We are moving towards separate kernel and module function descriptor
dereference callbacks. This patch enables it for powerpc64.
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@xxxxxxxxx>
---
arch/powerpc/include/asm/module.h | 3 +++
arch/powerpc/include/asm/sections.h | 12 ++++++++++++
arch/powerpc/kernel/module_64.c | 14 ++++++++++++++
arch/powerpc/kernel/vmlinux.lds.S | 2 ++
4 files changed, 31 insertions(+)
diff --git a/arch/powerpc/include/asm/module.h b/arch/powerpc/include/asm/module.h
index 6c0132c7212f..7e28442827f1 100644
--- a/arch/powerpc/include/asm/module.h
+++ b/arch/powerpc/include/asm/module.h
@@ -45,6 +45,9 @@ struct mod_arch_specific {
unsigned long tramp;
#endif
+ /* For module function descriptor dereference */
+ unsigned long start_opd;
+ unsigned long end_opd;
#else /* powerpc64 */
/* Indices of PLT sections within module. */
unsigned int core_plt_section;
diff --git a/arch/powerpc/include/asm/sections.h b/arch/powerpc/include/asm/sections.h
index 82bec63bbd4f..e335a8f846af 100644
--- a/arch/powerpc/include/asm/sections.h
+++ b/arch/powerpc/include/asm/sections.h
@@ -66,6 +66,9 @@ static inline int overlaps_kvm_tmp(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)
{
@@ -76,6 +79,15 @@ static inline void *dereference_function_descriptor(void *ptr)
ptr = p;
return ptr;
}
+
+#undef dereference_kernel_function_descriptor
+static inline void *dereference_kernel_function_descriptor(void *ptr)
+{
+ if (ptr < (void *)__start_opd || ptr >= (void *)__end_opd)
+ return ptr;
+
+ return dereference_function_descriptor(ptr);
+}
#endif /* PPC64_ELF_ABI_v1 */
#endif
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index 759104b99f9f..218971ac7e04 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -93,6 +93,15 @@ static unsigned int local_entry_offset(const Elf64_Sym *sym)
{
return 0;
}
+
+void *dereference_module_function_descriptor(struct module *mod, void *ptr)
+{
+ if (ptr < (void *)mod->arch.start_opd ||
+ ptr >= (void *)mod->arch.end_opd)
+ return ptr;
+
+ return dereference_function_descriptor(ptr);
+}
#endif
#define STUB_MAGIC 0x73747562 /* stub */
@@ -344,6 +353,11 @@ int module_frob_arch_sections(Elf64_Ehdr *hdr,
else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
sechdrs[i].sh_size);
+ else if (!strcmp(secstrings + sechdrs[i].sh_name, ".opd")) {
+ me->arch.start_opd = sechdrs[i].sh_addr;
+ me->arch.end_opd = sechdrs[i].sh_addr +
+ sechdrs[i].sh_size;
+ }
/* We don't handle .init for the moment: rename to _init */
while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init")))
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 0494e1566ee2..5dac5ab22fa2 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -278,7 +278,9 @@ SECTIONS
}
.opd : AT(ADDR(.opd) - LOAD_OFFSET) {
+ __start_opd = .;
*(.opd)
+ __end_opd = .;
}
. = ALIGN(256);
--
2.15.0
--
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