[PATCH 1/2] modules: add default loader hook implementations

From: Jonas Bonn
Date: Thu Jun 30 2011 - 15:22:25 EST



The module loader code allows architectures to hook into the code by
providing a small number of entry points that each arch must implement.
This patch provides __weakly linked generic implementations of these
entry points for architectures that don't need to do anything special.

Signed-off-by: Jonas Bonn <jonas@xxxxxxxxxxxx>
---
include/linux/moduleloader.h | 7 +++++-
kernel/module.c | 49 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 55 insertions(+), 1 deletions(-)

diff --git a/include/linux/moduleloader.h b/include/linux/moduleloader.h
index c1f40c2..b2be02e 100644
--- a/include/linux/moduleloader.h
+++ b/include/linux/moduleloader.h
@@ -5,7 +5,12 @@
#include <linux/module.h>
#include <linux/elf.h>

-/* These must be implemented by the specific architecture */
+/* These may be implemented by architectures that need to hook into the
+ * module loader code. Architectures that don't need to do anything special
+ * can just rely on the 'weak' default hooks defined in kernel/module.c.
+ * Note, however, that at least one of apply_relocate or apply_relocate_add
+ * must be implemented by each architecture.
+ */

/* Adjust arch-specific sections. Return 0 on success. */
int module_frob_arch_sections(Elf_Ehdr *hdr,
diff --git a/kernel/module.c b/kernel/module.c
index 795bdc7..6301d6e 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1697,6 +1697,15 @@ static void unset_module_core_ro_nx(struct module *mod) { }
static void unset_module_init_ro_nx(struct module *mod) { }
#endif

+void __weak module_free(struct module *mod, void *module_region)
+{
+ vfree(module_region);
+}
+
+void __weak module_arch_cleanup(struct module *mod)
+{
+}
+
/* Free a module, remove from lists, etc. */
static void free_module(struct module *mod)
{
@@ -1851,6 +1860,26 @@ static int simplify_symbols(struct module *mod, const struct load_info *info)
return ret;
}

+int __weak apply_relocate(Elf_Shdr *sechdrs,
+ const char *strtab,
+ unsigned int symindex,
+ unsigned int relsec,
+ struct module *me)
+{
+ pr_err("module %s: REL relocation unsupported\n", me->name);
+ return -ENOEXEC;
+}
+
+int __weak apply_relocate_add(Elf_Shdr *sechdrs,
+ const char *strtab,
+ unsigned int symindex,
+ unsigned int relsec,
+ struct module *me)
+{
+ pr_err("module %s: RELA relocation unsupported\n", me->name);
+ return -ENOEXEC;
+}
+
static int apply_relocations(struct module *mod, const struct load_info *info)
{
unsigned int i;
@@ -2235,6 +2264,11 @@ static void dynamic_debug_remove(struct _ddebug *debug)
ddebug_remove_module(debug->modname);
}

+void * __weak module_alloc(unsigned long size)
+{
+ return size == 0 ? NULL : vmalloc_exec(size);
+}
+
static void *module_alloc_update_bounds(unsigned long size)
{
void *ret = module_alloc(size);
@@ -2645,6 +2679,14 @@ static void flush_module_icache(const struct module *mod)
set_fs(old_fs);
}

+int __weak module_frob_arch_sections(Elf_Ehdr *hdr,
+ Elf_Shdr *sechdrs,
+ char *secstrings,
+ struct module *mod)
+{
+ return 0;
+}
+
static struct module *layout_and_allocate(struct load_info *info)
{
/* Module within temporary copy. */
@@ -2716,6 +2758,13 @@ static void module_deallocate(struct module *mod, struct load_info *info)
module_free(mod, mod->module_core);
}

+int __weak module_finalize(const Elf_Ehdr *hdr,
+ const Elf_Shdr *sechdrs,
+ struct module *me)
+{
+ return 0;
+}
+
static int post_relocation(struct module *mod, const struct load_info *info)
{
/* Sort exception table now relocations are done. */
--
1.7.4.1

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