release/5.2.29/x86-entry-64-Simplify-idtentry-a-little.patch

From f42d0df86836e55459566a6d760b3cc4debeef0e Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 11 Jul 2019 13:40:57 +0200
Subject: [PATCH] x86/entry/64: Simplify idtentry a little

commit 2fd37912cfb019228bf246215938e6f7619516a2 upstream.

There's a bunch of duplication in idtentry, namely the
.Lfrom_usermode_switch_stack is a paranoid=0 copy of the normal flow.

Make this explicit by creating a idtentry_part helper macro.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: bp@alien8.de
Cc: torvalds@linux-foundation.org
Cc: hpa@zytor.com
Cc: dave.hansen@linux.intel.com
Cc: jgross@suse.com
Cc: zhe.he@windriver.com
Cc: joel@joelfernandes.org
Cc: devel@etsukata.com
Link: https://lkml.kernel.org/r/20190711114336.002429503@infradead.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 594b2fa7da80..18a80606f157 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -866,6 +866,52 @@ apicinterrupt IRQ_WORK_VECTOR			irq_work_interrupt		smp_irq_work_interrupt
  */
 #define CPU_TSS_IST(x) PER_CPU_VAR(cpu_tss_rw) + (TSS_ist + (x) * 8)
 
+.macro idtentry_part do_sym, has_error_code:req, paranoid:req, shift_ist=-1, ist_offset=0
+
+	.if \paranoid
+	call	paranoid_entry
+	/* returned flag: ebx=0: need swapgs on exit, ebx=1: don't need it */
+	.else
+	call	error_entry
+	.endif
+	UNWIND_HINT_REGS
+
+	.if \paranoid
+	.if \shift_ist != -1
+	TRACE_IRQS_OFF_DEBUG			/* reload IDT in case of recursion */
+	.else
+	TRACE_IRQS_OFF
+	.endif
+	.endif
+
+	movq	%rsp, %rdi			/* pt_regs pointer */
+
+	.if \has_error_code
+	movq	ORIG_RAX(%rsp), %rsi		/* get error code */
+	movq	$-1, ORIG_RAX(%rsp)		/* no syscall to restart */
+	.else
+	xorl	%esi, %esi			/* no error code */
+	.endif
+
+	.if \shift_ist != -1
+	subq	$\ist_offset, CPU_TSS_IST(\shift_ist)
+	.endif
+
+	call	\do_sym
+
+	.if \shift_ist != -1
+	addq	$\ist_offset, CPU_TSS_IST(\shift_ist)
+	.endif
+
+	.if \paranoid
+	/* this procedure expect "no swapgs" flag in ebx */
+	jmp	paranoid_exit
+	.else
+	jmp	error_exit
+	.endif
+
+.endm
+
 /**
  * idtentry - Generate an IDT entry stub
  * @sym:		Name of the generated entry point
@@ -936,47 +982,7 @@ ENTRY(\sym)
 .Lfrom_usermode_no_gap_\@:
 	.endif
 
-	.if \paranoid
-	call	paranoid_entry
-	.else
-	call	error_entry
-	.endif
-	UNWIND_HINT_REGS
-	/* returned flag: ebx=0: need swapgs on exit, ebx=1: don't need it */
-
-	.if \paranoid
-	.if \shift_ist != -1
-	TRACE_IRQS_OFF_DEBUG			/* reload IDT in case of recursion */
-	.else
-	TRACE_IRQS_OFF
-	.endif
-	.endif
-
-	movq	%rsp, %rdi			/* pt_regs pointer */
-
-	.if \has_error_code
-	movq	ORIG_RAX(%rsp), %rsi		/* get error code */
-	movq	$-1, ORIG_RAX(%rsp)		/* no syscall to restart */
-	.else
-	xorl	%esi, %esi			/* no error code */
-	.endif
-
-	.if \shift_ist != -1
-	subq	$\ist_offset, CPU_TSS_IST(\shift_ist)
-	.endif
-
-	call	\do_sym
-
-	.if \shift_ist != -1
-	addq	$\ist_offset, CPU_TSS_IST(\shift_ist)
-	.endif
-
-	/* these procedures expect "no swapgs" flag in ebx */
-	.if \paranoid
-	jmp	paranoid_exit
-	.else
-	jmp	error_exit
-	.endif
+	idtentry_part \do_sym, \has_error_code, \paranoid, \shift_ist, \ist_offset
 
 	.if \paranoid == 1
 	/*
@@ -985,21 +991,9 @@ ENTRY(\sym)
 	 * run in real process context if user_mode(regs).
 	 */
 .Lfrom_usermode_switch_stack_\@:
-	call	error_entry
-
-	movq	%rsp, %rdi			/* pt_regs pointer */
-
-	.if \has_error_code
-	movq	ORIG_RAX(%rsp), %rsi		/* get error code */
-	movq	$-1, ORIG_RAX(%rsp)		/* no syscall to restart */
-	.else
-	xorl	%esi, %esi			/* no error code */
+	idtentry_part \do_sym, \has_error_code, paranoid=0
 	.endif
 
-	call	\do_sym
-
-	jmp	error_exit
-	.endif
 _ASM_NOKPROBE(\sym)
 END(\sym)
 .endm
-- 
2.7.4