linux-kernel - [RFC PATCH 1/7] x86/entry: Move PUSH_AND_CLEAR_REGS out of paranoid

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Message-Id: <20230403140605.540512-2-jiangshanlai@gmail.com>
Date:   Mon,  3 Apr 2023 22:05:59 +0800
From:   Lai Jiangshan <jiangshanlai@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Lai Jiangshan <jiangshan.ljs@...group.com>,
        "H. Peter Anvin" <hpa@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        Andy Lutomirski <luto@...nel.org>,
        Asit Mallick <asit.k.mallick@...el.com>,
        Cfir Cohen <cfir@...gle.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Hansen <dave.hansen@...el.com>,
        David Kaplan <David.Kaplan@....com>,
        David Rientjes <rientjes@...gle.com>,
        Dirk Hohndel <dirkhh@...are.com>,
        Erdem Aktas <erdemaktas@...gle.com>,
        Jan Kiszka <jan.kiszka@...mens.com>,
        Jiri Slaby <jslaby@...e.cz>, Joerg Roedel <joro@...tes.org>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Mike Stunes <mstunes@...are.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Raj Ashok <ashok.raj@...el.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        Tony Luck <tony.luck@...el.com>, kvm@...r.kernel.org,
        linux-coco@...ts.linux.dev, x86@...nel.org,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [RFC PATCH 1/7] x86/entry: Move PUSH_AND_CLEAR_REGS out of paranoid_entry

From: Lai Jiangshan <jiangshan.ljs@...group.com>

Prepare to call paranoid_entry() with pt_regs pushed.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@...group.com>
---
 arch/x86/entry/entry_64.S | 33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index eccc3431e515..49ddc4dd3117 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -475,11 +475,13 @@ SYM_CODE_START(\asmsym)
 	testb	$3, CS-ORIG_RAX(%rsp)
 	jnz	.Lfrom_usermode_switch_stack_\@
 
+	PUSH_AND_CLEAR_REGS
+	UNWIND_HINT_REGS
+	ENCODE_FRAME_POINTER
+
 	/* paranoid_entry returns GS information for paranoid_exit in EBX. */
 	call	paranoid_entry
 
-	UNWIND_HINT_REGS
-
 	movq	%rsp, %rdi		/* pt_regs pointer */
 
 	call	\cfunc
@@ -530,14 +532,16 @@ SYM_CODE_START(\asmsym)
 	testb	$3, CS-ORIG_RAX(%rsp)
 	jnz	.Lfrom_usermode_switch_stack_\@
 
+	PUSH_AND_CLEAR_REGS
+	UNWIND_HINT_REGS
+	ENCODE_FRAME_POINTER
+
 	/*
 	 * paranoid_entry returns SWAPGS flag for paranoid_exit in EBX.
 	 * EBX == 0 -> SWAPGS, EBX == 1 -> no SWAPGS
 	 */
 	call	paranoid_entry
 
-	UNWIND_HINT_REGS
-
 	/*
 	 * Switch off the IST stack to make it free for nested exceptions. The
 	 * vc_switch_off_ist() function will switch back to the interrupted
@@ -587,9 +591,12 @@ SYM_CODE_START(\asmsym)
 	ASM_CLAC
 	cld
 
+	PUSH_AND_CLEAR_REGS
+	UNWIND_HINT_REGS
+	ENCODE_FRAME_POINTER
+
 	/* paranoid_entry returns GS information for paranoid_exit in EBX. */
 	call	paranoid_entry
-	UNWIND_HINT_REGS
 
 	movq	%rsp, %rdi		/* pt_regs pointer into first argument */
 	movq	ORIG_RAX(%rsp), %rsi	/* get error code into 2nd argument*/
@@ -903,8 +910,8 @@ SYM_CODE_END(xen_failsafe_callback)
 #endif /* CONFIG_XEN_PV */
 
 /*
- * Save all registers in pt_regs. Return GSBASE related information
- * in EBX depending on the availability of the FSGSBASE instructions:
+ * Return GSBASE related information in EBX depending on the availability
+ * of the FSGSBASE instructions:
  *
  * FSGSBASE	R/EBX
  *     N        0 -> SWAPGS on exit
@@ -915,11 +922,8 @@ SYM_CODE_END(xen_failsafe_callback)
  * R14 - old CR3
  * R15 - old SPEC_CTRL
  */
-SYM_CODE_START(paranoid_entry)
+SYM_FUNC_START(paranoid_entry)
 	ANNOTATE_NOENDBR
-	UNWIND_HINT_FUNC
-	PUSH_AND_CLEAR_REGS save_ret=1
-	ENCODE_FRAME_POINTER 8
 
 	/*
 	 * Always stash CR3 in %r14.  This value will be restored,
@@ -988,7 +992,7 @@ SYM_CODE_START(paranoid_entry)
 	UNTRAIN_RET_FROM_CALL
 
 	RET
-SYM_CODE_END(paranoid_entry)
+SYM_FUNC_END(paranoid_entry)
 
 /*
  * "Paranoid" exit path from exception stack.  This is invoked
@@ -1443,6 +1447,10 @@ end_repeat_nmi:
 	 */
 	pushq	$-1				/* ORIG_RAX: no syscall to restart */
 
+	PUSH_AND_CLEAR_REGS
+	UNWIND_HINT_REGS
+	ENCODE_FRAME_POINTER
+
 	/*
 	 * Use paranoid_entry to handle SWAPGS, but no need to use paranoid_exit
 	 * as we should not be calling schedule in NMI context.
@@ -1451,7 +1459,6 @@ end_repeat_nmi:
 	 * exceptions might do.
 	 */
 	call	paranoid_entry
-	UNWIND_HINT_REGS
 
 	movq	%rsp, %rdi
 	movq	$-1, %rsi
-- 
2.19.1.6.gb485710b