linux-kernel - [tip: x86/cleanups] x86/asm: Drop unused RDPID macro

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Date:   Thu, 26 Nov 2020 12:14:42 -0000
From:   "tip-bot2 for Sean Christopherson" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Borislav Petkov <bp@...e.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/cleanups] x86/asm: Drop unused RDPID macro

The following commit has been merged into the x86/cleanups branch of tip:

Commit-ID:     8539d3f06710a9e91b9968fa736549d7c6b44206
Gitweb:        https://git.kernel.org/tip/8539d3f06710a9e91b9968fa736549d7c6b44206
Author:        Sean Christopherson <sean.j.christopherson@...el.com>
AuthorDate:    Tue, 27 Oct 2020 14:45:32 -07:00
Committer:     Borislav Petkov <bp@...e.de>
CommitterDate: Thu, 26 Nov 2020 12:58:56 +01:00

x86/asm: Drop unused RDPID macro

Drop the GAS-compatible RDPID macro. RDPID is unsafe in the kernel
because KVM loads guest's TSC_AUX on VM-entry and may not restore the
host's value until the CPU returns to userspace.

See

  6a3ea3e68b8a ("x86/entry/64: Do not use RDPID in paranoid entry to accomodate KVM")

for details.

It can always be resurrected from git history, if needed.

 [ bp: Massage commit message. ]

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Link: https://lkml.kernel.org/r/20201027214532.1792-1-sean.j.christopherson@intel.com
---
 arch/x86/include/asm/inst.h | 15 ---------------
 1 file changed, 15 deletions(-)

diff --git a/arch/x86/include/asm/inst.h b/arch/x86/include/asm/inst.h
index bd7f024..438ccd4 100644
--- a/arch/x86/include/asm/inst.h
+++ b/arch/x86/include/asm/inst.h
@@ -143,21 +143,6 @@
 	.macro MODRM mod opd1 opd2
 	.byte \mod | (\opd1 & 7) | ((\opd2 & 7) << 3)
 	.endm
-
-.macro RDPID opd
-	REG_TYPE rdpid_opd_type \opd
-	.if rdpid_opd_type == REG_TYPE_R64
-	R64_NUM rdpid_opd \opd
-	.else
-	R32_NUM rdpid_opd \opd
-	.endif
-	.byte 0xf3
-	.if rdpid_opd > 7
-	PFX_REX rdpid_opd 0
-	.endif
-	.byte 0x0f, 0xc7
-	MODRM 0xc0 rdpid_opd 0x7
-.endm
 #endif
 
 #endif