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>

diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 456a304..8a024ba 100644 (file)
--- 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 {                                                   \

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index ad535b6..7cf0a6b 100644 (file)
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -356,7 +356,7 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
        percpu_write(old_rsp, new_sp);
        regs->cs                = __USER_CS;
        regs->ss                = __USER_DS;
-       regs->flags             = 0x200;
+       regs->flags             = X86_EFLAGS_IF;
        set_fs(USER_DS);
        /*
         * Free the old FP and other extended state
@@ -365,6 +365,27 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
 }
 EXPORT_SYMBOL_GPL(start_thread);
 
+#ifdef CONFIG_IA32_EMULATION
+void start_thread_ia32(struct pt_regs *regs, u32 new_ip, u32 new_sp)
+{
+       loadsegment(fs, 0);
+       loadsegment(ds, __USER32_DS);
+       loadsegment(es, __USER32_DS);
+       load_gs_index(0);
+       regs->ip                = new_ip;
+       regs->sp                = new_sp;
+       percpu_write(old_rsp, new_sp);
+       regs->cs                = __USER32_CS;
+       regs->ss                = __USER32_DS;
+       regs->flags             = X86_EFLAGS_IF;
+       set_fs(USER_DS);
+       /*
+        * Free the old FP and other extended state
+        */
+       free_thread_xstate(current);
+}
+#endif
+
 /*
  *     switch_to(x,y) should switch tasks from x to y.
  *