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From: David Woodhouse <dwmw@amazon.co.uk>
To: Andi Kleen <ak@linux.intel.com>
Cc: Paul Turner <pjt@google.com>, LKML <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@linux-foundation.org>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Dave Hansen <dave.hansen@intel.com>,
	tglx@linutronix.de, Kees Cook <keescook@google.com>,
	Rik van Riel <riel@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Andy Lutomirski <luto@amacapital.net>,
	Jiri Kosina <jikos@kernel.org>,
	gnomes@lxorguk.ukuu.org.uk, x86@kernel.org,
	thomas.lendacky@amd.com, Josh Poimboeuf <jpoimboe@redhat.com>
Subject: [PATCH v8 06/12] x86/retpoline/entry: Convert entry assembler indirect jumps
Date: Thu, 11 Jan 2018 21:46:28 +0000
Message-ID: <1515707194-20531-7-git-send-email-dwmw@amazon.co.uk> (raw)
In-Reply-To: <1515707194-20531-1-git-send-email-dwmw@amazon.co.uk>

Convert indirect jumps in core 32/64bit entry assembler code to use
non-speculative sequences when CONFIG_RETPOLINE is enabled.

Don't use CALL_NOSPEC in entry_SYSCALL_64_fastpath because the return
address after the 'call' instruction must be *precisely* at the
.Lentry_SYSCALL_64_after_fastpath label for stub_ptregs_64 to work,
and the use of alternatives will mess that up unless we play horrid
games to prepend with NOPs and make the variants the same length. It's
not worth it; in the case where we ALTERNATIVE out the retpoline, the
first instruction at __x86.indirect_thunk.rax is going to be a bare
jmp *%rax anyway.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kees Cook <keescook@google.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: https://lkml.kernel.org/r/1515508997-6154-6-git-send-email-dwmw@amazon.co.uk
---
 arch/x86/entry/entry_32.S |  5 +++--
 arch/x86/entry/entry_64.S | 12 +++++++++---
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index ace8f32..a1f28a5 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -44,6 +44,7 @@
 #include <asm/asm.h>
 #include <asm/smap.h>
 #include <asm/frame.h>
+#include <asm/nospec-branch.h>
 
 	.section .entry.text, "ax"
 
@@ -290,7 +291,7 @@ ENTRY(ret_from_fork)
 
 	/* kernel thread */
 1:	movl	%edi, %eax
-	call	*%ebx
+	CALL_NOSPEC %ebx
 	/*
 	 * A kernel thread is allowed to return here after successfully
 	 * calling do_execve().  Exit to userspace to complete the execve()
@@ -919,7 +920,7 @@ common_exception:
 	movl	%ecx, %es
 	TRACE_IRQS_OFF
 	movl	%esp, %eax			# pt_regs pointer
-	call	*%edi
+	CALL_NOSPEC %edi
 	jmp	ret_from_exception
 END(common_exception)
 
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index ed31d00..59874bc 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -37,6 +37,7 @@
 #include <asm/pgtable_types.h>
 #include <asm/export.h>
 #include <asm/frame.h>
+#include <asm/nospec-branch.h>
 #include <linux/err.h>
 
 #include "calling.h"
@@ -187,7 +188,7 @@ ENTRY(entry_SYSCALL_64_trampoline)
 	 */
 	pushq	%rdi
 	movq	$entry_SYSCALL_64_stage2, %rdi
-	jmp	*%rdi
+	JMP_NOSPEC %rdi
 END(entry_SYSCALL_64_trampoline)
 
 	.popsection
@@ -266,7 +267,12 @@ entry_SYSCALL_64_fastpath:
 	 * It might end up jumping to the slow path.  If it jumps, RAX
 	 * and all argument registers are clobbered.
 	 */
+#ifdef CONFIG_RETPOLINE
+	movq	sys_call_table(, %rax, 8), %rax
+	call	__x86_indirect_thunk_rax
+#else
 	call	*sys_call_table(, %rax, 8)
+#endif
 .Lentry_SYSCALL_64_after_fastpath_call:
 
 	movq	%rax, RAX(%rsp)
@@ -438,7 +444,7 @@ ENTRY(stub_ptregs_64)
 	jmp	entry_SYSCALL64_slow_path
 
 1:
-	jmp	*%rax				/* Called from C */
+	JMP_NOSPEC %rax				/* Called from C */
 END(stub_ptregs_64)
 
 .macro ptregs_stub func
@@ -517,7 +523,7 @@ ENTRY(ret_from_fork)
 1:
 	/* kernel thread */
 	movq	%r12, %rdi
-	call	*%rbx
+	CALL_NOSPEC %rbx
 	/*
 	 * A kernel thread is allowed to return here after successfully
 	 * calling do_execve().  Exit to userspace to complete the execve()
-- 
2.7.4

  parent reply index

Thread overview: 85+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-11 21:46 [PATCH v8 00/12] Retpoline: Avoid speculative indirect calls in kernel David Woodhouse
2018-01-11 21:46 ` [PATCH v8 01/12] objtool: Detect jumps to retpoline thunks David Woodhouse
2018-01-11 23:22   ` [tip:x86/pti] " tip-bot for Josh Poimboeuf
2018-01-11 21:46 ` [PATCH v8 02/12] objtool: Allow alternatives to be ignored David Woodhouse
2018-01-11 23:22   ` [tip:x86/pti] " tip-bot for Josh Poimboeuf
2018-01-18 19:09   ` [v8,02/12] " Guenter Roeck
2018-01-18 19:33     ` Josh Poimboeuf
2018-01-18 19:41       ` Guenter Roeck
2018-01-22 19:34         ` David Woodhouse
2018-01-22 20:25           ` Guenter Roeck
2018-01-22 20:27             ` David Woodhouse
2018-01-28 21:06             ` Josh Poimboeuf
2018-01-29  1:26               ` Guenter Roeck
2018-01-29 17:15               ` Guenter Roeck
2018-01-29 17:30                 ` Josh Poimboeuf
2018-01-22 19:27       ` Guenter Roeck
2018-01-11 21:46 ` [PATCH v8 03/12] x86/retpoline: Add initial retpoline support David Woodhouse
2018-01-11 23:23   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 23:58   ` [PATCH v8 03/12] " Tom Lendacky
2018-01-12 10:28     ` David Woodhouse
2018-01-12 14:02       ` Tom Lendacky
2018-01-14 15:02   ` Borislav Petkov
2018-01-14 15:53     ` Josh Poimboeuf
2018-01-14 15:59       ` Borislav Petkov
2018-01-11 21:46 ` [PATCH v8 04/12] x86/spectre: Add boot time option to select Spectre v2 mitigation David Woodhouse
2018-01-11 23:23   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-23 22:40   ` [PATCH v8 04/12] " Borislav Petkov
2018-01-23 22:53     ` David Woodhouse
2018-01-23 23:05       ` Andi Kleen
2018-01-23 22:55     ` Jiri Kosina
2018-01-23 23:05       ` Borislav Petkov
2018-01-24  0:32         ` Kees Cook
2018-01-24  9:58           ` Borislav Petkov
2018-01-23 23:06       ` Jiri Kosina
2018-01-23 23:21       ` Andi Kleen
2018-01-23 23:24         ` Jiri Kosina
2018-01-23 23:45           ` Andi Kleen
2018-01-23 23:49             ` Jiri Kosina
2018-01-24  4:26               ` Greg Kroah-Hartman
2018-01-24  9:56                 ` Jiri Kosina
2018-01-24 13:58                   ` Greg Kroah-Hartman
2018-01-24 14:03                     ` Jiri Kosina
2018-01-24 14:22                       ` Greg Kroah-Hartman
2018-01-11 21:46 ` [PATCH v8 05/12] x86/retpoline/crypto: Convert crypto assembler indirect jumps David Woodhouse
2018-01-11 23:24   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` David Woodhouse [this message]
2018-01-11 23:24   ` [tip:x86/pti] x86/retpoline/entry: Convert entry " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 07/12] x86/retpoline/ftrace: Convert ftrace " David Woodhouse
2018-01-11 23:25   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 08/12] x86/retpoline/hyperv: Convert " David Woodhouse
2018-01-11 23:25   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 09/12] x86/retpoline/xen: Convert Xen hypercall " David Woodhouse
2018-01-11 23:25   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 10/12] x86/retpoline/checksum32: Convert assembler " David Woodhouse
2018-01-11 23:26   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 21:46 ` [PATCH v8 11/12] x86/retpoline/irq32: " David Woodhouse
2018-01-11 23:26   ` [tip:x86/pti] " tip-bot for Andi Kleen
2018-01-11 21:46 ` [PATCH v8 12/12] x86/retpoline: Fill return stack buffer on vmexit David Woodhouse
2018-01-11 23:27   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-11 23:51   ` [PATCH v8 12/12] " Andi Kleen
2018-01-12 11:11     ` [PATCH v8.1 " David Woodhouse
2018-01-12 11:15       ` Thomas Gleixner
2018-01-12 11:21         ` Woodhouse, David
2018-01-12 11:37       ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-14 14:50         ` Borislav Petkov
2018-01-14 15:28           ` Thomas Gleixner
2018-01-14 15:35         ` Borislav Petkov
2018-01-25 12:07         ` Borislav Petkov
2018-01-25 12:20           ` David Woodhouse
2018-01-25 12:45             ` Borislav Petkov
2018-01-25 15:10               ` Josh Poimboeuf
2018-01-25 15:51                 ` Borislav Petkov
2018-01-25 16:03                   ` David Woodhouse
2018-01-25 16:56                     ` Josh Poimboeuf
2018-01-25 17:00                       ` David Woodhouse
2018-01-25 17:05                         ` Andy Lutomirski
2018-01-25 17:44                           ` Josh Poimboeuf
2018-01-25 18:41                           ` Jiri Kosina
2018-01-25 17:10                         ` Thomas Gleixner
2018-01-25 17:32                         ` Josh Poimboeuf
2018-01-25 17:53                         ` Borislav Petkov
2018-01-25 18:04                           ` David Woodhouse
2018-01-25 18:32                             ` Josh Poimboeuf
2018-01-25 19:07                             ` Borislav Petkov
2018-01-25 19:10                               ` Borislav Petkov

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