[PATCH 3/5] powerpc64: Add .opd based function descriptor dereference
From: Sergey Senozhatsky <hidden>
Date: 2017-09-16 03:59:02
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
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 <redacted> --- arch/powerpc/include/asm/module.h | 3 +++ arch/powerpc/include/asm/sections.h | 13 +++++++++++++ arch/powerpc/kernel/module_64.c | 16 ++++++++++++++++ arch/powerpc/kernel/vmlinux.lds.S | 2 ++ 4 files changed, 34 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 7902d6358854..7cc4db86952b 100644
--- a/arch/powerpc/include/asm/sections.h
+++ b/arch/powerpc/include/asm/sections.h@@ -16,6 +16,9 @@ extern char __end_interrupts[]; extern char __prom_init_toc_start[]; extern char __prom_init_toc_end[]; +extern char __start_opd[]; +extern char __end_opd[]; + static inline int in_kernel_text(unsigned long addr) { if (addr >= (unsigned long)_stext && addr < (unsigned long)__init_end)
@@ -66,6 +69,8 @@ static inline int overlaps_kvm_tmp(unsigned long start, unsigned long end) #ifdef PPC64_ELF_ABI_v1 #undef dereference_function_descriptor +#undef dereference_kernel_function_descriptor + static inline void *dereference_function_descriptor(void *ptr) { struct ppc64_opd_entry *desc = ptr;
@@ -75,6 +80,14 @@ static inline void *dereference_function_descriptor(void *ptr) ptr = p; return ptr; } + +static inline void *dereference_kernel_function_descriptor(void *ptr) +{ + if (ptr < (void *)__start_opd || (void *)__end_opd < ptr) + 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 0b0f89685b67..52aa5d668364 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c@@ -344,6 +344,11 @@ 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")==0) { + me->arch.start_opd = sechdrs[i].sh_offset; + me->arch.end_opd = me->arch.start_opd + + sechdrs[i].sh_size; + } /* We don't handle .init for the moment: rename to _init */ while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init")))
@@ -712,6 +717,17 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, return 0; } +#ifdef PPC64_ELF_ABI_v1 +unsigned long dereference_module_function_descriptor(struct module *mod, + unsigned long addr) +{ + if (addr < mod->arch.start_opd || mod->arch.end_opd < addr) + return addr; + + return dereference_function_descriptor(addr); +} +#endif /* PPC64_ELF_ABI_v1 */ + #ifdef CONFIG_DYNAMIC_FTRACE #ifdef CC_USING_MPROFILE_KERNEL
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 882628fa6987..70e10251e083 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S@@ -277,7 +277,9 @@ SECTIONS } .opd : AT(ADDR(.opd) - LOAD_OFFSET) { + __start_opd = .; *(.opd) + __end_opd = .; } . = ALIGN(256);
--
2.14.1