From: Denys Vlasenko <dvlasenk@redhat.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Denys Vlasenko <dvlasenk@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Steven Rostedt <rostedt@goodmis.org>,
Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@amacapital.net>,
Oleg Nesterov <oleg@redhat.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Alexei Starovoitov <ast@plumgrid.com>,
Will Drewry <wad@chromium.org>, Kees Cook <keescook@chromium.org>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 8/9] x86/asm/entry/64: simplify jumps in ret_from_fork
Date: Thu, 2 Apr 2015 16:36:17 +0200 [thread overview]
Message-ID: <1427985378-4287-8-git-send-email-dvlasenk@redhat.com> (raw)
In-Reply-To: <1427985378-4287-1-git-send-email-dvlasenk@redhat.com>
Replace
test
jz 1f
jmp label
1:
with
test
jnz label
Run-tested.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
CC: Linus Torvalds <torvalds@linux-foundation.org>
CC: Steven Rostedt <rostedt@goodmis.org>
CC: Ingo Molnar <mingo@kernel.org>
CC: Borislav Petkov <bp@alien8.de>
CC: "H. Peter Anvin" <hpa@zytor.com>
CC: Andy Lutomirski <luto@amacapital.net>
CC: Oleg Nesterov <oleg@redhat.com>
CC: Frederic Weisbecker <fweisbec@gmail.com>
CC: Alexei Starovoitov <ast@plumgrid.com>
CC: Will Drewry <wad@chromium.org>
CC: Kees Cook <keescook@chromium.org>
CC: x86@kernel.org
CC: linux-kernel@vger.kernel.org
---
arch/x86/kernel/entry_64.S | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 36a360a..0124f6f 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -512,18 +512,18 @@ ENTRY(ret_from_fork)
RESTORE_EXTRA_REGS
testl $3,CS(%rsp) # from kernel_thread?
- jz 1f
/*
* By the time we get here, we have no idea whether our pt_regs,
* ti flags, and ti status came from the 64-bit SYSCALL fast path,
* the slow path, or one of the ia32entry paths.
- * Use int_ret_from_sys_call to return, since it can safely handle
+ * Use IRET code path to return, since it can safely handle
* all of the above.
*/
- jmp int_ret_from_sys_call
+ jnz int_ret_from_sys_call
-1:
+ /* We came from from kernel_thread */
+ /* nb: we depend on RESTORE_EXTRA_REGS above */
movq %rbp, %rdi
call *%rbx
xorl %eax, %eax
--
1.8.1.4
next prev parent reply other threads:[~2015-04-02 14:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-02 14:36 [PATCH 1/9] x86/asm/entry/64: reuse stub return code Denys Vlasenko
2015-04-02 14:36 ` [PATCH 2/9] x86/asm/entry/64: optimize [v]fork/clone stubs Denys Vlasenko
2015-04-02 14:36 ` [PATCH 3/9] x86/asm/entry/64: do not SAVE_EXTRA_REGS in stub_sigreturn Denys Vlasenko
2015-04-02 15:01 ` Brian Gerst
2015-04-02 15:20 ` Denys Vlasenko
2015-04-02 19:10 ` Brian Gerst
2015-04-02 19:40 ` Denys Vlasenko
2015-04-02 19:40 ` Andy Lutomirski
2015-04-02 14:36 ` [PATCH 4/9] x86/asm/entry/64: delay popping return address in stubs Denys Vlasenko
2015-04-02 14:36 ` [PATCH 5/9] x86/asm/entry/64: if execve fails, no need to use IRET return Denys Vlasenko
2015-04-02 14:36 ` [PATCH 6/9] x86/asm/entry/64: reuse stub epilogue by ret_from_fork Denys Vlasenko
2015-04-02 14:36 ` [PATCH 7/9] x86/asm/entry/64: remove a redundant jump Denys Vlasenko
2015-04-02 14:36 ` Denys Vlasenko [this message]
2015-04-02 14:36 ` [PATCH 9/9] x86/asm/entry/64: Remove GET_THREAD_INFO in ret_from_fork Denys Vlasenko
2015-04-02 19:02 ` Andy Lutomirski
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