Merge branch 'topic/func-desc-lkdtm' into next

Merge a topic branch we are maintaining with some cross-architecture
changes to function descriptor handling and their use in LKDTM.

From Christophe's cover letter:

Fix LKDTM for PPC64/IA64/PARISC

PPC64/IA64/PARISC have function descriptors. LKDTM doesn't work on those
three architectures because LKDTM messes up function descriptors with
functions.

This series does some cleanup in the three architectures and refactors
function descriptors so that it can then easily use it in a generic way
in LKDTM.

10 files changed, 40 insertions, 70 deletions

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 28e4047e99e8..23ce71367467 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -207,6 +207,7 @@ config PPC
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS	if !(CPU_LITTLE_ENDIAN && POWER7_CPU)
 	select HAVE_FAST_GUP
 	select HAVE_FTRACE_MCOUNT_RECORD
+	select HAVE_FUNCTION_DESCRIPTORS	if PPC64 && !CPU_LITTLE_ENDIAN
 	select HAVE_FUNCTION_ERROR_INJECTION
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 1e1ef4352f62..eb541e730d3c 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -213,7 +213,7 @@ CHECKFLAGS	+= -m$(BITS) -D__powerpc__ -D__powerpc$(BITS)__
 ifdef CONFIG_CPU_BIG_ENDIAN
 CHECKFLAGS	+= -D__BIG_ENDIAN__
 else
-CHECKFLAGS	+= -D__LITTLE_ENDIAN__
+CHECKFLAGS	+= -D__LITTLE_ENDIAN__ -D_CALL_ELF=2
 endif
 
 ifdef CONFIG_476FPE_ERR46
diff --git a/arch/powerpc/include/asm/code-patching.h b/arch/powerpc/include/asm/code-patching.h
index e26080539c31..409483b2d0ce 100644
--- a/arch/powerpc/include/asm/code-patching.h
+++ b/arch/powerpc/include/asm/code-patching.h
@@ -118,7 +118,7 @@ static inline unsigned long ppc_function_entry(void *func)
 	 * function's descriptor. The first entry in the descriptor is the
 	 * address of the function text.
 	 */
-	return ((func_descr_t *)func)->entry;
+	return ((struct func_desc *)func)->addr;
 #else
 	return (unsigned long)func;
 #endif
diff --git a/arch/powerpc/include/asm/elf.h b/arch/powerpc/include/asm/elf.h
index b8425e3cfd81..971589a21bc0 100644
--- a/arch/powerpc/include/asm/elf.h
+++ b/arch/powerpc/include/asm/elf.h
@@ -176,4 +176,10 @@ do {									\
 /* Relocate the kernel image to @final_address */
 void relocate(unsigned long final_address);
 
+struct func_desc {
+	unsigned long addr;
+	unsigned long toc;
+	unsigned long env;
+};
+
 #endif /* _ASM_POWERPC_ELF_H */
diff --git a/arch/powerpc/include/asm/sections.h b/arch/powerpc/include/asm/sections.h
index 38f79e42bf3c..8be2c491c733 100644
--- a/arch/powerpc/include/asm/sections.h
+++ b/arch/powerpc/include/asm/sections.h
@@ -6,6 +6,10 @@
 #include <linux/elf.h>
 #include <linux/uaccess.h>
 
+#ifdef CONFIG_HAVE_FUNCTION_DESCRIPTORS
+typedef struct func_desc func_desc_t;
+#endif
+
 #include <asm-generic/sections.h>
 
 extern char __head_end[];
@@ -54,31 +58,6 @@ static inline int overlaps_kernel_text(unsigned long start, unsigned long end)
 		(unsigned long)_stext < end;
 }
 
-#ifdef PPC64_ELF_ABI_v1
-
-#define HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR 1
-
-#undef dereference_function_descriptor
-static inline void *dereference_function_descriptor(void *ptr)
-{
-	struct ppc64_opd_entry *desc = ptr;
-	void *p;
-
-	if (!get_kernel_nofault(p, (void *)&desc->funcaddr))
-		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
 
 #endif /* __KERNEL__ */
diff --git a/arch/powerpc/include/asm/types.h b/arch/powerpc/include/asm/types.h
index f1630c553efe..97da77bc48c9 100644
--- a/arch/powerpc/include/asm/types.h
+++ b/arch/powerpc/include/asm/types.h
@@ -23,12 +23,6 @@
 
 typedef __vector128 vector128;
 
-typedef struct {
-	unsigned long entry;
-	unsigned long toc;
-	unsigned long env;
-} func_descr_t;
-
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_POWERPC_TYPES_H */
diff --git a/arch/powerpc/include/uapi/asm/elf.h b/arch/powerpc/include/uapi/asm/elf.h
index 860c59291bfc..308857123a08 100644
--- a/arch/powerpc/include/uapi/asm/elf.h
+++ b/arch/powerpc/include/uapi/asm/elf.h
@@ -289,12 +289,4 @@ typedef elf_fpreg_t elf_vsrreghalf_t32[ELF_NVSRHALFREG];
 /* Keep this the last entry.  */
 #define R_PPC64_NUM		253
 
-/* There's actually a third entry here, but it's unused */
-struct ppc64_opd_entry
-{
-	unsigned long funcaddr;
-	unsigned long r2;
-};
-
-
 #endif /* _UAPI_ASM_POWERPC_ELF_H */
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index 94d14cf99bca..794720530442 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -33,20 +33,13 @@
 
 #ifdef PPC64_ELF_ABI_v2
 
-/* An address is simply the address of the function. */
-typedef unsigned long func_desc_t;
-
 static func_desc_t func_desc(unsigned long addr)
 {
-	return addr;
-}
-static unsigned long func_addr(unsigned long addr)
-{
-	return addr;
-}
-static unsigned long stub_func_addr(func_desc_t func)
-{
-	return func;
+	func_desc_t desc = {
+		.addr = addr,
+	};
+
+	return desc;
 }
 
 /* PowerPC64 specific values for the Elf64_Sym st_other field.  */
@@ -64,20 +57,9 @@ static unsigned int local_entry_offset(const Elf64_Sym *sym)
 }
 #else
 
-/* An address is address of the OPD entry, which contains address of fn. */
-typedef struct ppc64_opd_entry func_desc_t;
-
 static func_desc_t func_desc(unsigned long addr)
 {
-	return *(struct ppc64_opd_entry *)addr;
-}
-static unsigned long func_addr(unsigned long addr)
-{
-	return func_desc(addr).funcaddr;
-}
-static unsigned long stub_func_addr(func_desc_t func)
-{
-	return func.funcaddr;
+	return *(struct func_desc *)addr;
 }
 static unsigned int local_entry_offset(const Elf64_Sym *sym)
 {
@@ -94,6 +76,16 @@ void *dereference_module_function_descriptor(struct module *mod, void *ptr)
 }
 #endif
 
+static unsigned long func_addr(unsigned long addr)
+{
+	return func_desc(addr).addr;
+}
+
+static unsigned long stub_func_addr(func_desc_t func)
+{
+	return func.addr;
+}
+
 #define STUB_MAGIC 0x73747562 /* stub */
 
 /* Like PPC32, we need little trampolines to do > 24-bit jumps (into
@@ -188,7 +180,7 @@ static int relacmp(const void *_x, const void *_y)
 static unsigned long get_stubs_size(const Elf64_Ehdr *hdr,
 				    const Elf64_Shdr *sechdrs)
 {
-	/* One extra reloc so it's always 0-funcaddr terminated */
+	/* One extra reloc so it's always 0-addr terminated */
 	unsigned long relocs = 1;
 	unsigned i;
 
diff --git a/arch/powerpc/kernel/ptrace/ptrace.c b/arch/powerpc/kernel/ptrace/ptrace.c
index c43f77e2ac31..1212a812a7ab 100644
--- a/arch/powerpc/kernel/ptrace/ptrace.c
+++ b/arch/powerpc/kernel/ptrace/ptrace.c
@@ -445,4 +445,10 @@ void __init pt_regs_check(void)
 	 * real registers.
 	 */
 	BUILD_BUG_ON(PT_DSCR < sizeof(struct user_pt_regs) / sizeof(unsigned long));
+
+#ifdef PPC64_ELF_ABI_v1
+	BUILD_BUG_ON(!IS_ENABLED(CONFIG_HAVE_FUNCTION_DESCRIPTORS));
+#else
+	BUILD_BUG_ON(IS_ENABLED(CONFIG_HAVE_FUNCTION_DESCRIPTORS));
+#endif
 }
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index d1e1fc0acbea..73d483b07ff3 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -936,11 +936,11 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
 		 * descriptor is the entry address of signal and the second
 		 * entry is the TOC value we need to use.
 		 */
-		func_descr_t __user *funct_desc_ptr =
-			(func_descr_t __user *) ksig->ka.sa.sa_handler;
+		struct func_desc __user *ptr =
+			(struct func_desc __user *)ksig->ka.sa.sa_handler;
 
-		err |= get_user(regs->ctr, &funct_desc_ptr->entry);
-		err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
+		err |= get_user(regs->ctr, &ptr->addr);
+		err |= get_user(regs->gpr[2], &ptr->toc);
 	}
 
 	/* enter the signal handler in native-endian mode */