[PATCH 09/10] mips compat: switch to compat_binfmt_elf.c

Al Viro
2020-12-03T21:47:41Z

From: Al Viro <viro@zeniv.linux.org.uk>

Like amd64, mips has two 32bit ABIs - o32 and n32. Unlike amd64,
it does not use compat_binfmt_elf.c for either of those; each
of those ABIs has a binfmt handler of its own, both very similar
to fs/compat_binfmt_elf.c. And the same technics as we use on
amd64 can be used to make fs/compat_binfmt_elf.c handle both.
* merge elfo32_check_arch() with elfn32_check_arch(),
make that serve as compat_elf_check_arch(). Note that
SET_PERSONALITY2() is already the same for all ABI variants -
it looks at the elf header to choose the flags to set.
* add asm/elfcore-compat.h, using the bigger (n32) variant
of elf32_prstatus as compat_elf_prstatus there.
* make PRSTATUS_SIZE() and SET_PR_FPVALID() choose the
right layout, same as done for amd64. test_thread_flag(TIF_32BIT_REGS)
is used as the predicate.

Voila - we are rid of binfmt_elf{n,o}32.c; fs/compat_binfmt_elf.c is
used, same as for all other ELF-supporting 64bit architectures that
need 32bit compat.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
arch/mips/Kconfig | 8 ++---
arch/mips/include/asm/elf.h | 54 +++++++++++--------------------
arch/mips/include/asm/elfcore-compat.h | 29 +++++++++++++++++
arch/mips/kernel/Makefile | 4 +--
arch/mips/kernel/binfmt_elfn32.c | 58 ---------------------------------
arch/mips/kernel/binfmt_elfo32.c | 59 ----------------------------------
arch/mips/kernel/scall64-n64.S | 2 +-
7 files changed, 54 insertions(+), 160 deletions(-)
create mode 100644 arch/mips/include/asm/elfcore-compat.h
delete mode 100644 arch/mips/kernel/binfmt_elfn32.c
delete mode 100644 arch/mips/kernel/binfmt_elfo32.c

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 32ce052aa3b4..f14731aee182 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -91,6 +91,7 @@ config MIPS
select SET_FS
select SYSCTL_EXCEPTION_TRACE
select VIRT_TO_BUS
+ select ARCH_HAS_ELFCORE_COMPAT

config MIPS_FIXUP_BIGPHYS_ADDR
bool
@@ -3270,6 +3271,7 @@ config MIPS32_O32
select ARCH_WANT_OLD_COMPAT_IPC
select COMPAT
select MIPS32_COMPAT
+ select COMPAT_BINFMT_ELF
select SYSVIPC_COMPAT if SYSVIPC
help
Select this option if you want to run o32 binaries. These are pure
@@ -3283,6 +3285,7 @@ config MIPS32_N32
depends on 64BIT
select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
select COMPAT
+ select COMPAT_BINFMT_ELF
select MIPS32_COMPAT
select SYSVIPC_COMPAT if SYSVIPC
help
@@ -3293,11 +3296,6 @@ 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 d29e43e4f9b1..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;
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 1aa32570fa9b..000000000000
--- a/arch/mips/kernel/binfmt_elfn32.c
+++ /dev/null
@@ -1,58 +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
-
-#include <asm/processor.h>
-#include <linux/elfcore.h>
-#include <linux/compat.h>
-#include <linux/math64.h>
-#include <linux/elfcore-compat.h>
-
-#define elf_prstatus elf_prstatus32
-#define elf_prstatus_common compat_elf_prstatus_common
-struct elf_prstatus32
-{
- struct compat_elf_prstatus_common common;
- elf_gregset_t pr_reg; /* GP registers */
- int pr_fpvalid; /* True if math co-processor being used. */
-};
-#define elf_prpsinfo compat_elf_prpsinfo
-
-#define init_elf_binfmt init_elfn32_binfmt
-
-#undef ns_to_kernel_old_timeval
-#define ns_to_kernel_old_timeval ns_to_old_timeval32
-
-#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 54fe6a4dac6d..000000000000
--- a/arch/mips/kernel/binfmt_elfo32.c
+++ /dev/null
@@ -1,59 +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
-
-#include <asm/processor.h>
-
-#include <linux/elfcore.h>
-#include <linux/compat.h>
-#include <linux/math64.h>
-#include <linux/elfcore-compat.h>
-
-#define elf_prstatus elf_prstatus32
-#define elf_prstatus_common compat_elf_prstatus_common
-struct elf_prstatus32
-{
- struct compat_elf_prstatus_common common;
- elf_gregset_t pr_reg; /* GP registers */
- int pr_fpvalid; /* True if math co-processor being used. */
-};
-#define elf_prpsinfo compat_elf_prpsinfo
-
-#define init_elf_binfmt init_elf32_binfmt
-
-#undef ns_to_kernel_old_timeval
-#define ns_to_kernel_old_timeval ns_to_old_timeval32
-
-#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
--
2.11.0