Re: [PATCH modules 1/2] module: allow arch overrides for .exit section names

[Jessica Yu <jeyu@kernel.org>]

+++ Matthias Schiffer [03/06/19 12:57 +0200]:
>Some archs like ARM store unwind information for .exit.text in sections
>with unusual names. As this unwind information refers to .exit.text, it
>must not be loaded when .exit.text is not loaded (when CONFIG_MODULE_UNLOAD
>is unset); otherwise, loading a module can fail due to relocation failures.
>
>Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
>---
> include/linux/moduleloader.h | 8 ++++++++
> kernel/module.c              | 2 +-
> 2 files changed, 9 insertions(+), 1 deletion(-)
>
>diff --git a/include/linux/moduleloader.h b/include/linux/moduleloader.h
>index 31013c2effd3..cddbd85fb659 100644
>--- a/include/linux/moduleloader.h
>+++ b/include/linux/moduleloader.h
>@@ -5,6 +5,7 @@
>
> #include <linux/module.h>
> #include <linux/elf.h>
>+#include <linux/string.h>
>
> /* These may be implemented by architectures that need to hook into the
>  * module loader code.  Architectures that don't need to do anything special
>@@ -93,4 +94,11 @@ void module_arch_freeing_init(struct module *mod);
> #define MODULE_ALIGN PAGE_SIZE
> #endif
>
>+#ifndef HAVE_ARCH_MODULE_EXIT_SECTION
>+static inline bool module_exit_section(const char *name)
>+{
>+	return strstarts(name, ".exit");
>+}
>+#endif
>+

Hi Matthias,

For sake of consistency, could we implement this as an arch-overridable
__weak symbol like the rest of the module arch-overrides in moduleloader.h?

> #endif
>diff --git a/kernel/module.c b/kernel/module.c
>index 6e6712b3aaf5..e8e4cd0a471f 100644
>--- a/kernel/module.c
>+++ b/kernel/module.c
>@@ -2924,7 +2924,7 @@ static int rewrite_section_headers(struct load_info *info, int flags)
>
> #ifndef CONFIG_MODULE_UNLOAD
> 		/* Don't load .exit sections */
>-		if (strstarts(info->secstrings+shdr->sh_name, ".exit"))
>+		if (module_exit_section(info->secstrings+shdr->sh_name))
> 			shdr->sh_flags &= ~(unsigned long)SHF_ALLOC;
> #endif
> 	}
>-- 
>2.17.1
>