x86/entry: Convert Alignment check exception to IDTENTRY

Convert #AC 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/20200505134905.928967113@linutronix.de

arch/x86/entry/entry_32.S

@@ -1311,12 +1311,6 @@ SYM_CODE_START(native_iret)
 SYM_CODE_END(native_iret)
 #endif
 
-SYM_CODE_START(alignment_check)
-	ASM_CLAC
-	pushl	$do_alignment_check
-	jmp	common_exception
-SYM_CODE_END(alignment_check)
-
 #ifdef CONFIG_X86_MCE
 SYM_CODE_START(machine_check)
 	ASM_CLAC

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_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
 
 idtentry	X86_TRAP_PF		page_fault		do_page_fault			has_error_code=1

arch/x86/include/asm/idtentry.h

@@ -137,5 +137,6 @@ DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_TS,	exc_invalid_tss);
 DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_NP,	exc_segment_not_present);
 DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_SS,	exc_stack_segment);
 DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_GP,	exc_general_protection);
+DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_AC,	exc_alignment_check);
 
 #endif

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 alignment_check(void);
 #ifdef CONFIG_X86_MCE
 asmlinkage void machine_check(void);
 #endif /* CONFIG_X86_MCE */
@@ -31,7 +30,6 @@ 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_alignment_check(void);
 #ifdef CONFIG_X86_MCE
 asmlinkage void xen_machine_check(void);
 #endif /* CONFIG_X86_MCE */
@@ -43,7 +41,6 @@ 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_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
 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code);

arch/x86/kernel/idt.c

@@ -85,7 +85,7 @@ static const __initconst struct idt_data def_idts[] = {
 	INTG(X86_TRAP_GP,		asm_exc_general_protection),
 	INTG(X86_TRAP_SPURIOUS,		asm_exc_spurious_interrupt_bug),
 	INTG(X86_TRAP_MF,		asm_exc_coprocessor_error),
-	INTG(X86_TRAP_AC,		alignment_check),
+	INTG(X86_TRAP_AC,		asm_exc_alignment_check),
 	INTG(X86_TRAP_XF,		simd_coprocessor_error),
 
 #ifdef CONFIG_X86_32

arch/x86/kernel/traps.c

@@ -270,12 +270,10 @@ DEFINE_IDTENTRY_ERRORCODE(exc_stack_segment)
 		      0, NULL);
 }
 
-dotraplinkage void do_alignment_check(struct pt_regs *regs, long error_code)
+DEFINE_IDTENTRY_ERRORCODE(exc_alignment_check)
 {
 	char *str = "alignment check";
 
-	RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
-
 	if (notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_AC, SIGBUS) == NOTIFY_STOP)
 		return;
 

arch/x86/xen/enlighten_pv.c

@@ -633,7 +633,7 @@ static struct trap_array_entry trap_array[] = {
 	TRAP_ENTRY(exc_general_protection,		false ),
 	TRAP_ENTRY(exc_spurious_interrupt_bug,		false ),
 	TRAP_ENTRY(exc_coprocessor_error,		false ),
-	{ alignment_check,             xen_alignment_check,             false },
+	TRAP_ENTRY(exc_alignment_check,			false ),
 	{ simd_coprocessor_error,      xen_simd_coprocessor_error,      false },
 };
 

arch/x86/xen/xen-asm_64.S

@@ -46,7 +46,7 @@ xen_pv_trap asm_exc_general_protection
 xen_pv_trap page_fault
 xen_pv_trap asm_exc_spurious_interrupt_bug
 xen_pv_trap asm_exc_coprocessor_error
-xen_pv_trap alignment_check
+xen_pv_trap asm_exc_alignment_check
 #ifdef CONFIG_X86_MCE
 xen_pv_trap machine_check
 #endif /* CONFIG_X86_MCE */