Implement kmemdumping into an ELF coreimage.
With this feature enabled, kmemdump will assemble all the regions
into a coreimage, by having an initial first region with an ELF header,
a second region with vmcoreinfo data, and then register vital kernel
information in the subsequent regions.
This image can then be dumped, assembled into a single file and loaded
into debugging tools like crash/gdb.
Signed-off-by: Eugen Hristev <eugen.hris...@linaro.org>
---
MAINTAINERS | 1 +
include/linux/kmemdump.h | 67 ++++++++++
mm/kmemdump/Kconfig.debug | 18 ++-
mm/kmemdump/Makefile | 1 +
mm/kmemdump/kmemdump.c | 32 +++++
mm/kmemdump/kmemdump_coreimage.c | 222 +++++++++++++++++++++++++++++++
6 files changed, 339 insertions(+), 2 deletions(-)
create mode 100644 mm/kmemdump/kmemdump_coreimage.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 974f43c3902b..fc8cd34cf190 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13816,6 +13816,7 @@ S: Maintained
F: Documentation/dev-tools/kmemdump.rst
F: include/linux/kmemdump.h
F: mm/kmemdump/kmemdump.c
+F: mm/kmemdump/kmemdump_coreimage.c
KMEMLEAK
M: Catalin Marinas <catalin.mari...@arm.com>
diff --git a/include/linux/kmemdump.h b/include/linux/kmemdump.h
index 8e764bb2d8ac..ac2eb1b4ba06 100644
--- a/include/linux/kmemdump.h
+++ b/include/linux/kmemdump.h
@@ -4,6 +4,52 @@
enum kmemdump_uid {
KMEMDUMP_ID_START = 0,
+ KMEMDUMP_ID_COREIMAGE_ELF,
+ KMEMDUMP_ID_COREIMAGE_VMCOREINFO,
+ KMEMDUMP_ID_COREIMAGE_CONFIG,
+ KMEMDUMP_ID_COREIMAGE_MEMSECT,
+ KMEMDUMP_ID_COREIMAGE__totalram_pages,
+ KMEMDUMP_ID_COREIMAGE___cpu_possible_mask,
+ KMEMDUMP_ID_COREIMAGE___cpu_present_mask,
+ KMEMDUMP_ID_COREIMAGE___cpu_online_mask,
+ KMEMDUMP_ID_COREIMAGE___cpu_active_mask,
+ KMEMDUMP_ID_COREIMAGE_jiffies_64,
+ KMEMDUMP_ID_COREIMAGE_linux_banner,
+ KMEMDUMP_ID_COREIMAGE_nr_threads,
+ KMEMDUMP_ID_COREIMAGE_nr_irqs,
+ KMEMDUMP_ID_COREIMAGE_tainted_mask,
+ KMEMDUMP_ID_COREIMAGE_taint_flags,
+ KMEMDUMP_ID_COREIMAGE_mem_section,
+ KMEMDUMP_ID_COREIMAGE_node_data,
+ KMEMDUMP_ID_COREIMAGE_node_states,
+ KMEMDUMP_ID_COREIMAGE___per_cpu_offset,
+ KMEMDUMP_ID_COREIMAGE_nr_swapfiles,
+ KMEMDUMP_ID_COREIMAGE_init_uts_ns,
+ KMEMDUMP_ID_COREIMAGE_printk_rb_static,
+ KMEMDUMP_ID_COREIMAGE_printk_rb_dynamic,
+ KMEMDUMP_ID_COREIMAGE_prb,
+ KMEMDUMP_ID_COREIMAGE_prb_descs,
+ KMEMDUMP_ID_COREIMAGE_prb_infos,
+ KMEMDUMP_ID_COREIMAGE_prb_data,
+ KMEMDUMP_ID_COREIMAGE_runqueues,
+ KMEMDUMP_ID_COREIMAGE_high_memory,
+ KMEMDUMP_ID_COREIMAGE_init_mm,
+ KMEMDUMP_ID_COREIMAGE_init_mm_pgd,
+ KMEMDUMP_ID_COREIMAGE__sinittext,
+ KMEMDUMP_ID_COREIMAGE__einittext,
+ KMEMDUMP_ID_COREIMAGE__end,
+ KMEMDUMP_ID_COREIMAGE__text,
+ KMEMDUMP_ID_COREIMAGE__stext,
+ KMEMDUMP_ID_COREIMAGE__etext,
+ KMEMDUMP_ID_COREIMAGE_kallsyms_num_syms,
+ KMEMDUMP_ID_COREIMAGE_kallsyms_relative_base,
+ KMEMDUMP_ID_COREIMAGE_kallsyms_offsets,
+ KMEMDUMP_ID_COREIMAGE_kallsyms_names,
+ KMEMDUMP_ID_COREIMAGE_kallsyms_token_table,
+ KMEMDUMP_ID_COREIMAGE_kallsyms_token_index,
+ KMEMDUMP_ID_COREIMAGE_kallsyms_markers,
+ KMEMDUMP_ID_COREIMAGE_kallsyms_seqs_of_names,
+ KMEMDUMP_ID_COREIMAGE_swapper_pg_dir,
KMEMDUMP_ID_USER_START,
KMEMDUMP_ID_USER_END,
KMEMDUMP_ID_NO_ID,
@@ -60,4 +106,25 @@ static inline void kmemdump_unregister(enum kmemdump_uid id)
}
#endif
+#ifdef CONFIG_KMEMDUMP
+#ifdef CONFIG_KMEMDUMP_COREIMAGE
+int init_elfheader(void);
+void update_elfheader(const struct kmemdump_zone *z);
+int clear_elfheader(const struct kmemdump_zone *z);
+#else
+static inline int init_elfheader(void)
+{
+ return 0;
+}
+
+static inline void update_elfheader(const struct kmemdump_zone *z)
+{
+}
+
+static inline int clear_elfheader(const struct kmemdump_zone *z)
+{
+ return 0;
+}
+#endif
+#endif
#endif
diff --git a/mm/kmemdump/Kconfig.debug b/mm/kmemdump/Kconfig.debug
index 5654180141c0..f62bde50a81b 100644
--- a/mm/kmemdump/Kconfig.debug
+++ b/mm/kmemdump/Kconfig.debug
@@ -1,7 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
-config KMEMDUMP
- bool "KMEMDUMP: Allow the kernel to register memory regions for dumping
purpose"
+menuconfig KMEMDUMP
+ bool "KMEMDUMP: Register memory regions for dumping purpose"
help
Kmemdump mechanism allows any driver to mark a specific memory area
for later dumping/debugging purpose, depending on the functionality
@@ -12,3 +12,17 @@ config KMEMDUMP
Note that modules using this feature must be rebuilt if option
changes.
+
+config KMEMDUMP_COREIMAGE
+ depends on KMEMDUMP
+ select VMCORE_INFO
+ bool "Assemble memory regions into a coredump readable with debuggers"
+ help
+ Enabling this will assemble all the memory regions into a
+ core ELF file. The first region will include program headers for
+ all the regions. The second region is the vmcoreinfo and specific
+ coredump structures.
+ All the other regions follow. Specific kernel variables required
+ for debug tools are being registered.
+ The coredump file can then be loaded into GDB or crash tool and
+ further inspected.
diff --git a/mm/kmemdump/Makefile b/mm/kmemdump/Makefile
index f5b917a6ef5e..eed67f15a8d0 100644
--- a/mm/kmemdump/Makefile
+++ b/mm/kmemdump/Makefile
@@ -1,3 +1,4 @@
# SPDX-License-Identifier: GPL-2.0
obj-y += kmemdump.o
+obj-$(CONFIG_KMEMDUMP_COREIMAGE) += kmemdump_coreimage.o
diff --git a/mm/kmemdump/kmemdump.c b/mm/kmemdump/kmemdump.c
index c016457620a4..3827b0597cac 100644
--- a/mm/kmemdump/kmemdump.c
+++ b/mm/kmemdump/kmemdump.c
@@ -28,6 +28,32 @@ static const struct kmemdump_backend
kmemdump_default_backend = {
static const struct kmemdump_backend *backend = &kmemdump_default_backend;
static DEFINE_MUTEX(kmemdump_lock);
static struct kmemdump_zone kmemdump_zones[MAX_ZONES];
+static bool kmemdump_initialized;
+
+static int __init init_kmemdump(void)
+{
+ enum kmemdump_uid uid;
+
+ init_elfheader();
+
+ mutex_lock(&kmemdump_lock);
+ /*
+ * Some regions may have been registered very early.
+ * Update the elf header for all existing regions,
+ * except for KMEMDUMP_ID_COREIMAGE_ELF and
+ * KMEMDUMP_ID_COREIMAGE_VMCOREINFO, those are included in the
+ * ELF header upon its creation.
+ */
+ for (uid = KMEMDUMP_ID_COREIMAGE_CONFIG; uid < MAX_ZONES; uid++)
+ if (kmemdump_zones[uid].id)
+ update_elfheader(&kmemdump_zones[uid]);
+
+ kmemdump_initialized = true;
+ mutex_unlock(&kmemdump_lock);
+
+ return 0;
+}
+late_initcall(init_kmemdump);
/**
* kmemdump_register_id() - Register region into kmemdump with given ID.
@@ -83,6 +109,9 @@ int kmemdump_register_id(enum kmemdump_uid req_id, void
*zone, size_t size)
z->size = size;
z->id = uid;
+ if (kmemdump_initialized)
+ update_elfheader(z);
+
mutex_unlock(&kmemdump_lock);
return uid;
@@ -110,6 +139,9 @@ void kmemdump_unregister(enum kmemdump_uid id)
backend->unregister_region(backend, z->id);
+ if (kmemdump_initialized)
+ clear_elfheader(z);
+
memset(z, 0, sizeof(*z));
mutex_unlock(&kmemdump_lock);
diff --git a/mm/kmemdump/kmemdump_coreimage.c b/mm/kmemdump/kmemdump_coreimage.c
new file mode 100644
index 000000000000..a7b51a171d8e
--- /dev/null
+++ b/mm/kmemdump/kmemdump_coreimage.c
@@ -0,0 +1,222 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/io.h>
+#include <linux/elfcore.h>
+#include <linux/kmemdump.h>
+#include <linux/vmcore_info.h>
+
+#define CORE_STR "CORE"
+
+#define MAX_NUM_ENTRIES 201
+
+static struct elfhdr *ehdr;
+static size_t elf_offset;
+
+static void append_kcore_note(char *notes, size_t *i, const char *name,
+ unsigned int type, const void *desc,
+ size_t descsz)
+{
+ struct elf_note *note = (struct elf_note *)¬es[*i];
+
+ note->n_namesz = strlen(name) + 1;
+ note->n_descsz = descsz;
+ note->n_type = type;
+ *i += sizeof(*note);
+ memcpy(¬es[*i], name, note->n_namesz);
+ *i = ALIGN(*i + note->n_namesz, 4);
+ memcpy(¬es[*i], desc, descsz);
+ *i = ALIGN(*i + descsz, 4);
+}
+
+static void append_kcore_note_nodesc(char *notes, size_t *i, const char *name,
+ unsigned int type, size_t descsz)
+{
+ struct elf_note *note = (struct elf_note *)¬es[*i];
+
+ note->n_namesz = strlen(name) + 1;
+ note->n_descsz = descsz;
+ note->n_type = type;
+ *i += sizeof(*note);
+ memcpy(¬es[*i], name, note->n_namesz);
+ *i = ALIGN(*i + note->n_namesz, 4);
+}
+
+static struct elf_phdr *elf_phdr_entry_addr(struct elfhdr *ehdr, int idx)
+{
+ struct elf_phdr *ephdr = (struct elf_phdr *)((size_t)ehdr +
ehdr->e_phoff);
+
+ return &ephdr[idx];
+}
+
+/**
+ * clear_elfheader() - Remove the program header for a specific memory zone
+ * @z: pointer to the kmemdump zone
+ *
+ * Return: On success, it returns 0, errno otherwise
+ */
+int clear_elfheader(const struct kmemdump_zone *z)
+{
+ struct elf_phdr *phdr;
+ struct elf_phdr *tmp_phdr;
+ unsigned int phidx;
+ unsigned int i;
+
+ for (i = 0; i < ehdr->e_phnum; i++) {
+ phdr = elf_phdr_entry_addr(ehdr, i);
+ if (phdr->p_paddr == virt_to_phys(z->zone) &&
+ phdr->p_memsz == ALIGN(z->size, 4))
+ break;
+ }
+
+ if (i == ehdr->e_phnum) {
+ pr_debug("Cannot find program header entry in elf\n");
+ return -EINVAL;
+ }
+
+ phidx = i;
+
+ /* Clear program header */
+ tmp_phdr = elf_phdr_entry_addr(ehdr, phidx);
+ for (i = phidx; i < ehdr->e_phnum - 1; i++) {
+ tmp_phdr = elf_phdr_entry_addr(ehdr, i + 1);
+ phdr = elf_phdr_entry_addr(ehdr, i);
+ memcpy(phdr, tmp_phdr, sizeof(*phdr));
+ phdr->p_offset = phdr->p_offset - ALIGN(z->size, 4);
+ }
+ memset(tmp_phdr, 0, sizeof(*tmp_phdr));
+ ehdr->e_phnum--;
+
+ elf_offset -= ALIGN(z->size, 4);
+
+ return 0;
+}
+
+/**
+ * update_elfheader() - Add the program header for a specific memory zone
+ * @z: pointer to the kmemdump zone
+ *
+ * Return: None
+ */
+void update_elfheader(const struct kmemdump_zone *z)
+{
+ struct elf_phdr *phdr;
+
+ phdr = elf_phdr_entry_addr(ehdr, ehdr->e_phnum++);
+
+ phdr->p_type = PT_LOAD;
+ phdr->p_offset = elf_offset;
+ phdr->p_vaddr = (elf_addr_t)z->zone;
+ phdr->p_paddr = (elf_addr_t)virt_to_phys(z->zone);
+ phdr->p_filesz = phdr->p_memsz = ALIGN(z->size, 4);
+ phdr->p_flags = PF_R | PF_W;
+
+ elf_offset += ALIGN(z->size, 4);
+}
+
+/**
+ * init_elfheader() - Prepare coreinfo elf header
+ * This function prepares the elf header for the coredump image.
+ * Initially there is a single program header for the elf NOTE.
+ * The note contains the usual core dump information, and the
+ * vmcoreinfo.
+ *
+ * Return: 0 on success, errno otherwise
+ */
+int init_elfheader(void)
+{
+ struct elf_phdr *phdr;
+ void *notes;
+ unsigned int elfh_size;
+ unsigned int phdr_off;
+ size_t note_len, i = 0;
+
+ struct elf_prstatus prstatus = {};
+ struct elf_prpsinfo prpsinfo = {
+ .pr_sname = 'R',
+ .pr_fname = "vmlinux",
+ };
+
+ /*
+ * Header buffer contains:
+ * ELF header, Note entry with PR status, PR ps info, and vmcoreinfo
+ * MAX_NUM_ENTRIES Program headers,
+ */
+ elfh_size = sizeof(*ehdr);
+ elfh_size += sizeof(struct elf_prstatus);
+ elfh_size += sizeof(struct elf_prpsinfo);
+ elfh_size += sizeof(VMCOREINFO_NOTE_NAME);
+ elfh_size += ALIGN(vmcoreinfo_size, 4);
+ elfh_size += (sizeof(*phdr)) * (MAX_NUM_ENTRIES);
+
+ elfh_size = ALIGN(elfh_size, 4);
+
+ /* Never freed */
+ ehdr = kzalloc(elfh_size, GFP_KERNEL);
+ if (!ehdr)
+ return -ENOMEM;
+
+ /* Assign Program headers offset, it's right after the elf header. */
+ phdr = (struct elf_phdr *)(ehdr + 1);
+ phdr_off = sizeof(*ehdr);
+
+ memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
+ ehdr->e_ident[EI_CLASS] = ELF_CLASS;
+ ehdr->e_ident[EI_DATA] = ELF_DATA;
+ ehdr->e_ident[EI_VERSION] = EV_CURRENT;
+ ehdr->e_ident[EI_OSABI] = ELF_OSABI;
+ ehdr->e_type = ET_CORE;
+ ehdr->e_machine = ELF_ARCH;
+ ehdr->e_version = EV_CURRENT;
+ ehdr->e_ehsize = sizeof(*ehdr);
+ ehdr->e_phentsize = sizeof(*phdr);
+
+ elf_offset = elfh_size;
+
+ notes = (void *)(((char *)ehdr) + elf_offset);
+
+ /* we have a single program header now */
+ ehdr->e_phnum = 1;
+
+ /* Length of the note is made of :
+ * 3 elf notes structs (prstatus, prpsinfo, vmcoreinfo)
+ * 3 notes names (2 core strings, 1 vmcoreinfo name)
+ * sizeof each note
+ */
+ note_len = (3 * sizeof(struct elf_note) +
+ 2 * ALIGN(sizeof(CORE_STR), 4) +
+ VMCOREINFO_NOTE_NAME_BYTES +
+ ALIGN(sizeof(struct elf_prstatus), 4) +
+ ALIGN(sizeof(struct elf_prpsinfo), 4) +
+ ALIGN(vmcoreinfo_size, 4));
+
+ phdr->p_type = PT_NOTE;
+ phdr->p_offset = elf_offset;
+ phdr->p_filesz = note_len;
+
+ /* advance elf offset */
+ elf_offset += note_len;
+
+ strscpy(prpsinfo.pr_psargs, saved_command_line,
+ sizeof(prpsinfo.pr_psargs));
+
+ append_kcore_note(notes, &i, CORE_STR, NT_PRSTATUS, &prstatus,
+ sizeof(prstatus));
+ append_kcore_note(notes, &i, CORE_STR, NT_PRPSINFO, &prpsinfo,
+ sizeof(prpsinfo));
+ append_kcore_note_nodesc(notes, &i, VMCOREINFO_NOTE_NAME, 0,
+ ALIGN(vmcoreinfo_size, 4));
+
+ ehdr->e_phoff = phdr_off;
+
+ /* This is the first kmemdump region, the ELF header */
+ kmemdump_register_id(KMEMDUMP_ID_COREIMAGE_ELF, ehdr,
+ elfh_size + note_len - ALIGN(vmcoreinfo_size, 4));
+
+ /*
+ * The second region is the vmcoreinfo, which goes right after.
+ * It's being registered through vmcoreinfo.
+ */
+
+ return 0;
+}
+
--
2.43.0
