From 4c9ad387aa2d6785299722e54224d34764edaeb3 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Wed, 13 May 2026 16:53:54 +0200 Subject: [PATCH] iommu, debugobjects: avoid gcc-16.1 section mismatch warnings gcc-16 has gained some more advanced inter-procedual optimization techniques that enable it to inline the dummy_tlb_add_page() and dummy_tlb_flush() function pointers into a specialized version of __arm_v7s_unmap: WARNING: modpost: vmlinux: section mismatch in reference: __arm_v7s_unmap+0x2cc (section: .text) -> dummy_tlb_add_page (section: .init.text) ERROR: modpost: Section mismatches detected. >From what I can tell, the transformation is correct, as this is only called when __arm_v7s_unmap() is called from arm_v7s_do_selftests(), which is also __init. Since __arm_v7s_unmap() however is not __init, gcc cannot inline the inner function calls directly. In debug_objects_selftest(), the same thing happens. Both the caller and the leaf function are __init, but the IPA pulls it into a non-init one: WARNING: modpost: vmlinux: section mismatch in reference: lookup_object_or_alloc+0x7c (section: .text.lookup_object_or_alloc) -> is_static_object (section: .init.text) Marking the affected functions as not "__init" would reliably avoid this issue but is not a good solution because it removes an otherwise correct annotation. I tried marking the functions as 'noinline', but that ended up not covering all the affected configurations. With some more experimenting, I found that marking these functions as __attribute__((noipa)) is both logical and reliable. In order to keep the syntax readable, add a custom macro for this in include/linux/compiler_attributes.h next to other related macros and use it to annotate both files. Link: https://lore.kernel.org/all/abRB6g-48ZX6Yl2r@willie-the-truck/ Cc: Will Deacon Cc: Thomas Gleixner Cc: Andrew Morton Cc: Miguel Ojeda Cc: linux-kbuild@vger.kernel.org Cc: stable@vger.kernel.org Signed-off-by: Arnd Bergmann Acked-by: Will Deacon Acked-by: Thomas Gleixner Acked-by: Miguel Ojeda Signed-off-by: Joerg Roedel --- drivers/iommu/io-pgtable-arm-v7s.c | 18 ++++++++++++------ include/linux/compiler_attributes.h | 11 +++++++++++ lib/debugobjects.c | 2 +- 3 files changed, 24 insertions(+), 7 deletions(-) diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c index 40e33257d3c2..1dbef8c55007 100644 --- a/drivers/iommu/io-pgtable-arm-v7s.c +++ b/drivers/iommu/io-pgtable-arm-v7s.c @@ -777,21 +777,27 @@ struct io_pgtable_init_fns io_pgtable_arm_v7s_init_fns = { static struct io_pgtable_cfg *cfg_cookie __initdata; -static void __init dummy_tlb_flush_all(void *cookie) +/* + * __noipa prevents gcc from turning indirect iommu_flush_ops calls + * into direct calls from a specialized __arm_v7s_unmap() that triggers + * a build time section mismatch assertion. + */ +static __noipa void __init dummy_tlb_flush_all(void *cookie) { WARN_ON(cookie != cfg_cookie); } -static void __init dummy_tlb_flush(unsigned long iova, size_t size, - size_t granule, void *cookie) +static __noipa void __init dummy_tlb_flush(unsigned long iova, size_t size, + size_t granule, void *cookie) { WARN_ON(cookie != cfg_cookie); WARN_ON(!(size & cfg_cookie->pgsize_bitmap)); } -static void __init dummy_tlb_add_page(struct iommu_iotlb_gather *gather, - unsigned long iova, size_t granule, - void *cookie) +static __noipa void __init dummy_tlb_add_page(struct iommu_iotlb_gather *gather, + unsigned long iova, + size_t granule, + void *cookie) { dummy_tlb_flush(iova, granule, granule, cookie); } diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h index c16d4199bf92..836a50f5917a 100644 --- a/include/linux/compiler_attributes.h +++ b/include/linux/compiler_attributes.h @@ -396,6 +396,17 @@ # define __disable_sanitizer_instrumentation #endif +/* + * Optional: not supported by clang + * + * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Attributes.html#index-noipa + */ +#if __has_attribute(noipa) +# define __noipa __attribute__((noipa)) +#else +# define __noipa +#endif + /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-weak-function-attribute * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-weak-variable-attribute diff --git a/lib/debugobjects.c b/lib/debugobjects.c index 12e2e42e6a31..c93b7ca3e1ab 100644 --- a/lib/debugobjects.c +++ b/lib/debugobjects.c @@ -1212,7 +1212,7 @@ struct self_test { static __initconst const struct debug_obj_descr descr_type_test; -static bool __init is_static_object(void *addr) +static __noipa bool __init is_static_object(void *addr) { struct self_test *obj = addr;