[Crash-utility] [RFC PATCH 07/15] Support percpu symbols for "sym" options
lijiang
lijiang at redhat.com
Fri May 26 10:37:34 UTC 2023
On Thu, May 11, 2023 at 12:35 PM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab at nec.com>
wrote:
> Support percpu symbols for "sym" options and etc.
>
> crash> mod -s kvm_intel
> MODULE NAME BASE SIZE OBJECT
> FILE
> ffffffffc0b1b480 kvm_intel ffffffffc0d0c000 372736
> /home/kernel/linux-next-next-20230310/arch/x86/kvm/kvm-intel.ko
> crash> sym -m kvm_intel | head
> 35020 MODULE PERCPU START: kvm_intel
> 35020 (d) loaded_vmcss_on_cpu
> 35030 (d) vmxarea
> 35038 (D) current_vmcs
> 35040 (d) wakeup_vcpus_on_cpu_lock
> 35050 (d) wakeup_vcpus_on_cpu
> 35060 MODULE PERCPU END: kvm_intel
> ffffffffc0aae000 MODULE RO_AFTER_INIT START: kvm_intel
> ffffffffc0ab1720 (D) vmx_capability
> ffffffffc0ab1740 (D) vmcs_config
> crash> sym vmxarea
> 35030 (d) vmxarea [kvm_intel]
>
> Signed-off-by: Kazuhito Hagio <k-hagio-ab at nec.com>
> ---
> symbols.c | 82 ++++++++++++++++++++++++++-----------------------------
> 1 file changed, 38 insertions(+), 44 deletions(-)
>
> diff --git a/symbols.c b/symbols.c
> index 8343081f51f7..40e992e9ee12 100644
> --- a/symbols.c
> +++ b/symbols.c
> @@ -1302,7 +1302,7 @@ symname_hash_search(struct syment *table[], char
> *name)
> static void
> module_symbol_dump(char *module)
> {
> - int i, j, m, start, percpu_syms;
> + int i, j, m;
> struct syment *sp, *sp_end;
> struct load_module *lm;
> const char *p1, *p2;
> @@ -1319,6 +1319,19 @@ module_symbol_dump(char *module)
> if (received_SIGINT() || output_closed())
> return;
>
> + /* The percpu area isn't included in any module memory
> area. */
>
Could you please point out where the percpu area is? That can help us to
understand easily. For example:
The percpu area is included in the .data..percpu section, and not in any
module memory areas.
# objdump -h vmlinux|grep percpu
19 .data..percpu 00035000 0000000000000000 0000000003240000 02600000
2**12
+ if (MODULE_PERCPU_SYMS_LOADED(lm)) {
> + p1 = "MODULE PERCPU START";
> + p2 = lm->mod_name;
> + fprintf(fp, "%lx %s: %s\n", lm->mod_percpu, p1,
> p2);
> +
> + dump_percpu_symbols(lm);
> +
> + p1 = "MODULE PERCPU END";
> + fprintf(fp, "%lx %s: %s\n",
> + lm->mod_percpu + lm->mod_percpu_size, p1,
> p2);
> + }
> +
> for (m = 0; m < lm->nr_mems; m++) {
> j = lm->address_order[m];
>
> @@ -1327,21 +1340,8 @@ module_symbol_dump(char *module)
>
> sp = lm->symtable[j];
> sp_end = lm->symend[j];
> - percpu_syms = 0;
>
> - for (start = FALSE; sp <= sp_end; sp++) {
> - /* TODO
> - if (IN_MODULE_PERCPU(sp->value, lm)) {
> - if (percpu_syms == DISPLAYED)
> - continue;
> - if (!start) {
> - percpu_syms = TBD;
> - continue;
> - }
> - dump_percpu_symbols(lm);
> - percpu_syms = DISPLAYED;
> - }
> - */
> + for ( ; sp <= sp_end; sp++) {
> if (MODULE_PSEUDO_SYMBOL(sp)) {
> if (MODULE_SECTION_START(sp)) {
> p1 = sp->name +
> strlen("_MODULE_SECTION_START ");
> @@ -1352,30 +1352,15 @@ module_symbol_dump(char *module)
> } else if (STRNEQ(sp->name,
> module_start_tags[j])) {
> p1 = module_start_strs[j];
> p2 = sp->name +
> strlen(module_start_tags[j]);
> - start = TRUE;
> } else if (STRNEQ(sp->name,
> module_end_tags[j])) {
> p1 = module_end_strs[j];
> p2 = sp->name +
> strlen(module_end_tags[j]);
> - /* TODO
> - if
> (MODULE_PERCPU_SYMS_LOADED(lm) &&
> - !percpu_syms) {
> -
> dump_percpu_symbols(lm);
> - percpu_syms =
> DISPLAYED;
> - }
> - */
> } else {
> p1 = "unknown tag";
> p2 = sp->name;
> }
>
> fprintf(fp, "%lx %s: %s\n",
> sp->value, p1, p2);
> -
> - /* TODO
> - if (percpu_syms == TBD) {
> - dump_percpu_symbols(lm);
> - percpu_syms = DISPLAYED;
> - }
> - */
> } else
> show_symbol(sp, 0, SHOW_RADIX());
> }
> @@ -1497,8 +1482,14 @@ dump_percpu_symbols(struct load_module *lm)
> struct syment *sp, *sp_end;
>
> if (MODULE_PERCPU_SYMS_LOADED(lm)) {
> - sp = lm->mod_symtable;
> - sp_end = lm->mod_symend;
> + if (MODULE_MEMORY()) {
> + /* The lm should have mod_load_symtable. */
> + sp = lm->mod_load_symtable;
> + sp_end = lm->mod_load_symend;
> + } else {
> + sp = lm->mod_symtable;
> + sp_end = lm->mod_symend;
> + }
> for ( ; sp <= sp_end; sp++) {
> if (IN_MODULE_PERCPU(sp->value, lm))
> show_symbol(sp, 0, SHOW_RADIX());
> @@ -2314,6 +2305,11 @@ store_module_symbols_v3(ulong total, int
> mods_installed)
> if (symbol_query("__insmod_", NULL, NULL))
> st->flags |= INSMOD_BUILTIN;
>
> + if (CRASHDEBUG(2)) {
> + for (sp = st->ext_module_symtable; sp <
> st->ext_module_symend; sp++)
> + fprintf(fp, "%16lx %s\n", sp->value, sp->name);
> + }
> +
> if (mcnt > total)
> error(FATAL, "store_module_symbols_v3: total: %ld mcnt:
> %d\n", total, mcnt);
> }
> @@ -12128,6 +12124,13 @@ store_section_data(struct load_module *lm, bfd
> *bfd, asection *section)
> lm->mod_section_data[i].section = section;
> lm->mod_section_data[i].priority = prio;
> lm->mod_section_data[i].flags = section->flags & ~SEC_FOUND;
> + lm->mod_section_data[i].size = bfd_section_size(section);
> + lm->mod_section_data[i].offset = 0;
> + lm->mod_section_data[i].addr = 0;
>
The variable mod_section_data should be initialized once the memory is
allocated successfully. Here it should set useful values to the member
variables, unless it needs to set the zero for some of the member variables
every time.
Thanks
Lianbo
+ if (strlen(name) < MAX_MOD_SEC_NAME)
> + strcpy(lm->mod_section_data[i].name, name);
> + else
> + strncpy(lm->mod_section_data[i].name, name,
> MAX_MOD_SEC_NAME-1);
> /*
> * The percpu section isn't included in kallsyms or module_core
> area.
> */
> @@ -12135,14 +12138,8 @@ store_section_data(struct load_module *lm, bfd
> *bfd, asection *section)
> (STREQ(name,".data.percpu") || STREQ(name, ".data..percpu"))) {
> lm->mod_percpu_size = bfd_section_size(section);
> lm->mod_section_data[i].flags |= SEC_FOUND;
> + lm->mod_section_data[i].addr = lm->mod_percpu;
> }
> - lm->mod_section_data[i].size = bfd_section_size(section);
> - lm->mod_section_data[i].offset = 0;
> - lm->mod_section_data[i].addr = 0;
> - if (strlen(name) < MAX_MOD_SEC_NAME)
> - strcpy(lm->mod_section_data[i].name, name);
> - else
> - strncpy(lm->mod_section_data[i].name, name,
> MAX_MOD_SEC_NAME-1);
> lm->mod_sections += 1;
> }
>
> @@ -13546,11 +13543,8 @@ append_section_symbols:
> }
> lm->symtable = lm->load_symtable;
> lm->symend = lm->load_symend;
> - for (i = MOD_TEXT; i < MOD_MEM_NUM_TYPES; i++) {
> - if (!lm->symtable[i])
> - continue;
> - mod_symtable_hash_install_range(lm->symtable[i],
> lm->symend[i]);
> - }
> + /* percpu symbols is out of the ranges.. */
> + mod_symtable_hash_install_range(lm->mod_load_symtable,
> lm->mod_load_symend);
> } else {
> mod_symtable_hash_remove_range(lm->mod_symtable,
> lm->mod_symend);
> lm->mod_symtable = lm->mod_load_symtable;
> --
> 2.31.1
>
>
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