%c' not supported.\n", format);
> +        return;
> +    case 'c':
> +        needle = data_str;
> +        wsize = strlen(data_str);
> +        if (wsize > MONITOR_S_CHUNK_SIZE) {
> +            monitor_printf(mon, "search string too long [max %d].\n",
> +                           MONITOR_S_CHUNK_SIZE);
> +            return;
> +        }
> +        break;
> +    case 'o':
> +        format_str = "%" SCNo64;
> +        break;
> +    default:
> +    case 'x':
> +        format_str = "%" SCNx64;
> +        break;
> +    case 'u':
> +        format_str = "%" SCNu64;
> +        break;
> +    case 'd':
> +        format_str = "%" SCNd64;
> +        break;
> +    }
> +    if (format != 'c') {
> +        uint64_t value;      /* numeric input value */
> +        void *from = &value;
> +        if (sscanf(data_str, format_str, &value) != 1) {
> +            monitor_printf(mon, "could not parse search string "
> +                           "\"%s\" as format '%c'.\n", data_str, format);
> +            return;
> +        }
> +#if defined(HOST_WORDS_BIGENDIAN) != defined(TARGET_WORDS_BIGENDIAN)
> +        value = bswap64(value);
> +#endif
> +#if defined(TARGET_WORDS_BIGENDIAN)
> +        from += 8 - wsize;
> +#endif
> +        memcpy(value_raw, from, wsize);
> +        needle = value_raw;
> +    }
> +    monitor_printf(mon, "searching memory area ");
> +    if (is_physical) {
> +        monitor_printf(mon, "[" TARGET_FMT_plx "-" TARGET_FMT_plx "]\n",
> +                       addr, addr + len);
> +    } else {
> +        monitor_printf(mon, "[" TARGET_FMT_lx "-" TARGET_FMT_lx "]\n",
> +                       (target_ulong)addr, (target_ulong)addr + len);
> +    }
> +    hay_size = len < MONITOR_S_CHUNK_SIZE ? len : MONITOR_S_CHUNK_SIZE;
> +    hay = g_malloc0(hay_size);
> +
> +    for (pos = 0; pos < len;) {
> +        char *mark, *match; /* mark new starting position, eventual match */
> +        int l, todo;        /* total length to be processed in current chunk 
> */
> +        l = len - pos;
> +        if (l > hay_size) {
> +            l = hay_size;
> +        }
> +        if (is_physical) {
> +            cpu_physical_memory_read(addr, hay, l);
> +        } else if (cpu_memory_rw_debug(ENV_GET_CPU(mon_get_cpu()), addr,
> +                                       (uint8_t *)hay, l, 0) < 0) {
> +            monitor_printf(mon, " Cannot access memory\n");
> +            break;
> +        }
> +        for (mark = hay, todo = l; todo >= wsize;) {
> +            match = memmem(mark, todo, needle, wsize);
> +            if (!match) {
> +                break;
> +            }
> +            monitor_print_addr(mon, addr + (match - hay), is_physical);
> +            mark = match + 1;
> +            todo = mark - hay;
> +        }
> +        if (pos + l < len) {
> +            /* catch potential matches across chunks. */
> +            pos += l - (wsize - 1);
> +            addr += l - (wsize - 1);
> +        } else {
> +            pos += l;
> +            addr += l;
> +        }
> +    }
> +    g_free(hay);
> +}
> +
>  static void memory_dump(Monitor *mon, int count, int format, int wsize,
>                          hwaddr addr, int is_physical)
>  {
> @@ -1332,6 +1450,28 @@ static void memory_dump(Monitor *mon, int count, int 
> format, int wsize,
>      }
>  }
>  
> +static void hmp_memory_search(Monitor *mon, const QDict *qdict)
> +{
> +    int count = qdict_get_int(qdict, "count");
> +    int format = qdict_get_int(qdict, "format");
> +    int size = qdict_get_int(qdict, "size");
> +    target_long addr = qdict_get_int(qdict, "addr");
> +    const char *data_str = qdict_get_str(qdict, "data");
> +
> +    memory_search(mon, count, format, size, addr, data_str, false);
> +}
> +
> +static void hmp_physical_memory_search(Monitor *mon, const QDict *qdict)
> +{
> +    int count = qdict_get_int(qdict, "count");
> +    int format = qdict_get_int(qdict, "format");
> +    int size = qdict_get_int(qdict, "size");
> +    hwaddr addr = qdict_get_int(qdict, "addr");
> +    const char *data_str = qdict_get_str(qdict, "data");
> +
> +    memory_search(mon, count, format, size, addr, data_str, true);
> +}
> +
>  static void hmp_memory_dump(Monitor *mon, const QDict *qdict)
>  {
>      int count = qdict_get_int(qdict, "count");
> 


-- 
Claudio Fontana
Server Virtualization Architect
Huawei Technologies Duesseldorf GmbH
Riesstra├če 25 - 80992 M├╝nchen

office: +49 89 158834 4135
mobile: +49 15253060158



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