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From: Andy Lutomirski <luto@kernel.org>
To: x86@kernel.org, linux-kernel@vger.kernel.org
Cc: "Frédéric Weisbecker" <fweisbec@gmail.com>,
	"Rik van Riel" <riel@redhat.com>,
	"Oleg Nesterov" <oleg@redhat.com>,
	"Denys Vlasenko" <vda.linux@googlemail.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"Kees Cook" <keescook@chromium.org>,
	"Brian Gerst" <brgerst@gmail.com>,
	"Andy Lutomirski" <luto@kernel.org>
Subject: [RFC/INCOMPLETE 07/13] x86/entry/64: Really create an error-entry-from-usermode code path
Date: Tue, 16 Jun 2015 13:16:53 -0700	[thread overview]
Message-ID: <9789d956587eb3d1746467d56ba1dce11b49fa30.1434485184.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1434485184.git.luto@kernel.org>
In-Reply-To: <cover.1434485184.git.luto@kernel.org>

In 539f51136500 ("x86/asm/entry/64: Disentangle error_entry/exit
gsbase/ebx/usermode code"), I arranged the code slightly wrong --
IRET faults would skip the code path that was intended to execute on
all error entries from user mode.  Fix it up.

This does not fix a bug, but we'll need it, and it slightly shrinks
the code.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 arch/x86/entry/entry_64.S | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 3bb2c4302df1..33acc3dcc281 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1145,7 +1145,11 @@ ENTRY(error_entry)
 	testb	$3, CS+8(%rsp)
 	jz	error_kernelspace
 
-	/* We entered from user mode */
+error_entry_from_usermode:
+	/*
+	 * We entered from user mode or we're pretending to have entered
+	 * from user mode due to an IRET fault.
+	 */
 	SWAPGS
 
 error_entry_done:
@@ -1174,8 +1178,7 @@ error_kernelspace:
 	 * gsbase and proceed.  We'll fix up the exception and land in
 	 * gs_change's error handler with kernel gsbase.
 	 */
-	SWAPGS
-	jmp	error_entry_done
+	jmp	error_entry_from_usermode
 
 bstep_iret:
 	/* Fix truncated RIP */
-- 
2.4.3


  parent reply	other threads:[~2015-06-16 20:18 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-16 20:16 [RFC/INCOMPLETE 00/13] x86: Rewrite exit-to-userspace code Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 01/13] context_tracking: Add context_tracking_assert_state Andy Lutomirski
2015-06-17  9:41   ` Ingo Molnar
2015-06-17 14:15     ` Andy Lutomirski
2015-06-18  9:57       ` Ingo Molnar
2015-06-18 11:07         ` Andy Lutomirski
2015-06-18 15:52           ` Andy Lutomirski
2015-06-18 16:17             ` Ingo Molnar
2015-06-18 16:26               ` Frederic Weisbecker
2015-06-18 19:26                 ` Andy Lutomirski
2015-06-17 15:27     ` Paul E. McKenney
2015-06-18  9:59       ` Ingo Molnar
2015-06-18 22:54         ` Paul E. McKenney
2015-06-19  2:19           ` Paul E. McKenney
2015-06-30 11:04           ` Ingo Molnar
2015-06-30 16:16             ` Paul E. McKenney
2015-06-16 20:16 ` [RFC/INCOMPLETE 02/13] notifiers: Assert that RCU is watching in notify_die Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 03/13] x86: Move C entry and exit code to arch/x86/entry/common.c Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 04/13] x86/traps: Assert that we're in CONTEXT_KERNEL in exception entries Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 05/13] x86/entry: Add enter_from_user_mode and use it in syscalls Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 06/13] x86/entry: Add new, comprehensible entry and exit hooks Andy Lutomirski
2015-06-16 20:16 ` Andy Lutomirski [this message]
2015-06-16 20:16 ` [RFC/INCOMPLETE 08/13] x86/entry/64: Migrate 64-bit syscalls to new " Andy Lutomirski
2015-06-17 10:00   ` Ingo Molnar
2015-06-17 10:02     ` Ingo Molnar
2015-06-17 14:12       ` Andy Lutomirski
2015-06-18 10:17         ` Ingo Molnar
2015-06-18 10:19           ` Ingo Molnar
2015-06-16 20:16 ` [RFC/INCOMPLETE 09/13] x86/entry/compat: Migrate compat " Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 10/13] x86/asm/entry/64: Save all regs on interrupt entry Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 11/13] x86/asm/entry/64: Simplify irq stack pt_regs handling Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 12/13] x86/asm/entry/64: Migrate error and interrupt exit work to C Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 13/13] x86/entry: Remove SCHEDULE_USER and asm/context-tracking.h Andy Lutomirski
2015-06-17  9:48 ` [RFC/INCOMPLETE 00/13] x86: Rewrite exit-to-userspace code Ingo Molnar
2015-06-17 10:13   ` Richard Weinberger
2015-06-17 11:04     ` Ingo Molnar
2015-06-17 14:19     ` Andy Lutomirski
2015-06-17 15:16   ` Andy Lutomirski
2015-06-18 10:14     ` Ingo Molnar
2015-06-17 10:32 ` Ingo Molnar
2015-06-17 11:14   ` Ingo Molnar
2015-06-17 14:23   ` Andy Lutomirski
2015-06-18 10:11     ` Ingo Molnar
2015-06-18 11:06       ` Andy Lutomirski
2015-06-18 16:24         ` Ingo Molnar

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