[tip: x86/cleanups] x86/elf: Use e_machine to choose DLINFO in compat

[tip-bot2 for Gabriel Krisman Bertazi]

The following commit has been merged into the x86/cleanups branch of tip:

Commit-ID:     2656af0d5abfa26d7f1e40f92e9953fe155b950a
Gitweb:        https://git.kernel.org/tip/2656af0d5abfa26d7f1e40f92e9953fe155b950a
Author:        Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
AuthorDate:    Sat, 03 Oct 2020 23:25:30 -04:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Mon, 26 Oct 2020 13:46:46 +01:00

x86/elf: Use e_machine to choose DLINFO in compat

Since TIF_X32 is going away, avoid using it to find the ELF type on
ARCH_DLINFO.

According to SysV AMD64 ABI Draft, an AMD64 ELF object using ILP32 must
have ELFCLASS32 with (E_MACHINE == EM_X86_64), so use that ELF field to
differentiate a x32 object from a IA32 object when loading ARCH_DLINFO in
compat mode.

Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Andy Lutomirski <luto@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20201004032536.1229030-5-krisman@xxxxxxxxxxxxx

---
 arch/x86/include/asm/elf.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index b9a5d48..9220efc 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -361,7 +361,7 @@ do {									\
 #define AT_SYSINFO		32
 
 #define COMPAT_ARCH_DLINFO						\
-if (test_thread_flag(TIF_X32))						\
+if (exec->e_machine == EM_X86_64)					\
 	ARCH_DLINFO_X32;						\
 else									\
 	ARCH_DLINFO_IA32