[PATCH v3 07/12] asm-generic: Define 'func_desc_t' to commonly describe function descriptors

[Christophe Leroy <christophe.leroy@csgroup.eu>]

We have three architectures using function descriptors, each with its
own type and name.

Add a common typedef that can be used in generic code.

Also add a stub typedef for architecture without function descriptors,
to avoid a forest of #ifdefs.

It replaces the similar 'func_desc_t' previously defined in
arch/powerpc/kernel/module_64.c

Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/ia64/include/asm/sections.h    | 3 +++
 arch/parisc/include/asm/sections.h  | 5 +++++
 arch/powerpc/include/asm/sections.h | 4 ++++
 arch/powerpc/kernel/module_64.c     | 8 --------
 include/asm-generic/sections.h      | 3 +++
 5 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/arch/ia64/include/asm/sections.h b/arch/ia64/include/asm/sections.h
index 2460d365a057..3abe0562b01a 100644
--- a/arch/ia64/include/asm/sections.h
+++ b/arch/ia64/include/asm/sections.h
@@ -9,6 +9,9 @@
 
 #include <linux/elf.h>
 #include <linux/uaccess.h>
+
+typedef struct fdesc func_desc_t;
+
 #include <asm-generic/sections.h>
 
 extern char __phys_per_cpu_start[];
diff --git a/arch/parisc/include/asm/sections.h b/arch/parisc/include/asm/sections.h
index c8092e4d94de..ace1d4047a0b 100644
--- a/arch/parisc/include/asm/sections.h
+++ b/arch/parisc/include/asm/sections.h
@@ -2,6 +2,11 @@
 #ifndef _PARISC_SECTIONS_H
 #define _PARISC_SECTIONS_H
 
+#ifdef CONFIG_HAVE_FUNCTION_DESCRIPTORS
+#include <asm/elf.h>
+typedef Elf64_Fdesc func_desc_t;
+#endif
+
 /* nothing to see, move along */
 #include <asm-generic/sections.h>
 
diff --git a/arch/powerpc/include/asm/sections.h b/arch/powerpc/include/asm/sections.h
index fb11544d7e6a..1e6b6e732fb3 100644
--- a/arch/powerpc/include/asm/sections.h
+++ b/arch/powerpc/include/asm/sections.h
@@ -8,6 +8,10 @@
 
 #define arch_is_kernel_initmem_freed arch_is_kernel_initmem_freed
 
+#ifdef CONFIG_HAVE_FUNCTION_DESCRIPTORS
+typedef struct func_desc func_desc_t;
+#endif
+
 #include <asm-generic/sections.h>
 
 extern bool init_mem_is_free;
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index b687ef88c4c4..3d06b996d504 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -32,11 +32,6 @@
 
 #ifdef PPC64_ELF_ABI_v2
 
-/* An address is simply the address of the function. */
-typedef struct {
-	unsigned long addr;
-} func_desc_t;
-
 static func_desc_t func_desc(unsigned long addr)
 {
 	return (func_desc_t){addr};
@@ -57,9 +52,6 @@ static unsigned int local_entry_offset(const Elf64_Sym *sym)
 }
 #else
 
-/* An address is address of the OPD entry, which contains address of fn. */
-typedef struct func_desc func_desc_t;
-
 static func_desc_t func_desc(unsigned long addr)
 {
 	return *(struct func_desc *)addr;
diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index a918388d9bf6..33b51efe3a24 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -63,6 +63,9 @@ extern __visible const void __nosave_begin, __nosave_end;
 #else
 #define dereference_function_descriptor(p) ((void *)(p))
 #define dereference_kernel_function_descriptor(p) ((void *)(p))
+typedef struct {
+	unsigned long addr;
+} func_desc_t;
 #endif
 
 static inline bool have_function_descriptors(void)
-- 
2.31.1