x86: get rid of the insane TIF_ABI_PENDING bit

Now that the previous commit made it possible to do the personality
setting at the point of no return, we do just that for ELF binaries.
And suddenly all the reasons for that insane TIF_ABI_PENDING bit go
away, and we can just make SET_PERSONALITY() just do the obvious thing
for a 32-bit compat process.

Everything becomes much more straightforward this way.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/ia32/ia32_aout.c

@@ -311,7 +311,6 @@ static int load_aout_binary(struct linux_binprm *bprm, struct pt_regs *regs)
 	/* OK, This is the point of no return */
 	set_personality(PER_LINUX);
 	set_thread_flag(TIF_IA32);
-	clear_thread_flag(TIF_ABI_PENDING);
 
 	setup_new_exec(bprm);
 

arch/x86/include/asm/elf.h

@@ -181,14 +181,8 @@ do {							\
 void start_thread_ia32(struct pt_regs *regs, u32 new_ip, u32 new_sp);
 #define compat_start_thread start_thread_ia32
 
-#define COMPAT_SET_PERSONALITY(ex)			\
-do {							\
-	if (test_thread_flag(TIF_IA32))			\
-		clear_thread_flag(TIF_ABI_PENDING);	\
-	else						\
-		set_thread_flag(TIF_ABI_PENDING);	\
-	current->personality |= force_personality32;	\
-} while (0)
+void set_personality_ia32(void);
+#define COMPAT_SET_PERSONALITY(ex) set_personality_ia32()
 
 #define COMPAT_ELF_PLATFORM			("i686")
 

arch/x86/include/asm/thread_info.h

@@ -87,7 +87,6 @@ struct thread_info {
 #define TIF_NOTSC		16	/* TSC is not accessible in userland */
 #define TIF_IA32		17	/* 32bit process */
 #define TIF_FORK		18	/* ret_from_fork */
-#define TIF_ABI_PENDING		19
 #define TIF_MEMDIE		20
 #define TIF_DEBUG		21	/* uses debug registers */
 #define TIF_IO_BITMAP		22	/* uses I/O bitmap */
@@ -112,7 +111,6 @@ struct thread_info {
 #define _TIF_NOTSC		(1 << TIF_NOTSC)
 #define _TIF_IA32		(1 << TIF_IA32)
 #define _TIF_FORK		(1 << TIF_FORK)
-#define _TIF_ABI_PENDING	(1 << TIF_ABI_PENDING)
 #define _TIF_DEBUG		(1 << TIF_DEBUG)
 #define _TIF_IO_BITMAP		(1 << TIF_IO_BITMAP)
 #define _TIF_FREEZE		(1 << TIF_FREEZE)

arch/x86/kernel/process.c

@@ -115,18 +115,6 @@ void flush_thread(void)
 {
 	struct task_struct *tsk = current;
 
-#ifdef CONFIG_X86_64
-	if (test_tsk_thread_flag(tsk, TIF_ABI_PENDING)) {
-		clear_tsk_thread_flag(tsk, TIF_ABI_PENDING);
-		if (test_tsk_thread_flag(tsk, TIF_IA32)) {
-			clear_tsk_thread_flag(tsk, TIF_IA32);
-		} else {
-			set_tsk_thread_flag(tsk, TIF_IA32);
-			current_thread_info()->status |= TS_COMPAT;
-		}
-	}
-#endif
-
 	flush_ptrace_hw_breakpoint(tsk);
 	memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
 	/*

arch/x86/kernel/process_64.c

@@ -521,6 +521,17 @@ void set_personality_64bit(void)
 	current->personality &= ~READ_IMPLIES_EXEC;
 }
 
+void set_personality_ia32(void)
+{
+	/* inherit personality from parent */
+
+	/* Make sure to be in 32bit mode */
+	set_thread_flag(TIF_IA32);
+
+	/* Prepare the first "return" to user space */
+	current_thread_info()->status |= TS_COMPAT;
+}
+
 unsigned long get_wchan(struct task_struct *p)
 {
 	unsigned long stack;