MIPS: Use a union to access the ELF file header

Rewrite `arch_elf_pt_proc' and `arch_check_elf' using a union to access
the ELF file header.

Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11474/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/kernel/elf.c b/arch/mips/kernel/elf.c
index 4a4d9e067c89427fc34e990586f0e8237a9418ba..858605639965fcbe79278e6744195be05784766c 100644 (file)
--- a/arch/mips/kernel/elf.c
+++ b/arch/mips/kernel/elf.c
@@ -68,15 +68,23 @@ static struct mode_req none_req = { true, true, false, true, true };
 int arch_elf_pt_proc(void *_ehdr, void *_phdr, struct file *elf,
                     bool is_interp, struct arch_elf_state *state)
 {
-       struct elf32_hdr *ehdr32 = _ehdr;
+       union {
+               struct elf32_hdr e32;
+               struct elf64_hdr e64;
+       } *ehdr = _ehdr;
        struct elf32_phdr *phdr32 = _phdr;
        struct elf64_phdr *phdr64 = _phdr;
        struct mips_elf_abiflags_v0 abiflags;
+       bool elf32;
+       u32 flags;
        int ret;
 
+       elf32 = ehdr->e32.e_ident[EI_CLASS] == ELFCLASS32;
+       flags = elf32 ? ehdr->e32.e_flags : ehdr->e64.e_flags;
+
        /* Lets see if this is an O32 ELF */
-       if (ehdr32->e_ident[EI_CLASS] == ELFCLASS32) {
-               if (ehdr32->e_flags & EF_MIPS_FP64) {
+       if (elf32) {
+               if (flags & EF_MIPS_FP64) {
                        /*
                         * Set MIPS_ABI_FP_OLD_64 for EF_MIPS_FP64. We will override it
                         * later if needed
@@ -123,10 +131,17 @@ int arch_elf_pt_proc(void *_ehdr, void *_phdr, struct file *elf,
 int arch_check_elf(void *_ehdr, bool has_interpreter,
                   struct arch_elf_state *state)
 {
-       struct elf32_hdr *ehdr = _ehdr;
+       union {
+               struct elf32_hdr e32;
+               struct elf64_hdr e64;
+       } *ehdr = _ehdr;
        struct mode_req prog_req, interp_req;
        int fp_abi, interp_fp_abi, abi0, abi1, max_abi;
-       bool is_mips64;
+       bool elf32;
+       u32 flags;
+
+       elf32 = ehdr->e32.e_ident[EI_CLASS] == ELFCLASS32;
+       flags = elf32 ? ehdr->e32.e_flags : ehdr->e64.e_flags;
 
        if (!config_enabled(CONFIG_MIPS_O32_FP64_SUPPORT))
                return 0;
@@ -142,21 +157,18 @@ int arch_check_elf(void *_ehdr, bool has_interpreter,
                abi0 = abi1 = fp_abi;
        }
 
-       is_mips64 = (ehdr->e_ident[EI_CLASS] == ELFCLASS64) ||
-                   (ehdr->e_flags & EF_MIPS_ABI2);
+       if (elf32 && !(flags & EF_MIPS_ABI2)) {
+               /* Default to a mode capable of running code expecting FR=0 */
+               state->overall_fp_mode = cpu_has_mips_r6 ? FP_FRE : FP_FR0;
 
-       if (is_mips64) {
+               /* Allow all ABIs we know about */
+               max_abi = MIPS_ABI_FP_64A;
+       } else {
                /* MIPS64 code always uses FR=1, thus the default is easy */
                state->overall_fp_mode = FP_FR1;
 
                /* Disallow access to the various FPXX & FP64 ABIs */
                max_abi = MIPS_ABI_FP_SOFT;
-       } else {
-               /* Default to a mode capable of running code expecting FR=0 */
-               state->overall_fp_mode = cpu_has_mips_r6 ? FP_FRE : FP_FR0;
-
-               /* Allow all ABIs we know about */
-               max_abi = MIPS_ABI_FP_64A;
        }
 
        if ((abi0 > max_abi && abi0 != MIPS_ABI_FP_UNKNOWN) ||