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h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Ik1PM2pUOLDwsjM0pqh49zNwLFsJWsVvCOj193iIxEYzWbmWmPkLOpNjbPdzrjX3v 011IuXpNubhbptoPBokYY/dElyxPQHBCRBjU3Lulkb2yxO4epZ6XSk5+/VuLkmyTKm 0Ud2Zan/4XorBw9nLxr1az3pZ8UdL1JipoDA4C6q89BQQ1lor7RIvGuJ3g6OnfiFiz CnEXvlTclGzLsYNkl8D2WwBsbJipZUTOsHbneDfOJuaejckEKDSBWeybOIBPjijOO0 KGDNLUtdX+eqbIB7ygYhUbhkhUiAb06+5ytRj+5jyUF4CBn/8fUyg6Mi66qsYtwZ4H VoszEMjA20uGw== Message-ID: <2cbb468c-188e-4e6b-9b17-b60a66208c7a@zytor.com> Date: Fri, 2 May 2025 11:09:29 -0700 Precedence: bulk X-Mailing-List: linux-edac@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 02/15] x86/msr: Move rdtsc{,_ordered}() to To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-hyperv@vger.kernel.org, virtualization@lists.linux.dev, linux-pm@vger.kernel.org, linux-edac@vger.kernel.org, xen-devel@lists.xenproject.org, linux-acpi@vger.kernel.org, linux-hwmon@vger.kernel.org, netdev@vger.kernel.org, platform-driver-x86@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, acme@kernel.org, jgross@suse.com, andrew.cooper3@citrix.com, peterz@infradead.org, namhyung@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, kan.liang@linux.intel.com, wei.liu@kernel.org, ajay.kaher@broadcom.com, bcm-kernel-feedback-list@broadcom.com, tony.luck@intel.com, pbonzini@redhat.com, vkuznets@redhat.com, seanjc@google.com, luto@kernel.org, boris.ostrovsky@oracle.com, kys@microsoft.com, haiyangz@microsoft.com, decui@microsoft.com, dapeng1.mi@linux.intel.com, ilpo.jarvinen@linux.intel.com References: <20250427092027.1598740-1-xin@zytor.com> <20250427092027.1598740-3-xin@zytor.com> Content-Language: en-US From: Xin Li Autocrypt: addr=xin@zytor.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 5/2/2025 1:02 AM, Ingo Molnar wrote: > > * Xin Li (Intel) wrote: > >> index 94408a784c8e..13335a130edf 100644 >> --- a/arch/x86/include/asm/tsc.h >> +++ b/arch/x86/include/asm/tsc.h >> @@ -7,7 +7,81 @@ >> >> #include >> #include >> -#include >> + >> +/* >> + * both i386 and x86_64 returns 64-bit value in edx:eax, but gcc's "A" >> + * constraint has different meanings. For i386, "A" means exactly >> + * edx:eax, while for x86_64 it doesn't mean rdx:rax or edx:eax. Instead, >> + * it means rax *or* rdx. >> + */ >> +#ifdef CONFIG_X86_64 >> +/* Using 64-bit values saves one instruction clearing the high half of low */ >> +#define DECLARE_ARGS(val, low, high) unsigned long low, high >> +#define EAX_EDX_VAL(val, low, high) ((low) | (high) << 32) >> +#define EAX_EDX_RET(val, low, high) "=a" (low), "=d" (high) >> +#else >> +#define DECLARE_ARGS(val, low, high) u64 val >> +#define EAX_EDX_VAL(val, low, high) (val) >> +#define EAX_EDX_RET(val, low, high) "=A" (val) >> +#endif > > Meh, this patch creates a duplicate copy of DECLARE_ARGS() et al in > now: > > arch/x86/include/asm/msr.h:#define DECLARE_ARGS(val, low, high) unsigned long low, high > arch/x86/include/asm/msr.h:#define DECLARE_ARGS(val, low, high) u64 val > arch/x86/include/asm/msr.h: DECLARE_ARGS(val, low, high); > arch/x86/include/asm/msr.h: DECLARE_ARGS(val, low, high); > arch/x86/include/asm/msr.h: DECLARE_ARGS(val, low, high); > arch/x86/include/asm/tsc.h:#define DECLARE_ARGS(val, low, high) unsigned long low, high > arch/x86/include/asm/tsc.h:#define DECLARE_ARGS(val, low, high) u64 val > arch/x86/include/asm/tsc.h: DECLARE_ARGS(val, low, high); > arch/x86/include/asm/tsc.h: DECLARE_ARGS(val, low, high); > arch/x86/include/asm/tsc.h:#undef DECLARE_ARGS > > Which was both an undeclared change, bloats the code, causes various > problems, and is totally unnecessary to boot. > > Please don't do that ... Learned! Especially that every change needs to explicitly called out.