[RFC PATCH v9 23/27] ELF: Introduce arch_setup_elf_property()

[Yu-cheng Yu]

An ELF file's .note.gnu.property indicates architecture features of the
file.  These features are extracted earlier and stored in the struct
'arch_elf_state'.  Introduce arch_setup_elf_property() to setup and enable
these features.  The first use-case of this function is Shadow Stack and
Indirect Branch Tracking, which are introduced later.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
---
 fs/binfmt_elf.c     | 4 ++++
 include/linux/elf.h | 6 ++++++
 2 files changed, 10 insertions(+)

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 054446f93442..56fe6cd437fe 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1213,6 +1213,10 @@ static int load_elf_binary(struct linux_binprm *bprm)
 
 	set_binfmt(&elf_format);
 
+	retval = arch_setup_elf_property(&arch_state);
+	if (retval < 0)
+		goto out;
+
 #ifdef ARCH_HAS_SETUP_ADDITIONAL_PAGES
 	retval = arch_setup_additional_pages(bprm, !!interpreter);
 	if (retval < 0)
diff --git a/include/linux/elf.h b/include/linux/elf.h
index 7bdc6da160c7..81f2161fa4a8 100644
--- a/include/linux/elf.h
+++ b/include/linux/elf.h
@@ -78,9 +78,15 @@ static inline int arch_parse_elf_property(u32 type, const void *data,
 {
 	return 0;
 }
+
+static inline int arch_setup_elf_property(struct arch_elf_state *arch)
+{
+	return 0;
+}
 #else
 extern int arch_parse_elf_property(u32 type, const void *data, size_t datasz,
 				   bool compat, struct arch_elf_state *arch);
+extern int arch_setup_elf_property(struct arch_elf_state *arch);
 #endif
 
 #endif /* _LINUX_ELF_H */
-- 
2.21.0