[Crash-utility] [PATCH 2/2] dis: Report duplicate symbols

[Dave Anderson]

----- Original Message -----
> Notify the user if there is more than one symbol of the given target.
> 
> For example, after this patch:
> 
> - The 'dis' command now reports that more than one symbol of "watchdog"
>   exists, to allow the user to be more specific
> 
>   crash> dis watchdog
>   duplicate symbols found: watchdog
>   ffffffff810e6100 (t) watchdog
>   /usr/src/debug/kernel-2.6.32-431.1.2.el6/linux-2.6.32-431.1.2.el6.x86_64/kernel/hung_task.c:
>   199
>   ffffffff810e6990 (t) watchdog
>   /usr/src/debug/kernel-2.6.32-431.1.2.el6/linux-2.6.32-431.1.2.el6.x86_64/kernel/watchdog.c:
>   332
>   ffffffff81eb3fc8 (b) watchdog
> 
> - Choose to disassemble the watchdog() function defined in
>   kernel/watchdog.c by using the address of the first function
> 
>   crash> dis ffffffff810e6990
>   0xffffffff810e6990 <watchdog>:	push   %rbp
>   0xffffffff810e6991 <watchdog+1>:	mov    %rsp,%rbp
>   0xffffffff810e6994 <watchdog+4>:	push   %r13
>   0xffffffff810e699d <watchdog+13>:	nopl   0x0(%rax,%rax,1)
>   ...
> 
> Signed-off-by: Aaron Tomlin <atomlin at redhat.com>

Hi Aaron,

Good plan.  

But is there any particular reason for adding "show_flags"?  Since the symbol
passed to show_symbol() will never have an offset, it doesn't make any difference
to save and use the incoming radix, as opposed to the -x|d override, or for that
matter, nothing.

Dave


> ---
>  defs.h    |  1 +
>  kernel.c  | 28 ++++++++++++++++++++++++----
>  symbols.c |  3 +--
>  3 files changed, 26 insertions(+), 6 deletions(-)
> 
> diff --git a/defs.h b/defs.h
> index f21137d..26aa963 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -4585,6 +4585,7 @@ void show_symbol(struct syment *, ulong, ulong);
>  #define SHOW_DEC_OFFS (0x8)
>  #define SHOW_RADIX() (*gdb_output_radix == 16 ? SHOW_HEX_OFFS :
>  SHOW_DEC_OFFS)
>  #define SHOW_MODULE  (0x10)
> +int symbol_name_count(char *);
>  int symbol_query(char *, char *, struct syment **);
>  struct syment *next_symbol(char *, struct syment *);
>  struct syment *prev_symbol(char *, struct syment *);
> diff --git a/kernel.c b/kernel.c
> index 628779c..b87d9ec 100644
> --- a/kernel.c
> +++ b/kernel.c
> @@ -1339,6 +1339,7 @@ cmd_dis(void)
>  	ulong revtarget;
>  	ulong count;
>  	ulong offset;
> +	ulong show_flags;
>  	struct syment *sp;
>  	struct gnu_request *req;
>  	char *savename;
> @@ -1362,6 +1363,7 @@ cmd_dis(void)
>  	sp = NULL;
>  	unfiltered = user_mode = do_machdep_filter = do_load_module_filter = 0;
>  	radix = 0;
> +	show_flags = SHOW_LINENUM | SHOW_RADIX();
>  
>  	req = (struct gnu_request *)getbuf(sizeof(struct gnu_request));
>  	req->buf = GETBUF(BUFSIZE);
> @@ -1425,7 +1427,28 @@ cmd_dis(void)
>  		radix = pc->output_radix;
>  
>          if (args[optind]) {
> -                if (can_eval(args[optind]))
> +		if ((sp = symbol_search(args[optind])) &&
> +		    ((symbol_name_count(sp->name)) > 1)) {
> +                        fprintf(fp, "duplicate symbols found: %s\n",
> +			    args[optind]);
> +
> +			do {
> +				if (module_symbol(sp->value, NULL, NULL,
> +				    NULL, 0))
> +					show_symbol(sp, 0, show_flags|SHOW_MODULE);
> +				else
> +					show_symbol(sp, 0, show_flags);
> +
> +			} while ((sp = symbol_search_next(sp->name, sp)));
> +
> +			FREEBUF(req->buf);
> +			FREEBUF(req);
> +			return;
> +		}
> +		if (sp) {
> +			req->addr = sp->value;
> +			req->flags |= GNU_FUNCTION_ONLY;
> +		} else if (can_eval(args[optind]))
>                          req->addr = eval(args[optind], FAULT_ON_ERROR,
>                          NULL);
>                  else if (hexadecimal(args[optind], 0)) {
>                          req->addr = htol(args[optind], FAULT_ON_ERROR,
>                          NULL);
> @@ -1438,9 +1461,6 @@ cmd_dis(void)
>  			}
>  			if (!offset)
>  				req->flags |= GNU_FUNCTION_ONLY;
> -                } else if ((sp = symbol_search(args[optind]))) {
> -                        req->addr = sp->value;
> -			req->flags |= GNU_FUNCTION_ONLY;
>  		} else {
>                          fprintf(fp, "symbol not found: %s\n", args[optind]);
>                          fprintf(fp, "possible alternatives:\n");
> diff --git a/symbols.c b/symbols.c
> index 48d9f58..958181a 100644
> --- a/symbols.c
> +++ b/symbols.c
> @@ -37,7 +37,6 @@ static asection *get_kernel_section(char *);
>  static char * get_section(ulong vaddr, char *buf);
>  static void symbol_dump(ulong, char *);
>  static void check_for_dups(struct load_module *);
> -static int symbol_name_count(char *);
>  static struct syment *kallsyms_module_symbol(struct load_module *,
>  symbol_info *);
>  static void store_load_module_symbols \
>  	(bfd *, int, void *, long, uint, ulong, char *);
> @@ -4156,7 +4155,7 @@ symbol_search(char *s)
>  /*
>   *  Count the number of instances of a symbol name.
>   */
> -static int
> +int
>  symbol_name_count(char *s)
>  {
>          int i;
> --
> 2.4.3
> 
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