[PATCH v2 06/13] asm-generic: Use HAVE_FUNCTION_DESCRIPTORS to define associated stubs

Christophe Leroy
2021-10-14T06:25:22Z

Replace HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR by
HAVE_FUNCTION_DESCRIPTORS and use it instead of
'dereference_function_descriptor' macro to know
whether an arch has function descriptors.

To limit churn in one of the following patches, use
an #ifdef/#else construct with empty first part
instead of an #ifndef in asm-generic/sections.h

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/ia64/include/asm/sections.h | 5 +++--
arch/parisc/include/asm/sections.h | 6 ++++--
arch/powerpc/include/asm/sections.h | 6 ++++--
include/asm-generic/sections.h | 3 ++-
include/linux/kallsyms.h | 2 +-
5 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/arch/ia64/include/asm/sections.h b/arch/ia64/include/asm/sections.h
index 35f24e52149a..6e55e545bf02 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>
+
+#define HAVE_FUNCTION_DESCRIPTORS 1
+
#include <asm-generic/sections.h>

extern char __phys_per_cpu_start[];
@@ -27,8 +30,6 @@ extern char __start_gate_brl_fsys_bubble_down_patchlist[], __end_gate_brl_fsys_b
extern char __start_unwind[], __end_unwind[];
extern char __start_ivt_text[], __end_ivt_text[];

-#define HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR 1
-
#undef dereference_function_descriptor
static inline void *dereference_function_descriptor(void *ptr)
{
diff --git a/arch/parisc/include/asm/sections.h b/arch/parisc/include/asm/sections.h
index bb52aea0cb21..85149a89ff3e 100644
--- a/arch/parisc/include/asm/sections.h
+++ b/arch/parisc/include/asm/sections.h
@@ -2,6 +2,10 @@
#ifndef _PARISC_SECTIONS_H
#define _PARISC_SECTIONS_H

+#ifdef CONFIG_64BIT
+#define HAVE_FUNCTION_DESCRIPTORS 1
+#endif
+
/* nothing to see, move along */
#include <asm-generic/sections.h>

@@ -9,8 +13,6 @@ extern char __alt_instructions[], __alt_instructions_end[];

#ifdef CONFIG_64BIT

-#define HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR 1
-
#undef dereference_function_descriptor
void *dereference_function_descriptor(void *);

diff --git a/arch/powerpc/include/asm/sections.h b/arch/powerpc/include/asm/sections.h
index 32e7035863ac..bba97b8c38cf 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 PPC64_ELF_ABI_v1
+#define HAVE_FUNCTION_DESCRIPTORS 1
+#endif
+
#include <asm-generic/sections.h>

extern bool init_mem_is_free;
@@ -69,8 +73,6 @@ static inline int overlaps_kernel_text(unsigned long start, unsigned long end)

#ifdef PPC64_ELF_ABI_v1

-#define HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR 1
-
#undef dereference_function_descriptor
static inline void *dereference_function_descriptor(void *ptr)
{
diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index d16302d3eb59..b677e926e6b3 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -59,7 +59,8 @@ extern char __noinstr_text_start[], __noinstr_text_end[];
extern __visible const void __nosave_begin, __nosave_end;

/* Function descriptor handling (if any). Override in asm/sections.h */
-#ifndef dereference_function_descriptor
+#ifdef HAVE_FUNCTION_DESCRIPTORS
+#else
#define dereference_function_descriptor(p) ((void *)(p))
#define dereference_kernel_function_descriptor(p) ((void *)(p))
#endif
diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
index a1d6fc82d7f0..9f277baeb559 100644
--- a/include/linux/kallsyms.h
+++ b/include/linux/kallsyms.h
@@ -57,7 +57,7 @@ static inline int is_ksym_addr(unsigned long addr)

static inline void *dereference_symbol_descriptor(void *ptr)
{
-#ifdef HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR
+#ifdef HAVE_FUNCTION_DESCRIPTORS
struct module *mod;

ptr = dereference_kernel_function_descriptor(ptr);
--
2.31.1