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>

1 files changed, 33 insertions, 33 deletions

diff --git a/arch/x86/math-emu/get_address.c b/arch/x86/math-emu/get_address.c
index 62daa7fcc44c..420b3b6e3915 100644
--- a/arch/x86/math-emu/get_address.c
+++ b/arch/x86/math-emu/get_address.c
@@ -29,43 +29,43 @@
 #define FPU_WRITE_BIT 0x10
 
 static int reg_offset[] = {
-        offsetof(struct math_emu_info, regs.ax),
-        offsetof(struct math_emu_info, regs.cx),
-        offsetof(struct math_emu_info, regs.dx),
-        offsetof(struct math_emu_info, regs.bx),
-        offsetof(struct math_emu_info, regs.sp),
-        offsetof(struct math_emu_info, regs.bp),
-        offsetof(struct math_emu_info, regs.si),
-        offsetof(struct math_emu_info, regs.di)
+        offsetof(struct pt_regs, ax),
+        offsetof(struct pt_regs, cx),
+        offsetof(struct pt_regs, dx),
+        offsetof(struct pt_regs, bx),
+        offsetof(struct pt_regs, sp),
+        offsetof(struct pt_regs, bp),
+        offsetof(struct pt_regs, si),
+        offsetof(struct pt_regs, di)
 };
 
-#define REG_(x) (*(long *)(reg_offset[(x)]+(u_char *) FPU_info))
+#define REG_(x) (*(long *)(reg_offset[(x)] + (u_char *)FPU_info->regs))
 
 static int reg_offset_vm86[] = {
-        offsetof(struct math_emu_info, regs.cs),
-        offsetof(struct math_emu_info, vm86.ds),
-        offsetof(struct math_emu_info, vm86.es),
-        offsetof(struct math_emu_info, vm86.fs),
-        offsetof(struct math_emu_info, vm86.gs),
-        offsetof(struct math_emu_info, regs.ss),
-        offsetof(struct math_emu_info, vm86.ds)
+        offsetof(struct pt_regs, cs),
+        offsetof(struct kernel_vm86_regs, ds),
+        offsetof(struct kernel_vm86_regs, es),
+        offsetof(struct kernel_vm86_regs, fs),
+        offsetof(struct kernel_vm86_regs, gs),
+        offsetof(struct pt_regs, ss),
+        offsetof(struct kernel_vm86_regs, ds)
 };
 
 #define VM86_REG_(x) (*(unsigned short *) \
-                      (reg_offset_vm86[((unsigned)x)]+(u_char *) FPU_info))
+                (reg_offset_vm86[((unsigned)x)] + (u_char *)FPU_info->regs))
 
 static int reg_offset_pm[] = {
-        offsetof(struct math_emu_info, regs.cs),
-        offsetof(struct math_emu_info, regs.ds),
-        offsetof(struct math_emu_info, regs.es),
-        offsetof(struct math_emu_info, regs.fs),
-        offsetof(struct math_emu_info, regs.ds), /* dummy, not saved on stack */
-        offsetof(struct math_emu_info, regs.ss),
-        offsetof(struct math_emu_info, regs.ds)
+        offsetof(struct pt_regs, cs),
+        offsetof(struct pt_regs, ds),
+        offsetof(struct pt_regs, es),
+        offsetof(struct pt_regs, fs),
+        offsetof(struct pt_regs, ds),   /* dummy, not saved on stack */
+        offsetof(struct pt_regs, ss),
+        offsetof(struct pt_regs, ds)
 };
 
 #define PM_REG_(x) (*(unsigned short *) \
-                      (reg_offset_pm[((unsigned)x)]+(u_char *) FPU_info))
+                (reg_offset_pm[((unsigned)x)] + (u_char *)FPU_info->regs))
 
 /* Decode the SIB byte. This function assumes mod != 0 */
 static int sib(int mod, unsigned long *fpu_eip)
@@ -346,34 +346,34 @@ void __user *FPU_get_address_16(u_char FPU_modrm, unsigned long *fpu_eip,
         }
         switch (rm) {
         case 0:
-                address += FPU_info->regs.bx + FPU_info->regs.si;
+                address += FPU_info->regs->bx + FPU_info->regs->si;
                 break;
         case 1:
-                address += FPU_info->regs.bx + FPU_info->regs.di;
+                address += FPU_info->regs->bx + FPU_info->regs->di;
                 break;
         case 2:
-                address += FPU_info->regs.bp + FPU_info->regs.si;
+                address += FPU_info->regs->bp + FPU_info->regs->si;
                 if (addr_modes.override.segment == PREFIX_DEFAULT)
                         addr_modes.override.segment = PREFIX_SS_;
                 break;
         case 3:
-                address += FPU_info->regs.bp + FPU_info->regs.di;
+                address += FPU_info->regs->bp + FPU_info->regs->di;
                 if (addr_modes.override.segment == PREFIX_DEFAULT)
                         addr_modes.override.segment = PREFIX_SS_;
                 break;
         case 4:
-                address += FPU_info->regs.si;
+                address += FPU_info->regs->si;
                 break;
         case 5:
-                address += FPU_info->regs.di;
+                address += FPU_info->regs->di;
                 break;
         case 6:
-                address += FPU_info->regs.bp;
+                address += FPU_info->regs->bp;
                 if (addr_modes.override.segment == PREFIX_DEFAULT)
                         addr_modes.override.segment = PREFIX_SS_;
                 break;
         case 7:
-                address += FPU_info->regs.bx;
+                address += FPU_info->regs->bx;
                 break;
         }