On 9/16/19 11:59 AM, Pawel Wieczorkiewicz wrote:
With default implementation the ELF_LIVEPATCH_FUNC section containing
all functions to be replaced or added must be part of the hotpatch
payload, otherwise the payload is rejected (with -EINVAL).
However, with the extended hooks implementation, a hotpatch may be
constructed of only hooks to perform certain actions without any code
to be added or replaced.
Therefore, do not always expect the functions section and allow it to
be missing, provided there is at least one section containing hooks
present. The functions section, when present in a payload, must be a
single, non-empty section.
Check also all extended hooks sections if they are a single, non-empty
sections each.
At least one of the functions or hooks section must be present in a
valid payload.
snip
+ /*
+ * The patching sections are optional, but at least one
+ * must be present. Otherwise, there is nothing to do.
+ * All the existing sections must not be empty and must
+ * be present at most once.
+ */
+ for ( i = 0; i < ARRAY_SIZE(names); i++ )
+ {
+ const struct livepatch_elf_sec *sec;
+
+ sec = livepatch_elf_sec_by_name(elf, names[i]);
+ if ( !sec )
+ {
+ dprintk(XENLOG_DEBUG, LIVEPATCH "%s: %s is missing\n",
+ elf->name, names[i]);
+ continue; /* This section is optional */
+ }
+
+ if ( !sec->sec->sh_size )
+ {
+ printk(XENLOG_ERR LIVEPATCH "%s: %s is empty\n",
+ elf->name, names[i]);
+ return -EINVAL;
+ }
+
+ if ( test_and_set_bit(i, found) )
+ {
+ printk(XENLOG_ERR LIVEPATCH "%s: %s was seen more than once\n",
+ elf->name, names[i]);
This indentation is wrong.
+ return -EINVAL;
+ }
+ }
+
+ /* Checking if at least one section is present. */
+ if ( bitmap_empty(found, ARRAY_SIZE(names)) )
+ {
+ printk(XENLOG_ERR LIVEPATCH "%s: Nothing to patch. Aborting...\n",
+ elf->name);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
LGTM,
Reviewed-by: Ross Lagerwall <ross.lagerw...@citrix.com>
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