Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751499AbdILW6C (ORCPT ); Tue, 12 Sep 2017 18:58:02 -0400 Received: from vmicros1.altlinux.org ([194.107.17.57]:42354 "EHLO vmicros1.altlinux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751003AbdILW57 (ORCPT ); Tue, 12 Sep 2017 18:57:59 -0400 Date: Wed, 13 Sep 2017 01:57:57 +0300 From: "Dmitry V. Levin" To: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org Cc: Andy Lutomirski , Oleg Nesterov , Eugene Syromyatnikov , linux-kernel@vger.kernel.org Subject: [PATCH] x86/asm/64: do not clear high 32 bits of syscall number when CONFIG_X86_X32=y Message-ID: <20170912225756.GA19364@altlinux.org> Mail-Followup-To: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Andy Lutomirski , Oleg Nesterov , Eugene Syromyatnikov , linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1327 Lines: 49 Before this change, CONFIG_X86_X32=y fastpath behaviour was different from slowpath: $ gcc -xc -Wall -O2 - <<'EOF' #include #include int main(void) { unsigned long nr = ~0xffffffffUL | __NR_exit; return !!syscall(nr, 42, 1, 2, 3, 4, 5); } EOF $ ./a.out; echo \$?=$? $?=42 $ strace -enone ./a.out syscall_18446744069414584380(0x2a, 0x1, 0x2, 0x3, 0x4, 0x5) = -1 (errno 38) +++ exited with 1 +++ This change syncs CONFIG_X86_X32=y fastpath behaviour with the case when CONFIG_X86_X32 is not enabled. Fixes: fca460f95e92 ("x32: Handle the x32 system call flag") Cc: stable@vger.kernel.org Signed-off-by: Dmitry V. Levin --- arch/x86/entry/entry_64.S | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 4916725..3bab6af 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -185,12 +185,10 @@ entry_SYSCALL_64_fastpath: */ TRACE_IRQS_ON ENABLE_INTERRUPTS(CLBR_NONE) -#if __SYSCALL_MASK == ~0 - cmpq $__NR_syscall_max, %rax -#else - andl $__SYSCALL_MASK, %eax - cmpl $__NR_syscall_max, %eax +#if __SYSCALL_MASK != ~0 + andq $__SYSCALL_MASK, %rax #endif + cmpq $__NR_syscall_max, %rax ja 1f /* return -ENOSYS (already in pt_regs->ax) */ movq %r10, %rcx -- ldv