x86/entry: Convert Coprocessor error exception to IDTENTRY

Convert #MF to IDTENTRY_ERRORCODE:
  - 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: Peter Zijlstra <peterz@infradead.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200505134905.838823510@linutronix.de

arch/x86/entry/entry_32.S

@@ -1290,13 +1290,6 @@ SYM_FUNC_END(name)
 /* The include is where all of the SMP etc. interrupts come from */
 #include <asm/entry_arch.h>
 
-SYM_CODE_START(coprocessor_error)
-	ASM_CLAC
-	pushl	$0
-	pushl	$do_coprocessor_error
-	jmp	common_exception
-SYM_CODE_END(coprocessor_error)
-
 SYM_CODE_START(simd_coprocessor_error)
 	ASM_CLAC
 	pushl	$0

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_MF		coprocessor_error	do_coprocessor_error		has_error_code=0
 idtentry	X86_TRAP_AC		alignment_check		do_alignment_check		has_error_code=1
 idtentry	X86_TRAP_XF		simd_coprocessor_error	do_simd_coprocessor_error	has_error_code=0
 

arch/x86/include/asm/idtentry.h

@@ -130,6 +130,7 @@ DECLARE_IDTENTRY(X86_TRAP_UD,		exc_invalid_op);
 DECLARE_IDTENTRY(X86_TRAP_NM,		exc_device_not_available);
 DECLARE_IDTENTRY(X86_TRAP_OLD_MF,	exc_coproc_segment_overrun);
 DECLARE_IDTENTRY(X86_TRAP_SPURIOUS,	exc_spurious_interrupt_bug);
+DECLARE_IDTENTRY(X86_TRAP_MF,		exc_coprocessor_error);
 
 /* Simple exception entries with error code pushed by hardware */
 DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_TS,	exc_invalid_tss);

arch/x86/include/asm/traps.h

@@ -19,7 +19,6 @@ asmlinkage void double_fault(void);
 #endif
 asmlinkage void page_fault(void);
 asmlinkage void async_page_fault(void);
-asmlinkage void coprocessor_error(void);
 asmlinkage void alignment_check(void);
 #ifdef CONFIG_X86_MCE
 asmlinkage void machine_check(void);
@@ -32,7 +31,6 @@ asmlinkage void xen_xendebug(void);
 asmlinkage void xen_int3(void);
 asmlinkage void xen_double_fault(void);
 asmlinkage void xen_page_fault(void);
-asmlinkage void xen_coprocessor_error(void);
 asmlinkage void xen_alignment_check(void);
 #ifdef CONFIG_X86_MCE
 asmlinkage void xen_machine_check(void);
@@ -45,7 +43,6 @@ 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_double_fault(struct pt_regs *regs, long error_code, unsigned long cr2);
 dotraplinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code, unsigned long address);
-dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code);
 dotraplinkage void do_alignment_check(struct pt_regs *regs, long error_code);
 dotraplinkage void do_simd_coprocessor_error(struct pt_regs *regs, long error_code);
 #ifdef CONFIG_X86_32

arch/x86/kernel/idt.c

@@ -84,7 +84,7 @@ static const __initconst struct idt_data def_idts[] = {
 	INTG(X86_TRAP_SS,		asm_exc_stack_segment),
 	INTG(X86_TRAP_GP,		asm_exc_general_protection),
 	INTG(X86_TRAP_SPURIOUS,		asm_exc_spurious_interrupt_bug),
-	INTG(X86_TRAP_MF,		coprocessor_error),
+	INTG(X86_TRAP_MF,		asm_exc_coprocessor_error),
 	INTG(X86_TRAP_AC,		alignment_check),
 	INTG(X86_TRAP_XF,		simd_coprocessor_error),
 

arch/x86/kernel/traps.c

@@ -854,10 +854,9 @@ static void math_error(struct pt_regs *regs, int error_code, int trapnr)
 	cond_local_irq_disable(regs);
 }
 
-dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
+DEFINE_IDTENTRY(exc_coprocessor_error)
 {
-	RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
-	math_error(regs, error_code, X86_TRAP_MF);
+	math_error(regs, 0, X86_TRAP_MF);
 }
 
 dotraplinkage void

arch/x86/xen/enlighten_pv.c

@@ -632,7 +632,7 @@ static struct trap_array_entry trap_array[] = {
 	TRAP_ENTRY(exc_stack_segment,			false ),
 	TRAP_ENTRY(exc_general_protection,		false ),
 	TRAP_ENTRY(exc_spurious_interrupt_bug,		false ),
-	{ coprocessor_error,           xen_coprocessor_error,           false },
+	TRAP_ENTRY(exc_coprocessor_error,		false ),
 	{ alignment_check,             xen_alignment_check,             false },
 	{ simd_coprocessor_error,      xen_simd_coprocessor_error,      false },
 };

arch/x86/xen/xen-asm_64.S

@@ -45,7 +45,7 @@ xen_pv_trap asm_exc_stack_segment
 xen_pv_trap asm_exc_general_protection
 xen_pv_trap page_fault
 xen_pv_trap asm_exc_spurious_interrupt_bug
-xen_pv_trap coprocessor_error
+xen_pv_trap asm_exc_coprocessor_error
 xen_pv_trap alignment_check
 #ifdef CONFIG_X86_MCE
 xen_pv_trap machine_check