linux-kernel - [PATCH v5 2/2] mips: Differentiate between 32 and 64 bit ELF header

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Message-Id: <1455194215-20026-3-git-send-email-daniel.wagner@bmw-carit.de>
Date:	Thu, 11 Feb 2016 13:36:55 +0100
From:	Daniel Wagner <daniel.wagner@...-carit.de>
To:	"Maciej W. Rozycki" <macro@...tec.com>
Cc:	Ralf Baechle <ralf@...ux-mips.org>, linux-kernel@...r.kernel.org,
	linux-mips@...ux-mips.org,
	Daniel Wagner <daniel.wagner@...-carit.de>
Subject: [PATCH v5 2/2] mips: Differentiate between 32 and 64 bit ELF header

Depending on the configuration either the 32 or 64 bit version of
elf_check_arch() is defined. parse_crash_elf{32|64}_headers() does
some basic verification of the ELF header via
vmcore_elf{32|64}_check_arch() which happen to map to elf_check_arch().
Since the implementation 32 and 64 bit version of elf_check_arch()
differ, we use the wrong type:

   In file included from include/linux/elf.h:4:0,
                    from fs/proc/vmcore.c:13:
   fs/proc/vmcore.c: In function 'parse_crash_elf64_headers':
>> arch/mips/include/asm/elf.h:228:23: error: initialization from incompatible pointer type [-Werror=incompatible-pointer-types]
     struct elfhdr *__h = (hdr);     \
                          ^
   include/linux/crash_dump.h:41:37: note: in expansion of macro 'elf_check_arch'
    #define vmcore_elf64_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x))
                                        ^
   fs/proc/vmcore.c:1015:4: note: in expansion of macro 'vmcore_elf64_check_arch'
      !vmcore_elf64_check_arch(&ehdr) ||
       ^

Therefore, we rather define vmcore_elf{32|64}_check_arch() as a
basic machine check and use it also in binfm_elf?32.c as well.

Signed-off-by: Daniel Wagner <daniel.wagner@...-carit.de>
Suggested-by: Maciej W. Rozycki <macro@...tec.com>
Reviewed-by: Maciej W. Rozycki <macro@...tec.com>
Reported-by: Fengguang Wu <fengguang.wu@...el.com>
---
 arch/mips/include/asm/elf.h      | 13 +++++++++----
 arch/mips/kernel/binfmt_elfn32.c |  4 ++--
 arch/mips/kernel/binfmt_elfo32.c |  4 ++--
 3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/arch/mips/include/asm/elf.h b/arch/mips/include/asm/elf.h
index cefb7a5..ac53fbd 100644
--- a/arch/mips/include/asm/elf.h
+++ b/arch/mips/include/asm/elf.h
@@ -225,9 +225,9 @@ struct mips_elf_abiflags_v0 {
 #define elf_check_arch(hdr)						\
 ({									\
 	int __res = 1;							\
-	struct elfhdr *__h = (hdr);					\
+	typeof(*(hdr)) *__h = (hdr);					\
 									\
-	if (__h->e_machine != EM_MIPS)					\
+	if (!mips_elf_check_machine(__h))				\
 		__res = 0;						\
 	if (__h->e_ident[EI_CLASS] != ELFCLASS32)			\
 		__res = 0;						\
@@ -256,9 +256,9 @@ struct mips_elf_abiflags_v0 {
 #define elf_check_arch(hdr)						\
 ({									\
 	int __res = 1;							\
-	struct elfhdr *__h = (hdr);					\
+	typeof(*(hdr)) *__h = (hdr);					\
 									\
-	if (__h->e_machine != EM_MIPS)					\
+	if (!mips_elf_check_machine(__h))				\
 		__res = 0;						\
 	if (__h->e_ident[EI_CLASS] != ELFCLASS64)			\
 		__res = 0;						\
@@ -285,6 +285,11 @@ struct mips_elf_abiflags_v0 {
 
 #endif /* !defined(ELF_ARCH) */
 
+#define mips_elf_check_machine(x) ((x)->e_machine == EM_MIPS)
+
+#define vmcore_elf32_check_arch mips_elf_check_machine
+#define vmcore_elf64_check_arch mips_elf_check_machine
+
 struct mips_abi;
 
 extern struct mips_abi mips_abi;
diff --git a/arch/mips/kernel/binfmt_elfn32.c b/arch/mips/kernel/binfmt_elfn32.c
index 1188e00..601935c 100644
--- a/arch/mips/kernel/binfmt_elfn32.c
+++ b/arch/mips/kernel/binfmt_elfn32.c
@@ -33,9 +33,9 @@ typedef elf_fpreg_t elf_fpregset_t[ELF_NFPREG];
 #define elf_check_arch(hdr)						\
 ({									\
 	int __res = 1;							\
-	struct elfhdr *__h = (hdr);					\
+	typeof(*(hdr)) *__h = (hdr);					\
 									\
-	if (__h->e_machine != EM_MIPS)					\
+	if (!mips_elf_check_machine(__h))				\
 		__res = 0;						\
 	if (__h->e_ident[EI_CLASS] != ELFCLASS32)			\
 		__res = 0;						\
diff --git a/arch/mips/kernel/binfmt_elfo32.c b/arch/mips/kernel/binfmt_elfo32.c
index 9287678..a8c3702 100644
--- a/arch/mips/kernel/binfmt_elfo32.c
+++ b/arch/mips/kernel/binfmt_elfo32.c
@@ -45,9 +45,9 @@ typedef elf_fpreg_t elf_fpregset_t[ELF_NFPREG];
 #define elf_check_arch(hdr)						\
 ({									\
 	int __res = 1;							\
-	struct elfhdr *__h = (hdr);					\
+	typeof(*(hdr)) *__h = (hdr);					\
 									\
-	if (__h->e_machine != EM_MIPS)					\
+	if (!mips_elf_check_machine(__h))				\
 		__res = 0;						\
 	if (__h->e_ident[EI_CLASS] != ELFCLASS32)			\
 		__res = 0;						\
-- 
2.5.0