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[82.11.253.99]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4587054e37dsm20889375e9.14.2025.07.24.06.56.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Jul 2025 06:56:48 -0700 (PDT) From: Eugen Hristev To: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, tglx@linutronix.de, andersson@kernel.org, pmladek@suse.com Cc: linux-arm-kernel@lists.infradead.org, linux-hardening@vger.kernel.org, eugen.hristev@linaro.org, corbet@lwn.net, mojha@qti.qualcomm.com, rostedt@goodmis.org, jonechou@google.com, tudor.ambarus@linaro.org Subject: [RFC][PATCH v2 29/29] kmemdump: Add Kinfo backend driver Date: Thu, 24 Jul 2025 16:55:12 +0300 Message-ID: <20250724135512.518487-30-eugen.hristev@linaro.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250724135512.518487-1-eugen.hristev@linaro.org> References: <20250724135512.518487-1-eugen.hristev@linaro.org> Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add Kinfo backend driver. This backend driver will select only regions of interest for the firmware, and it copy those into a shared memory area that is supplied via OF. The firmware is only interested in addresses for some symbols. The list format is kinfo-compatible, with devices like Google Pixel phone. Based on original work from Jone Chou Signed-off-by: Eugen Hristev --- As stated in the cover letter I did not test this on a device as I do not have one. Testing is appreciated and feedback welcome ! This kinfo backend is how we envision it to look like, while preserving compatibility with existing devices and firmware. Yes I also know the compatible is not documented. But if we want to have this driver in the kernel, I can easily add one MAINTAINERS | 5 + drivers/debug/Kconfig | 13 ++ drivers/debug/Makefile | 1 + drivers/debug/kinfo.c | 304 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 323 insertions(+) create mode 100644 drivers/debug/kinfo.c diff --git a/MAINTAINERS b/MAINTAINERS index 68797717175c..bc605480d6e8 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -13625,6 +13625,11 @@ F: drivers/debug/kmemdump.c F: drivers/debug/kmemdump_coreimage.c F: include/linux/kmemdump.h +KMEMDUMP KINFO BACKEND DRIVER +M: Eugen Hristev +S: Maintained +F: drivers/debug/kinfo.c + KMEMDUMP QCOM MINIDUMP BACKEND DRIVER M: Eugen Hristev S: Maintained diff --git a/drivers/debug/Kconfig b/drivers/debug/Kconfig index d34ceaf99bd8..1a44990c2824 100644 --- a/drivers/debug/Kconfig +++ b/drivers/debug/Kconfig @@ -39,4 +39,17 @@ config KMEMDUMP_QCOM_MINIDUMP_BACKEND into the minidump table of contents. Further on, the firmware will be able to read the table of contents and extract the memory regions on case-by-case basis. + +config KMEMDUMP_KINFO_BACKEND + tristate "Shared memory KInfo compatible backend" + depends on KMEMDUMP + help + Say y here to enable the Shared memory KInfo compatible backend + driver. + With this backend, the registered regions are copied to a shared + memory zone at register time. + The shared memory zone is supplied via OF. + This backend will select only regions that are of interest, + and keep only addresses. The format of the list is Kinfo compatible. + endmenu diff --git a/drivers/debug/Makefile b/drivers/debug/Makefile index 7f70b84049cb..861f2e2c4fe2 100644 --- a/drivers/debug/Makefile +++ b/drivers/debug/Makefile @@ -3,3 +3,4 @@ obj-$(CONFIG_KMEMDUMP) += kmemdump.o obj-$(CONFIG_KMEMDUMP_COREIMAGE) += kmemdump_coreimage.o obj-$(CONFIG_KMEMDUMP_QCOM_MINIDUMP_BACKEND) += qcom_minidump.o +obj-$(CONFIG_KMEMDUMP_KINFO_BACKEND) += kinfo.o diff --git a/drivers/debug/kinfo.c b/drivers/debug/kinfo.c new file mode 100644 index 000000000000..bdf50254fa92 --- /dev/null +++ b/drivers/debug/kinfo.c @@ -0,0 +1,304 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define BUILD_INFO_LEN 256 +#define DEBUG_KINFO_MAGIC 0xCCEEDDFF + +/* + * Header structure must be byte-packed, since the table is provided to + * bootloader. + */ +struct kernel_info { + /* For kallsyms */ + __u8 enabled_all; + __u8 enabled_base_relative; + __u8 enabled_absolute_percpu; + __u8 enabled_cfi_clang; + __u32 num_syms; + __u16 name_len; + __u16 bit_per_long; + __u16 module_name_len; + __u16 symbol_len; + __u64 _relative_pa; + __u64 _text_pa; + __u64 _stext_pa; + __u64 _etext_pa; + __u64 _sinittext_pa; + __u64 _einittext_pa; + __u64 _end_pa; + __u64 _offsets_pa; + __u64 _names_pa; + __u64 _token_table_pa; + __u64 _token_index_pa; + __u64 _markers_pa; + __u64 _seqs_of_names_pa; + + /* For frame pointer */ + __u32 thread_size; + + /* For virt_to_phys */ + __u64 swapper_pg_dir_pa; + + /* For linux banner */ + __u8 last_uts_release[__NEW_UTS_LEN]; + + /* Info of running build */ + __u8 build_info[BUILD_INFO_LEN]; + + /* For module kallsyms */ + __u32 enabled_modules_tree_lookup; + __u32 mod_mem_offset; + __u32 mod_kallsyms_offset; +} __packed; + +struct kernel_all_info { + __u32 magic_number; + __u32 combined_checksum; + struct kernel_info info; +} __packed; + +struct debug_kinfo { + struct device *dev; + void *all_info_addr; + u32 all_info_size; + struct kmemdump_backend kinfo_be; +}; + +static struct debug_kinfo *kinfo; + +#define be_to_kinfo(be) container_of(be, struct debug_kinfo, kinfo_be) + +static void update_kernel_all_info(struct kernel_all_info *all_info) +{ + int index; + struct kernel_info *info; + u32 *checksum_info; + + all_info->magic_number = DEBUG_KINFO_MAGIC; + all_info->combined_checksum = 0; + + info = &all_info->info; + checksum_info = (u32 *)info; + for (index = 0; index < sizeof(*info) / sizeof(u32); index++) + all_info->combined_checksum ^= checksum_info[index]; +} + +static int build_info_set(const char *str, const struct kernel_param *kp) +{ + struct kernel_all_info *all_info = kinfo->all_info_addr; + size_t build_info_size; + + if (kinfo->all_info_addr == 0 || kinfo->all_info_size == 0) + return -ENAVAIL; + + all_info = (struct kernel_all_info *)kinfo->all_info_addr; + build_info_size = sizeof(all_info->info.build_info); + + memcpy(&all_info->info.build_info, str, min(build_info_size - 1, + strlen(str))); + update_kernel_all_info(all_info); + + if (strlen(str) > build_info_size) { + pr_warn("%s: Build info buffer (len: %zd) can't hold entire string '%s'\n", + __func__, build_info_size, str); + return -ENOMEM; + } + + return 0; +} + +static const struct kernel_param_ops build_info_op = { + .set = build_info_set, +}; + +module_param_cb(build_info, &build_info_op, NULL, 0200); +MODULE_PARM_DESC(build_info, "Write build info to field 'build_info' of debug kinfo."); + +/** + * register_kinfo_region() - Register a new kinfo region + * @be: pointer to backend + * @id: unique id to identify the region + * @vaddr: virtual memory address of the region start + * @size: size of the region + * + * Return: On success, it returns 0 and negative error value on failure. + */ +static int register_kinfo_region(const struct kmemdump_backend *be, + enum kmemdump_uid id, void *vaddr, size_t size) +{ + struct debug_kinfo *kinfo = be_to_kinfo(be); + struct kernel_all_info *all_info = kinfo->all_info_addr; + struct kernel_info *info = &all_info->info; + + switch (id) { + case KMEMDUMP_ID_COREIMAGE__sinittext: + info->_sinittext_pa = (u64)__pa(vaddr); + break; + case KMEMDUMP_ID_COREIMAGE__einittext: + info->_einittext_pa = (u64)__pa(vaddr); + break; + case KMEMDUMP_ID_COREIMAGE__end: + info->_end_pa = (u64)__pa(vaddr); + break; + case KMEMDUMP_ID_COREIMAGE__text: + info->_text_pa = (u64)__pa(vaddr); + break; + case KMEMDUMP_ID_COREIMAGE__stext: + info->_stext_pa = (u64)__pa(vaddr); + break; + case KMEMDUMP_ID_COREIMAGE__etext: + info->_etext_pa = (u64)__pa(vaddr); + break; + case KMEMDUMP_ID_COREIMAGE_kallsyms_num_syms: + info->num_syms = *(__u32 *)vaddr; + break; + case KMEMDUMP_ID_COREIMAGE_kallsyms_relative_base: + info->_relative_pa = (u64)__pa(vaddr); + break; + case KMEMDUMP_ID_COREIMAGE_kallsyms_offsets: + info->_offsets_pa = (u64)__pa(vaddr); + break; + case KMEMDUMP_ID_COREIMAGE_kallsyms_names: + info->_names_pa = (u64)__pa(vaddr); + break; + case KMEMDUMP_ID_COREIMAGE_kallsyms_token_table: + info->_token_table_pa = (u64)__pa(vaddr); + break; + case KMEMDUMP_ID_COREIMAGE_kallsyms_token_index: + info->_token_index_pa = (u64)__pa(vaddr); + break; + case KMEMDUMP_ID_COREIMAGE_kallsyms_markers: + info->_markers_pa = (u64)__pa(vaddr); + break; + case KMEMDUMP_ID_COREIMAGE_kallsyms_seqs_of_names: + info->_seqs_of_names_pa = (u64)__pa(vaddr); + break; + case KMEMDUMP_ID_COREIMAGE_swapper_pg_dir: + info->swapper_pg_dir_pa = (u64)__pa(vaddr); + break; + case KMEMDUMP_ID_COREIMAGE_init_uts_ns_name: + strscpy(info->last_uts_release, vaddr, __NEW_UTS_LEN); + break; + default: + }; + + update_kernel_all_info(all_info); + return 0; +} + +/** + * unregister_md_region() - Unregister a previously registered kinfo region + * @id: unique id to identify the region + * + * Return: On success, it returns 0 and negative error value on failure. + */ +static int unregister_kinfo_region(const struct kmemdump_backend *be, + enum kmemdump_uid id) +{ + return 0; +} + +static int debug_kinfo_probe(struct platform_device *pdev) +{ + struct device_node *mem_region; + struct reserved_mem *rmem; + struct kernel_info *info; + struct kernel_all_info *all_info; + + mem_region = of_parse_phandle(pdev->dev.of_node, "memory-region", 0); + if (!mem_region) { + dev_warn(&pdev->dev, "no such memory-region\n"); + return -ENODEV; + } + + rmem = of_reserved_mem_lookup(mem_region); + if (!rmem) { + dev_warn(&pdev->dev, "no such reserved mem of node name %s\n", + pdev->dev.of_node->name); + return -ENODEV; + } + + /* Need to wait for reserved memory to be mapped */ + if (!rmem->priv) + return -EPROBE_DEFER; + + if (!rmem->base || !rmem->size) { + dev_warn(&pdev->dev, "unexpected reserved memory\n"); + return -EINVAL; + } + + if (rmem->size < sizeof(struct kernel_all_info)) { + dev_warn(&pdev->dev, "unexpected reserved memory size\n"); + return -EINVAL; + } + + kinfo = kzalloc(sizeof(*kinfo), GFP_KERNEL); + if (!kinfo) + return -ENOMEM; + + kinfo->dev = &pdev->dev; + + strscpy(kinfo->kinfo_be.name, "debug_kinfo"); + kinfo->kinfo_be.register_region = register_kinfo_region; + kinfo->kinfo_be.unregister_region = unregister_kinfo_region; + kinfo->all_info_addr = rmem->priv; + kinfo->all_info_size = rmem->size; + + all_info = kinfo->all_info_addr; + + memset(all_info, 0, sizeof(struct kernel_all_info)); + info = &all_info->info; + info->enabled_all = IS_ENABLED(CONFIG_KALLSYMS_ALL); + info->enabled_absolute_percpu = IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU); + info->enabled_cfi_clang = IS_ENABLED(CONFIG_CFI_CLANG); + info->name_len = KSYM_NAME_LEN; + info->bit_per_long = BITS_PER_LONG; + info->module_name_len = MODULE_NAME_LEN; + info->symbol_len = KSYM_SYMBOL_LEN; + info->thread_size = THREAD_SIZE; + info->enabled_modules_tree_lookup = IS_ENABLED(CONFIG_MODULES_TREE_LOOKUP); + info->mod_mem_offset = offsetof(struct module, mem); + info->mod_kallsyms_offset = offsetof(struct module, kallsyms); + + return kmemdump_register_backend(&kinfo->kinfo_be); +} + +static void debug_kinfo_remove(struct platform_device *pdev) +{ + kfree(kinfo); + kmemdump_unregister_backend(&kinfo->kinfo_be); +} + +static const struct of_device_id debug_kinfo_of_match[] = { + { .compatible = "google,debug-kinfo" }, + {}, +}; +MODULE_DEVICE_TABLE(of, debug_kinfo_of_match); + +static struct platform_driver debug_kinfo_driver = { + .probe = debug_kinfo_probe, + .remove = debug_kinfo_remove, + .driver = { + .name = "debug-kinfo", + .of_match_table = of_match_ptr(debug_kinfo_of_match), + }, +}; +module_platform_driver(debug_kinfo_driver); + +MODULE_AUTHOR("Eugen Hristev "); +MODULE_AUTHOR("Jone Chou "); +MODULE_DESCRIPTION("Debug Kinfo Driver"); +MODULE_LICENSE("GPL"); -- 2.43.0