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

[Ross Lagerwall]

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.lagerw...@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

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