powerpc64: Add .opd based function descriptor dereference

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).

Link: http://lkml.kernel.org/r/20171109234830.5067-4-sergey.senozhatsky@gmail.com
To: Tony Luck <tony.luck@intel.com>
To: Fenghua Yu <fenghua.yu@intel.com>
To: Helge Deller <deller@gmx.de>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Paul Mackerras <paulus@samba.org>
To: Michael Ellerman <mpe@ellerman.id.au>
To: James Bottomley <jejb@parisc-linux.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-ia64@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Tested-by: Santosh Sivaraj <santosh@fossix.org> #powerpc
Signed-off-by: Petr Mladek <pmladek@suse.com>

diff --git a/arch/powerpc/include/asm/module.h b/arch/powerpc/include/asm/module.h
index 6c0132c7212f8ea484805c9a9f72b682b79f6a39..7e28442827f1e6feb966c4aeeabd3961e4cb360f 100644 (file)
--- 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 82bec63bbd4f214a43b8f6094d55bb9cbbe7e376..e335a8f846afdd0d8388e782b02c5dba563bf206 100644 (file)
--- 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 759104b99f9feb5940d186d0402ab5622e7ca347..218971ac7e04c72499aa3dbb020fa490a091463d 100644 (file)
--- 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 0494e1566ee2ab9b976cb0d9edb8c195a4490a23..5dac5ab22fa2898a57bb3b21181221c4ed14dcc6 100644 (file)
--- 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);