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

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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>
This commit is contained in:
H. Peter Anvin
2009-10-08 18:02:54 -07:00
parent 36a07902c2
commit a6f05a6a0a
2 changed files with 24 additions and 19 deletions
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23
arch/x86/kernel/process_64.c
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@@ -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.
*