[PATCH v4 08/13] asm-generic: Define 'func_desc_t' to commonly describe function descriptors

Christophe Leroy
2022-02-15T12:50:27Z

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>
Acked-by: Helge Deller <deller@gmx.de>
---
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 | 5 +++++
5 files changed, 17 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 7728a7a146c3..fddfb3937868 100644
--- a/arch/powerpc/include/asm/sections.h
+++ b/arch/powerpc/include/asm/sections.h
@@ -6,6 +6,10 @@
#include <linux/elf.h>
#include <linux/uaccess.h>

+#ifdef CONFIG_HAVE_FUNCTION_DESCRIPTORS
+typedef struct func_desc func_desc_t;
+#endif
+
#include <asm-generic/sections.h>

extern char __head_end[];
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index ff93ef4cb5a2..9abc0e783e36 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)
{
func_desc_t desc = {
@@ -61,9 +56,6 @@ 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 3ef83e1aebee..bbf97502470c 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -63,6 +63,11 @@ extern __visible const void __nosave_begin, __nosave_end;
#else
#define dereference_function_descriptor(p) ((void *)(p))
#define dereference_kernel_function_descriptor(p) ((void *)(p))
+
+/* An address is simply the address of the function. */
+typedef struct {
+ unsigned long addr;
+} func_desc_t;
#endif

static inline bool have_function_descriptors(void)
--
2.34.1