[tip:x86/asm] x86/entry/64/compat: Disable SYSENTER and SYSCALL32 entries

[tip-bot for Andy Lutomirski]

Commit-ID:  e62a254a1f93fcc7299497a5c7231639400b8c3c
Gitweb:     http://git.kernel.org/tip/e62a254a1f93fcc7299497a5c7231639400b8c3c
Author:     Andy Lutomirski <luto@xxxxxxxxxx>
AuthorDate: Mon, 5 Oct 2015 17:48:02 -0700
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 9 Oct 2015 09:41:07 +0200

x86/entry/64/compat: Disable SYSENTER and SYSCALL32 entries

We've disabled the vDSO helpers to call them, so turn off the
entries entirely (temporarily) in preparation for cleaning them
up.

Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/8d6e84bf651519289dc532dcc230adfabbd2a3eb.1444091584.git.luto@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/entry/entry_64_compat.S | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index bc678f0..06a8966 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -103,6 +103,14 @@ ENTRY(entry_SYSENTER_compat)
 	jnz	sysenter_fix_flags
 sysenter_flags_fixed:
 
+	/* Temporary: SYSENTER is disabled. */
+#ifdef CONFIG_CONTEXT_TRACKING
+	call enter_from_user_mode
+#endif
+	ENABLE_INTERRUPTS(CLBR_NONE)
+	movl $11, %edi
+	call do_exit
+
 	/*
 	 * Re-enable interrupts.  IRQ tracing already thinks that IRQs are
 	 * on (since we treat user mode as having IRQs on), and the
@@ -324,6 +332,11 @@ ENTRY(entry_SYSCALL_compat)
 	 * it is too small to ever cause noticeable irq latency.
 	 */
 	SWAPGS_UNSAFE_STACK
+
+	/* Temporary: SYSCALL32 is disabled. */
+	movl	$-ENOSYS, %eax
+	USERGS_SYSRET32
+
 	movl	%esp, %r8d
 	movq	PER_CPU_VAR(cpu_current_top_of_stack), %rsp
 	ENABLE_INTERRUPTS(CLBR_NONE)
--
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