x86/entry: Convert Segment not present exception to IDTENTRY

Convert #NP 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

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/20200505134905.443591450@linutronix.de

arch/x86/entry/entry_32.S

@@ -1318,12 +1318,6 @@ SYM_CODE_START(native_iret)
 SYM_CODE_END(native_iret)
 #endif
 
-SYM_CODE_START(segment_not_present)
-	ASM_CLAC
-	pushl	$do_segment_not_present
-	jmp	common_exception
-SYM_CODE_END(segment_not_present)
-
 SYM_CODE_START(stack_segment)
 	ASM_CLAC
 	pushl	$do_stack_segment

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_NP		segment_not_present	do_segment_not_present		has_error_code=1
 idtentry	X86_TRAP_SS		stack_segment		do_stack_segment		has_error_code=1
 idtentry	X86_TRAP_GP		general_protection	do_general_protection		has_error_code=1
 idtentry	X86_TRAP_SPURIOUS	spurious_interrupt_bug	do_spurious_interrupt_bug	has_error_code=0

arch/x86/include/asm/idtentry.h

@@ -132,5 +132,6 @@ DECLARE_IDTENTRY(X86_TRAP_OLD_MF,	exc_coproc_segment_overrun);
 
 /* Simple exception entries with error code pushed by hardware */
 DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_TS,	exc_invalid_tss);
+DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_NP,	exc_segment_not_present);
 
 #endif

arch/x86/include/asm/traps.h

@@ -17,7 +17,6 @@ asmlinkage void int3(void);
 #ifdef CONFIG_X86_64
 asmlinkage void double_fault(void);
 #endif
-asmlinkage void segment_not_present(void);
 asmlinkage void stack_segment(void);
 asmlinkage void general_protection(void);
 asmlinkage void page_fault(void);
@@ -35,7 +34,6 @@ asmlinkage void xen_xennmi(void);
 asmlinkage void xen_xendebug(void);
 asmlinkage void xen_int3(void);
 asmlinkage void xen_double_fault(void);
-asmlinkage void xen_segment_not_present(void);
 asmlinkage void xen_stack_segment(void);
 asmlinkage void xen_general_protection(void);
 asmlinkage void xen_page_fault(void);
@@ -52,7 +50,6 @@ 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_double_fault(struct pt_regs *regs, long error_code, unsigned long cr2);
-dotraplinkage void do_segment_not_present(struct pt_regs *regs, long error_code);
 dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code);
 dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code);
 dotraplinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code, unsigned long address);

arch/x86/kernel/idt.c

@@ -80,7 +80,7 @@ static const __initconst struct idt_data def_idts[] = {
 	INTG(X86_TRAP_NM,		asm_exc_device_not_available),
 	INTG(X86_TRAP_OLD_MF,		asm_exc_coproc_segment_overrun),
 	INTG(X86_TRAP_TS,		asm_exc_invalid_tss),
-	INTG(X86_TRAP_NP,		segment_not_present),
+	INTG(X86_TRAP_NP,		asm_exc_segment_not_present),
 	INTG(X86_TRAP_SS,		stack_segment),
 	INTG(X86_TRAP_GP,		general_protection),
 	INTG(X86_TRAP_SPURIOUS,		spurious_interrupt_bug),

arch/x86/kernel/traps.c

@@ -258,6 +258,12 @@ DEFINE_IDTENTRY_ERRORCODE(exc_invalid_tss)
 		      0, NULL);
 }
 
+DEFINE_IDTENTRY_ERRORCODE(exc_segment_not_present)
+{
+	do_error_trap(regs, error_code, "segment not present", X86_TRAP_NP,
+		      SIGBUS, 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)	   \
@@ -265,7 +271,6 @@ 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_NP,     SIGBUS,           0, NULL, "segment not present", segment_not_present)
 DO_ERROR(X86_TRAP_SS,     SIGBUS,           0, NULL, "stack segment",       stack_segment)
 #undef IP
 

arch/x86/xen/enlighten_pv.c

@@ -628,7 +628,7 @@ static struct trap_array_entry trap_array[] = {
 	TRAP_ENTRY(exc_device_not_available,		false ),
 	TRAP_ENTRY(exc_coproc_segment_overrun,		false ),
 	TRAP_ENTRY(exc_invalid_tss,			false ),
-	{ segment_not_present,         xen_segment_not_present,         false },
+	TRAP_ENTRY(exc_segment_not_present,		false ),
 	{ stack_segment,               xen_stack_segment,               false },
 	{ general_protection,          xen_general_protection,          false },
 	{ spurious_interrupt_bug,      xen_spurious_interrupt_bug,      false },

arch/x86/xen/xen-asm_64.S

@@ -40,7 +40,7 @@ xen_pv_trap asm_exc_device_not_available
 xen_pv_trap double_fault
 xen_pv_trap asm_exc_coproc_segment_overrun
 xen_pv_trap asm_exc_invalid_tss
-xen_pv_trap segment_not_present
+xen_pv_trap asm_exc_segment_not_present
 xen_pv_trap stack_segment
 xen_pv_trap general_protection
 xen_pv_trap page_fault