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From: Andy Lutomirski <luto@kernel.org>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org, Borislav Petkov <bp@alien8.de>,
	Brian Gerst <brgerst@gmail.com>, Andi Kleen <andi@firstfloor.org>,
	Andy Lutomirski <luto@kernel.org>
Subject: [PATCH 4/8] x86/segments/64: When load_gs_index fails, clear the base
Date: Tue, 26 Apr 2016 12:23:27 -0700	[thread overview]
Message-ID: <1a6c4d3a8a4e7be79ba448b42685e0321d50c14c.1461698311.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1461698311.git.luto@kernel.org>
In-Reply-To: <cover.1461698311.git.luto@kernel.org>

On AMD CPUs, a failed load_gs_base currently may not clear the FS
base.  Fix it.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 arch/x86/entry/entry_64.S | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 1693c17dbf81..6344629ae1ce 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -794,6 +794,12 @@ END(native_load_gs_index)
 	/* running with kernelgs */
 bad_gs:
 	SWAPGS					/* switch back to user gs */
+.macro ZAP_GS
+	/* This can't be a string because the preprocessor needs to see it. */
+	movl $__USER_DS, %eax
+	movl %eax, %gs
+.endm
+	ALTERNATIVE "", "ZAP_GS", X86_BUG_NULL_SEG
 	xorl	%eax, %eax
 	movl	%eax, %gs
 	jmp	2b
-- 
2.5.5

  parent reply	other threads:[~2016-04-26 19:24 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-26 19:23 [PATCH 0/8] x86: A round of x86 segmentation improvements Andy Lutomirski
2016-04-26 19:23 ` [PATCH 1/8] x86/asm: Stop depending on ptrace.h in alternative.h Andy Lutomirski
2016-04-29 10:48   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-04-26 19:23 ` [PATCH 2/8] x86/asm: Make asm/alternative.h safe from assembly Andy Lutomirski
2016-04-29 10:49   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-04-26 19:23 ` [PATCH 3/8] x86/segments/64: When loadsegment(fs, ...) fails, clear the base Andy Lutomirski
2016-04-29 10:49   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-04-26 19:23 ` Andy Lutomirski [this message]
2016-04-29 10:49   ` [tip:x86/asm] x86/segments/64: When load_gs_index " tip-bot for Andy Lutomirski
2016-04-26 19:23 ` [PATCH 5/8] x86/arch_prctl/64: Remove FSBASE/GSBASE < 4G optimization Andy Lutomirski
2016-04-26 20:50   ` Andi Kleen
2016-04-26 22:33     ` Andy Lutomirski
2016-04-29 10:50   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-04-26 19:23 ` [PATCH 6/8] x86/asm/64: Rename thread_struct's fs and gs to fsbase and gsbase Andy Lutomirski
2016-04-29 10:50   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-04-26 19:23 ` [PATCH 7/8] x86/tls: Synchronize segment registers in set_thread_area Andy Lutomirski
2016-04-29 10:51   ` [tip:x86/asm] x86/tls: Synchronize segment registers in set_thread_area() tip-bot for Andy Lutomirski
2016-04-26 19:23 ` [PATCH 8/8] selftests/x86/ldt_gdt: Test set_thread_area deletion of an active segment Andy Lutomirski
2016-04-29 10:51   ` [tip:x86/asm] selftests/x86/ldt_gdt: Test set_thread_area() " tip-bot for Andy Lutomirski

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