linux-kernel - [tip:x86/asm] x86/asm/entry/64: Simplify jumps in ret_from

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <tip-66ad4efa51805964521db03d8aa827a8dd9058b9@git.kernel.org>
Date:	Thu, 9 Apr 2015 02:03:29 -0700
From:	tip-bot for Denys Vlasenko <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	wad@...omium.org, ast@...mgrid.com, mingo@...nel.org,
	linux-kernel@...r.kernel.org, hpa@...or.com, luto@...capital.net,
	torvalds@...ux-foundation.org, dvlasenk@...hat.com,
	keescook@...omium.org, brgerst@...il.com, fweisbec@...il.com,
	oleg@...hat.com, rostedt@...dmis.org, bp@...en8.de,
	tglx@...utronix.de
Subject: [tip:x86/asm] x86/asm/entry/64: Simplify jumps in ret_from_fork

Commit-ID:  66ad4efa51805964521db03d8aa827a8dd9058b9
Gitweb:     http://git.kernel.org/tip/66ad4efa51805964521db03d8aa827a8dd9058b9
Author:     Denys Vlasenko <dvlasenk@...hat.com>
AuthorDate: Tue, 7 Apr 2015 22:43:42 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 9 Apr 2015 10:31:25 +0200

x86/asm/entry/64: Simplify jumps in ret_from_fork

Replace
        test
        jz  1f
        jmp label
    1:

with
        test
        jnz label

Run-tested.

Signed-off-by: Denys Vlasenko <dvlasenk@...hat.com>
Cc: Alexei Starovoitov <ast@...mgrid.com>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Will Drewry <wad@...omium.org>
Link: http://lkml.kernel.org/r/1428439424-7258-6-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.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 e8ddd51..a35e5e4 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -608,18 +608,18 @@ 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 kernel_thread */
+	/* nb: we depend on RESTORE_EXTRA_REGS above */
 	movq %rbp, %rdi
 	call *%rbx
 	movl $0, RAX(%rsp)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/