x86/entry: Convert Device not available exception to IDTENTRY

Convert #NM to IDTENTRY:
  - Implement the C entry point with DEFINE_IDTENTRY
  - Emit the ASM stub with DECLARE_IDTENTRY
  - Remove the ASM idtentry in 64bit
  - Remove the open coded ASM entry code in 32bit
  - Fixup the XEN/PV code
  - Remove the old prototypes
  - Remove the RCU warning as the new entry macro ensures correctness

No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134905.056243863@linutronix.de

arch/x86/entry/entry_32.S

@@ -1311,13 +1311,6 @@ SYM_CODE_START(simd_coprocessor_error)
 	jmp	common_exception
 SYM_CODE_END(simd_coprocessor_error)
 
-SYM_CODE_START(device_not_available)
-	ASM_CLAC
-	pushl	$0
-	pushl	$do_device_not_available
-	jmp	common_exception
-SYM_CODE_END(device_not_available)
-
 #ifdef CONFIG_PARAVIRT
 SYM_CODE_START(native_iret)
 	iret

arch/x86/entry/entry_64.S

@@ -1073,7 +1073,6 @@ apicinterrupt IRQ_WORK_VECTOR			irq_work_interrupt		smp_irq_work_interrupt
  */
 
 idtentry	X86_TRAP_BP		int3			do_int3				has_error_code=0
-idtentry	X86_TRAP_NM		device_not_available	do_device_not_available		has_error_code=0
 idtentry	X86_TRAP_OLD_MF		coprocessor_segment_overrun	do_coprocessor_segment_overrun	has_error_code=0
 idtentry	X86_TRAP_TS		invalid_TSS		do_invalid_TSS			has_error_code=1
 idtentry	X86_TRAP_NP		segment_not_present	do_segment_not_present		has_error_code=1

arch/x86/include/asm/idtentry.h

@@ -81,5 +81,6 @@ DECLARE_IDTENTRY(X86_TRAP_DE,		exc_divide_error);
 DECLARE_IDTENTRY(X86_TRAP_OF,		exc_overflow);
 DECLARE_IDTENTRY(X86_TRAP_BR,		exc_bounds);
 DECLARE_IDTENTRY(X86_TRAP_UD,		exc_invalid_op);
+DECLARE_IDTENTRY(X86_TRAP_NM,		exc_device_not_available);
 
 #endif

arch/x86/include/asm/traps.h

@@ -14,7 +14,6 @@
 asmlinkage void debug(void);
 asmlinkage void nmi(void);
 asmlinkage void int3(void);
-asmlinkage void device_not_available(void);
 #ifdef CONFIG_X86_64
 asmlinkage void double_fault(void);
 #endif
@@ -37,7 +36,6 @@ asmlinkage void simd_coprocessor_error(void);
 asmlinkage void xen_xennmi(void);
 asmlinkage void xen_xendebug(void);
 asmlinkage void xen_int3(void);
-asmlinkage void xen_device_not_available(void);
 asmlinkage void xen_double_fault(void);
 asmlinkage void xen_coprocessor_segment_overrun(void);
 asmlinkage void xen_invalid_TSS(void);
@@ -57,7 +55,6 @@ asmlinkage void xen_simd_coprocessor_error(void);
 dotraplinkage void do_debug(struct pt_regs *regs, long error_code);
 dotraplinkage void do_nmi(struct pt_regs *regs, long error_code);
 dotraplinkage void do_int3(struct pt_regs *regs, long error_code);
-dotraplinkage void do_device_not_available(struct pt_regs *regs, long error_code);
 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsigned long cr2);
 dotraplinkage void do_coprocessor_segment_overrun(struct pt_regs *regs, long error_code);
 dotraplinkage void do_invalid_TSS(struct pt_regs *regs, long error_code);

arch/x86/kernel/idt.c

@@ -77,7 +77,7 @@ static const __initconst struct idt_data def_idts[] = {
 	INTG(X86_TRAP_NMI,		nmi),
 	INTG(X86_TRAP_BR,		asm_exc_bounds),
 	INTG(X86_TRAP_UD,		asm_exc_invalid_op),
-	INTG(X86_TRAP_NM,		device_not_available),
+	INTG(X86_TRAP_NM,		asm_exc_device_not_available),
 	INTG(X86_TRAP_OLD_MF,		coprocessor_segment_overrun),
 	INTG(X86_TRAP_TS,		invalid_TSS),
 	INTG(X86_TRAP_NP,		segment_not_present),

arch/x86/kernel/traps.c

@@ -882,13 +882,10 @@ do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
 	 */
 }
 
-dotraplinkage void
-do_device_not_available(struct pt_regs *regs, long error_code)
+DEFINE_IDTENTRY(exc_device_not_available)
 {
 	unsigned long cr0 = read_cr0();
 
-	RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
-
 #ifdef CONFIG_MATH_EMULATION
 	if (!boot_cpu_has(X86_FEATURE_FPU) && (cr0 & X86_CR0_EM)) {
 		struct math_emu_info info = { };
@@ -913,10 +910,9 @@ do_device_not_available(struct pt_regs *regs, long error_code)
 		 * to kill the task than getting stuck in a never-ending
 		 * loop of #NM faults.
 		 */
-		die("unexpected #NM exception", regs, error_code);
+		die("unexpected #NM exception", regs, 0);
 	}
 }
-NOKPROBE_SYMBOL(do_device_not_available);
 
 #ifdef CONFIG_X86_32
 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)

arch/x86/xen/enlighten_pv.c

@@ -625,7 +625,7 @@ static struct trap_array_entry trap_array[] = {
 	TRAP_ENTRY(exc_divide_error,			false ),
 	TRAP_ENTRY(exc_bounds,				false ),
 	TRAP_ENTRY(exc_invalid_op,			false ),
-	{ device_not_available,        xen_device_not_available,        false },
+	TRAP_ENTRY(exc_device_not_available,		false ),
 	{ coprocessor_segment_overrun, xen_coprocessor_segment_overrun, false },
 	{ invalid_TSS,                 xen_invalid_TSS,                 false },
 	{ segment_not_present,         xen_segment_not_present,         false },

arch/x86/xen/xen-asm_64.S

@@ -36,7 +36,7 @@ xen_pv_trap xennmi
 xen_pv_trap asm_exc_overflow
 xen_pv_trap asm_exc_bounds
 xen_pv_trap asm_exc_invalid_op
-xen_pv_trap device_not_available
+xen_pv_trap asm_exc_device_not_available
 xen_pv_trap double_fault
 xen_pv_trap coprocessor_segment_overrun
 xen_pv_trap invalid_TSS