We are moving towards separate kernel and module function descriptor
dereference callbacks. This patch enables it for IA64.

For pointers that belong to the kernel
-  Added __start_opd and __end_opd pointers, to track the kernel
   .opd section address range;

-  Added dereference_kernel_function_descriptor(). Now we
   will dereference only function pointers that are within
   [__start_opd, __end_opd];

For pointers that belong to a module
-  Added dereference_module_function_descriptor() to handle module
   function descriptor dereference. Now we will dereference only
   pointers that are within [module->opd.start, module->opd.end].

Signed-off-by: Sergey Senozhatsky <sergey.senozhat...@gmail.com>
Tested-by: Helge Deller <del...@gmx.de> # parisc64
Tested-by: Santosh Sivaraj <sant...@fossix.org> # powerpc64
Acked-by: Michael Ellerman <m...@ellerman.id.au> # powerpc64
Tested-by: Tony Luck <tony.l...@intel.com> # ia64
---
 arch/ia64/include/asm/sections.h | 10 +++++++++-
 arch/ia64/kernel/module.c        | 13 +++++++++++++
 arch/ia64/kernel/vmlinux.lds.S   |  2 ++
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/ia64/include/asm/sections.h b/arch/ia64/include/asm/sections.h
index de6bfa1ef8fb..3ba7ce9d8bc8 100644
--- a/arch/ia64/include/asm/sections.h
+++ b/arch/ia64/include/asm/sections.h
@@ -37,6 +37,14 @@ static inline unsigned long 
dereference_function_descriptor(unsigned long ptr)
        return ptr;
 }
 
+#undef dereference_kernel_function_descriptor
+static inline unsigned long
+dereference_kernel_function_descriptor(unsigned long addr)
+{
+       if (addr < (unsigned long)__start_opd ||
+                       addr >= (unsigned long)__end_opd)
+               return addr;
+       return dereference_function_descriptor(addr);
+}
 
 #endif /* _ASM_IA64_SECTIONS_H */
-
diff --git a/arch/ia64/kernel/module.c b/arch/ia64/kernel/module.c
index d1d945c6bd05..0741ae6fa957 100644
--- a/arch/ia64/kernel/module.c
+++ b/arch/ia64/kernel/module.c
@@ -35,6 +35,7 @@
 
 #include <asm/patch.h>
 #include <asm/unaligned.h>
+#include <asm/sections.h>
 
 #define ARCH_MODULE_DEBUG 0
 
@@ -917,3 +918,15 @@ module_arch_cleanup (struct module *mod)
        if (mod->arch.core_unw_table)
                unw_remove_unwind_table(mod->arch.core_unw_table);
 }
+
+unsigned long
+dereference_module_function_descriptor(struct module *mod, unsigned long addr)
+{
+       Elf64_Shdr *opd = mod->arch.opd;
+
+       if (addr < opd->sh_addr ||
+                       addr >= (opd->sh_addr + opd->sh_size))
+               return addr;
+
+       return dereference_function_descriptor(addr);
+}
diff --git a/arch/ia64/kernel/vmlinux.lds.S b/arch/ia64/kernel/vmlinux.lds.S
index 798026dde52e..f872ba5ff82a 100644
--- a/arch/ia64/kernel/vmlinux.lds.S
+++ b/arch/ia64/kernel/vmlinux.lds.S
@@ -107,7 +107,9 @@ SECTIONS {
        RODATA
 
        .opd : AT(ADDR(.opd) - LOAD_OFFSET) {
+               __start_opd = .;
                *(.opd)
+               __end_opd = .;
        }
 
        /*
-- 
2.14.2

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