x86/entry: Convert Stack segment exception to IDTENTRY

Convert #SS 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: Peter Zijlstra <peterz@infradead.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200505134905.539867572@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(stack_segment)
-	ASM_CLAC
-	pushl	$do_stack_segment
-	jmp	common_exception
-SYM_CODE_END(stack_segment)
-
 SYM_CODE_START(alignment_check)
 	ASM_CLAC
 	pushl	$do_alignment_check

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_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
 idtentry	X86_TRAP_MF		coprocessor_error	do_coprocessor_error		has_error_code=0

arch/x86/include/asm/idtentry.h

@@ -133,5 +133,6 @@ 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);
+DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_SS,	exc_stack_segment);
 
 #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 stack_segment(void);
 asmlinkage void general_protection(void);
 asmlinkage void page_fault(void);
 asmlinkage void async_page_fault(void);
@@ -34,7 +33,6 @@ asmlinkage void xen_xennmi(void);
 asmlinkage void xen_xendebug(void);
 asmlinkage void xen_int3(void);
 asmlinkage void xen_double_fault(void);
-asmlinkage void xen_stack_segment(void);
 asmlinkage void xen_general_protection(void);
 asmlinkage void xen_page_fault(void);
 asmlinkage void xen_spurious_interrupt_bug(void);
@@ -50,7 +48,6 @@ 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_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);
 dotraplinkage void do_spurious_interrupt_bug(struct pt_regs *regs, long error_code);

arch/x86/kernel/idt.c

@@ -81,7 +81,7 @@ static const __initconst struct idt_data def_idts[] = {
 	INTG(X86_TRAP_OLD_MF,		asm_exc_coproc_segment_overrun),
 	INTG(X86_TRAP_TS,		asm_exc_invalid_tss),
 	INTG(X86_TRAP_NP,		asm_exc_segment_not_present),
-	INTG(X86_TRAP_SS,		stack_segment),
+	INTG(X86_TRAP_SS,		asm_exc_stack_segment),
 	INTG(X86_TRAP_GP,		general_protection),
 	INTG(X86_TRAP_SPURIOUS,		spurious_interrupt_bug),
 	INTG(X86_TRAP_MF,		coprocessor_error),

arch/x86/kernel/traps.c

@@ -264,16 +264,12 @@ DEFINE_IDTENTRY_ERRORCODE(exc_segment_not_present)
 		      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)	   \
-{									   \
-	do_error_trap(regs, error_code, str, trapnr, signr, sicode, addr); \
+DEFINE_IDTENTRY_ERRORCODE(exc_stack_segment)
+{
+	do_error_trap(regs, error_code, "stack segment", X86_TRAP_SS, SIGBUS,
+		      0, NULL);
 }
 
-DO_ERROR(X86_TRAP_SS,     SIGBUS,           0, NULL, "stack segment",       stack_segment)
-#undef IP
-
 dotraplinkage void do_alignment_check(struct pt_regs *regs, long error_code)
 {
 	char *str = "alignment check";

arch/x86/xen/enlighten_pv.c

@@ -629,7 +629,7 @@ static struct trap_array_entry trap_array[] = {
 	TRAP_ENTRY(exc_coproc_segment_overrun,		false ),
 	TRAP_ENTRY(exc_invalid_tss,			false ),
 	TRAP_ENTRY(exc_segment_not_present,		false ),
-	{ stack_segment,               xen_stack_segment,               false },
+	TRAP_ENTRY(exc_stack_segment,			false ),
 	{ general_protection,          xen_general_protection,          false },
 	{ spurious_interrupt_bug,      xen_spurious_interrupt_bug,      false },
 	{ coprocessor_error,           xen_coprocessor_error,           false },

arch/x86/xen/xen-asm_64.S

@@ -41,7 +41,7 @@ xen_pv_trap double_fault
 xen_pv_trap asm_exc_coproc_segment_overrun
 xen_pv_trap asm_exc_invalid_tss
 xen_pv_trap asm_exc_segment_not_present
-xen_pv_trap stack_segment
+xen_pv_trap asm_exc_stack_segment
 xen_pv_trap general_protection
 xen_pv_trap page_fault
 xen_pv_trap spurious_interrupt_bug