module: Add CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC

Add CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC to allow architectures
to request having modules data in vmalloc area instead of module area.

This is required on powerpc book3s/32 in order to set data non
executable, because it is not possible to set executability on page
basis, this is done per 256 Mbytes segments. The module area has exec
right, vmalloc area has noexec.

This can also be useful on other powerpc/32 in order to maximize the
chance of code being close enough to kernel core to avoid branch
trampolines.

Cc: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mcgrof: rebased in light of kernel/module/kdb.c move]
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/linux/module.h b/include/linux/module.h
index 5e2059f3afc7..46d4d5f2516e 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -422,6 +422,9 @@ struct module {
 	/* Core layout: rbtree is accessed frequently, so keep together. */
 	struct module_layout core_layout __module_layout_align;
 	struct module_layout init_layout;
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+	struct module_layout data_layout;
+#endif
 
 	/* Arch-specific module values */
 	struct mod_arch_specific arch;
@@ -569,6 +572,11 @@ bool is_module_text_address(unsigned long addr);
 static inline bool within_module_core(unsigned long addr,
 				      const struct module *mod)
 {
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+	if ((unsigned long)mod->data_layout.base <= addr &&
+	    addr < (unsigned long)mod->data_layout.base + mod->data_layout.size)
+		return true;
+#endif
 	return (unsigned long)mod->core_layout.base <= addr &&
 	       addr < (unsigned long)mod->core_layout.base + mod->core_layout.size;
 }