[Crash-utility] [RFC PATCH 09/15] Support "sym -n" option

[lijiang]

On Thu, May 11, 2023 at 12:35 PM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab at nec.com>
wrote:

> and fix off-by-one bug in "help -s" output with CRASHDEBUG(1)
>
> Signed-off-by: Kazuhito Hagio <k-hagio-ab at nec.com>
> ---
>  symbols.c | 111 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 109 insertions(+), 2 deletions(-)
>
> diff --git a/symbols.c b/symbols.c
> index 5399c7494cb1..a432909ff28e 100644
> --- a/symbols.c
> +++ b/symbols.c
> @@ -110,6 +110,7 @@ static int module_mem_type(ulong, struct load_module
> *);
>  static ulong module_mem_end(ulong, struct load_module *);
>  static int _in_module_range(ulong, struct load_module *, int, int);
>  struct syment *value_search_module_v2(ulong, ulong *);
> +struct syment *next_module_symbol(char *, struct syment *, ulong);
>
>  static const char *module_start_tags[];
>  static const char *module_start_strs[];
> @@ -4116,9 +4117,9 @@ dump_symbol_table(void)
>
>                 fprintf(fp, "        loaded_objfile: %lx\n",
> (ulong)lm->loaded_objfile);
>
> -               if (CRASHDEBUG(1)) {
> +               if (CRASHDEBUG(1) && lm->mod_load_symtable) {
>                         for (sp = lm->mod_load_symtable;
> -                            sp < lm->mod_load_symend; sp++) {
> +                            sp <= lm->mod_load_symend; sp++) {
>

The real problem might not be here? Some member variables are not properly
initialized?

                                fprintf(fp, "  %lx  %s\n",
>                                         sp->value, sp->name);
>                         }
> @@ -5857,6 +5858,106 @@ closest_symbol_value(ulong value)
>                  return(0);
>  }
>
> +/* Only for 6.4 and later */
> +struct syment *
> +next_module_symbol(char *symbol, struct syment *sp_in, ulong val_in)
> +{
> +       int i, j, k;
> +       struct load_module *lm;
> +       struct syment *sp, *sp_end;
> +
> +       if (symbol)
> +               goto symbol_search;
> +       if (val_in)
> +               goto value_search;
> +
> +       /* for sp_in */
> +       for (i = 0; i < st->mods_installed; i++) {
> +               lm = &st->load_modules[i];
> +
> +               /* quick check: sp_in is not in the module range. */
> +               if (sp_in < lm->symtable[lm->address_order[0]] ||
> +                   sp_in > lm->symend[lm->address_order[lm->nr_mems-1]])
> +                       continue;
> +
> +               for (j = 0; j < lm->nr_mems; j++) {
> +                       k = lm->address_order[j];
> +                       if (sp_in < lm->symtable[k] || sp_in >
> lm->symend[k])
> +                               continue;
> +
> +                       if (sp_in == lm->symend[k])
> +                               return next_module_symbol(NULL, NULL,
> sp_in->value);
> +
>

This means it has to be invoked recursively.

+                       sp = sp_in + 1;
> +                       if (MODULE_PSEUDO_SYMBOL(sp))
> +                               return next_module_symbol(NULL, NULL,
> sp->value);
> +
> +                       return sp;
> +               }
> +       }
> +       return NULL;
> +
> +value_search:
> +       sp = sp_end = NULL;
> +       for (i = 0; i < st->mods_installed; i++) {
> +               lm = &st->load_modules[i];
> +
> +               /* quick check: val_in is higher than the highest in the
> module. */
> +               if (val_in >
> lm->symend[lm->address_order[lm->nr_mems-1]]->value)
> +                       continue;
> +
> +               for (j = 0; j < lm->nr_mems; j++) {
> +                       k = lm->address_order[j];
> +                       if (val_in < lm->symtable[k]->value &&
> +                           (sp == NULL || lm->symtable[k]->value <
> sp->value)) {
> +                               sp = lm->symtable[k];
> +                               sp_end = lm->symend[k];
> +                               break;
> +                       }
> +               }
> +       }
> +       for ( ; sp < sp_end; sp++) {
> +               if (MODULE_PSEUDO_SYMBOL(sp))
> +                       continue;
> +               if (sp->value > val_in)
> +                       return sp;
> +       }
> +       return NULL;
> +
> +symbol_search:
> +       /*
> +        *  Deal with a few special cases...
> +        *
> +        * hmm, looks like crash now does not use these special cases.
> +        *
> +       if (strstr(symbol, " module)")) {
> +                sprintf(buf, "_MODULE_START_");
> +                strcat(buf, &symbol[1]);
> +                p1 = strstr(buf, " module)");
> +                *p1 = NULLCHAR;
> +                symbol = buf;
> +       }
> +
> +       if (STREQ(symbol, "_end")) {
> +               if (!st->mods_installed)
> +                       return NULL;
> +
> +                lm = &st->load_modules[0];
> +
> +               return lm->mod_symtable;
> +       }
> +       */
>

I tried to find the old code, but still did not get the changed history,
and did not see the similar symbols  " module)" in the latest kernel.

The symbol_search code block can be moved to the beginning of this
function, the current code has become very simple, that can avoid the goto
statement.

+        if ((sp = symbol_search(symbol))) {
> +               sp++;
> +               if (MODULE_PSEUDO_SYMBOL(sp) && strstr(sp->name, "_END"))
> +                       return next_module_symbol(NULL, NULL, sp->value);
> +
> +               return sp;
> +       }
> +
> +       return NULL;
> +}
> +
>  /*
>   *  For a given symbol, return a pointer to the next (higher) symbol's
> syment.
>   *  Either a symbol name or syment pointer may be passed as an argument.
> @@ -5886,6 +5987,9 @@ next_symbol(char *symbol, struct syment *sp_in)
>
>                 search_init = FALSE;
>
> +               if (MODULE_MEMORY())
> +                       return next_module_symbol(NULL, sp_in, 0);
> +
>

The above if-code block should be moved before the "search_init = FALSE".

Thanks.
Lianbo

                for (i = 0; i < st->mods_installed; i++) {
>                         lm = &st->load_modules[i];
>                         if (lm->mod_flags & MOD_INIT)
> @@ -5928,6 +6032,9 @@ next_symbol(char *symbol, struct syment *sp_in)
>         }
>
>
> +       if (MODULE_MEMORY())
> +               return next_module_symbol(symbol, NULL, 0);
> +
>         /*
>          *  Deal with a few special cases...
>          */
> --
> 2.31.1
>
>
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