[xen staging] x86/dom0: placate GCC 12 compile-time errors with UBSAN and PVH_GUEST

[patchbot@xxxxxxx]

commit 932898d4492609f99e3016d423a9323235392864
Author:     Roger Pau Monne <roger.pau@xxxxxxxxxx>
AuthorDate: Thu Mar 13 11:08:05 2025 +0100
Commit:     Roger Pau Monne <roger.pau@xxxxxxxxxx>
CommitDate: Mon Mar 17 13:33:28 2025 +0100

    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@xxxxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/setup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 4a32d84911..bde5d75ea6 100644
--- 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;
--
generated by git-patchbot for /home/xen/git/xen.git#staging