x86/entry: Convert Bounds exception to IDTENTRY

Convert #BR 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/20200505134904.863001309@linutronix.de

arch/x86/entry/entry_32.S

@@ -1325,13 +1325,6 @@ SYM_CODE_START(native_iret)
 SYM_CODE_END(native_iret)
 #endif
 
-SYM_CODE_START(bounds)
-	ASM_CLAC
-	pushl	$0
-	pushl	$do_bounds
-	jmp	common_exception
-SYM_CODE_END(bounds)
-
 SYM_CODE_START(invalid_op)
 	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_BR		bounds			do_bounds			has_error_code=0
 idtentry	X86_TRAP_UD		invalid_op		do_invalid_op			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

arch/x86/include/asm/idtentry.h

@@ -79,5 +79,6 @@ static __always_inline void __##func(struct pt_regs *regs)
 /* Simple exception entry points. No hardware error code */
 DECLARE_IDTENTRY(X86_TRAP_DE,		exc_divide_error);
 DECLARE_IDTENTRY(X86_TRAP_OF,		exc_overflow);
+DECLARE_IDTENTRY(X86_TRAP_BR,		exc_bounds);
 
 #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 bounds(void);
 asmlinkage void invalid_op(void);
 asmlinkage void device_not_available(void);
 #ifdef CONFIG_X86_64
@@ -39,7 +38,6 @@ asmlinkage void simd_coprocessor_error(void);
 asmlinkage void xen_xennmi(void);
 asmlinkage void xen_xendebug(void);
 asmlinkage void xen_int3(void);
-asmlinkage void xen_bounds(void);
 asmlinkage void xen_invalid_op(void);
 asmlinkage void xen_device_not_available(void);
 asmlinkage void xen_double_fault(void);
@@ -61,7 +59,6 @@ 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_bounds(struct pt_regs *regs, long error_code);
 dotraplinkage void do_invalid_op(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);

arch/x86/kernel/idt.c

@@ -75,7 +75,7 @@ static const __initconst struct idt_data early_idts[] = {
 static const __initconst struct idt_data def_idts[] = {
 	INTG(X86_TRAP_DE,		asm_exc_divide_error),
 	INTG(X86_TRAP_NMI,		nmi),
-	INTG(X86_TRAP_BR,		bounds),
+	INTG(X86_TRAP_BR,		asm_exc_bounds),
 	INTG(X86_TRAP_UD,		invalid_op),
 	INTG(X86_TRAP_NM,		device_not_available),
 	INTG(X86_TRAP_OLD_MF,		coprocessor_segment_overrun),

arch/x86/kernel/traps.c

@@ -410,18 +410,17 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign
 	panic("Machine halted.");
 }
 
-dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
+DEFINE_IDTENTRY(exc_bounds)
 {
-	RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
-	if (notify_die(DIE_TRAP, "bounds", regs, error_code,
+	if (notify_die(DIE_TRAP, "bounds", regs, 0,
 			X86_TRAP_BR, SIGSEGV) == NOTIFY_STOP)
 		return;
 	cond_local_irq_enable(regs);
 
 	if (!user_mode(regs))
-		die("bounds", regs, error_code);
+		die("bounds", regs, 0);
 
-	do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, 0, NULL);
+	do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, 0, 0, NULL);
 
 	cond_local_irq_disable(regs);
 }

arch/x86/xen/enlighten_pv.c

@@ -623,7 +623,7 @@ static struct trap_array_entry trap_array[] = {
 #endif
 	{ page_fault,                  xen_page_fault,                  false },
 	TRAP_ENTRY(exc_divide_error,			false ),
-	{ bounds,                      xen_bounds,                      false },
+	TRAP_ENTRY(exc_bounds,				false ),
 	{ invalid_op,                  xen_invalid_op,                  false },
 	{ device_not_available,        xen_device_not_available,        false },
 	{ coprocessor_segment_overrun, xen_coprocessor_segment_overrun, false },

arch/x86/xen/xen-asm_64.S

@@ -34,7 +34,7 @@ xen_pv_trap xendebug
 xen_pv_trap int3
 xen_pv_trap xennmi
 xen_pv_trap asm_exc_overflow
-xen_pv_trap bounds
+xen_pv_trap asm_exc_bounds
 xen_pv_trap invalid_op
 xen_pv_trap device_not_available
 xen_pv_trap double_fault