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Subject[RFC][PATCH v2 3/7] ia64: Add .opd based function descriptor dereference
Date
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.senozhatsky@gmail.com>
---
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 = .;
}

/*
--
2.14.1
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