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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D887DC10F27 for ; Tue, 10 Mar 2020 07:09:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9E52C24677 for ; Tue, 10 Mar 2020 07:09:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=atishpatra.org header.i=@atishpatra.org header.b="YLuE6SI3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726268AbgCJHJC (ORCPT ); Tue, 10 Mar 2020 03:09:02 -0400 Received: from mail-wr1-f66.google.com ([209.85.221.66]:46382 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725919AbgCJHJC (ORCPT ); Tue, 10 Mar 2020 03:09:02 -0400 Received: by mail-wr1-f66.google.com with SMTP id n15so14332911wrw.13 for ; Tue, 10 Mar 2020 00:08:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=atishpatra.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=tTCoR/CCNaXq1FOvzXwAgeXX2l2MsSCD9apFaZmeBWM=; b=YLuE6SI3gxQyzQVjsUjvP8gTTJJ1WcGl5C6N6SeNI2r8E7WOAnFx4SoSbsb5C5gqXY Er9Y5eIqAdrQm0Dsc+GN9pUzArPlxjfLbJ+eK7IjrKq8i2oBBEyV9K31sFgvKTq9UiRY 9sZ5KeSrGUdz10VndnUpGD2nHxR5IeFVLH/aNc44o/cLv57N8FxD8fXjXJZ+3CgG9fD8 TYOfTi2jon61UBv+wwNJL40ZJjMpoy+Iar11lQdmk3IXCG+jnmsX/rpjqqx15BEk9Mcy FQiNfsuyVV5EuEoCZ4R3NH6TzzfAGq3OqVH9bCf4xDJpzG8atQ0PJ6bawgMSMRqcJ9Ny fplQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=tTCoR/CCNaXq1FOvzXwAgeXX2l2MsSCD9apFaZmeBWM=; b=AjFuBr0swnQpsqDUofW1OPnpwPlGoUawGXDsAwxUTfvBFbkLES4C+2PiIZYn+5V4Ci Ik+2cx8twGskRHddUA2V6elsjeXz902q9ethfWu5kJmLMDlUuAqJgFGDcLxLB0f7TUms PNv4oeRBKER0gDbR/w4Vh/nyPDBj53QPNgVUnJ28/KQypD9veaIrWF5CKSoOQHwTr7wQ 0hHtPHcEaj4Dtj5tFdz/1khFXl9FoEEWGQ07vdNkRn+5tFqP+ZLaBlq9xnj2C8h5ePrh l75lA8CD//0h2aE+JQsGler5LlycdjhO1zO5zO1inveZqOn4u9iPBR3Xy6nXhmd6Fj1S vEQw== X-Gm-Message-State: ANhLgQ1zvUE+0iuv5US/j/DxkQWHGMh9xtRUzAKj/yHPTxGPHdby6uyQ RVlkGNGZfsp5w4ka9171Ad/n5DTzIwIY4gWyPBWl X-Google-Smtp-Source: ADFU+vs1apM0VoS4vrkx/AlvsxaJjXfeemK1n2070pj//svyZs06PXbNZkxvZNk2TF6v3cekKagzYvO9h0mSol0kzrI= X-Received: by 2002:a5d:522c:: with SMTP id i12mr5999547wra.176.1583824139112; Tue, 10 Mar 2020 00:08:59 -0700 (PDT) MIME-Version: 1.0 References: <20200226011037.7179-1-atish.patra@wdc.com> <20200226011037.7179-6-atish.patra@wdc.com> <26172d39fdb5ecd951ade0a89566c010f6166a03.camel@wdc.com> <46e9873e288134f638cd8726a2c15c9ca63860ce.camel@wdc.com> In-Reply-To: From: Atish Patra Date: Tue, 10 Mar 2020 00:08:48 -0700 Message-ID: Subject: Re: [RFC PATCH 5/5] RISC-V: Add EFI stub support. To: Ard Biesheuvel Cc: Atish Patra , "linux@armlinux.org.uk" , "abner.chang@hpe.com" , "linux-riscv@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "daniel.schaefer@hpe.com" , Anup Patel , "palmer@dabbelt.com" , "linux-efi@vger.kernel.org" , "agraf@csgraf.de" , "paul.walmsley@sifive.com" , "leif@nuviainc.com" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 27, 2020 at 10:57 PM Ard Biesheuvel wrote: > > On Fri, 28 Feb 2020 at 02:05, Atish Patra wrote: > > > > On Thu, 2020-02-27 at 20:59 +0100, Ard Biesheuvel wrote: > > > On Thu, 27 Feb 2020 at 20:53, Atish Patra > > > wrote: > > > > On Wed, 2020-02-26 at 08:28 +0100, Ard Biesheuvel wrote: > > > > > On Wed, 26 Feb 2020 at 02:10, Atish Patra > > > > > wrote: > > > > > > Add a RISC-V architecture specific stub code that actually > > > > > > copies > > > > > > the > > > > > > actual kernel image to a valid address and jump to it after > > > > > > boot > > > > > > services > > > > > > are terminated. Enable UEFI related kernel configs as well for > > > > > > RISC-V. > > > > > > > > > > > > Signed-off-by: Atish Patra > > > > > > --- > > > > > > arch/riscv/Kconfig | 20 ++++ > > > > > > arch/riscv/Makefile | 1 + > > > > > > arch/riscv/configs/defconfig | 1 + > > > > > > drivers/firmware/efi/libstub/Makefile | 8 ++ > > > > > > drivers/firmware/efi/libstub/riscv-stub.c | 135 > > > > > > ++++++++++++++++++++++ > > > > > > 5 files changed, 165 insertions(+) > > > > > > create mode 100644 drivers/firmware/efi/libstub/riscv-stub.c > > > > > > > > > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > > > > > > index 42c122170cfd..68b1d565e51d 100644 > > > > > > --- a/arch/riscv/Kconfig > > > > > > +++ b/arch/riscv/Kconfig > > > > > > @@ -372,10 +372,30 @@ config CMDLINE_FORCE > > > > > > > > > > > > endchoice > > > > > > > > > > > > +config EFI_STUB > > > > > > + bool > > > > > > + > > > > > > +config EFI > > > > > > + bool "UEFI runtime support" > > > > > > + depends on OF > > > > > > + select LIBFDT > > > > > > + select UCS2_STRING > > > > > > + select EFI_PARAMS_FROM_FDT > > > > > > + select EFI_STUB > > > > > > + select EFI_GENERIC_ARCH_STUB > > > > > > + default y > > > > > > + help > > > > > > + This option provides support for runtime services > > > > > > provided > > > > > > + by UEFI firmware (such as non-volatile variables, > > > > > > realtime > > > > > > + clock, and platform reset). A UEFI stub is also > > > > > > provided > > > > > > to > > > > > > + allow the kernel to be booted as an EFI application. > > > > > > This > > > > > > + is only useful on systems that have UEFI firmware. > > > > > > + > > > > > > endmenu > > > > > > > > > > > > menu "Power management options" > > > > > > > > > > > > source "kernel/power/Kconfig" > > > > > > +source "drivers/firmware/Kconfig" > > > > > > > > > > > > endmenu > > > > > > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile > > > > > > index b9009a2fbaf5..0afaa89ba9ad 100644 > > > > > > --- a/arch/riscv/Makefile > > > > > > +++ b/arch/riscv/Makefile > > > > > > @@ -78,6 +78,7 @@ head-y := arch/riscv/kernel/head.o > > > > > > core-y += arch/riscv/ > > > > > > > > > > > > libs-y += arch/riscv/lib/ > > > > > > +core-$(CONFIG_EFI_STUB) += > > > > > > $(objtree)/drivers/firmware/efi/libstub/lib.a > > > > > > > > > > > > PHONY += vdso_install > > > > > > vdso_install: > > > > > > diff --git a/arch/riscv/configs/defconfig > > > > > > b/arch/riscv/configs/defconfig > > > > > > index e2ff95cb3390..0a5d3578f51e 100644 > > > > > > --- a/arch/riscv/configs/defconfig > > > > > > +++ b/arch/riscv/configs/defconfig > > > > > > @@ -125,3 +125,4 @@ CONFIG_DEBUG_BLOCK_EXT_DEVT=y > > > > > > # CONFIG_FTRACE is not set > > > > > > # CONFIG_RUNTIME_TESTING_MENU is not set > > > > > > CONFIG_MEMTEST=y > > > > > > +CONFIG_EFI=y > > > > > > diff --git a/drivers/firmware/efi/libstub/Makefile > > > > > > b/drivers/firmware/efi/libstub/Makefile > > > > > > index 2c5b76787126..38facb61745b 100644 > > > > > > --- a/drivers/firmware/efi/libstub/Makefile > > > > > > +++ b/drivers/firmware/efi/libstub/Makefile > > > > > > @@ -21,6 +21,8 @@ cflags-$(CONFIG_ARM64) := > > > > > > $(subst > > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ > > > > > > cflags-$(CONFIG_ARM) := $(subst > > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ > > > > > > -fno-builtin -fpic \ > > > > > > $(call cc-option,-mno- > > > > > > single- > > > > > > pic-base) > > > > > > +cflags-$(CONFIG_RISCV) := $(subst > > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ > > > > > > + -fpic > > > > > > > > > > > > cflags-$(CONFIG_EFI_GENERIC_ARCH_STUB) += > > > > > > -I$(srctree)/scripts/dtc/libfdt > > > > > > > > > > > > @@ -55,6 +57,7 @@ lib- > > > > > > $(CONFIG_EFI_GENERIC_ARCH_STUB) += > > > > > > efi-stub.o fdt.o string.o \ > > > > > > lib-$(CONFIG_ARM) += arm32-stub.o > > > > > > lib-$(CONFIG_ARM64) += arm64-stub.o > > > > > > lib-$(CONFIG_X86) += x86-stub.o > > > > > > +lib-$(CONFIG_RISCV) += riscv-stub.o > > > > > > CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) > > > > > > CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) > > > > > > > > > > > > @@ -79,6 +82,11 @@ STUBCOPY_FLAGS-$(CONFIG_ARM64) += -- > > > > > > prefix-alloc-sections=.init \ > > > > > > --prefix-symbols=__efistub_ > > > > > > STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS > > > > > > > > > > > > +STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc- > > > > > > sections=.init \ > > > > > > + --prefix-symbols=__efistub_ > > > > > > +STUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20 > > > > > > + > > > > > > + > > > > > > $(obj)/%.stub.o: $(obj)/%.o FORCE > > > > > > $(call if_changed,stubcopy) > > > > > > > > > > > > diff --git a/drivers/firmware/efi/libstub/riscv-stub.c > > > > > > b/drivers/firmware/efi/libstub/riscv-stub.c > > > > > > new file mode 100644 > > > > > > index 000000000000..3935b29ea93a > > > > > > --- /dev/null > > > > > > +++ b/drivers/firmware/efi/libstub/riscv-stub.c > > > > > > @@ -0,0 +1,135 @@ > > > > > > +// SPDX-License-Identifier: GPL-2.0 > > > > > > +/* > > > > > > + * Copyright (C) 2013, 2014 Linaro Ltd; > > > > > > > > > > > > + * Copyright (C) 2020 Western Digital Corporation or its > > > > > > affiliates. > > > > > > + * > > > > > > + * This file implements the EFI boot stub for the RISC-V > > > > > > kernel. > > > > > > + * Adapted from ARM64 version at > > > > > > drivers/firmware/efi/libstub/arm64-stub.c. > > > > > > + */ > > > > > > + > > > > > > +#include > > > > > > +#include > > > > > > +#include > > > > > > +#include > > > > > > +#include > > > > > > + > > > > > > +#include "efistub.h" > > > > > > +/* > > > > > > + * RISCV requires the kernel image to placed TEXT_OFFSET bytes > > > > > > beyond a 2 MB > > > > > > + * aligned base for 64 bit and 4MB for 32 bit. > > > > > > + */ > > > > > > +#if IS_ENABLED(CONFIG_64BIT) > > > > > > > > > > You can use #ifdef here > > > > > > > > > > > > > ok. > > > > > > > > > > +#define MIN_KIMG_ALIGN SZ_2M > > > > > > +#else > > > > > > +#define MIN_KIMG_ALIGN SZ_4M > > > > > > +#endif > > > > > > +/* > > > > > > + * TEXT_OFFSET ensures that we don't overwrite the firmware > > > > > > that > > > > > > probably sits > > > > > > + * at the beginning of the DRAM. > > > > > > + */ > > > > > > > > > > Ugh. Really? On an EFI system, that memory should be reserved in > > > > > some > > > > > way, we shouldn't be able to stomp on it like that. > > > > > > > > > > > > > Currently, we reserve the initial 128KB for run time firmware(only > > > > openSBI for now, EDK2 later) by using PMP (physical memory > > > > protection). > > > > Any acess to that region from supervisor mode (i.e. U-Boot) will > > > > result > > > > in a fault. > > > > > > > > Is it mandatory for UEFI to reserve the beginning of the DRAM ? > > > > > > > > > > It is mandatory to describe which memory is usable and which memory > > > is > > > reserved. If this memory is not usable, you either describe it as > > > reserved, or not describe it at all. Describing it as usable memory, > > > allocating it for the kernel but with a hidden agreement that it is > > > reserved is highly likely to cause problems down the road. > > > > > > > I completely agree with you on this. We have been talking to have a > > booting guide and memory map document for RISC-V Linux to document all > > the idiosyncries of RISC-V. But that has not happend until now. > > Once, the ordered booting patches are merged, I will try to take a stab > > at it. > > > > Other than that, do we need to describe it somewhere in U-boot wrt to > > UEFI so that it doesn't allocate memory from that region ? > > > > It is an idiosyncrasy that the firmware should hide from the OS. > > What if GRUB comes along and attempts to allocate that memory? Do we > also have to teach it that the first 128 KB memory of free memory are > magic and should not be touched? > > So the answer is to mark it as reserved. This way, no UEFI tools, > bootloaders etc will ever try to use it. Sounds good to me. We are currently discussing the best approach to provide reserved memory information to U-Boot/EDK2. The idea is to U-Boot/EDK2 may have to update the DT with reserved-memory node so that Linux is aware of the reservation as well. Then, in the stub, you can > tweak the existing code to cheat a bit, and make the TEXT_OFFSET > window overlap the 128 KB reserved window at the bottom of memory. > Doing that in the stub is fine - this is part of the kernel so it can > know about crazy RISC-V rules. I am bit confused here. Why does EFI stub need to overlap the reserved memory. I thought EFI stub just needs to parse the DT to find out the reserved memory region to make sure that it doesn't try to access/overwrite that region. -- Regards, Atish 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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 84D4EC18E5A for ; Tue, 10 Mar 2020 07:09:05 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5BEB424677 for ; Tue, 10 Mar 2020 07:09:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="PaJgwpwv"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=atishpatra.org header.i=@atishpatra.org header.b="YLuE6SI3" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5BEB424677 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=atishpatra.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:To: Subject:Message-ID:Date:From:In-Reply-To:References:MIME-Version:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=tTCoR/CCNaXq1FOvzXwAgeXX2l2MsSCD9apFaZmeBWM=; b=PaJgwpwvlNwzYkVbdD7PflIU0 5SJrpkrur7IQ62dJed5k3DYtgW6N7qLwofPV/CL1qrVJVMrgz9aKE4wxHNiAE/Rwpt7DkVL17sxTG vnjTcUnVVqXjrB63H6rtNMfWSAxywvEaOzrNZBXi24C3pZTmbhXmSy6wicl1Scz0Oh6mcu97lcynk zaebFE6kPmgbxisy5tReY3hWiNDYEmj1UUM0uamEc+1KruXSqHA4TGrtmN+KqarUWHQRwBMv70HNa sXIewohKaI8mHCVnzeSytk1pXn2n/SH/XNfciMoPbvXv/RvqITOOk7mVnBo4JRszZKfGMkiW9hsNp QOUGEYadw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jBZ0i-0005oZ-6w; Tue, 10 Mar 2020 07:09:04 +0000 Received: from mail-wr1-x444.google.com ([2a00:1450:4864:20::444]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jBZ0f-0005nl-28 for linux-riscv@lists.infradead.org; Tue, 10 Mar 2020 07:09:02 +0000 Received: by mail-wr1-x444.google.com with SMTP id z15so14394370wrl.1 for ; Tue, 10 Mar 2020 00:09:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=atishpatra.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=tTCoR/CCNaXq1FOvzXwAgeXX2l2MsSCD9apFaZmeBWM=; b=YLuE6SI3gxQyzQVjsUjvP8gTTJJ1WcGl5C6N6SeNI2r8E7WOAnFx4SoSbsb5C5gqXY Er9Y5eIqAdrQm0Dsc+GN9pUzArPlxjfLbJ+eK7IjrKq8i2oBBEyV9K31sFgvKTq9UiRY 9sZ5KeSrGUdz10VndnUpGD2nHxR5IeFVLH/aNc44o/cLv57N8FxD8fXjXJZ+3CgG9fD8 TYOfTi2jon61UBv+wwNJL40ZJjMpoy+Iar11lQdmk3IXCG+jnmsX/rpjqqx15BEk9Mcy FQiNfsuyVV5EuEoCZ4R3NH6TzzfAGq3OqVH9bCf4xDJpzG8atQ0PJ6bawgMSMRqcJ9Ny fplQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=tTCoR/CCNaXq1FOvzXwAgeXX2l2MsSCD9apFaZmeBWM=; b=S/RKv80SFBq9XhL1rEeV9y4WJpKMy4fBNiawppuFyvSip3b6bztjvZenqmvQ0v8bWd 117XnZ1p0XSgleyeT++C3wm0/Bom3IwC4XuNSwYsltMXnnlsFjc75RtJbgb29EpwwiRf EsPNtK1VgYicjnK4MzYizm2pIDg7AudnTSzbi/L8Mqw5qLaD05nugpkUw87DVOs+Hvbg +fHlKWb0G+/0vHXEAKOP8GHFw9LDztJMvK9GFl363X+43toWOsdV+WvJhDs3nhL9wY3N eAkIxlv4JTLvM0rk0WNWY3cAlJDCThi3jMdH2kuFIOZ3+MqivrBjdx7gZslrzu4turuu 3k9Q== X-Gm-Message-State: ANhLgQ0XnYCJRmpB+JpwqgDzfFlEWL6G4BH1d6PqLdQdyRb7+rvvU9Mo yGVdklNEGrLcAQpwzLpChfPVyqDrYDBPOwuc5gZi X-Google-Smtp-Source: ADFU+vs1apM0VoS4vrkx/AlvsxaJjXfeemK1n2070pj//svyZs06PXbNZkxvZNk2TF6v3cekKagzYvO9h0mSol0kzrI= X-Received: by 2002:a5d:522c:: with SMTP id i12mr5999547wra.176.1583824139112; Tue, 10 Mar 2020 00:08:59 -0700 (PDT) MIME-Version: 1.0 References: <20200226011037.7179-1-atish.patra@wdc.com> <20200226011037.7179-6-atish.patra@wdc.com> <26172d39fdb5ecd951ade0a89566c010f6166a03.camel@wdc.com> <46e9873e288134f638cd8726a2c15c9ca63860ce.camel@wdc.com> In-Reply-To: From: Atish Patra Date: Tue, 10 Mar 2020 00:08:48 -0700 Message-ID: Subject: Re: [RFC PATCH 5/5] RISC-V: Add EFI stub support. To: Ard Biesheuvel Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200310_000901_106475_726F4071 X-CRM114-Status: GOOD ( 37.31 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "daniel.schaefer@hpe.com" , "linux-efi@vger.kernel.org" , "abner.chang@hpe.com" , Anup Patel , "linux@armlinux.org.uk" , "linux-kernel@vger.kernel.org" , Atish Patra , "agraf@csgraf.de" , "palmer@dabbelt.com" , "paul.walmsley@sifive.com" , "linux-riscv@lists.infradead.org" , "leif@nuviainc.com" Sender: "linux-riscv" Errors-To: linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org On Thu, Feb 27, 2020 at 10:57 PM Ard Biesheuvel wrote: > > On Fri, 28 Feb 2020 at 02:05, Atish Patra wrote: > > > > On Thu, 2020-02-27 at 20:59 +0100, Ard Biesheuvel wrote: > > > On Thu, 27 Feb 2020 at 20:53, Atish Patra > > > wrote: > > > > On Wed, 2020-02-26 at 08:28 +0100, Ard Biesheuvel wrote: > > > > > On Wed, 26 Feb 2020 at 02:10, Atish Patra > > > > > wrote: > > > > > > Add a RISC-V architecture specific stub code that actually > > > > > > copies > > > > > > the > > > > > > actual kernel image to a valid address and jump to it after > > > > > > boot > > > > > > services > > > > > > are terminated. Enable UEFI related kernel configs as well for > > > > > > RISC-V. > > > > > > > > > > > > Signed-off-by: Atish Patra > > > > > > --- > > > > > > arch/riscv/Kconfig | 20 ++++ > > > > > > arch/riscv/Makefile | 1 + > > > > > > arch/riscv/configs/defconfig | 1 + > > > > > > drivers/firmware/efi/libstub/Makefile | 8 ++ > > > > > > drivers/firmware/efi/libstub/riscv-stub.c | 135 > > > > > > ++++++++++++++++++++++ > > > > > > 5 files changed, 165 insertions(+) > > > > > > create mode 100644 drivers/firmware/efi/libstub/riscv-stub.c > > > > > > > > > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > > > > > > index 42c122170cfd..68b1d565e51d 100644 > > > > > > --- a/arch/riscv/Kconfig > > > > > > +++ b/arch/riscv/Kconfig > > > > > > @@ -372,10 +372,30 @@ config CMDLINE_FORCE > > > > > > > > > > > > endchoice > > > > > > > > > > > > +config EFI_STUB > > > > > > + bool > > > > > > + > > > > > > +config EFI > > > > > > + bool "UEFI runtime support" > > > > > > + depends on OF > > > > > > + select LIBFDT > > > > > > + select UCS2_STRING > > > > > > + select EFI_PARAMS_FROM_FDT > > > > > > + select EFI_STUB > > > > > > + select EFI_GENERIC_ARCH_STUB > > > > > > + default y > > > > > > + help > > > > > > + This option provides support for runtime services > > > > > > provided > > > > > > + by UEFI firmware (such as non-volatile variables, > > > > > > realtime > > > > > > + clock, and platform reset). A UEFI stub is also > > > > > > provided > > > > > > to > > > > > > + allow the kernel to be booted as an EFI application. > > > > > > This > > > > > > + is only useful on systems that have UEFI firmware. > > > > > > + > > > > > > endmenu > > > > > > > > > > > > menu "Power management options" > > > > > > > > > > > > source "kernel/power/Kconfig" > > > > > > +source "drivers/firmware/Kconfig" > > > > > > > > > > > > endmenu > > > > > > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile > > > > > > index b9009a2fbaf5..0afaa89ba9ad 100644 > > > > > > --- a/arch/riscv/Makefile > > > > > > +++ b/arch/riscv/Makefile > > > > > > @@ -78,6 +78,7 @@ head-y := arch/riscv/kernel/head.o > > > > > > core-y += arch/riscv/ > > > > > > > > > > > > libs-y += arch/riscv/lib/ > > > > > > +core-$(CONFIG_EFI_STUB) += > > > > > > $(objtree)/drivers/firmware/efi/libstub/lib.a > > > > > > > > > > > > PHONY += vdso_install > > > > > > vdso_install: > > > > > > diff --git a/arch/riscv/configs/defconfig > > > > > > b/arch/riscv/configs/defconfig > > > > > > index e2ff95cb3390..0a5d3578f51e 100644 > > > > > > --- a/arch/riscv/configs/defconfig > > > > > > +++ b/arch/riscv/configs/defconfig > > > > > > @@ -125,3 +125,4 @@ CONFIG_DEBUG_BLOCK_EXT_DEVT=y > > > > > > # CONFIG_FTRACE is not set > > > > > > # CONFIG_RUNTIME_TESTING_MENU is not set > > > > > > CONFIG_MEMTEST=y > > > > > > +CONFIG_EFI=y > > > > > > diff --git a/drivers/firmware/efi/libstub/Makefile > > > > > > b/drivers/firmware/efi/libstub/Makefile > > > > > > index 2c5b76787126..38facb61745b 100644 > > > > > > --- a/drivers/firmware/efi/libstub/Makefile > > > > > > +++ b/drivers/firmware/efi/libstub/Makefile > > > > > > @@ -21,6 +21,8 @@ cflags-$(CONFIG_ARM64) := > > > > > > $(subst > > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ > > > > > > cflags-$(CONFIG_ARM) := $(subst > > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ > > > > > > -fno-builtin -fpic \ > > > > > > $(call cc-option,-mno- > > > > > > single- > > > > > > pic-base) > > > > > > +cflags-$(CONFIG_RISCV) := $(subst > > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ > > > > > > + -fpic > > > > > > > > > > > > cflags-$(CONFIG_EFI_GENERIC_ARCH_STUB) += > > > > > > -I$(srctree)/scripts/dtc/libfdt > > > > > > > > > > > > @@ -55,6 +57,7 @@ lib- > > > > > > $(CONFIG_EFI_GENERIC_ARCH_STUB) += > > > > > > efi-stub.o fdt.o string.o \ > > > > > > lib-$(CONFIG_ARM) += arm32-stub.o > > > > > > lib-$(CONFIG_ARM64) += arm64-stub.o > > > > > > lib-$(CONFIG_X86) += x86-stub.o > > > > > > +lib-$(CONFIG_RISCV) += riscv-stub.o > > > > > > CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) > > > > > > CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) > > > > > > > > > > > > @@ -79,6 +82,11 @@ STUBCOPY_FLAGS-$(CONFIG_ARM64) += -- > > > > > > prefix-alloc-sections=.init \ > > > > > > --prefix-symbols=__efistub_ > > > > > > STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS > > > > > > > > > > > > +STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc- > > > > > > sections=.init \ > > > > > > + --prefix-symbols=__efistub_ > > > > > > +STUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20 > > > > > > + > > > > > > + > > > > > > $(obj)/%.stub.o: $(obj)/%.o FORCE > > > > > > $(call if_changed,stubcopy) > > > > > > > > > > > > diff --git a/drivers/firmware/efi/libstub/riscv-stub.c > > > > > > b/drivers/firmware/efi/libstub/riscv-stub.c > > > > > > new file mode 100644 > > > > > > index 000000000000..3935b29ea93a > > > > > > --- /dev/null > > > > > > +++ b/drivers/firmware/efi/libstub/riscv-stub.c > > > > > > @@ -0,0 +1,135 @@ > > > > > > +// SPDX-License-Identifier: GPL-2.0 > > > > > > +/* > > > > > > + * Copyright (C) 2013, 2014 Linaro Ltd; > > > > > > > > > > > > + * Copyright (C) 2020 Western Digital Corporation or its > > > > > > affiliates. > > > > > > + * > > > > > > + * This file implements the EFI boot stub for the RISC-V > > > > > > kernel. > > > > > > + * Adapted from ARM64 version at > > > > > > drivers/firmware/efi/libstub/arm64-stub.c. > > > > > > + */ > > > > > > + > > > > > > +#include > > > > > > +#include > > > > > > +#include > > > > > > +#include > > > > > > +#include > > > > > > + > > > > > > +#include "efistub.h" > > > > > > +/* > > > > > > + * RISCV requires the kernel image to placed TEXT_OFFSET bytes > > > > > > beyond a 2 MB > > > > > > + * aligned base for 64 bit and 4MB for 32 bit. > > > > > > + */ > > > > > > +#if IS_ENABLED(CONFIG_64BIT) > > > > > > > > > > You can use #ifdef here > > > > > > > > > > > > > ok. > > > > > > > > > > +#define MIN_KIMG_ALIGN SZ_2M > > > > > > +#else > > > > > > +#define MIN_KIMG_ALIGN SZ_4M > > > > > > +#endif > > > > > > +/* > > > > > > + * TEXT_OFFSET ensures that we don't overwrite the firmware > > > > > > that > > > > > > probably sits > > > > > > + * at the beginning of the DRAM. > > > > > > + */ > > > > > > > > > > Ugh. Really? On an EFI system, that memory should be reserved in > > > > > some > > > > > way, we shouldn't be able to stomp on it like that. > > > > > > > > > > > > > Currently, we reserve the initial 128KB for run time firmware(only > > > > openSBI for now, EDK2 later) by using PMP (physical memory > > > > protection). > > > > Any acess to that region from supervisor mode (i.e. U-Boot) will > > > > result > > > > in a fault. > > > > > > > > Is it mandatory for UEFI to reserve the beginning of the DRAM ? > > > > > > > > > > It is mandatory to describe which memory is usable and which memory > > > is > > > reserved. If this memory is not usable, you either describe it as > > > reserved, or not describe it at all. Describing it as usable memory, > > > allocating it for the kernel but with a hidden agreement that it is > > > reserved is highly likely to cause problems down the road. > > > > > > > I completely agree with you on this. We have been talking to have a > > booting guide and memory map document for RISC-V Linux to document all > > the idiosyncries of RISC-V. But that has not happend until now. > > Once, the ordered booting patches are merged, I will try to take a stab > > at it. > > > > Other than that, do we need to describe it somewhere in U-boot wrt to > > UEFI so that it doesn't allocate memory from that region ? > > > > It is an idiosyncrasy that the firmware should hide from the OS. > > What if GRUB comes along and attempts to allocate that memory? Do we > also have to teach it that the first 128 KB memory of free memory are > magic and should not be touched? > > So the answer is to mark it as reserved. This way, no UEFI tools, > bootloaders etc will ever try to use it. Sounds good to me. We are currently discussing the best approach to provide reserved memory information to U-Boot/EDK2. The idea is to U-Boot/EDK2 may have to update the DT with reserved-memory node so that Linux is aware of the reservation as well. Then, in the stub, you can > tweak the existing code to cheat a bit, and make the TEXT_OFFSET > window overlap the 128 KB reserved window at the bottom of memory. > Doing that in the stub is fine - this is part of the kernel so it can > know about crazy RISC-V rules. I am bit confused here. Why does EFI stub need to overlap the reserved memory. I thought EFI stub just needs to parse the DT to find out the reserved memory region to make sure that it doesn't try to access/overwrite that region. -- Regards, Atish