x86: disable image size check for test builds

64-bit allyesconfig builds fail with

x86_64-linux-ld: kernel image bigger than KERNEL_IMAGE_SIZE

Bisect points to commit 6f110a5 ("Disable SLUB_TINY for build
testing") as the responsible commit.  Reverting that patch does indeed fix
the problem.  Further analysis shows that disabling SLUB_TINY enables
KASAN, and that KASAN is responsible for the image size increase.

Solve the build problem by disabling the image size check for test
builds.

[[email protected]: add comment, fix nearby typo (sink->sync)]
[[email protected]: fix comment snafu
  Link: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 6f110a5 ("Disable SLUB_TINY for build testing")
Signed-off-by: Guenter Roeck <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Borislav Betkov <[email protected]>
Cc: Dmitriy Vyukov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Thomas Gleinxer <[email protected]>
Cc: Vincenzo Frascino <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: groeck

arch/x86/kernel/vmlinux.lds.S

@@ -466,10 +466,18 @@ SECTIONS
 }
 
 /*
- * The ASSERT() sink to . is intentional, for binutils 2.14 compatibility:
+ * COMPILE_TEST kernels can be large - CONFIG_KASAN, for example, can cause
+ * this.  Let's assume that nobody will be running a COMPILE_TEST kernel and
+ * let's assert that fuller build coverage is more valuable than being able to
+ * run a COMPILE_TEST kernel.
+ */
+#ifndef CONFIG_COMPILE_TEST
+/*
+ * The ASSERT() sync to . is intentional, for binutils 2.14 compatibility:
  */
 . = ASSERT((_end - LOAD_OFFSET <= KERNEL_IMAGE_SIZE),
 	   "kernel image bigger than KERNEL_IMAGE_SIZE");
+#endif
 
 /* needed for Clang - see arch/x86/entry/entry.S */
 PROVIDE(__ref_stack_chk_guard = __stack_chk_guard);