x86/dom0: placate GCC 12 compile-time errors with UBSAN and PVH_GUEST

When building Xen with GCC 12 with UBSAN and PVH_GUEST both enabled the
compiler emits the following errors:

arch/x86/setup.c: In function '__start_xen':
arch/x86/setup.c:1504:19: error: 'consider_modules' reading 40 bytes from a region of size 4 [-Werror=stringop-overread]
 1504 |             end = consider_modules(s, e, reloc_size + mask,
      |                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1505 |                                    bi->mods, bi->nr_modules, -1);
      |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/x86/setup.c:1504:19: note: referencing argument 4 of type 'const struct boot_module[0]'
arch/x86/setup.c:686:24: note: in a call to function 'consider_modules'
  686 | static uint64_t __init consider_modules(
      |                        ^~~~~~~~~~~~~~~~
arch/x86/setup.c:1535:19: error: 'consider_modules' reading 40 bytes from a region of size 4 [-Werror=stringop-overread]
 1535 |             end = consider_modules(s, e, size, bi->mods,
      |                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1536 |                                    bi->nr_modules + relocated, j);
      |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/x86/setup.c:1535:19: note: referencing argument 4 of type 'const struct boot_module[0]'
arch/x86/setup.c:686:24: note: in a call to function 'consider_modules'
  686 | static uint64_t __init consider_modules(
      |                        ^~~~~~~~~~~~~~~~

This seems to be the result of some function manipulation done by UBSAN
triggering GCC stringops related errors.  Placate the errors by declaring
the function parameter as `const struct *boot_module` instead of `const
struct boot_module[]`.

Note that GCC 13 seems to be fixed, and doesn't trigger the error when
using `[]`.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 4a32d8491186d8d36a87c81c48331a9fc3baa99c..bde5d75ea6abd546d8cc40a3a02a3e9285bd5677 100644 (file)
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -684,7 +684,7 @@ static void __init noinline move_xen(void)
 #undef BOOTSTRAP_MAP_LIMIT
 
 static uint64_t __init consider_modules(
-    uint64_t s, uint64_t e, uint32_t size, const struct boot_module mods[],
+    uint64_t s, uint64_t e, uint32_t size, const struct boot_module *mods,
     unsigned int nr_mods, unsigned int this_mod)
 {
     unsigned int i;