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

20 files changed, 94 insertions, 298 deletions

diff --git a/arch/Kconfig b/arch/Kconfig
index 24862d15f3a3..b8bbfd3c66b8 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1111,6 +1111,9 @@ config ARCH_SPLIT_ARG64
 	   If a 32-bit architecture requires 64-bit arguments to be split into
 	   pairs of 32-bit arguments, select this option.
 
+config ARCH_HAS_ELFCORE_COMPAT
+	bool
+
 source "kernel/gcov/Kconfig"
 
 source "scripts/gcc-plugins/Kconfig"
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index f39568b28ec1..52bc8f6206b7 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1213,7 +1213,6 @@ config ARM64_TAGGED_ADDR_ABI
 menuconfig COMPAT
 	bool "Kernel support for 32-bit EL0"
 	depends on ARM64_4K_PAGES || EXPERT
-	select COMPAT_BINFMT_ELF if BINFMT_ELF
 	select HAVE_UID16
 	select OLD_SIGSUSPEND3
 	select COMPAT_OLD_SIGACTION
diff --git a/arch/ia64/kernel/crash.c b/arch/ia64/kernel/crash.c
index fec70d662d0c..4f47741005d2 100644
--- a/arch/ia64/kernel/crash.c
+++ b/arch/ia64/kernel/crash.c
@@ -43,7 +43,7 @@ crash_save_this_cpu(void)
 
 	elf_greg_t *dst = (elf_greg_t *)&(prstatus->pr_reg);
 	memset(prstatus, 0, sizeof(*prstatus));
-	prstatus->pr_pid = current->pid;
+	prstatus->common.pr_pid = current->pid;
 
 	ia64_dump_cpu_regs(dst);
 	cfm = dst[43];
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 0a17bedf4f0d..f29ec95e3458 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -92,6 +92,7 @@ config MIPS
 	select SET_FS
 	select SYSCTL_EXCEPTION_TRACE
 	select VIRT_TO_BUS
+	select ARCH_HAS_ELFCORE_COMPAT
 
 config MIPS_FIXUP_BIGPHYS_ADDR
 	bool
@@ -2182,7 +2183,7 @@ endchoice
 config KVM_GUEST
 	bool "KVM Guest Kernel"
 	depends on CPU_MIPS32_R2
-	depends on BROKEN_ON_SMP
+	depends on !64BIT && BROKEN_ON_SMP
 	help
 	  Select this option if building a guest kernel for KVM (Trap & Emulate)
 	  mode.
@@ -3300,11 +3301,6 @@ config MIPS32_N32
 
 	  If unsure, say N.
 
-config BINFMT_ELF32
-	bool
-	default y if MIPS32_O32 || MIPS32_N32
-	select ELFCORE
-
 menu "Power management options"
 
 config ARCH_HIBERNATION_POSSIBLE
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
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 2a05b923f579..943eaeef73e9 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -80,8 +80,8 @@ obj-$(CONFIG_KPROBES)		+= kprobes.o
 obj-$(CONFIG_32BIT)		+= scall32-o32.o
 obj-$(CONFIG_64BIT)		+= scall64-n64.o
 obj-$(CONFIG_MIPS32_COMPAT)	+= linux32.o ptrace32.o signal32.o
-obj-$(CONFIG_MIPS32_N32)	+= binfmt_elfn32.o scall64-n32.o signal_n32.o
-obj-$(CONFIG_MIPS32_O32)	+= binfmt_elfo32.o scall64-o32.o signal_o32.o
+obj-$(CONFIG_MIPS32_N32)	+= scall64-n32.o signal_n32.o
+obj-$(CONFIG_MIPS32_O32)	+= scall64-o32.o signal_o32.o
 
 obj-$(CONFIG_KGDB)		+= kgdb.o
 obj-$(CONFIG_PROC_FS)		+= proc.o
diff --git a/arch/mips/kernel/binfmt_elfn32.c b/arch/mips/kernel/binfmt_elfn32.c
deleted file mode 100644
index c4441416e96b..000000000000
--- a/arch/mips/kernel/binfmt_elfn32.c
+++ /dev/null
@@ -1,113 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Support for n32 Linux/MIPS ELF binaries.
- * Author: Ralf Baechle (ralf@linux-mips.org)
- *
- * Copyright (C) 1999, 2001 Ralf Baechle
- * Copyright (C) 1999, 2001 Silicon Graphics, Inc.
- *
- * Heavily inspired by the 32-bit Sparc compat code which is
- * Copyright (C) 1995, 1996, 1997, 1998 David S. Miller (davem@redhat.com)
- * Copyright (C) 1995, 1996, 1997, 1998 Jakub Jelinek	(jj@ultra.linux.cz)
- */
-
-#define ELF_ARCH		EM_MIPS
-#define ELF_CLASS		ELFCLASS32
-#ifdef __MIPSEB__
-#define ELF_DATA		ELFDATA2MSB;
-#else /* __MIPSEL__ */
-#define ELF_DATA		ELFDATA2LSB;
-#endif
-
-/* ELF register definitions */
-#define ELF_NGREG	45
-#define ELF_NFPREG	33
-
-typedef unsigned long elf_greg_t;
-typedef elf_greg_t elf_gregset_t[ELF_NGREG];
-
-typedef double elf_fpreg_t;
-typedef elf_fpreg_t elf_fpregset_t[ELF_NFPREG];
-
-/*
- * This is used to ensure we don't load something for the wrong architecture.
- */
-#define elf_check_arch elfn32_check_arch
-
-#define TASK32_SIZE		0x7fff8000UL
-#undef ELF_ET_DYN_BASE
-#define ELF_ET_DYN_BASE		(TASK32_SIZE / 3 * 2)
-
-#include <asm/processor.h>
-#include <linux/elfcore.h>
-#include <linux/compat.h>
-#include <linux/math64.h>
-
-#define elf_prstatus elf_prstatus32
-struct elf_prstatus32
-{
-	struct elf_siginfo pr_info;	/* Info associated with signal */
-	short	pr_cursig;		/* Current signal */
-	unsigned int pr_sigpend;	/* Set of pending signals */
-	unsigned int pr_sighold;	/* Set of held signals */
-	pid_t	pr_pid;
-	pid_t	pr_ppid;
-	pid_t	pr_pgrp;
-	pid_t	pr_sid;
-	struct old_timeval32 pr_utime; /* User time */
-	struct old_timeval32 pr_stime; /* System time */
-	struct old_timeval32 pr_cutime;/* Cumulative user time */
-	struct old_timeval32 pr_cstime;/* Cumulative system time */
-	elf_gregset_t pr_reg;	/* GP registers */
-	int pr_fpvalid;		/* True if math co-processor being used.  */
-};
-
-#define elf_prpsinfo elf_prpsinfo32
-struct elf_prpsinfo32
-{
-	char	pr_state;	/* numeric process state */
-	char	pr_sname;	/* char for pr_state */
-	char	pr_zomb;	/* zombie */
-	char	pr_nice;	/* nice val */
-	unsigned int pr_flag;	/* flags */
-	__kernel_uid_t	pr_uid;
-	__kernel_gid_t	pr_gid;
-	pid_t	pr_pid, pr_ppid, pr_pgrp, pr_sid;
-	/* Lots missing */
-	char	pr_fname[16];	/* filename of executable */
-	char	pr_psargs[ELF_PRARGSZ]; /* initial part of arg list */
-};
-
-#define elf_caddr_t	u32
-#define init_elf_binfmt init_elfn32_binfmt
-
-#define jiffies_to_timeval jiffies_to_old_timeval32
-static __inline__ void
-jiffies_to_old_timeval32(unsigned long jiffies, struct old_timeval32 *value)
-{
-	/*
-	 * Convert jiffies to nanoseconds and separate with
-	 * one divide.
-	 */
-	u64 nsec = (u64)jiffies * TICK_NSEC;
-	u32 rem;
-	value->tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem);
-	value->tv_usec = rem / NSEC_PER_USEC;
-}
-
-#define ELF_CORE_EFLAGS EF_MIPS_ABI2
-
-#undef TASK_SIZE
-#define TASK_SIZE TASK_SIZE32
-
-#undef ns_to_kernel_old_timeval
-#define ns_to_kernel_old_timeval ns_to_old_timeval32
-
-/*
- * Some data types as stored in coredump.
- */
-#define user_long_t             compat_long_t
-#define user_siginfo_t          compat_siginfo_t
-#define copy_siginfo_to_external        copy_siginfo_to_external32
-
-#include "../../../fs/binfmt_elf.c"
diff --git a/arch/mips/kernel/binfmt_elfo32.c b/arch/mips/kernel/binfmt_elfo32.c
deleted file mode 100644
index 7b2a23f48c1a..000000000000
--- a/arch/mips/kernel/binfmt_elfo32.c
+++ /dev/null
@@ -1,116 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Support for o32 Linux/MIPS ELF binaries.
- * Author: Ralf Baechle (ralf@linux-mips.org)
- *
- * Copyright (C) 1999, 2001 Ralf Baechle
- * Copyright (C) 1999, 2001 Silicon Graphics, Inc.
- *
- * Heavily inspired by the 32-bit Sparc compat code which is
- * Copyright (C) 1995, 1996, 1997, 1998 David S. Miller (davem@redhat.com)
- * Copyright (C) 1995, 1996, 1997, 1998 Jakub Jelinek	(jj@ultra.linux.cz)
- */
-
-#define ELF_ARCH		EM_MIPS
-#define ELF_CLASS		ELFCLASS32
-#ifdef __MIPSEB__
-#define ELF_DATA		ELFDATA2MSB;
-#else /* __MIPSEL__ */
-#define ELF_DATA		ELFDATA2LSB;
-#endif
-
-/* ELF register definitions */
-#define ELF_NGREG	45
-#define ELF_NFPREG	33
-
-typedef unsigned int elf_greg_t;
-typedef elf_greg_t elf_gregset_t[ELF_NGREG];
-
-typedef double elf_fpreg_t;
-typedef elf_fpreg_t elf_fpregset_t[ELF_NFPREG];
-
-/*
- * This is used to ensure we don't load something for the wrong architecture.
- */
-#define elf_check_arch elfo32_check_arch
-
-#ifdef CONFIG_KVM_GUEST
-#define TASK32_SIZE		0x3fff8000UL
-#else
-#define TASK32_SIZE		0x7fff8000UL
-#endif
-#undef ELF_ET_DYN_BASE
-#define ELF_ET_DYN_BASE		(TASK32_SIZE / 3 * 2)
-
-#include <asm/processor.h>
-
-#include <linux/elfcore.h>
-#include <linux/compat.h>
-#include <linux/math64.h>
-
-#define elf_prstatus elf_prstatus32
-struct elf_prstatus32
-{
-	struct elf_siginfo pr_info;	/* Info associated with signal */
-	short	pr_cursig;		/* Current signal */
-	unsigned int pr_sigpend;	/* Set of pending signals */
-	unsigned int pr_sighold;	/* Set of held signals */
-	pid_t	pr_pid;
-	pid_t	pr_ppid;
-	pid_t	pr_pgrp;
-	pid_t	pr_sid;
-	struct old_timeval32 pr_utime; /* User time */
-	struct old_timeval32 pr_stime; /* System time */
-	struct old_timeval32 pr_cutime;/* Cumulative user time */
-	struct old_timeval32 pr_cstime;/* Cumulative system time */
-	elf_gregset_t pr_reg;	/* GP registers */
-	int pr_fpvalid;		/* True if math co-processor being used.  */
-};
-
-#define elf_prpsinfo elf_prpsinfo32
-struct elf_prpsinfo32
-{
-	char	pr_state;	/* numeric process state */
-	char	pr_sname;	/* char for pr_state */
-	char	pr_zomb;	/* zombie */
-	char	pr_nice;	/* nice val */
-	unsigned int pr_flag;	/* flags */
-	__kernel_uid_t	pr_uid;
-	__kernel_gid_t	pr_gid;
-	pid_t	pr_pid, pr_ppid, pr_pgrp, pr_sid;
-	/* Lots missing */
-	char	pr_fname[16];	/* filename of executable */
-	char	pr_psargs[ELF_PRARGSZ]; /* initial part of arg list */
-};
-
-#define elf_caddr_t	u32
-#define init_elf_binfmt init_elf32_binfmt
-
-#define jiffies_to_timeval jiffies_to_old_timeval32
-static inline void
-jiffies_to_old_timeval32(unsigned long jiffies, struct old_timeval32 *value)
-{
-	/*
-	 * Convert jiffies to nanoseconds and separate with
-	 * one divide.
-	 */
-	u64 nsec = (u64)jiffies * TICK_NSEC;
-	u32 rem;
-	value->tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem);
-	value->tv_usec = rem / NSEC_PER_USEC;
-}
-
-#undef TASK_SIZE
-#define TASK_SIZE TASK_SIZE32
-
-#undef ns_to_kernel_old_timeval
-#define ns_to_kernel_old_timeval ns_to_old_timeval32
-
-/*
- * Some data types as stored in coredump.
- */
-#define user_long_t             compat_long_t
-#define user_siginfo_t          compat_siginfo_t
-#define copy_siginfo_to_external        copy_siginfo_to_external32
-
-#include "../../../fs/binfmt_elf.c"
diff --git a/arch/mips/kernel/scall64-n64.S b/arch/mips/kernel/scall64-n64.S
index 23b2e2b1609c..5e9c497ce099 100644
--- a/arch/mips/kernel/scall64-n64.S
+++ b/arch/mips/kernel/scall64-n64.S
@@ -20,7 +20,7 @@
 #include <asm/unistd.h>
 #include <asm/war.h>
 
-#ifndef CONFIG_BINFMT_ELF32
+#ifndef CONFIG_MIPS32_COMPAT
 /* Neither O32 nor N32, so define handle_sys here */
 #define handle_sys64 handle_sys
 #endif
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 278462186ac4..b09d6923f156 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -335,7 +335,6 @@ source "kernel/Kconfig.hz"
 config COMPAT
 	def_bool y
 	depends on 64BIT
-	select COMPAT_BINFMT_ELF if BINFMT_ELF
 
 config SYSVIPC_COMPAT
 	def_bool y
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 107bb4319e0e..d26a89cd8908 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -282,7 +282,6 @@ config COMPAT
 	bool "Enable support for 32bit binaries"
 	depends on PPC64
 	default y if !CPU_LITTLE_ENDIAN
-	select COMPAT_BINFMT_ELF
 	select ARCH_WANT_OLD_COMPAT_IPC
 	select COMPAT_OLD_SIGACTION
 
diff --git a/arch/powerpc/platforms/powernv/opal-core.c b/arch/powerpc/platforms/powernv/opal-core.c
index 23571f0b555a..0d9ba70f7251 100644
--- a/arch/powerpc/platforms/powernv/opal-core.c
+++ b/arch/powerpc/platforms/powernv/opal-core.c
@@ -119,8 +119,8 @@ static void fill_prstatus(struct elf_prstatus *prstatus, int pir,
 	 * As a PIR value could also be '0', add an offset of '100'
 	 * to every PIR to avoid misinterpretations in GDB.
 	 */
-	prstatus->pr_pid  = cpu_to_be32(100 + pir);
-	prstatus->pr_ppid = cpu_to_be32(1);
+	prstatus->common.pr_pid  = cpu_to_be32(100 + pir);
+	prstatus->common.pr_ppid = cpu_to_be32(1);
 
 	/*
 	 * Indicate SIGUSR1 for crash initiated from kernel.
@@ -130,7 +130,7 @@ static void fill_prstatus(struct elf_prstatus *prstatus, int pir,
 		short sig;
 
 		sig = kernel_initiated ? SIGUSR1 : SIGTERM;
-		prstatus->pr_cursig = cpu_to_be16(sig);
+		prstatus->common.pr_cursig = cpu_to_be16(sig);
 	}
 }
 
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index c72874f09741..73483614b66b 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -426,7 +426,6 @@ config 64BIT
 config COMPAT
 	def_bool y
 	prompt "Kernel support for 31 bit emulation"
-	select COMPAT_BINFMT_ELF if BINFMT_ELF
 	select ARCH_WANT_OLD_COMPAT_IPC
 	select COMPAT_OLD_SIGACTION
 	select HAVE_UID16
diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
index 205b2e2648aa..0e36dfc9ccd6 100644
--- a/arch/s390/kernel/crash_dump.c
+++ b/arch/s390/kernel/crash_dump.c
@@ -365,7 +365,7 @@ static void *fill_cpu_elf_notes(void *ptr, int cpu, struct save_area *sa)
 	memcpy(&nt_prstatus.pr_reg.gprs, sa->gprs, sizeof(sa->gprs));
 	memcpy(&nt_prstatus.pr_reg.psw, sa->psw, sizeof(sa->psw));
 	memcpy(&nt_prstatus.pr_reg.acrs, sa->acrs, sizeof(sa->acrs));
-	nt_prstatus.pr_pid = cpu;
+	nt_prstatus.common.pr_pid = cpu;
 	/* Prepare fpregset (floating point) note */
 	memset(&nt_fpregset, 0, sizeof(nt_fpregset));
 	memcpy(&nt_fpregset.fpc, &sa->fpc, sizeof(sa->fpc));
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index c9c34dc52b7d..1a2b5649d267 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -494,7 +494,6 @@ config COMPAT
 	bool
 	depends on SPARC64
 	default y
-	select COMPAT_BINFMT_ELF
 	select HAVE_UID16
 	select ARCH_WANT_OLD_COMPAT_IPC
 	select COMPAT_OLD_SIGACTION
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 3d498caca1ea..31d94448b4e1 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -32,6 +32,7 @@ config X86_64
 	select MODULES_USE_ELF_RELA
 	select NEED_DMA_MAP_STATE
 	select SWIOTLB
+	select ARCH_HAS_ELFCORE_COMPAT
 
 config FORCE_DYNAMIC_FTRACE
 	def_bool y
@@ -2860,7 +2861,6 @@ config IA32_EMULATION
 	depends on X86_64
 	select ARCH_WANT_OLD_COMPAT_IPC
 	select BINFMT_ELF
-	select COMPAT_BINFMT_ELF
 	select COMPAT_OLD_SIGACTION
 	help
 	  Include code to run legacy 32-bit programs under a
diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index f145e3326c6d..be09c7eac89f 100644
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -159,17 +159,6 @@ struct compat_shmid64_ds {
 	compat_ulong_t __unused5;
 };
 
-/*
- * The type of struct elf_prstatus.pr_reg in compatible core dumps.
- */
-typedef struct user_regs_struct compat_elf_gregset_t;
-
-/* Full regset -- prstatus on x32, otherwise on ia32 */
-#define PRSTATUS_SIZE(S, R) (R != sizeof(S.pr_reg) ? 144 : 296)
-#define SET_PR_FPVALID(S, V, R) \
-  do { *(int *) (((void *) &((S)->pr_reg)) + R) = (V); } \
-  while (0)
-
 #ifdef CONFIG_X86_X32_ABI
 #define COMPAT_USE_64BIT_TIME \
 	(!!(task_pt_regs(current)->orig_ax & __X32_SYSCALL_BIT))
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 66bdfe838d61..9224d40cdefe 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -364,7 +364,7 @@ do {									\
 #define COMPAT_ARCH_DLINFO						\
 if (exec->e_machine == EM_X86_64)					\
 	ARCH_DLINFO_X32;						\
-else									\
+else if (IS_ENABLED(CONFIG_IA32_EMULATION))				\
 	ARCH_DLINFO_IA32
 
 #define COMPAT_ELF_ET_DYN_BASE	(TASK_UNMAPPED_BASE + 0x1000000)
diff --git a/arch/x86/include/asm/elfcore-compat.h b/arch/x86/include/asm/elfcore-compat.h
new file mode 100644
index 000000000000..f1b6c7a8d8fc
--- /dev/null
+++ b/arch/x86/include/asm/elfcore-compat.h
@@ -0,0 +1,31 @@
+#ifndef _ASM_X86_ELFCORE_COMPAT_H
+#define _ASM_X86_ELFCORE_COMPAT_H
+
+#include <asm/user32.h>
+
+/*
+ * On amd64 we have two 32bit ABIs - i386 and x32.  The latter
+ * has bigger registers, so we use it for compat_elf_regset_t.
+ * The former uses i386_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 struct user_regs_struct compat_elf_gregset_t;
+
+struct i386_elf_prstatus
+{
+	struct compat_elf_prstatus_common	common;
+	struct user_regs_struct32		pr_reg;
+	compat_int_t			pr_fpvalid;
+};
+
+#define PRSTATUS_SIZE \
+	(user_64bit_mode(task_pt_regs(current)) \
+		? sizeof(struct compat_elf_prstatus) \
+		: sizeof(struct i386_elf_prstatus))
+#define SET_PR_FPVALID(S) \
+	(*(user_64bit_mode(task_pt_regs(current)) \
+		? &(S)->pr_fpvalid 	\
+		: &((struct i386_elf_prstatus *)(S))->pr_fpvalid) = 1)
+
+#endif