[PATCH 4/5] parisc64: Add .opd based function descriptor dereference

Sergey Senozhatsky
2017-09-16T03:53:46Z

We are moving towards separate kernel and module function descriptor
dereference callbacks. This patch enables it for parisc64.

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/parisc/boot/compressed/vmlinux.lds.S | 2 ++
arch/parisc/include/asm/sections.h | 3 +++
arch/parisc/kernel/module.c | 14 ++++++++++++++
arch/parisc/kernel/process.c | 10 ++++++++++
arch/parisc/kernel/vmlinux.lds.S | 2 ++
5 files changed, 31 insertions(+)

diff --git a/arch/parisc/boot/compressed/vmlinux.lds.S b/arch/parisc/boot/compressed/vmlinux.lds.S
index a4ce3314e78e..4ebd4e65524c 100644
--- a/arch/parisc/boot/compressed/vmlinux.lds.S
+++ b/arch/parisc/boot/compressed/vmlinux.lds.S
@@ -29,7 +29,9 @@ SECTIONS
. = ALIGN(16);
/* Linkage tables */
.opd : {
+ __start_opd = .;
*(.opd)
+ __end_opd = .;
} PROVIDE (__gp = .);
.plt : {
*(.plt)
diff --git a/arch/parisc/include/asm/sections.h b/arch/parisc/include/asm/sections.h
index 9d13c3507ad6..e3cde650b2f9 100644
--- a/arch/parisc/include/asm/sections.h
+++ b/arch/parisc/include/asm/sections.h
@@ -6,7 +6,10 @@

#ifdef CONFIG_64BIT
#undef dereference_function_descriptor
+#undef dereference_kernel_function_descriptor
+
void *dereference_function_descriptor(void *);
+void *dereference_kernel_function_descriptor(void *);
#endif

#endif
diff --git a/arch/parisc/kernel/module.c b/arch/parisc/kernel/module.c
index f1a76935a314..bc2eae8634fd 100644
--- a/arch/parisc/kernel/module.c
+++ b/arch/parisc/kernel/module.c
@@ -954,3 +954,17 @@ void module_arch_cleanup(struct module *mod)
{
deregister_unwind_table(mod);
}
+
+#ifdef CONFIG_64BIT
+unsigned long dereference_module_function_descriptor(struct module *mod,
+ unsigned long addr)
+{
+ void *opd_sz = mod->arch.fdesc_offset +
+ mod->arch.fdesc_max * sizeof(Elf64_Fdesc);
+
+ if (addr < mod->arch.fdesc_offset || opd_sz < addr)
+ return addr;
+
+ return dereference_function_descriptor(addr);
+}
+#endif
diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
index 30f92391a93e..f30776bdaa79 100644
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -267,6 +267,8 @@ get_wchan(struct task_struct *p)
}

#ifdef CONFIG_64BIT
+extern char __start_opd[], __end_opd[];
+
void *dereference_function_descriptor(void *ptr)
{
Elf64_Fdesc *desc = ptr;
@@ -276,6 +278,14 @@ void *dereference_function_descriptor(void *ptr)
ptr = p;
return ptr;
}
+
+void *dereference_kernel_function_descriptor(void *ptr)
+{
+ if (ptr < (void *)__start_opd || (void *)__end_opd < ptr)
+ return ptr;
+
+ return dereference_function_descriptor(ptr);
+}
#endif

static inline unsigned long brk_rnd(void)
diff --git a/arch/parisc/kernel/vmlinux.lds.S b/arch/parisc/kernel/vmlinux.lds.S
index ffe2cbf52d1a..ab030895dd1e 100644
--- a/arch/parisc/kernel/vmlinux.lds.S
+++ b/arch/parisc/kernel/vmlinux.lds.S
@@ -99,7 +99,9 @@ SECTIONS
. = ALIGN(16);
/* Linkage tables */
.opd : {
+ __start_opd = .;
*(.opd)
+ __end_opd = .;
} PROVIDE (__gp = .);
.plt : {
*(.plt)
--
2.14.1