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x86: fix math_emu register frame access

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do_device_not_available() is the handler for #NM and it declares that
it takes a unsigned long and calls math_emu(), which takes a long
argument and surprisingly expects the stack frame starting at the zero
argument would match struct math_emu_info, which isn't true regardless
of configuration in the current code.

This patch makes do_device_not_available() take struct pt_regs like
other exception handlers and initialize struct math_emu_info with
pointer to it and pass pointer to the math_emu_info to math_emulate()
like normal C functions do.  This way, unless gcc makes a copy of
struct pt_regs in do_device_not_available(), the register frame is
correctly accessed regardless of kernel configuration or compiler
used.

This doesn't fix all math_emu problems but it at least gets it
somewhat working.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Tejun Heo
2009-02-09 22:17:39 +09:00
committed by Ingo Molnar
parent ae6af41f5a
commit d315760ffa
7 changed files with 55 additions and 56 deletions
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15
arch/x86/kernel/traps.c
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@@ -896,7 +896,7 @@ asmlinkage void math_state_restore(void)
EXPORT_SYMBOL_GPL(math_state_restore);
#ifndef CONFIG_MATH_EMULATION
asmlinkage void math_emulate(long arg)
void math_emulate(struct math_emu_info *info)
{
printk(KERN_EMERG
"math-emulation not enabled and no coprocessor found.\n");
@@ -906,16 +906,19 @@ asmlinkage void math_emulate(long arg)
}
#endif /* CONFIG_MATH_EMULATION */
dotraplinkage void __kprobes
do_device_not_available(struct pt_regs *regs, long error)
dotraplinkage void __kprobes do_device_not_available(struct pt_regs regs)
{
#ifdef CONFIG_X86_32
if (read_cr0() & X86_CR0_EM) {
conditional_sti(regs);
math_emulate(0);
struct math_emu_info info = { };
conditional_sti(&regs);
info.regs = &regs;
math_emulate(&info);
} else {
math_state_restore(); /* interrupts still off */
conditional_sti(regs);
conditional_sti(&regs);
}
#else
math_state_restore();