x86/entry: Convert SIMD coprocessor error exception to IDTENTRY

Convert #XF to IDTENTRY_ERRORCODE:
  - Implement the C entry point with DEFINE_IDTENTRY
  - Emit the ASM stub with DECLARE_IDTENTRY
  - Handle INVD_BUG in C
  - 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/20200505134906.021552202@linutronix.de

arch/x86/entry/entry_32.S

@@ -1290,20 +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(simd_coprocessor_error)
-	ASM_CLAC
-	pushl	$0
-#ifdef CONFIG_X86_INVD_BUG
-	/* AMD 486 bug: invd from userspace calls exception 19 instead of #GP */
-	ALTERNATIVE "pushl	$exc_general_protection",	\
-		    "pushl	$do_simd_coprocessor_error",	\
-		    X86_FEATURE_XMM
-#else
-	pushl	$do_simd_coprocessor_error
-#endif
-	jmp	common_exception
-SYM_CODE_END(simd_coprocessor_error)
-
 #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_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

@@ -131,6 +131,7 @@ 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);
+DECLARE_IDTENTRY(X86_TRAP_XF,		exc_simd_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

@@ -22,7 +22,6 @@ asmlinkage void async_page_fault(void);
 #ifdef CONFIG_X86_MCE
 asmlinkage void machine_check(void);
 #endif /* CONFIG_X86_MCE */
-asmlinkage void simd_coprocessor_error(void);
 
 #if defined(CONFIG_X86_64) && defined(CONFIG_XEN_PV)
 asmlinkage void xen_xennmi(void);
@@ -33,7 +32,6 @@ asmlinkage void xen_page_fault(void);
 #ifdef CONFIG_X86_MCE
 asmlinkage void xen_machine_check(void);
 #endif /* CONFIG_X86_MCE */
-asmlinkage void xen_simd_coprocessor_error(void);
 #endif
 
 dotraplinkage void do_debug(struct pt_regs *regs, long error_code);
@@ -41,7 +39,6 @@ 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_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);
 #endif

arch/x86/kernel/idt.c

@@ -86,7 +86,7 @@ static const __initconst struct idt_data def_idts[] = {
 	INTG(X86_TRAP_SPURIOUS,		asm_exc_spurious_interrupt_bug),
 	INTG(X86_TRAP_MF,		asm_exc_coprocessor_error),
 	INTG(X86_TRAP_AC,		asm_exc_alignment_check),
-	INTG(X86_TRAP_XF,		simd_coprocessor_error),
+	INTG(X86_TRAP_XF,		asm_exc_simd_coprocessor_error),
 
 #ifdef CONFIG_X86_32
 	TSKG(X86_TRAP_DF,		GDT_ENTRY_DOUBLEFAULT_TSS),

arch/x86/kernel/traps.c

@@ -810,7 +810,7 @@ NOKPROBE_SYMBOL(do_debug);
  * the correct behaviour even in the presence of the asynchronous
  * IRQ13 behaviour
  */
-static void math_error(struct pt_regs *regs, int error_code, int trapnr)
+static void math_error(struct pt_regs *regs, int trapnr)
 {
 	struct task_struct *task = current;
 	struct fpu *fpu = &task->thread.fpu;
@@ -821,15 +821,15 @@ static void math_error(struct pt_regs *regs, int error_code, int trapnr)
 	cond_local_irq_enable(regs);
 
 	if (!user_mode(regs)) {
-		if (fixup_exception(regs, trapnr, error_code, 0))
+		if (fixup_exception(regs, trapnr, 0, 0))
 			goto exit;
 
-		task->thread.error_code = error_code;
+		task->thread.error_code = 0;
 		task->thread.trap_nr = trapnr;
 
-		if (notify_die(DIE_TRAP, str, regs, error_code,
-					trapnr, SIGFPE) != NOTIFY_STOP)
-			die(str, regs, error_code);
+		if (notify_die(DIE_TRAP, str, regs, 0, trapnr,
+			       SIGFPE) != NOTIFY_STOP)
+			die(str, regs, 0);
 		goto exit;
 	}
 
@@ -839,7 +839,7 @@ static void math_error(struct pt_regs *regs, int error_code, int trapnr)
 	fpu__save(fpu);
 
 	task->thread.trap_nr	= trapnr;
-	task->thread.error_code = error_code;
+	task->thread.error_code = 0;
 
 	si_code = fpu__exception_code(fpu, trapnr);
 	/* Retry when we get spurious exceptions: */
@@ -854,14 +854,19 @@ static void math_error(struct pt_regs *regs, int error_code, int trapnr)
 
 DEFINE_IDTENTRY(exc_coprocessor_error)
 {
-	math_error(regs, 0, X86_TRAP_MF);
+	math_error(regs, X86_TRAP_MF);
 }
 
-dotraplinkage void
-do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
+DEFINE_IDTENTRY(exc_simd_coprocessor_error)
 {
-	RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
-	math_error(regs, error_code, X86_TRAP_XF);
+	if (IS_ENABLED(CONFIG_X86_INVD_BUG)) {
+		/* AMD 486 bug: INVD in CPL 0 raises #XF instead of #GP */
+		if (!static_cpu_has(X86_FEATURE_XMM)) {
+			__exc_general_protection(regs, 0);
+			return;
+		}
+	}
+	math_error(regs, X86_TRAP_XF);
 }
 
 DEFINE_IDTENTRY(exc_spurious_interrupt_bug)

arch/x86/xen/enlighten_pv.c

@@ -634,7 +634,7 @@ static struct trap_array_entry trap_array[] = {
 	TRAP_ENTRY(exc_spurious_interrupt_bug,		false ),
 	TRAP_ENTRY(exc_coprocessor_error,		false ),
 	TRAP_ENTRY(exc_alignment_check,			false ),
-	{ simd_coprocessor_error,      xen_simd_coprocessor_error,      false },
+	TRAP_ENTRY(exc_simd_coprocessor_error,		false ),
 };
 
 static bool __ref get_trap_addr(void **addr, unsigned int ist)

arch/x86/xen/xen-asm_64.S

@@ -50,7 +50,7 @@ xen_pv_trap asm_exc_alignment_check
 #ifdef CONFIG_X86_MCE
 xen_pv_trap machine_check
 #endif /* CONFIG_X86_MCE */
-xen_pv_trap simd_coprocessor_error
+xen_pv_trap asm_exc_simd_coprocessor_error
 #ifdef CONFIG_IA32_EMULATION
 xen_pv_trap entry_INT80_compat
 #endif