On 01/14/2016 09:47 PM, Konrad Rzeszutek Wilk wrote:
From: Ross Lagerwall <ross.lagerw...@citrix.com>
Add support for loading xsplice payloads. This is somewhat similar to
the Linux kernel module loader, implementing the following steps:
- Verify the elf file.
- Parse the elf file.
- Allocate a region of memory mapped within a free area of
[xen_virt_end, XEN_VIRT_END].
- Copy allocated sections into the new region.
- Resolve section symbols. All other symbols must be absolute addresses.
- Perform relocations.
Note that the structure 'xsplice_patch_func' differs a bit from the design
by usurping 8 bytes from the padding. We use that for our own uses.
Signed-off-by: Ross Lagerwall <ross.lagerw...@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
---
v2: - Change the 'xsplice_patch_func' structure layout/size.
- Add more error checking. Fix memory leak.
- Move elf_resolve and elf_perform relocs in elf file.
- Print the payload address and pages in keyhandler.
v3:
- Make it build under ARM
snip
+static void find_hole(ssize_t pages, unsigned long *hole_start,
+ unsigned long *hole_end)
+{
+ struct payload *data, *data2;
+
+ spin_lock(&payload_list_lock);
+ list_for_each_entry ( data, &payload_list, list )
+ {
+ list_for_each_entry ( data2, &payload_list, list )
+ {
+ unsigned long start, end;
+
+ start = (unsigned long)data2->payload_address;
+ end = start + data2->payload_pages * PAGE_SIZE;
+ if ( *hole_end > start && *hole_start < end )
+ {
+ *hole_start = end;
+ *hole_end = *hole_start + pages * PAGE_SIZE;
+ break;
+ }
+ }
+ if ( &data2->list == &payload_list )
+ break;
+ }
+ spin_unlock(&payload_list_lock);
+}
This function above should go down into the CONFIG_X86 section below.
+
+/*
+ * The following functions prepare an xSplice payload to be executed by
+ * allocating space, loading the allocated sections, resolving symbols,
+ * performing relocations, etc.
+ */
+#ifdef CONFIG_X86
+static void *alloc_payload(size_t size)
+{
+ mfn_t *mfn, *mfn_ptr;
+ size_t pages, i;
+ struct page_info *pg;
+ unsigned long hole_start, hole_end, cur;
+
+ ASSERT(size);
+
+ /*
+ * Copied from vmalloc which allocates pages and then maps them to an
+ * arbitrary virtual address with PAGE_HYPERVISOR. We need specific
+ * virtual address with PAGE_HYPERVISOR_RWX.
+ */
+ pages = PFN_UP(size);
+ mfn = xmalloc_array(mfn_t, pages);
+ if ( mfn == NULL )
+ return NULL;
+
+ for ( i = 0; i < pages; i++ )
+ {
+ pg = alloc_domheap_page(NULL, 0);
+ if ( pg == NULL )
+ goto error;
+ mfn[i] = _mfn(page_to_mfn(pg));
snip
diff --git a/xen/common/xsplice_elf.c b/xen/common/xsplice_elf.c
index a5e9d63..ea7eb73 100644
--- a/xen/common/xsplice_elf.c
+++ b/xen/common/xsplice_elf.c
@@ -199,3 +199,87 @@ void xsplice_elf_free(struct xsplice_elf *elf)
elf->name = NULL;
elf->len = 0;
}
+
+int xsplice_elf_resolve_symbols(struct xsplice_elf *elf)
+{
+ unsigned int i;
+
+ /*
+ * The first entry of an ELF symbol table is the "undefined symbol index".
+ * aka reserved so we skip it.
+ */
+ ASSERT( elf->sym );
+ for ( i = 1; i < elf->nsym; i++ )
+ {
+ switch ( elf->sym[i].sym->st_shndx )
+ {
+ case SHN_COMMON:
+ printk(XENLOG_ERR "%s: Unexpected common symbol: %s\n",
+ elf->name, elf->sym[i].name);
+ return_(-EINVAL);
+ break;
+ case SHN_UNDEF:
+ printk(XENLOG_ERR "%s: Unknown symbol: %s\n", elf->name,
+ elf->sym[i].name);
+ return_(-ENOENT);
+ break;
+ case SHN_ABS:
+ printk(XENLOG_DEBUG "%s: Absolute symbol: %s => 0x%p\n",
+ elf->name, elf->sym[i].name,
+ (void *)elf->sym[i].sym->st_value);
+ break;
+ default:
+ if ( elf->sec[elf->sym[i].sym->st_shndx].sec->sh_flags &
SHF_ALLOC )
+ {
+ elf->sym[i].sym->st_value +=
+ (unsigned
long)elf->sec[elf->sym[i].sym->st_shndx].load_addr;
+ printk(XENLOG_DEBUG "%s: Symbol resolved: %s => 0x%p\n",
+ elf->name, elf->sym[i].name,
+ (void *)elf->sym[i].sym->st_value);
+ }
+ }
+ }
+
+ return 0;
+}
+
+int xsplice_elf_perform_relocs(struct xsplice_elf *elf)
+{
+ struct xsplice_elf_sec *rela, *base;
+ unsigned int i;
+ int rc;
+
+ /*
+ * The first entry of an ELF symbol table is the "undefined symbol index".
+ * aka reserved so we skip it.
+ */
+ ASSERT( elf->sym );
+ for ( i = 1; i < elf->hdr->e_shnum; i++ )
+ {
+ rela = &elf->sec[i];
+
+ if ( (rela->sec->sh_type != SHT_RELA ) &&
+ (rela->sec->sh_type != SHT_REL ) )
+ continue;
+
+ /* Is it a valid relocation section? */
+ if ( rela->sec->sh_info >= elf->hdr->e_shnum )
+ continue;
+
+ base = &elf->sec[rela->sec->sh_info];
+
+ /* Don't relocate non-allocated sections. */
+ if ( !(base->sec->sh_flags & SHF_ALLOC) )
+ continue;
+
+ if ( elf->sec[i].sec->sh_type == SHT_RELA )
+ rc = xsplice_perform_rela(elf, base, rela);
+ else /* SHT_REL */
+ rc = xsplice_perform_rel(elf, base, rela);
+
+ if ( rc )
+ return rc;
+ }
+
+ return 0;
+}
Is there a reason the above two functions weren't put in the previous patch?
diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h
index bd832df..4ea66bf 100644
--- a/xen/include/asm-arm/config.h
+++ b/xen/include/asm-arm/config.h
@@ -15,8 +15,10 @@
#if defined(CONFIG_ARM_64)
# define LONG_BYTEORDER 3
+# define ELFSIZE 64
#else
# define LONG_BYTEORDER 2
+# define ELFSIZE 32
#endif
What does this do?
(And perhaps it should also be in the previous patch since it's
mentioned in the previous patch's changelog?)
--
Ross Lagerwall
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