linux-kernel - [tip:x86/urgent] x86/entry/64: Simplify idtentry a little

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Date:   Wed, 17 Jul 2019 14:24:28 -0700
From:   tip-bot for Peter Zijlstra <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     tglx@...utronix.de, rostedt@...dmis.org, luto@...nel.org,
        hpa@...or.com, mingo@...nel.org, linux-kernel@...r.kernel.org,
        peterz@...radead.org
Subject: [tip:x86/urgent] x86/entry/64: Simplify idtentry a little

Commit-ID:  2fd37912cfb019228bf246215938e6f7619516a2
Gitweb:     https://git.kernel.org/tip/2fd37912cfb019228bf246215938e6f7619516a2
Author:     Peter Zijlstra <peterz@...radead.org>
AuthorDate: Thu, 11 Jul 2019 13:40:57 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Wed, 17 Jul 2019 23:17:37 +0200

x86/entry/64: Simplify idtentry a little

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@...radead.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
Acked-by: Andy Lutomirski <luto@...nel.org>
Cc: bp@...en8.de
Cc: torvalds@...ux-foundation.org
Cc: hpa@...or.com
Cc: dave.hansen@...ux.intel.com
Cc: jgross@...e.com
Cc: zhe.he@...driver.com
Cc: joel@...lfernandes.org
Cc: devel@...ukata.com
Link: https://lkml.kernel.org/r/20190711114336.002429503@infradead.org

---
 arch/x86/entry/entry_64.S | 102 ++++++++++++++++++++++------------------------
 1 file changed, 48 insertions(+), 54 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 0ea4831a72a4..3db5fede743b 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -864,6 +864,52 @@ 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
@@ -934,47 +980,7 @@ 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
 	/*
@@ -983,21 +989,9 @@ 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