linux-kernel - [PATCH V3 45/49] x86/sev: Use C entry code

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Date:   Thu, 14 Oct 2021 11:58:31 +0800
From:   Lai Jiangshan <jiangshanlai@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, Lai Jiangshan <laijs@...ux.alibaba.com>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, Juergen Gross <jgross@...e.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Joerg Roedel <jroedel@...e.de>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Chester Lin <clin@...e.com>
Subject: [PATCH V3 45/49] x86/sev: Use C entry code

From: Lai Jiangshan <laijs@...ux.alibaba.com>

Use DEFINE_IDTENTRY_IST_ETNRY_ERRORCODE to emit C entry function and
use the function directly in entry_64.S.

Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
---
 arch/x86/entry/entry_64.S       | 22 +---------------------
 arch/x86/include/asm/idtentry.h |  1 +
 arch/x86/kernel/Makefile        |  1 +
 3 files changed, 3 insertions(+), 21 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 58f33e86c6c8..48b4c320f5e7 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -528,28 +528,8 @@ SYM_CODE_START(\asmsym)
 
 	UNWIND_HINT_REGS
 
-	/*
-	 * paranoid_entry returns SWAPGS flag for paranoid_exit in EBX.
-	 * EBX == 0 -> SWAPGS, EBX == 1 -> no SWAPGS
-	 */
-	call	paranoid_entry
-
-	UNWIND_HINT_REGS
-
-	/* Update pt_regs */
-	movq	ORIG_RAX(%rsp), %rsi	/* get error code into 2nd argument*/
-	movq	$-1, ORIG_RAX(%rsp)	/* no syscall to restart */
-
 	movq	%rsp, %rdi		/* pt_regs pointer */
-
-	call	kernel_\cfunc
-
-	/*
-	 * No need to switch back to the IST stack. The current stack is either
-	 * identical to the stack in the IRET frame or the VC fall-back stack,
-	 * so it is definitely mapped even with PTI enabled.
-	 */
-	call	paranoid_exit
+	call	ist_kernel_\cfunc
 	jmp	restore_regs_and_return_to_kernel
 
 	/* Switch to the regular task stack */
diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index 931b689f464c..84ce63f03c7f 100644
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -426,6 +426,7 @@ __visible __entry_text void ist_##func(struct pt_regs *regs)		\
  * Maps to DEFINE_IDTENTRY_RAW_ERRORCODE
  */
 #define DEFINE_IDTENTRY_VC_KERNEL(func)				\
+	DEFINE_IDTENTRY_IST_ETNRY_ERRORCODE(kernel_##func)	\
 	DEFINE_IDTENTRY_RAW_ERRORCODE(kernel_##func)
 
 /**
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 28815c2e6cb2..9535d03aaa61 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -52,6 +52,7 @@ CFLAGS_head$(BITS).o	+= -fno-stack-protector
 CFLAGS_cc_platform.o	+= -fno-stack-protector
 CFLAGS_traps.o		+= -fno-stack-protector
 CFLAGS_nmi.o		+= -fno-stack-protector
+CFLAGS_sev.o		+= -fno-stack-protector
 
 CFLAGS_irq.o := -I $(srctree)/$(src)/../include/asm/trace
 
-- 
2.19.1.6.gb485710b