x86-64: make compat_start_thread() match start_thread()

For no real good reason, compat_start_thread() was embedded inline in
<asm/elf.h> whereas the native start_thread() lives in process_*.c.
Move compat_start_thread() to process_64.c, remove gratuitious
differences, and fix a few items which mostly look like bit rot.

In particular, compat_start_thread() didn't do free_thread_xstate(),
which means it was hanging on to the xstate store area even when it
was not needed.  It was also not setting old_rsp, but it looks like
that generally shouldn't matter for a 32-bit process.

Note: compat_start_thread *has* to be a macro, since it is tested with
start_thread_ia32() as the out of line function name.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>

1 files changed, 2 insertions, 18 deletions

diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 456a304b8172..8a024babe5e6 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -157,19 +157,6 @@ do {						\
 
 #define compat_elf_check_arch(x)	elf_check_arch_ia32(x)
 
-static inline void start_ia32_thread(struct pt_regs *regs, u32 ip, u32 sp)
-{
-	loadsegment(fs, 0);
-	loadsegment(ds, __USER32_DS);
-	loadsegment(es, __USER32_DS);
-	load_gs_index(0);
-	regs->ip = ip;
-	regs->sp = sp;
-	regs->flags = X86_EFLAGS_IF;
-	regs->cs = __USER32_CS;
-	regs->ss = __USER32_DS;
-}
-
 static inline void elf_common_init(struct thread_struct *t,
 				   struct pt_regs *regs, const u16 ds)
 {
@@ -191,11 +178,8 @@ do {							\
 #define	COMPAT_ELF_PLAT_INIT(regs, load_addr)		\
 	elf_common_init(&current->thread, regs, __USER_DS)
 
-#define	compat_start_thread(regs, ip, sp)		\
-do {							\
-	start_ia32_thread(regs, ip, sp);		\
-	set_fs(USER_DS);				\
-} while (0)
+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 {							\