[PATCH v4][makedumpfile 6/7] Add makedumpfile extensions support
HAGIO KAZUHITO(萩尾 一仁)
k-hagio-ab at nec.com
Fri Apr 3 01:14:07 PDT 2026
On 2026/03/18 0:07, Tao Liu wrote:
> The extensions can be specified by makedumpfile cmdline parameter as
> "--extension", followed by extension's filename or absolute path. If
> filename is give, then "./extenisons" and "/usr/lib64/makedumpfile/extensions/"
> will be searched.
>
> The procedures of extensions are as follows:
>
> Step 0: Every extensions will declare which kernel symbol/types they needed
> during programming. This info will be stored within .init_ksyms/ktypes section.
> Also extension will have a callback function for makedumpfile to call.
>
> Step 1: Register .init_ksyms and .init_ktypes sections of makedumpfile
> itself and extension's .so files, then tell kallsyms/btf subcomponent that which
> kernel symbols/types will be resolved. And callbacks are also registered.
>
> Step 2: Init kernel/module's btf/kallsyms on demand. Any un-needed kenrel
> modules will be skipped.
>
> Step 3: During btf/kallsyms parsing, the needed info will be filled. For
> syms/types which are defined via INIT_OPT(...) macro, these are optinal
> syms/types, it won't fail at parsing step if any are missing, instead, they
> need to be checked within extension_init() of each extensions; For
> syms/types which defined via INIT_(...) macro, these are must-have syms/types,
> if any missing, the extension will fail at this step and as a result
> this extension will be skipped.
>
> After this step, required kernel symbol value and kernel types size/offset
> are resolved, the extensions are ready to go.
>
> Step 4: When makedumpfile doing page filtering, in addition to its
> original filtering mechanism, it will call extensions callbacks for advice
> whether the page should be included/excluded.
>
> Suggested-by: Stephen Brennan <stephen.s.brennan at oracle.com>
> Signed-off-by: Tao Liu <ltao at redhat.com>
> ---
> Makefile | 7 +-
> extension.c | 300 ++++++++++++++++++++++++++++++++++++++++++++
> extension.h | 12 ++
> extensions/Makefile | 10 ++
> makedumpfile.c | 38 +++++-
> makedumpfile.h | 2 +
> 6 files changed, 363 insertions(+), 6 deletions(-)
> create mode 100644 extension.c
> create mode 100644 extension.h
> create mode 100644 extensions/Makefile
>
> diff --git a/Makefile b/Makefile
> index 320677d..1bb67d9 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -45,7 +45,7 @@ CFLAGS_ARCH += -m32
> endif
>
> SRC_BASE = makedumpfile.c makedumpfile.h diskdump_mod.h sadump_mod.h sadump_info.h
> -SRC_PART = print_info.c dwarf_info.c elf_info.c erase_info.c sadump_info.c cache.c tools.c printk.c detect_cycle.c kallsyms.c btf_info.c
> +SRC_PART = print_info.c dwarf_info.c elf_info.c erase_info.c sadump_info.c cache.c tools.c printk.c detect_cycle.c kallsyms.c btf_info.c extension.c
> OBJ_PART=$(patsubst %.c,%.o,$(SRC_PART))
> SRC_ARCH = arch/arm.c arch/arm64.c arch/x86.c arch/x86_64.c arch/ia64.c arch/ppc64.c arch/s390x.c arch/ppc.c arch/sparc64.c arch/mips64.c arch/loongarch64.c arch/riscv64.c
> OBJ_ARCH=$(patsubst %.c,%.o,$(SRC_ARCH))
> @@ -126,6 +126,7 @@ eppic_makedumpfile.so: extension_eppic.c
>
> clean:
> rm -f $(OBJ) $(OBJ_PART) $(OBJ_ARCH) makedumpfile makedumpfile.8 makedumpfile.conf.5
> + $(MAKE) -C extensions clean
>
> install:
> install -m 755 -d ${DESTDIR}/${SBINDIR} ${DESTDIR}/usr/share/man/man5 ${DESTDIR}/usr/share/man/man8
> @@ -135,3 +136,7 @@ install:
> mkdir -p ${DESTDIR}/usr/share/makedumpfile/eppic_scripts
> install -m 644 -D $(VPATH)makedumpfile.conf ${DESTDIR}/usr/share/makedumpfile/makedumpfile.conf.sample
> install -m 644 -t ${DESTDIR}/usr/share/makedumpfile/eppic_scripts/ $(VPATH)eppic_scripts/*
> +
> +.PHONY: extensions
> +extensions:
> + $(MAKE) -C extensions CC=$(CC)
> \ No newline at end of file
> diff --git a/extension.c b/extension.c
> new file mode 100644
> index 0000000..35e2756
> --- /dev/null
> +++ b/extension.c
> @@ -0,0 +1,300 @@
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <dirent.h>
> +#include <dlfcn.h>
> +#include <stdbool.h>
> +#include <unistd.h>
> +#include "kallsyms.h"
> +#include "btf_info.h"
> +#include "extension.h"
> +
> +typedef int (*callback_fn)(unsigned long, const void *);
> +
> +struct extension_handle_cb {
> + void *handle;
> + callback_fn cb;
> +};
> +
> +/* Extension .so extension_handle_cb array */
> +static struct extension_handle_cb **handle_cbs = NULL;
> +static int handle_cbs_len = 0;
> +static int handle_cbs_cap = 0;
> +
> +/* Extension option array */
> +static char **extension_opts = NULL;
> +static int extension_opts_len = 0;
> +static int extension_opts_cap = 0;
> +
> +static const char *dirs[] = {
> + "/usr/lib64/makedumpfile/extensions/",
> + "./extensions/",
> +};
I think we should add "./" to the first and arrange them in this order:
"./",
"./extensions/",
"/usr/lib64/makedumpfile/extensions/"
Without this, we cannot use a relative path like this, it's not natural.
$ ls
amdgpu_filter.so makedumpfile vmcore
$ ./makedumpfile -ld31 --extension amdgpu_filter.so vmcore dump
load_extensions: Not found amdgpu_filter.so
Copying data : [ 26.5 %]
> +
> +void add_extension_opts(char *opt)
> +{
> + if (!add_to_arr((void ***)&extension_opts, &extension_opts_len,
> + &extension_opts_cap, opt))
> + /*
> + * If fail, print error info and skip the extension.
> + */
> + fprintf(stderr, "%s: Fail to add extension %s\n", __func__, opt);
> +}
> +
> +static bool init_kallsyms_btf(void)
> +{
> + int count;
> + bool ret = false;
> + /* We will load module's btf/kallsyms on demand */
> + bool init_ksyms_module = false;
> + bool init_ktypes_module = false;
> +
> + if (check_ksyms_require_modname("vmlinux", &count)) {
> + if (!init_kernel_kallsyms())
> + goto out;
> + if (count >= 2)
> + init_ksyms_module = true;
I may have misread, if an extension depends only a module's symbols, no
init functions are run? or it can't be such a situation?
> + }
> + if (check_ktypes_require_modname("vmlinux", &count)) {
> + if (!init_kernel_btf())
> + goto out;
> + if (count >= 2)
> + init_ktypes_module = true;
> + }
> + if (init_ksyms_module && !init_module_kallsyms())
> + goto out;
> + if (init_ktypes_module && !init_module_btf())
> + goto out;
> + ret = true;
> +out:
> + return ret;
> +}
> +
> +static void cleanup_kallsyms_btf(void)
> +{
> + cleanup_kallsyms();
> + cleanup_btf();
> +}
> +
> +static void load_extensions(void)
> +{
> + char path[512];
> + int len, i, j;
> + void *handle;
> + struct extension_handle_cb *ehc;
> +
> + for (i = 0; i < extension_opts_len; i++) {
> + handle = NULL;
> + if (!extension_opts[i])
> + continue;
> + if ((len = strlen(extension_opts[i])) <= 3 ||
> + (strcmp(extension_opts[i] + len - 3, ".so") != 0)) {
> + fprintf(stderr, "%s: Skip invalid extension: %s\n",
> + __func__, extension_opts[i]);
> + continue;
> + }
> +
> + if (extension_opts[i][0] == '/') {
> + /* Path & filename */
> + snprintf(path, sizeof(path), "%s", extension_opts[i]);
> + handle = dlopen(path, RTLD_NOW);
> + if (!handle) {
> + fprintf(stderr, "%s: Failed to load %s\n",
> + __func__, dlerror());
> + continue;
> + }
> + } else {
> + /* Only filename */
> + for (j = 0; j < sizeof(dirs) / sizeof(char *); j++) {
> + snprintf(path, sizeof(path), "%s", dirs[j]);
> + len = strlen(path);
> + snprintf(path + len, sizeof(path) - len, "%s",
> + extension_opts[i]);
> + if (access(path, F_OK) == 0) {
> + handle = dlopen(path, RTLD_NOW);
> + if (handle)
> + break;
> + else
> + fprintf(stderr, "%s: Failed to load %s\n",
> + __func__, dlerror());
> + }
> + }
> + if (!handle && j >= sizeof(dirs) / sizeof(char *)) {
> + fprintf(stderr, "%s: Not found %s\n",
> + __func__, extension_opts[i]);
> + continue;
> + }
> + }
> +
> + if (dlsym(handle, "extension_init") == NULL) {
> + fprintf(stderr, "%s: Skip extension %s: No extension_init()\n",
> + __func__, path);
> + dlclose(handle);
> + continue;
> + }
> +
> + if ((ehc = malloc(sizeof(struct extension_handle_cb))) == NULL) {
> + fprintf(stderr, "%s: Skip extension %s: No memory\n",
> + __func__, path);
> + dlclose(handle);
> + continue;
Some lines have spaces at the end of line, please remove them.
Thanks,
Kazu
> + }
> +
> + ehc->handle = handle;
> + ehc->cb = dlsym(handle, "extension_callback");
> +
> + if (!add_to_arr((void ***)&handle_cbs, &handle_cbs_len, &handle_cbs_cap, ehc)) {
> + fprintf(stderr, "%s: Failed to load %s\n", __func__,
> + extension_opts[i]);
> + free(ehc);
> + dlclose(handle);
> + continue;
> + }
> + printf("Loaded extension: %s\n", path);
> + }
> +}
> +
> +static bool register_extension_sections(void)
> +{
> + char *start, *stop;
> + int i;
> + bool ret = false;
> +
> + for (i = 0; i < handle_cbs_len; i++) {
> + start = dlsym(handle_cbs[i]->handle, "__start_init_ksyms");
> + stop = dlsym(handle_cbs[i]->handle, "__stop_init_ksyms");
> + if (!register_ksym_section(start, stop))
> + goto out;
> +
> + start = dlsym(handle_cbs[i]->handle, "__start_init_ktypes");
> + stop = dlsym(handle_cbs[i]->handle, "__stop_init_ktypes");
> + if (!register_ktype_section(start, stop))
> + goto out;
> + }
> + ret = true;
> +out:
> + return ret;
> +}
> +
> +void cleanup_extensions(void)
> +{
> + for (int i = 0; i < handle_cbs_len; i++) {
> + dlclose(handle_cbs[i]->handle);
> + free(handle_cbs[i]);
> + }
> + if (handle_cbs) {
> + free(handle_cbs);
> + handle_cbs = NULL;
> + }
> + handle_cbs_len = 0;
> + handle_cbs_cap = 0;
> + if (extension_opts) {
> + free(extension_opts);
> + extension_opts = NULL;
> + }
> + extension_opts_len = 0;
> + extension_opts_cap = 0;
> +
> + cleanup_kallsyms_btf();
> +}
> +
> +static bool check_required_ksyms_all_resolved(void *handle)
> +{
> + char *start, *stop;
> + struct ksym_info **p;
> + bool ret = true;
> +
> + start = dlsym(handle, "__start_init_ksyms");
> + stop = dlsym(handle, "__stop_init_ksyms");
> +
> + for (p = (struct ksym_info **)start;
> + p < (struct ksym_info **)stop;
> + p++) {
> + if ((*p)->sym_required && !SYM_EXIST(*p)) {
> + ret = false;
> + fprintf(stderr, "Symbol %s in %s not found\n",
> + (*p)->symname, (*p)->modname);
> + }
> + }
> +
> + return ret;
> +}
> +
> +static bool check_required_ktypes_all_resolved(void *handle)
> +{
> + char *start, *stop;
> + struct ktype_info **p;
> + bool ret = true;
> +
> + start = dlsym(handle, "__start_init_ktypes");
> + stop = dlsym(handle, "__stop_init_ktypes");
> +
> + for (p = (struct ktype_info **)start;
> + p < (struct ktype_info **)stop;
> + p++) {
> + if (!TYPE_EXIST(*p)) {
> + if ((*p)->member_required) {
> + ret = false;
> + fprintf(stderr, "Member %s of struct %s in %s not found\n",
> + (*p)->member_name, (*p)->struct_name, (*p)->modname);
> + } else if ((*p)->struct_required) {
> + ret = false;
> + fprintf(stderr, "Struct %s in %s not found\n",
> + (*p)->struct_name, (*p)->modname);
> + }
> + }
> + }
> +
> + return ret;
> +}
> +
> +static bool extension_runnable(void *handle)
> +{
> + return check_required_ksyms_all_resolved(handle) &&
> + check_required_ktypes_all_resolved(handle);
> +}
> +
> +void init_extensions(void)
> +{
> + /* Entry of extension init */
> + void (*init)(void);
> +
> + load_extensions();
> + if (!register_extension_sections())
> + goto fail;
> + if (!init_kallsyms_btf())
> + goto fail;
> + for (int i = 0; i < handle_cbs_len; i++) {
> + if (extension_runnable(handle_cbs[i]->handle)) {
> + init = dlsym(handle_cbs[i]->handle, "extension_init");
> + init();
> + } else {
> + fprintf(stderr, "%s: Skip %dth extension\n",
> + __func__, i + 1);
> + }
> + }
> + return;
> +fail:
> + fprintf(stderr, "%s: fail & skip all extensions\n", __func__);
> + cleanup_extensions();
> +}
> +
> +int run_extension_callback(unsigned long pfn, const void *pcache)
> +{
> + int result;
> + int ret = PG_UNDECID;
> +
> + for (int i = 0; i < handle_cbs_len; i++) {
> + if (handle_cbs[i]->cb) {
> + result = handle_cbs[i]->cb(pfn, pcache);
> + if (result == PG_INCLUDE) {
> + ret = result;
> + goto out;
> + } else if (result == PG_EXCLUDE) {
> + ret = result;
> + }
> + }
> + }
> +out:
> + return ret;
> +}
> \ No newline at end of file
> diff --git a/extension.h b/extension.h
> new file mode 100644
> index 0000000..dc5902e
> --- /dev/null
> +++ b/extension.h
> @@ -0,0 +1,12 @@
> +#ifndef _EXTENSION_H
> +#define _EXTENSION_H
> +
> +enum {
> + PG_INCLUDE, // Exntesion will keep the page
> + PG_EXCLUDE, // Exntesion will discard the page
> + PG_UNDECID, // Exntesion makes no decision
> +};
> +int run_extension_callback(unsigned long pfn, const void *pcache);
> +void init_extensions(void);
> +void cleanup_extensions(void);
> +#endif /* _EXTENSION_H */
> \ No newline at end of file
> diff --git a/extensions/Makefile b/extensions/Makefile
> new file mode 100644
> index 0000000..b8bbfbc
> --- /dev/null
> +++ b/extensions/Makefile
> @@ -0,0 +1,10 @@
> +CC ?= gcc
> +CONTRIB_SO :=
> +
> +all: $(CONTRIB_SO)
> +
> +$(CONTRIB_SO): %.so: %.c
> + $(CC) -O2 -g -fPIC -shared -Wl,-T,../makedumpfile.ld -o $@ $^
> +
> +clean:
> + rm -f $(CONTRIB_SO)
> \ No newline at end of file
> diff --git a/makedumpfile.c b/makedumpfile.c
> index dba3628..ef7468f 100644
> --- a/makedumpfile.c
> +++ b/makedumpfile.c
> @@ -28,6 +28,7 @@
> #include <assert.h>
> #include <zlib.h>
> #include "kallsyms.h"
> +#include "extension.h"
>
> struct symbol_table symbol_table;
> struct size_table size_table;
> @@ -102,6 +103,7 @@ mdf_pfn_t pfn_free;
> mdf_pfn_t pfn_hwpoison;
> mdf_pfn_t pfn_offline;
> mdf_pfn_t pfn_elf_excluded;
> +mdf_pfn_t pfn_extension;
>
> mdf_pfn_t num_dumped;
>
> @@ -6459,6 +6461,7 @@ __exclude_unnecessary_pages(unsigned long mem_map,
> unsigned int order_offset, dtor_offset;
> unsigned long flags, mapping, private = 0;
> unsigned long compound_dtor, compound_head = 0;
> + int filter_pg;
>
> /*
> * If a multi-page exclusion is pending, do it first
> @@ -6531,6 +6534,14 @@ __exclude_unnecessary_pages(unsigned long mem_map,
> pfn_read_end = pfn + pfn_mm - 1;
> }
>
> + /*
> + * Include pages that specified by user via
> + * makedumpfile extensions
> + */
> + filter_pg = run_extension_callback(pfn, pcache);
> + if (filter_pg == PG_INCLUDE)
> + continue;
> +
> flags = ULONG(pcache + OFFSET(page.flags));
> _count = UINT(pcache + OFFSET(page._refcount));
> mapping = ULONG(pcache + OFFSET(page.mapping));
> @@ -6687,6 +6698,14 @@ check_order:
> else if (isOffline(flags, _mapcount)) {
> pfn_counter = &pfn_offline;
> }
> + /*
> + * Exclude pages that specified by user via
> + * makedumpfile extensions
> + */
> + else if (filter_pg == PG_EXCLUDE) {
> + nr_pages = 1;
> + pfn_counter = &pfn_extension;
> + }
> /*
> * Unexcludable page
> */
> @@ -8234,7 +8253,7 @@ write_elf_pages_cyclic(struct cache_data *cd_header, struct cache_data *cd_page)
> */
> if (info->flag_cyclic) {
> pfn_zero = pfn_cache = pfn_cache_private = 0;
> - pfn_user = pfn_free = pfn_hwpoison = pfn_offline = 0;
> + pfn_user = pfn_free = pfn_hwpoison = pfn_offline = pfn_extension = 0;
> pfn_memhole = info->max_mapnr;
> }
>
> @@ -9579,7 +9598,7 @@ write_kdump_pages_and_bitmap_cyclic(struct cache_data *cd_header, struct cache_d
> * Reset counter for debug message.
> */
> pfn_zero = pfn_cache = pfn_cache_private = 0;
> - pfn_user = pfn_free = pfn_hwpoison = pfn_offline = 0;
> + pfn_user = pfn_free = pfn_hwpoison = pfn_offline = pfn_extension = 0;
> pfn_memhole = info->max_mapnr;
>
> /*
> @@ -10528,7 +10547,7 @@ print_report(void)
> pfn_original = info->max_mapnr - pfn_memhole;
>
> pfn_excluded = pfn_zero + pfn_cache + pfn_cache_private
> - + pfn_user + pfn_free + pfn_hwpoison + pfn_offline;
> + + pfn_user + pfn_free + pfn_hwpoison + pfn_offline + pfn_extension;
>
> REPORT_MSG("\n");
> REPORT_MSG("Original pages : 0x%016llx\n", pfn_original);
> @@ -10544,6 +10563,7 @@ print_report(void)
> REPORT_MSG(" Free pages : 0x%016llx\n", pfn_free);
> REPORT_MSG(" Hwpoison pages : 0x%016llx\n", pfn_hwpoison);
> REPORT_MSG(" Offline pages : 0x%016llx\n", pfn_offline);
> + REPORT_MSG(" Extension filter pages : 0x%016llx\n", pfn_extension);
> REPORT_MSG(" Remaining pages : 0x%016llx\n",
> pfn_original - pfn_excluded);
>
> @@ -10584,7 +10604,7 @@ print_mem_usage(void)
> pfn_original = info->max_mapnr - pfn_memhole;
>
> pfn_excluded = pfn_zero + pfn_cache + pfn_cache_private
> - + pfn_user + pfn_free + pfn_hwpoison + pfn_offline;
> + + pfn_user + pfn_free + pfn_hwpoison + pfn_offline + pfn_extension;
> shrinking = (pfn_original - pfn_excluded) * 100;
> shrinking = shrinking / pfn_original;
> total_size = info->page_size * pfn_original;
> @@ -10878,6 +10898,7 @@ create_dumpfile(void)
> }
>
> print_vtop();
> + init_extensions();
>
> num_retry = 0;
> retry:
> @@ -10888,8 +10909,11 @@ retry:
> && !gather_filter_info())
> return FALSE;
>
> - if (!create_dump_bitmap())
> + if (!create_dump_bitmap()) {
> + cleanup_extensions();
> return FALSE;
> + }
> + cleanup_extensions();
>
> if (info->flag_split) {
> if ((status = writeout_multiple_dumpfiles()) == FALSE)
> @@ -12130,6 +12154,7 @@ static struct option longopts[] = {
> {"check-params", no_argument, NULL, OPT_CHECK_PARAMS},
> {"dry-run", no_argument, NULL, OPT_DRY_RUN},
> {"show-stats", no_argument, NULL, OPT_SHOW_STATS},
> + {"extension", required_argument, NULL, OPT_EXTENSION},
> {0, 0, 0, 0}
> };
>
> @@ -12317,6 +12342,9 @@ main(int argc, char *argv[])
> case OPT_SHOW_STATS:
> flag_show_stats = TRUE;
> break;
> + case OPT_EXTENSION:
> + add_extension_opts(optarg);
> + break;
> case '?':
> MSG("Commandline parameter is invalid.\n");
> MSG("Try `makedumpfile --help' for more information.\n");
> diff --git a/makedumpfile.h b/makedumpfile.h
> index 0f13743..d880ae7 100644
> --- a/makedumpfile.h
> +++ b/makedumpfile.h
> @@ -2747,6 +2747,7 @@ struct elf_prstatus {
> #define OPT_CHECK_PARAMS OPT_START+18
> #define OPT_DRY_RUN OPT_START+19
> #define OPT_SHOW_STATS OPT_START+20
> +#define OPT_EXTENSION OPT_START+21
>
> /*
> * Function Prototype.
> @@ -2777,5 +2778,6 @@ int write_and_check_space(int fd, void *buf, size_t buf_size,
> int open_dump_file(void);
> int dump_lockless_dmesg(void);
> unsigned long long memparse(char *ptr, char **retptr);
> +void add_extension_opts(char *opt);
>
> #endif /* MAKEDUMPFILE_H */
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