x86/entry: Switch page fault exception to IDTENTRY_RAW

Convert page fault exceptions to IDTENTRY_RAW:

  - Implement the C entry point with DEFINE_IDTENTRY_RAW
  - Add the CR2 read into the exception handler
  - Add the idtentry_enter/exit_cond_rcu() invocations in
    in the regular page fault handler and in the async PF
    part.
  - Emit the ASM stub with DECLARE_IDTENTRY_RAW
  - Remove the ASM idtentry in 64-bit
  - Remove the CR2 read from 64-bit
  - Remove the open coded ASM entry code in 32-bit
  - Fix up the XEN/PV code
  - Remove the old prototypes

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20200521202118.238455120@linutronix.de

arch/x86/entry/entry_32.S

@@ -1398,36 +1398,6 @@ BUILD_INTERRUPT3(hv_stimer0_callback_vector, HYPERV_STIMER0_VECTOR,
 
 #endif /* CONFIG_HYPERV */
 
-SYM_CODE_START(page_fault)
-	ASM_CLAC
-	pushl	$do_page_fault
-	jmp	common_exception_read_cr2
-SYM_CODE_END(page_fault)
-
-SYM_CODE_START_LOCAL_NOALIGN(common_exception_read_cr2)
-	/* the function address is in %gs's slot on the stack */
-	SAVE_ALL switch_stacks=1 skip_gs=1 unwind_espfix=1
-
-	ENCODE_FRAME_POINTER
-
-	/* fixup %gs */
-	GS_TO_REG %ecx
-	movl	PT_GS(%esp), %edi
-	REG_TO_PTGS %ecx
-	SET_KERNEL_GS %ecx
-
-	GET_CR2_INTO(%ecx)			# might clobber %eax
-
-	/* fixup orig %eax */
-	movl	PT_ORIG_EAX(%esp), %edx		# get the error code
-	movl	$-1, PT_ORIG_EAX(%esp)		# no syscall to restart
-
-	TRACE_IRQS_OFF
-	movl	%esp, %eax			# pt_regs pointer
-	CALL_NOSPEC edi
-	jmp	ret_from_exception
-SYM_CODE_END(common_exception_read_cr2)
-
 SYM_CODE_START_LOCAL_NOALIGN(common_exception)
 	/* the function address is in %gs's slot on the stack */
 	SAVE_ALL switch_stacks=1 skip_gs=1 unwind_espfix=1