Build of VMA and radix-tree tests is unhappy after the conversion of
kzalloc() to kzalloc_obj() in lib/idr.c:

  cc -I../shared -I. -I../../include -I../../arch/x86/include -I../../../lib -g -Og -Wall -D_LGPL_SOURCE -fsanitize=address -fsanitize=undefined  -DNUM_VMA_FLAG_BITS=128 -DNUM_MM_FLAG_BITS=128   -c -o idr.o idr.c
  idr.c: In function `ida_alloc_range':
  idr.c:420:34: error: implicit declaration of function `kzalloc_obj'; did you mean `kzalloc_node'? [-Wimplicit-function-declaration]
    420 |                         bitmap = kzalloc_obj(*bitmap, GFP_NOWAIT);
        |                                  ^~~~~~~~~~~
        |                                  kzalloc_node
  idr.c:420:32: error: assignment to `struct ida_bitmap *' from `int' makes pointer from integer without a cast [-Wint-conversion]
    420 |                         bitmap = kzalloc_obj(*bitmap, GFP_NOWAIT);
        |                                ^
  idr.c:447:40: error: assignment to `struct ida_bitmap *' from `int' makes pointer from integer without a cast [-Wint-conversion]
    447 |                                 bitmap = kzalloc_obj(*bitmap, GFP_NOWAIT);
        |                                        ^
  idr.c:468:15: error: assignment to `struct ida_bitmap *' from `int' makes pointer from integer without a cast [-Wint-conversion]
    468 |         alloc = kzalloc_obj(*bitmap, gfp);
        |               ^
  make: *** [<builtin>: idr.o] Error 1

Import necessary macros from include/linux to tools/include/linux to fix
the compilation.

Link: https://lkml.kernel.org/r/20260225233111.2760752-1-rppt@kernel.org
Fixes: 69050f8d6d07 ("treewide: Replace kmalloc with kmalloc_obj for non-scalar types")
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Once upgrading the minimum supported version of GCC to 5.1, we can drop
the fallback code for !COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW.

This is effectively a revert of commit f0907827a8a9 ("compiler.h: enable
builtin overflow checkers and add fallback code")

Link: https://github.com/ClangBuiltLinux/linux/issues/1438#issuecomment-916745801
Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

reallocarray() is a safer variant of realloc which checks for
multiplication overflow in case of array allocation.  Since it's
not available in Glibc < 2.26 import kernel's overflow.h and
add a static inline implementation when needed.  Use feature
detection to probe for existence of reallocarray.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>