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Fri, 12 Feb 2021 01:09:27 GMT Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 668D5AE062; Fri, 12 Feb 2021 01:09:27 +0000 (GMT) Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 44AA1AE05C; Fri, 12 Feb 2021 01:09:20 +0000 (GMT) Received: from manicouagan.localdomain (unknown [9.85.204.73]) by b01ledav005.gho.pok.ibm.com (Postfix) with ESMTPS; Fri, 12 Feb 2021 01:09:20 +0000 (GMT) References: <20210209182200.30606-1-nramas@linux.microsoft.com> <20210209182200.30606-3-nramas@linux.microsoft.com> User-agent: mu4e 1.4.10; emacs 27.1 From: Thiago Jung Bauermann To: Lakshmi Ramasubramanian Subject: Re: [PATCH v17 02/10] of: Add a common kexec FDT setup function In-reply-to: <20210209182200.30606-3-nramas@linux.microsoft.com> Date: Thu, 11 Feb 2021 22:09:18 -0300 Message-ID: <87k0reozwh.fsf@manicouagan.localdomain> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369, 18.0.737 definitions=2021-02-11_07:2021-02-11, 2021-02-11 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 suspectscore=0 priorityscore=1501 malwarescore=0 spamscore=0 adultscore=0 bulkscore=0 mlxscore=0 lowpriorityscore=0 clxscore=1015 phishscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102120002 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210211_200955_065431_F977B89E X-CRM114-Status: GOOD ( 36.36 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, benh@kernel.crashing.org, tao.li@vivo.com, zohar@linux.ibm.com, paulus@samba.org, vincenzo.frascino@arm.com, frowand.list@gmail.com, sashal@kernel.org, robh@kernel.org, mpe@ellerman.id.au, masahiroy@kernel.org, jmorris@namei.org, takahiro.akashi@linaro.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, serge@hallyn.com, devicetree@vger.kernel.org, pasha.tatashin@soleen.com, will@kernel.org, prsriva@linux.microsoft.com, hsinyi@chromium.org, allison@lohutok.net, christophe.leroy@c-s.fr, mbrugger@suse.com, balajib@linux.microsoft.com, dmitry.kasatkin@gmail.com, linux-kernel@vger.kernel.org, james.morse@arm.com, gregkh@linuxfoundation.org, joe@perches.com, linux-integrity@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org There's actually a complication that I just noticed and needs to be addressed. More below. Lakshmi Ramasubramanian writes: > From: Rob Herring > > Both arm64 and powerpc do essentially the same FDT /chosen setup for > kexec. The differences are either omissions that arm64 should have > or additional properties that will be ignored. The setup code can be > combined and shared by both powerpc and arm64. > > The differences relative to the arm64 version: > - If /chosen doesn't exist, it will be created (should never happen). > - Any old dtb and initrd reserved memory will be released. > - The new initrd and elfcorehdr are marked reserved. > - "linux,booted-from-kexec" is set. > > The differences relative to the powerpc version: > - "kaslr-seed" and "rng-seed" may be set. > - "linux,elfcorehdr" is set. > - Any existing "linux,usable-memory-range" is removed. > > Combine the code for setting up the /chosen node in the FDT and updating > the memory reservation for kexec, for powerpc and arm64, in > of_kexec_alloc_and_setup_fdt() and move it to "drivers/of/kexec.c". > > Signed-off-by: Rob Herring > Signed-off-by: Lakshmi Ramasubramanian > --- > drivers/of/Makefile | 6 ++ > drivers/of/kexec.c | 258 ++++++++++++++++++++++++++++++++++++++++++++ > include/linux/of.h | 13 +++ > 3 files changed, 277 insertions(+) > create mode 100644 drivers/of/kexec.c > > diff --git a/drivers/of/Makefile b/drivers/of/Makefile > index 6e1e5212f058..c13b982084a3 100644 > --- a/drivers/of/Makefile > +++ b/drivers/of/Makefile > @@ -14,4 +14,10 @@ obj-$(CONFIG_OF_RESOLVE) += resolver.o > obj-$(CONFIG_OF_OVERLAY) += overlay.o > obj-$(CONFIG_OF_NUMA) += of_numa.o > > +ifdef CONFIG_KEXEC_FILE > +ifdef CONFIG_OF_FLATTREE > +obj-y += kexec.o > +endif > +endif > + > obj-$(CONFIG_OF_UNITTEST) += unittest-data/ > diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c > new file mode 100644 > index 000000000000..469e09613cdd > --- /dev/null > +++ b/drivers/of/kexec.c > @@ -0,0 +1,258 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Copyright (C) 2020 Arm Limited > + * > + * Based on arch/arm64/kernel/machine_kexec_file.c: > + * Copyright (C) 2018 Linaro Limited > + * > + * And arch/powerpc/kexec/file_load.c: > + * Copyright (C) 2016 IBM Corporation > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +/* relevant device tree properties */ > +#define FDT_PROP_KEXEC_ELFHDR "linux,elfcorehdr" > +#define FDT_PROP_MEM_RANGE "linux,usable-memory-range" > +#define FDT_PROP_INITRD_START "linux,initrd-start" > +#define FDT_PROP_INITRD_END "linux,initrd-end" > +#define FDT_PROP_BOOTARGS "bootargs" > +#define FDT_PROP_KASLR_SEED "kaslr-seed" > +#define FDT_PROP_RNG_SEED "rng-seed" > +#define RNG_SEED_SIZE 128 > + > +/** > + * fdt_find_and_del_mem_rsv - delete memory reservation with given address and size > + * > + * @fdt: Flattened device tree for the current kernel. > + * @start: Starting address of the reserved memory. > + * @size: Size of the reserved memory. > + * > + * Return: 0 on success, or negative errno on error. > + */ > +static int fdt_find_and_del_mem_rsv(void *fdt, unsigned long start, unsigned long size) > +{ > + int i, ret, num_rsvs = fdt_num_mem_rsv(fdt); > + > + for (i = 0; i < num_rsvs; i++) { > + u64 rsv_start, rsv_size; > + > + ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size); > + if (ret) { > + pr_err("Malformed device tree.\n"); > + return -EINVAL; > + } > + > + if (rsv_start == start && rsv_size == size) { > + ret = fdt_del_mem_rsv(fdt, i); > + if (ret) { > + pr_err("Error deleting device tree reservation.\n"); > + return -EINVAL; > + } > + > + return 0; > + } > + } > + > + return -ENOENT; > +} > + > +/* > + * of_kexec_alloc_and_setup_fdt - Alloc and setup a new Flattened Device Tree > + * > + * @image: kexec image being loaded. > + * @initrd_load_addr: Address where the next initrd will be loaded. > + * @initrd_len: Size of the next initrd, or 0 if there will be none. > + * @cmdline: Command line for the next kernel, or NULL if there will > + * be none. > + * > + * Return: fdt on success, or NULL errno on error. > + */ > +void *of_kexec_alloc_and_setup_fdt(const struct kimage *image, > + unsigned long initrd_load_addr, > + unsigned long initrd_len, > + const char *cmdline) > +{ > + void *fdt; > + int ret, chosen_node; > + const void *prop; > + unsigned long fdt_size; > + > + fdt_size = fdt_totalsize(initial_boot_params) + > + (cmdline ? strlen(cmdline) : 0) + > + FDT_EXTRA_SPACE; Just adding 4 KB to initial_boot_params won't be enough for crash kernels on ppc64. The current powerpc code doubles the size of initial_boot_params (which is normally larger than 4 KB) and even that isn't enough. A patch was added to powerpc/next today which uses a more precise (but arch-specific) formula: https://lore.kernel.org/linuxppc-dev/161243826811.119001.14083048209224609814.stgit@hbathini/ So I believe we need a hook here where architectures can provide their own specific calculation for the size of the fdt. Perhaps a weakly defined function providing a default implementation which an arch-specific file can override (a la arch_kexec_kernel_image_load())? Then the powerpc specific hook would be the kexec_fdt_totalsize_ppc64() function from the patch I linked above. -- Thiago Jung Bauermann IBM Linux Technology Center _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel