x86: fix math_emu register frame access
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>
diff --git a/arch/x86/math-emu/fpu_system.h b/arch/x86/math-emu/fpu_system.h
index 6729c6a..50fa0ec 100644
--- a/arch/x86/math-emu/fpu_system.h
+++ b/arch/x86/math-emu/fpu_system.h
@@ -16,10 +16,6 @@
#include <linux/kernel.h>
#include <linux/mm.h>
-/* This sets the pointer FPU_info to point to the argument part
- of the stack frame of math_emulate() */
-#define SETUP_DATA_AREA(arg) FPU_info = (struct math_emu_info *) &arg
-
/* s is always from a cpu register, and the cpu does bounds checking
* during register load --> no further bounds checks needed */
#define LDT_DESCRIPTOR(s) (((struct desc_struct *)current->mm->context.ldt)[(s) >> 3])
@@ -38,12 +34,12 @@
#define I387 (current->thread.xstate)
#define FPU_info (I387->soft.info)
-#define FPU_CS (*(unsigned short *) &(FPU_info->regs.cs))
-#define FPU_SS (*(unsigned short *) &(FPU_info->regs.ss))
-#define FPU_DS (*(unsigned short *) &(FPU_info->regs.ds))
-#define FPU_EAX (FPU_info->regs.ax)
-#define FPU_EFLAGS (FPU_info->regs.flags)
-#define FPU_EIP (FPU_info->regs.ip)
+#define FPU_CS (*(unsigned short *) &(FPU_info->regs->cs))
+#define FPU_SS (*(unsigned short *) &(FPU_info->regs->ss))
+#define FPU_DS (*(unsigned short *) &(FPU_info->regs->ds))
+#define FPU_EAX (FPU_info->regs->ax)
+#define FPU_EFLAGS (FPU_info->regs->flags)
+#define FPU_EIP (FPU_info->regs->ip)
#define FPU_ORIG_EIP (FPU_info->___orig_eip)
#define FPU_lookahead (I387->soft.lookahead)
