x86/entry: Convert General protection exception to IDTENTRY

Convert #GP 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
  - Remove the RCU warning as the new entry macro ensures correctness

No functional change.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NAlexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200505134905.637269946@linutronix.de

arch/x86/entry/entry_32.S

@@ -1302,7 +1302,7 @@ SYM_CODE_START(simd_coprocessor_error)
 	pushl	$0
 #ifdef CONFIG_X86_INVD_BUG
 	/* AMD 486 bug: invd from userspace calls exception 19 instead of #GP */
-	ALTERNATIVE "pushl	$do_general_protection",	\
+	ALTERNATIVE "pushl	$exc_general_protection",	\
 		    "pushl	$do_simd_coprocessor_error",	\
 		    X86_FEATURE_XMM
 #else
@@ -1690,12 +1690,6 @@ SYM_CODE_START(int3)
 	jmp	common_exception
 SYM_CODE_END(int3)
 
-SYM_CODE_START(general_protection)
-	ASM_CLAC
-	pushl	$do_general_protection
-	jmp	common_exception
-SYM_CODE_END(general_protection)
-
 .pushsection .text, "ax"
 SYM_CODE_START(rewind_stack_do_exit)
 	/* Prevent any naive code from trying to unwind to our caller. */

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_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
 idtentry	X86_TRAP_AC		alignment_check		do_alignment_check		has_error_code=1
@@ -1209,7 +1208,7 @@ SYM_CODE_START(xen_failsafe_callback)
 	addq	$0x30, %rsp
 	pushq	$0				/* RIP */
 	UNWIND_HINT_IRET_REGS offset=8
-	jmp	general_protection
+	jmp	asm_exc_general_protection
 1:	/* Segment mismatch => Category 1 (Bad segment). Retry the IRET. */
 	movq	(%rsp), %rcx
 	movq	8(%rsp), %r11

arch/x86/include/asm/idtentry.h

@@ -134,5 +134,6 @@ DECLARE_IDTENTRY(X86_TRAP_OLD_MF,	exc_coproc_segment_overrun);
 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);
+DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_GP,	exc_general_protection);
 
 #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 general_protection(void);
 asmlinkage void page_fault(void);
 asmlinkage void async_page_fault(void);
 asmlinkage void spurious_interrupt_bug(void);
@@ -33,7 +32,6 @@ asmlinkage void xen_xennmi(void);
 asmlinkage void xen_xendebug(void);
 asmlinkage void xen_int3(void);
 asmlinkage void xen_double_fault(void);
-asmlinkage void xen_general_protection(void);
 asmlinkage void xen_page_fault(void);
 asmlinkage void xen_spurious_interrupt_bug(void);
 asmlinkage void xen_coprocessor_error(void);
@@ -48,7 +46,6 @@ 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_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);
 dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code);

arch/x86/kernel/idt.c

@@ -82,7 +82,7 @@ static const __initconst struct idt_data def_idts[] = {
 	INTG(X86_TRAP_TS,		asm_exc_invalid_tss),
 	INTG(X86_TRAP_NP,		asm_exc_segment_not_present),
 	INTG(X86_TRAP_SS,		asm_exc_stack_segment),
-	INTG(X86_TRAP_GP,		general_protection),
+	INTG(X86_TRAP_GP,		asm_exc_general_protection),
 	INTG(X86_TRAP_SPURIOUS,		spurious_interrupt_bug),
 	INTG(X86_TRAP_MF,		coprocessor_error),
 	INTG(X86_TRAP_AC,		alignment_check),

arch/x86/kernel/traps.c

@@ -145,7 +145,7 @@ do_trap_no_signal(struct task_struct *tsk, int trapnr, const char *str,
 	 * process no chance to handle the signal and notice the
 	 * kernel fault information, so that won't result in polluting
 	 * the information about previously queued, but not yet
-	 * delivered, faults.  See also do_general_protection below.
+	 * delivered, faults.  See also exc_general_protection below.
 	 */
 	tsk->thread.error_code = error_code;
 	tsk->thread.trap_nr = trapnr;
@@ -375,7 +375,7 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign
 		 * which is what the stub expects, given that the faulting
 		 * RIP will be the IRET instruction.
 		 */
-		regs->ip = (unsigned long)general_protection;
+		regs->ip = (unsigned long)asm_exc_general_protection;
 		regs->sp = (unsigned long)&gpregs->orig_ax;
 
 		return;
@@ -494,7 +494,7 @@ static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs,
 
 #define GPFSTR "general protection fault"
 
-dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code)
+DEFINE_IDTENTRY_ERRORCODE(exc_general_protection)
 {
 	char desc[sizeof(GPFSTR) + 50 + 2*sizeof(unsigned long) + 1] = GPFSTR;
 	enum kernel_gp_hint hint = GP_NO_HINT;
@@ -502,7 +502,6 @@ dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code)
 	unsigned long gp_addr;
 	int ret;
 
-	RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
 	cond_local_irq_enable(regs);
 
 	if (static_cpu_has(X86_FEATURE_UMIP)) {
@@ -570,7 +569,6 @@ dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code)
 exit:
 	cond_local_irq_disable(regs);
 }
-NOKPROBE_SYMBOL(do_general_protection);
 
 dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
 {

arch/x86/xen/enlighten_pv.c

@@ -630,7 +630,7 @@ static struct trap_array_entry trap_array[] = {
 	TRAP_ENTRY(exc_invalid_tss,			false ),
 	TRAP_ENTRY(exc_segment_not_present,		false ),
 	TRAP_ENTRY(exc_stack_segment,			false ),
-	{ general_protection,          xen_general_protection,          false },
+	TRAP_ENTRY(exc_general_protection,		false ),
 	{ spurious_interrupt_bug,      xen_spurious_interrupt_bug,      false },
 	{ coprocessor_error,           xen_coprocessor_error,           false },
 	{ alignment_check,             xen_alignment_check,             false },

arch/x86/xen/xen-asm_64.S

@@ -42,7 +42,7 @@ 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 asm_exc_stack_segment
-xen_pv_trap general_protection
+xen_pv_trap asm_exc_general_protection
 xen_pv_trap page_fault
 xen_pv_trap spurious_interrupt_bug
 xen_pv_trap coprocessor_error