Re: [PATCH v2 08/13] xsplice: Implement payload loading (v2)

[Ross Lagerwall <ross.lagerwall@citrix.com>]

On 01/14/2016 09:47 PM, Konrad Rzeszutek Wilk wrote:
snip
> +static int move_payload(struct payload *payload, struct xsplice_elf *elf)
> +{
> +    uint8_t *buf;
> +    unsigned int i;
> +    size_t core_size = 0;
> +
> +    /* Compute text regions */
> +    for ( i = 0; i < elf->hdr->e_shnum; i++ )
> +    {
> +        if ( (elf->sec[i].sec->sh_flags & (SHF_ALLOC|SHF_EXECINSTR)) ==
> +             (SHF_ALLOC|SHF_EXECINSTR) )
> +            calc_section(&elf->sec[i], &core_size);
> +    }
> +
> +    /* Compute rw data */
> +    for ( i = 0; i < elf->hdr->e_shnum; i++ )
> +    {
> +        if ( (elf->sec[i].sec->sh_flags & SHF_ALLOC) &&
> +             !(elf->sec[i].sec->sh_flags & SHF_EXECINSTR) &&
> +             (elf->sec[i].sec->sh_flags & SHF_WRITE) )
> +            calc_section(&elf->sec[i], &core_size);
> +    }
> +
> +    /* Compute ro data */
> +    for ( i = 0; i < elf->hdr->e_shnum; i++ )
> +    {
> +        if ( (elf->sec[i].sec->sh_flags & SHF_ALLOC) &&
> +             !(elf->sec[i].sec->sh_flags & SHF_EXECINSTR) &&
> +             !(elf->sec[i].sec->sh_flags & SHF_WRITE) )
> +            calc_section(&elf->sec[i], &core_size);
> +    }
> +
> +    buf = alloc_payload(core_size);
> +    if ( !buf ) {
> +        printk(XENLOG_ERR "%s: Could not allocate memory for module\n",
> +               elf->name);
> +        return -ENOMEM;
> +    }
> +    memset(buf, 0, core_size);
> +
> +    for ( i = 0; i < elf->hdr->e_shnum; i++ )
> +    {
> +        if ( elf->sec[i].sec->sh_flags & SHF_ALLOC )
> +        {
> +            elf->sec[i].load_addr = buf + elf->sec[i].sec->sh_entsize;
> +            memcpy(elf->sec[i].load_addr, elf->sec[i].data,
> +                   elf->sec[i].sec->sh_size);
> +            printk(XENLOG_DEBUG "%s: Loaded %s at 0x%p\n",
> +                   elf->name, elf->sec[i].name, elf->sec[i].load_addr);
> +        }
> +    }

I found this bug a while back but didn't get round to pushing it anywhere.

8-<------------------------------------------------
commit 72803a4c765026c54f31988a4c689048c8723575
Author: Ross Lagerwall <ross.lagerwall@citrix.com>
Date:   Fri Nov 6 12:48:39 2015 +0000

     Don't copy NOBITS sections (fixes BSS initialization)

diff --git a/xen/common/xsplice.c b/xen/common/xsplice.c
index 9450b2a..799ccb5 100644
--- a/xen/common/xsplice.c
+++ b/xen/common/xsplice.c
@@ -600,8 +600,9 @@ static int move_module(struct payload *payload, 
struct xsplice_elf *elf)
          if ( elf->sec[i].sec->sh_flags & SHF_ALLOC )
          {
              elf->sec[i].load_addr = buf + elf->sec[i].sec->sh_entsize;
-            memcpy(elf->sec[i].load_addr, elf->sec[i].data,
-                   elf->sec[i].sec->sh_size);
+            if ( elf->sec[i].sec->sh_type != SHT_NOBITS )
+                memcpy(elf->sec[i].load_addr, elf->sec[i].data,
+                       elf->sec[i].sec->sh_size);
              printk(XENLOG_DEBUG "Loaded %s at 0x%p\n",
                     elf->sec[i].name, elf->sec[i].load_addr);
          }

-- 
Ross Lagerwall