x86/entry: Convert Overflow exception to IDTENTRY

Convert #OF 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

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/20200505134904.771457898@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(overflow)
-	ASM_CLAC
-	pushl	$0
-	pushl	$do_overflow
-	jmp	common_exception
-SYM_CODE_END(overflow)
-
 SYM_CODE_START(bounds)
 	ASM_CLAC
 	pushl	$0

arch/x86/entry/entry_64.S

@@ -1072,7 +1072,6 @@ apicinterrupt IRQ_WORK_VECTOR			irq_work_interrupt		smp_irq_work_interrupt
  * Exception entry points.
  */
 
-idtentry	X86_TRAP_OF		overflow		do_overflow			has_error_code=0
 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

arch/x86/include/asm/idtentry.h

@@ -78,5 +78,6 @@ 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);
 
 #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 overflow(void);
 asmlinkage void bounds(void);
 asmlinkage void invalid_op(void);
 asmlinkage void device_not_available(void);
@@ -40,7 +39,6 @@ asmlinkage void simd_coprocessor_error(void);
 asmlinkage void xen_xennmi(void);
 asmlinkage void xen_xendebug(void);
 asmlinkage void xen_int3(void);
-asmlinkage void xen_overflow(void);
 asmlinkage void xen_bounds(void);
 asmlinkage void xen_invalid_op(void);
 asmlinkage void xen_device_not_available(void);
@@ -63,7 +61,6 @@ 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_overflow(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);

arch/x86/kernel/idt.c

@@ -99,7 +99,7 @@ static const __initconst struct idt_data def_idts[] = {
 	INTG(X86_TRAP_MC,		machine_check),
 #endif
 
-	SYSG(X86_TRAP_OF,		overflow),
+	SYSG(X86_TRAP_OF,		asm_exc_overflow),
 #if defined(CONFIG_IA32_EMULATION)
 	SYSG(IA32_SYSCALL_VECTOR,	entry_INT80_compat),
 #elif defined(CONFIG_X86_32)

arch/x86/kernel/traps.c

@@ -226,6 +226,11 @@ DEFINE_IDTENTRY(exc_divide_error)
 		      FPE_INTDIV, error_get_trap_addr(regs));
 }
 
+DEFINE_IDTENTRY(exc_overflow)
+{
+	do_error_trap(regs, 0, "overflow", X86_TRAP_OF, SIGSEGV, 0, NULL);
+}
+
 #define IP ((void __user *)uprobe_get_trap_addr(regs))
 #define DO_ERROR(trapnr, signr, sicode, addr, str, name)		   \
 dotraplinkage void do_##name(struct pt_regs *regs, long error_code)	   \
@@ -233,7 +238,6 @@ dotraplinkage void do_##name(struct pt_regs *regs, long error_code)	   \
 	do_error_trap(regs, error_code, str, trapnr, signr, sicode, addr); \
 }
 
-DO_ERROR(X86_TRAP_OF,     SIGSEGV,          0, NULL, "overflow",            overflow)
 DO_ERROR(X86_TRAP_UD,     SIGILL,  ILL_ILLOPN,   IP, "invalid opcode",      invalid_op)
 DO_ERROR(X86_TRAP_OLD_MF, SIGFPE,           0, NULL, "coprocessor segment overrun", coprocessor_segment_overrun)
 DO_ERROR(X86_TRAP_TS,     SIGSEGV,          0, NULL, "invalid TSS",         invalid_TSS)

arch/x86/xen/enlighten_pv.c

@@ -617,7 +617,7 @@ static struct trap_array_entry trap_array[] = {
 #endif
 	{ nmi,                         xen_xennmi,                      true },
 	{ int3,                        xen_int3,                        false },
-	{ overflow,                    xen_overflow,                    false },
+	TRAP_ENTRY(exc_overflow,			false ),
 #ifdef CONFIG_IA32_EMULATION
 	{ entry_INT80_compat,          xen_entry_INT80_compat,          false },
 #endif

arch/x86/xen/xen-asm_64.S

@@ -33,7 +33,7 @@ xen_pv_trap debug
 xen_pv_trap xendebug
 xen_pv_trap int3
 xen_pv_trap xennmi
-xen_pv_trap overflow
+xen_pv_trap asm_exc_overflow
 xen_pv_trap bounds
 xen_pv_trap invalid_op
 xen_pv_trap device_not_available