Merge branch 'work.elf-compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull ELF compat updates from Al Viro:
 "Sanitizing ELF compat support, especially for triarch architectures:

   - X32 handling cleaned up

   - MIPS64 uses compat_binfmt_elf.c both for O32 and N32 now

   - Kconfig side of things regularized

  Eventually I hope to have compat_binfmt_elf.c killed, with both native
  and compat built from fs/binfmt_elf.c, with -DELF_BITS={64,32} passed
  by kbuild, but that's a separate story - not included here"

* 'work.elf-compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  get rid of COMPAT_ELF_EXEC_PAGESIZE
  compat_binfmt_elf: don't bother with undef of ELF_ARCH
  Kconfig: regularize selection of CONFIG_BINFMT_ELF
  mips compat: switch to compat_binfmt_elf.c
  mips: don't bother with ELF_CORE_EFLAGS
  mips compat: don't bother with ELF_ET_DYN_BASE
  mips: KVM_GUEST makes no sense for 64bit builds...
  mips: kill unused definitions in binfmt_elf[on]32.c
  mips binfmt_elf*32.c: use elfcore-compat.h
  x32: make X32, !IA32_EMULATION setups able to execute x32 binaries
  [amd64] clean PRSTATUS_SIZE/SET_PR_FPVALID up properly
  elf_prstatus: collect the common part (everything before pr_reg) into a struct
  binfmt_elf: partially sanitize PRSTATUS_SIZE and SET_PR_FPVALID

2 files changed, 48 insertions, 37 deletions

diff --git a/arch/mips/include/asm/elf.h b/arch/mips/include/asm/elf.h
index 71c7622025d1..dc8d2863752c 100644
--- a/arch/mips/include/asm/elf.h
+++ b/arch/mips/include/asm/elf.h
@@ -201,7 +201,6 @@ struct mips_elf_abiflags_v0 {
 	uint32_t flags2;
 };
 
-#ifndef ELF_ARCH
 /* ELF register definitions */
 #define ELF_NGREG	45
 #define ELF_NFPREG	33
@@ -219,7 +218,7 @@ void mips_dump_regs64(u64 *uregs, const struct pt_regs *regs);
 /*
  * This is used to ensure we don't load something for the wrong architecture.
  */
-#define elf_check_arch elfo32_check_arch
+#define elf_check_arch elf32_check_arch
 
 /*
  * These are used to set parameters in the core dumps.
@@ -235,7 +234,8 @@ void mips_dump_regs64(u64 *uregs, const struct pt_regs *regs);
 /*
  * This is used to ensure we don't load something for the wrong architecture.
  */
-#define elf_check_arch elfn64_check_arch
+#define elf_check_arch elf64_check_arch
+#define compat_elf_check_arch elf32_check_arch
 
 /*
  * These are used to set parameters in the core dumps.
@@ -257,8 +257,6 @@ void mips_dump_regs64(u64 *uregs, const struct pt_regs *regs);
 #endif
 #define ELF_ARCH	EM_MIPS
 
-#endif /* !defined(ELF_ARCH) */
-
 /*
  * In order to be sure that we don't attempt to execute an O32 binary which
  * requires 64 bit FP (FR=1) on a system which does not support it we refuse
@@ -277,9 +275,9 @@ void mips_dump_regs64(u64 *uregs, const struct pt_regs *regs);
 #define vmcore_elf64_check_arch mips_elf_check_machine
 
 /*
- * Return non-zero if HDR identifies an o32 ELF binary.
+ * Return non-zero if HDR identifies an o32 or n32 ELF binary.
  */
-#define elfo32_check_arch(hdr)						\
+#define elf32_check_arch(hdr)						\
 ({									\
 	int __res = 1;							\
 	struct elfhdr *__h = (hdr);					\
@@ -288,21 +286,26 @@ void mips_dump_regs64(u64 *uregs, const struct pt_regs *regs);
 		__res = 0;						\
 	if (__h->e_ident[EI_CLASS] != ELFCLASS32)			\
 		__res = 0;						\
-	if ((__h->e_flags & EF_MIPS_ABI2) != 0)				\
-		__res = 0;						\
-	if (((__h->e_flags & EF_MIPS_ABI) != 0) &&			\
-	    ((__h->e_flags & EF_MIPS_ABI) != EF_MIPS_ABI_O32))		\
-		__res = 0;						\
-	if (__h->e_flags & __MIPS_O32_FP64_MUST_BE_ZERO)		\
-		__res = 0;						\
-									\
+	if ((__h->e_flags & EF_MIPS_ABI2) != 0) {			\
+		if (!IS_ENABLED(CONFIG_MIPS32_N32) ||			\
+		     (__h->e_flags & EF_MIPS_ABI))			\
+			__res = 0;					\
+	} else {							\
+		if (IS_ENABLED(CONFIG_64BIT) && !IS_ENABLED(CONFIG_MIPS32_O32)) \
+			__res = 0;					\
+		if (((__h->e_flags & EF_MIPS_ABI) != 0) &&		\
+		    ((__h->e_flags & EF_MIPS_ABI) != EF_MIPS_ABI_O32))	\
+			__res = 0;					\
+		if (__h->e_flags & __MIPS_O32_FP64_MUST_BE_ZERO)	\
+			__res = 0;					\
+	}								\
 	__res;								\
 })
 
 /*
  * Return non-zero if HDR identifies an n64 ELF binary.
  */
-#define elfn64_check_arch(hdr)						\
+#define elf64_check_arch(hdr)						\
 ({									\
 	int __res = 1;							\
 	struct elfhdr *__h = (hdr);					\
@@ -315,25 +318,6 @@ void mips_dump_regs64(u64 *uregs, const struct pt_regs *regs);
 	__res;								\
 })
 
-/*
- * Return non-zero if HDR identifies an n32 ELF binary.
- */
-#define elfn32_check_arch(hdr)						\
-({									\
-	int __res = 1;							\
-	struct elfhdr *__h = (hdr);					\
-									\
-	if (!mips_elf_check_machine(__h))				\
-		__res = 0;						\
-	if (__h->e_ident[EI_CLASS] != ELFCLASS32)			\
-		__res = 0;						\
-	if (((__h->e_flags & EF_MIPS_ABI2) == 0) ||			\
-	    ((__h->e_flags & EF_MIPS_ABI) != 0))			\
-		__res = 0;						\
-									\
-	__res;								\
-})
-
 struct mips_abi;
 
 extern struct mips_abi mips_abi;
@@ -469,9 +453,7 @@ extern const char *__elf_base_platform;
    the loader.	We need to make sure that it is out of the way of the program
    that it will "exec", and that there is sufficient room for the brk.	*/
 
-#ifndef ELF_ET_DYN_BASE
 #define ELF_ET_DYN_BASE		(TASK_SIZE / 3 * 2)
-#endif
 
 /* update AT_VECTOR_SIZE_ARCH if the number of NEW_AUX_ENT entries changes */
 #define ARCH_DLINFO							\
diff --git a/arch/mips/include/asm/elfcore-compat.h b/arch/mips/include/asm/elfcore-compat.h
new file mode 100644
index 000000000000..2f0f0103c75b
--- /dev/null
+++ b/arch/mips/include/asm/elfcore-compat.h
@@ -0,0 +1,29 @@
+#ifndef _ASM_MIPS_ELFCORE_COMPAT_H
+#define _ASM_MIPS_ELFCORE_COMPAT_H
+
+/*
+ * On mips we have two 32bit ABIs - o32 and n32.  The latter
+ * has bigger registers, so we use it for compat_elf_regset_t.
+ * The former uses o32_elf_prstatus and PRSTATUS_SIZE/SET_PR_FPVALID
+ * are used to choose the size and location of ->pr_fpvalid of
+ * the layout actually used.
+ */
+typedef elf_gregset_t compat_elf_gregset_t;
+
+struct o32_elf_prstatus
+{
+	struct compat_elf_prstatus_common	common;
+	unsigned int 			pr_reg[ELF_NGREG];
+	compat_int_t			pr_fpvalid;
+};
+
+#define PRSTATUS_SIZE \
+	(!test_thread_flag(TIF_32BIT_REGS) \
+		? sizeof(struct compat_elf_prstatus) \
+		: sizeof(struct o32_elf_prstatus))
+#define SET_PR_FPVALID(S) \
+	(*(!test_thread_flag(TIF_32BIT_REGS) \
+		? &(S)->pr_fpvalid 	\
+		: &((struct o32_elf_prstatus *)(S))->pr_fpvalid) = 1)
+
+#endif