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>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Andy Lutomirski" <luto@kernel.org>,
"Al Viro" <viro@zeniv.linux.org.uk>
Subject: [RFC/PATCH v2 v2 4/6] x86/entry/32: Remove unnecessary asm check for returns to kernel mode
Date: Thu, 9 Jul 2015 19:17:32 -0700 [thread overview]
Message-ID: <f4f033fb018e5ca8c77eae90a9abdfc3f793ca42.1436492057.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1436492057.git.luto@kernel.org>
In-Reply-To: <cover.1436492057.git.luto@kernel.org>
Unless I missed something, 44fbbb3dc687c ("x86: get rid of calling
do_notify_resume() when returning to kernel mode") was unnecessarily
paranoid. It split the exit path into resume_userspace and
resume_kernel, after which it was no longer possible to get to
work_notifysig when returning to kernel mode. The check for kernel
mode in work_notifysig is superfluous. Remove it.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/entry/entry_32.S | 4 ----
1 file changed, 4 deletions(-)
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index a36d5df6a749..66ff9c4055d7 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -491,10 +491,6 @@ work_notifysig: # deal with pending signals and
#endif
TRACE_IRQS_ON
ENABLE_INTERRUPTS(CLBR_NONE)
- movb PT_CS(%esp), %bl
- andb $SEGMENT_RPL_MASK, %bl
- cmpb $USER_RPL, %bl
- jb resume_kernel
xorl %edx, %edx
call do_notify_resume
jmp resume_userspace
--
2.4.3
next prev parent reply other threads:[~2015-07-10 2:18 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-10 2:17 [RFC/PATCH v2 v2 0/6] x86_32: Migrate to new entry/exit paths Andy Lutomirski
2015-07-10 2:17 ` [RFC/PATCH v2 v2 1/6] x86/selftests, x86/vm86: Improve entry_from_vm86 selftest Andy Lutomirski
2015-07-13 19:33 ` Andy Lutomirski
2015-07-21 9:44 ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2015-07-10 2:17 ` [RFC/PATCH v2 v2 2/6] x86/entry/32: Remove 32-bit syscall audit optimizations Andy Lutomirski
2015-07-10 2:17 ` [RFC/PATCH v2 v2 3/6] x86/entry/32: Fix an incorrect comment for work_notifysig_v86 Andy Lutomirski
2015-07-10 2:17 ` Andy Lutomirski [this message]
2015-07-10 2:17 ` [RFC/PATCH v2 v2 5/6] x86/entry/32: Migrate to C exit path and rework vm86 exit hack Andy Lutomirski
2015-07-10 2:17 ` [RFC/PATCH v2 v2 6/6] x86/entry: Remove do_notify_resume, syscall_trace_leave, and their TIF masks Andy Lutomirski
2015-07-10 14:45 ` [RFC/PATCH v2 v2 0/6] x86_32: Migrate to new entry/exit paths Brian Gerst
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