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Thu, 29 Apr 2021 06:05:53 GMT Received: from b06avi18878370.portsmouth.uk.ibm.com (b06avi18878370.portsmouth.uk.ibm.com [9.149.26.194]) by ppma03ams.nl.ibm.com with ESMTP id 384ay8j7rr-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 29 Apr 2021 06:05:53 +0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06avi18878370.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 13T65PfU36962688 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 29 Apr 2021 06:05:25 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7652EA4057; Thu, 29 Apr 2021 06:05:49 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E580CA404D; Thu, 29 Apr 2021 06:05:47 +0000 (GMT) Received: from [9.199.60.55] (unknown [9.199.60.55]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 29 Apr 2021 06:05:47 +0000 (GMT) Subject: Re: [PATCH v6] powerpc/kexec_file: use current CPU info while setting up FDT To: Tyrel Datwyler , mpe@ellerman.id.au References: <20210427045120.2109980-1-sourabhjain@linux.ibm.com> <8c3da505-f034-289a-819d-2841a5c7e580@linux.ibm.com> From: Sourabh Jain Message-ID: Date: Thu, 29 Apr 2021 11:35:46 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 In-Reply-To: <8c3da505-f034-289a-819d-2841a5c7e580@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: W9-AHAMgdtMV8HLCr99A6ioPO7n9lOnS X-Proofpoint-GUID: W9-AHAMgdtMV8HLCr99A6ioPO7n9lOnS Content-Transfer-Encoding: 7bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.761 definitions=2021-04-29_02:2021-04-28, 2021-04-29 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 mlxscore=0 phishscore=0 mlxlogscore=999 spamscore=0 lowpriorityscore=0 bulkscore=0 clxscore=1015 priorityscore=1501 suspectscore=0 adultscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104060000 definitions=main-2104290047 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mahesh@linux.vnet.ibm.com, bauerman@linux.ibm.com, hbathini@linux.ibm.com, stable@vger.kernel.org, linuxppc-dev@ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 28/04/21 6:02 am, Tyrel Datwyler wrote: > On 4/26/21 9:51 PM, Sourabh Jain wrote: >> kexec_file_load uses initial_boot_params in setting up the device-tree >> for the kernel to be loaded. Though initial_boot_params holds info >> about CPUs at the time of boot, it doesn't account for hot added CPUs. >> >> So, kexec'ing with kexec_file_load syscall would leave the kexec'ed >> kernel with inaccurate CPU info. Also, if kdump kernel is loaded with >> kexec_file_load syscall and the system crashes on a hot added CPU, >> capture kernel hangs failing to identify the boot CPU. >> >> Kernel panic - not syncing: sysrq triggered crash >> CPU: 24 PID: 6065 Comm: echo Kdump: loaded Not tainted 5.12.0-rc5upstream #54 >> Call Trace: >> [c0000000e590fac0] [c0000000007b2400] dump_stack+0xc4/0x114 (unreliable) >> [c0000000e590fb00] [c000000000145290] panic+0x16c/0x41c >> [c0000000e590fba0] [c0000000008892e0] sysrq_handle_crash+0x30/0x40 >> [c0000000e590fc00] [c000000000889cdc] __handle_sysrq+0xcc/0x1f0 >> [c0000000e590fca0] [c00000000088a538] write_sysrq_trigger+0xd8/0x178 >> [c0000000e590fce0] [c0000000005e9b7c] proc_reg_write+0x10c/0x1b0 >> [c0000000e590fd10] [c0000000004f26d0] vfs_write+0xf0/0x330 >> [c0000000e590fd60] [c0000000004f2aec] ksys_write+0x7c/0x140 >> [c0000000e590fdb0] [c000000000031ee0] system_call_exception+0x150/0x290 >> [c0000000e590fe10] [c00000000000ca5c] system_call_common+0xec/0x278 >> --- interrupt: c00 at 0x7fff905b9664 >> NIP: 00007fff905b9664 LR: 00007fff905320c4 CTR: 0000000000000000 >> REGS: c0000000e590fe80 TRAP: 0c00 Not tainted (5.12.0-rc5upstream) >> MSR: 800000000280f033 CR: 28000242 >> XER: 00000000 >> IRQMASK: 0 >> GPR00: 0000000000000004 00007ffff5fedf30 00007fff906a7300 0000000000000001 >> GPR04: 000001002a7355b0 0000000000000002 0000000000000001 00007ffff5fef616 >> GPR08: 0000000000000001 0000000000000000 0000000000000000 0000000000000000 >> GPR12: 0000000000000000 00007fff9073a160 0000000000000000 0000000000000000 >> GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> GPR20: 0000000000000000 00007fff906a4ee0 0000000000000002 0000000000000001 >> GPR24: 00007fff906a0898 0000000000000000 0000000000000002 000001002a7355b0 >> GPR28: 0000000000000002 00007fff906a1790 000001002a7355b0 0000000000000002 >> NIP [00007fff905b9664] 0x7fff905b9664 >> LR [00007fff905320c4] 0x7fff905320c4 >> --- interrupt: c00 >> >> To avoid this from happening, extract current CPU info from of_root >> device node and use it for setting up the fdt in kexec_file_load case. >> >> Fixes: 6ecd0163d360 ("powerpc/kexec_file: Add appropriate regions for memory reserve map") >> >> Signed-off-by: Sourabh Jain >> Reviewed-by: Hari Bathini >> Cc: >> --- >> arch/powerpc/kexec/file_load_64.c | 88 +++++++++++++++++++++++++++++++ >> 1 file changed, 88 insertions(+) >> >> --- >> Changelog: >> >> v1 -> v5 >> - https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-April/227950.html >> >> v5 -> v6 >> - use exiting macro (for_each_property_of_node) to loop through all >> properties of a node. >> - removed devtree_lock while accessing the node properties. >> - function name update, add_node_prop to add_node_props. >> --- >> >> diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c >> index 02b9e4d0dc40..4f7d4c10f939 100644 >> --- a/arch/powerpc/kexec/file_load_64.c >> +++ b/arch/powerpc/kexec/file_load_64.c >> @@ -960,6 +960,89 @@ unsigned int kexec_fdt_totalsize_ppc64(struct kimage *image) >> return fdt_size; >> } >> >> +/** >> + * add_node_props - Reads node properties from device node structure and add >> + * them to fdt. >> + * @fdt: Flattened device tree of the kernel >> + * @node_offset: offset of the node to add a property at >> + * @dn: device node pointer >> + * >> + * Returns 0 on success, negative errno on error. >> + */ >> +static int add_node_props(void *fdt, int node_offset, const struct device_node *dn) >> +{ >> + int ret = 0; >> + struct property *pp; >> + >> + if (!dn) >> + return -EINVAL; >> + >> + for_each_property_of_node(dn, pp) { >> + ret = fdt_setprop(fdt, node_offset, pp->name, pp->value, pp->length); >> + if (ret < 0) { >> + pr_err("Unable to add %s property: %s\n", pp->name, fdt_strerror(ret)); >> + return ret; >> + } >> + } >> + return ret; >> +} >> + >> +/** >> + * update_cpus_node - Update cpus node of flattened device tree using of_root >> + * device node. >> + * @fdt: Flattened device tree of the kernel. >> + * >> + * Returns 0 on success, negative errno on error. >> + */ >> +static int update_cpus_node(void *fdt) >> +{ >> + struct device_node *cpus_node, *dn; >> + int cpus_offset, cpus_subnode_offset, ret = 0; >> + >> + cpus_offset = fdt_path_offset(fdt, "/cpus"); >> + if (cpus_offset < 0 && cpus_offset != -FDT_ERR_NOTFOUND) { >> + pr_err("Malformed device tree: error reading /cpus node: %s\n", >> + fdt_strerror(cpus_offset)); >> + return cpus_offset; >> + } >> + >> + if (cpus_offset > 0) { >> + ret = fdt_del_node(fdt, cpus_offset); >> + if (ret < 0) { >> + pr_err("Error deleting /cpus node: %s\n", fdt_strerror(ret)); >> + return -EINVAL; >> + } >> + } >> + >> + /* Add cpus node to fdt */ >> + cpus_offset = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"), "cpus"); >> + if (cpus_offset < 0) { >> + pr_err("Error creating /cpus node: %s\n", fdt_strerror(cpus_offset)); >> + return -EINVAL; >> + } >> + >> + /* Add cpus node properties */ >> + cpus_node = of_find_node_by_path("/cpus"); > Pretty sure that of_find_node_by_path() returns a device_node with its refcount > incremented. > >> + ret = add_node_props(fdt, cpus_offset, cpus_node); > Need a of_node_put(cpus_node) here. > > Thanks for the review Tyrel. updated in v7. > > - Sourabh