From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELu7B34GSudAEpmAOizHU0aXjfd9UDmjk/ebgamWqnFGbBET38ZUnCTzE3nogmdCeQksKUoa ARC-Seal: i=1; a=rsa-sha256; t=1520955683; cv=none; d=google.com; s=arc-20160816; b=zbSJaBrwUN/d3HL+C6+fYnwH30sjZCr9LWvfF/+2T1+Hcbv8A0e8Njv1qTUbKCINzq HSF6Gtm+NB9SYwQvwvylTFCRutBPDnymW8jfB6crer801ZE0P2ZYL/rzPBBKx7qzkkn6 BtPaHPPcP08j47xqyLzsYQRzCAMRwoxgabzI0feaW67+HorioE8BA09fvfSwa9E8bJQ0 BgEKkUCiiFDWh7e1mCf2YFW6u9H+1mSiZRLTe9QTjtDIRqiw0SU+e8sFSYRIX0+TIaNS Qime1gtKbiV6657P/Efl2/kuQ1dLTN1DGfRykQN1rdp/K6KLELul7Su5nEHA9IM4YrbA f1qw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=jqf0UZ2rjG7tIDo1sszvcXpQS/cRo9IkXEQDkXfZNPs=; b=U9MUUklC7ahiKDj5UcutJHxvoYFjOPiTu+iFJT/GTKM5JZFbLAF7FPv4Cn72tz9FuW 6GVtWNtPntVQsDIRXJibG0sEuKr9E0em5BhZnOTCymLUutit0Gl+5pCRhs0ATnPdDad2 lgt4CCgnGuxfTYY1cTXvHHzfRPZROWf1abIF4pLm4GOdSo4WsTPP+Whx1KpRRueq1ygr Phz0+9g+vmieqBCLHzK5erIK16OmRGuAjLy0jHZJQ4/QKxwNBCj3XW+9gDQ/12DCF+nl 9HJC6kxs6L+ZI7CnUqTIdF5Wq6ViDO8T3w+PyUDcJwPDbfj/pL9kPVoLHTSstMt+/oEO oBfQ== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jan Beulich , Thomas Gleixner , Andy Lutomirski , Borislav Petkov , Brian Gerst , Denys Vlasenko , "H. Peter Anvin" , Josh Poimboeuf , Kees Cook , Linus Torvalds , Peter Zijlstra , Ingo Molnar Subject: [PATCH 4.14 120/140] x86/asm: Improve how GEN_*_SUFFIXED_RMWcc() specify clobbers Date: Tue, 13 Mar 2018 16:25:23 +0100 Message-Id: <20180313152506.254661547@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180313152458.201155692@linuxfoundation.org> References: <20180313152458.201155692@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1594837002793614983?= X-GMAIL-MSGID: =?utf-8?q?1594837626172424908?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jan Beulich commit 700b7c5409c3e9da279fbea78cf28a78fbc176cd upstream. Commit: df3405245a ("x86/asm: Add suffix macro for GEN_*_RMWcc()") ... introduced "suffix" RMWcc operations, adding bogus clobber specifiers: For one, on x86 there's no point explicitly clobbering "cc". In fact, with GCC properly fixed, this results in an overlap being detected by the compiler between outputs and clobbers. Furthermore it seems bad practice to me to have clobber specification and use of the clobbered register(s) disconnected - it should rather be at the invocation place of that GEN_{UN,BIN}ARY_SUFFIXED_RMWcc() macros that the clobber is specified which this particular invocation needs. Drop the "cc" clobber altogether and move the "cx" one to refcount.h. Signed-off-by: Jan Beulich Acked-by: Thomas Gleixner Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Kees Cook Cc: Linus Torvalds Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/5A8AF1F802000078001A91E1@prv-mh.provo.novell.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/refcount.h | 4 ++-- arch/x86/include/asm/rmwcc.h | 16 ++++++++-------- 2 files changed, 10 insertions(+), 10 deletions(-) --- a/arch/x86/include/asm/refcount.h +++ b/arch/x86/include/asm/refcount.h @@ -67,13 +67,13 @@ static __always_inline __must_check bool refcount_sub_and_test(unsigned int i, refcount_t *r) { GEN_BINARY_SUFFIXED_RMWcc(LOCK_PREFIX "subl", REFCOUNT_CHECK_LT_ZERO, - r->refs.counter, "er", i, "%0", e); + r->refs.counter, "er", i, "%0", e, "cx"); } static __always_inline __must_check bool refcount_dec_and_test(refcount_t *r) { GEN_UNARY_SUFFIXED_RMWcc(LOCK_PREFIX "decl", REFCOUNT_CHECK_LT_ZERO, - r->refs.counter, "%0", e); + r->refs.counter, "%0", e, "cx"); } static __always_inline __must_check --- a/arch/x86/include/asm/rmwcc.h +++ b/arch/x86/include/asm/rmwcc.h @@ -2,8 +2,7 @@ #ifndef _ASM_X86_RMWcc #define _ASM_X86_RMWcc -#define __CLOBBERS_MEM "memory" -#define __CLOBBERS_MEM_CC_CX "memory", "cc", "cx" +#define __CLOBBERS_MEM(clb...) "memory", ## clb #if !defined(__GCC_ASM_FLAG_OUTPUTS__) && defined(CC_HAVE_ASM_GOTO) @@ -40,18 +39,19 @@ do { \ #endif /* defined(__GCC_ASM_FLAG_OUTPUTS__) || !defined(CC_HAVE_ASM_GOTO) */ #define GEN_UNARY_RMWcc(op, var, arg0, cc) \ - __GEN_RMWcc(op " " arg0, var, cc, __CLOBBERS_MEM) + __GEN_RMWcc(op " " arg0, var, cc, __CLOBBERS_MEM()) -#define GEN_UNARY_SUFFIXED_RMWcc(op, suffix, var, arg0, cc) \ +#define GEN_UNARY_SUFFIXED_RMWcc(op, suffix, var, arg0, cc, clobbers...)\ __GEN_RMWcc(op " " arg0 "\n\t" suffix, var, cc, \ - __CLOBBERS_MEM_CC_CX) + __CLOBBERS_MEM(clobbers)) #define GEN_BINARY_RMWcc(op, var, vcon, val, arg0, cc) \ __GEN_RMWcc(op __BINARY_RMWcc_ARG arg0, var, cc, \ - __CLOBBERS_MEM, vcon (val)) + __CLOBBERS_MEM(), vcon (val)) -#define GEN_BINARY_SUFFIXED_RMWcc(op, suffix, var, vcon, val, arg0, cc) \ +#define GEN_BINARY_SUFFIXED_RMWcc(op, suffix, var, vcon, val, arg0, cc, \ + clobbers...) \ __GEN_RMWcc(op __BINARY_RMWcc_ARG arg0 "\n\t" suffix, var, cc, \ - __CLOBBERS_MEM_CC_CX, vcon (val)) + __CLOBBERS_MEM(clobbers), vcon (val)) #endif /* _ASM_X86_RMWcc */