From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 33B47C4332F for ; Mon, 5 Dec 2022 15:34:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232994AbiLEPeT (ORCPT ); Mon, 5 Dec 2022 10:34:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36716 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232700AbiLEPd4 (ORCPT ); Mon, 5 Dec 2022 10:33:56 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A1EF5DEA1; Mon, 5 Dec 2022 07:33:19 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 60C2DB81115; Mon, 5 Dec 2022 15:33:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 60959C433C1; Mon, 5 Dec 2022 15:33:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1670254397; bh=tzjiy+hdnVlsMz5YqQs/g6G7XYddLJKQ9a3cMaWwiFs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VOkftQm6ttXId2lm/OQ3M+JktSYRlz5Vzk/dFm8KQZ5O3PboyWaCHUyOwoBvgcwrj hD+2W3xjA3h7PjPGdfGSK3zvPPf/SGJO1DP5ySPuFzOhOCzp7vMfwFq9Y2nT1LzaPo pGfvlsC1680wFlPSAwP/3WRPnvSVnstTd9Txn8rqhgHIV8MW5Zlp4bxTzsXLqH7QYd VmFDq0ErClG5Gy0fTAdanHUpYZjLtvNLGU2+0hCvPkIM6l6fGI+671Kt/Sz8+GsLAi yWBZUGYchO6n8MZg122SgPpjoWXFxUcrELnoT+1a4pGRaAu7Zv/jdhTqcbJp+ZkunE Vy6mmaobe/xHg== Date: Mon, 5 Dec 2022 23:23:18 +0800 From: Jisheng Zhang To: Guo Ren Cc: Palmer Dabbelt , Paul Walmsley , Albert Ou , Anup Patel , Atish Patra , Heiko Stuebner , Andrew Jones , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org Subject: Re: [PATCH v2 10/13] riscv: alternative: patch alternatives in the vDSO Message-ID: References: <20221204174632.3677-1-jszhang@kernel.org> <20221204174632.3677-11-jszhang@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, Dec 05, 2022 at 09:56:37AM +0800, Guo Ren wrote: > Are there any patches that depend on it? Any existing utilization? My > first idea is to let __vdso_flush_icache use it, the standard > implementation is so heavy for user space JIT scenario, maybe vendors > could give a custom one. Hi Guo, the 11th patch of swtiching cpu_relax() to riscv_has_extension_likely() depends on this patch, the gettimeofday implementation calls cpu_relax() which may use ZIHINTPAUSE extension, so we need to patch vDSO. Thanks > > On Mon, Dec 5, 2022 at 1:57 AM Jisheng Zhang wrote: > > > > Make it possible to use alternatives in the vDSO, so that better > > implementations can be used if possible. > > > > Signed-off-by: Jisheng Zhang > > --- > > arch/riscv/include/asm/vdso.h | 4 ++++ > > arch/riscv/kernel/alternative.c | 25 +++++++++++++++++++++++++ > > arch/riscv/kernel/vdso.c | 5 ----- > > arch/riscv/kernel/vdso/vdso.lds.S | 7 +++++++ > > 4 files changed, 36 insertions(+), 5 deletions(-) > > > > diff --git a/arch/riscv/include/asm/vdso.h b/arch/riscv/include/asm/vdso.h > > index af981426fe0f..b6ff7473fb8a 100644 > > --- a/arch/riscv/include/asm/vdso.h > > +++ b/arch/riscv/include/asm/vdso.h > > @@ -28,8 +28,12 @@ > > #define COMPAT_VDSO_SYMBOL(base, name) \ > > (void __user *)((unsigned long)(base) + compat__vdso_##name##_offset) > > > > +extern char compat_vdso_start[], compat_vdso_end[]; > > + > > #endif /* CONFIG_COMPAT */ > > > > +extern char vdso_start[], vdso_end[]; > > + > > #endif /* !__ASSEMBLY__ */ > > > > #endif /* CONFIG_MMU */ > > diff --git a/arch/riscv/kernel/alternative.c b/arch/riscv/kernel/alternative.c > > index 9d88375624b5..eaf7ddaba54c 100644 > > --- a/arch/riscv/kernel/alternative.c > > +++ b/arch/riscv/kernel/alternative.c > > @@ -11,7 +11,9 @@ > > #include > > #include > > #include > > +#include > > #include > > +#include > > #include > > #include > > #include > > @@ -187,6 +189,27 @@ static void __init_or_module _apply_alternatives(struct alt_entry *begin, > > stage); > > } > > > > +static void __init apply_vdso_alternatives(void) > > +{ > > + const struct elf64_hdr *hdr; > > + const struct elf64_shdr *shdr; > > + const struct elf64_shdr *alt; > > + struct alt_entry *begin, *end; > > + > > + hdr = (struct elf64_hdr *)vdso_start; > > + shdr = (void *)hdr + hdr->e_shoff; > > + alt = find_section(hdr, shdr, ".alternative"); > > + if (!alt) > > + return; > > + > > + begin = (void *)hdr + alt->sh_offset, > > + end = (void *)hdr + alt->sh_offset + alt->sh_size, > > + > > + _apply_alternatives((struct alt_entry *)begin, > > + (struct alt_entry *)end, > > + RISCV_ALTERNATIVES_BOOT); > > +} > > + > > void __init apply_boot_alternatives(void) > > { > > /* If called on non-boot cpu things could go wrong */ > > @@ -195,6 +218,8 @@ void __init apply_boot_alternatives(void) > > _apply_alternatives((struct alt_entry *)__alt_start, > > (struct alt_entry *)__alt_end, > > RISCV_ALTERNATIVES_BOOT); > > + > > + apply_vdso_alternatives(); > > } > > > > /* > > diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c > > index 123d05255fcf..1f47bc6566cf 100644 > > --- a/arch/riscv/kernel/vdso.c > > +++ b/arch/riscv/kernel/vdso.c > > @@ -22,11 +22,6 @@ struct vdso_data { > > }; > > #endif > > > > -extern char vdso_start[], vdso_end[]; > > -#ifdef CONFIG_COMPAT > > -extern char compat_vdso_start[], compat_vdso_end[]; > > -#endif > > - > > enum vvar_pages { > > VVAR_DATA_PAGE_OFFSET, > > VVAR_TIMENS_PAGE_OFFSET, > > diff --git a/arch/riscv/kernel/vdso/vdso.lds.S b/arch/riscv/kernel/vdso/vdso.lds.S > > index 150b1a572e61..4a0606633290 100644 > > --- a/arch/riscv/kernel/vdso/vdso.lds.S > > +++ b/arch/riscv/kernel/vdso/vdso.lds.S > > @@ -40,6 +40,13 @@ SECTIONS > > . = 0x800; > > .text : { *(.text .text.*) } :text > > > > + . = ALIGN(4); > > + .alternative : { > > + __alt_start = .; > > + *(.alternative) > > + __alt_end = .; > > + } > > + > > .data : { > > *(.got.plt) *(.got) > > *(.data .data.* .gnu.linkonce.d.*) > > -- > > 2.37.2 > > > > > -- > Best Regards > Guo Ren