[Crash-utility] Re: [RFC] Provide minimal debugging to crash

[Dave Anderson]

Sharyathi Nagesh wrote:
> Dave
>    I have done the suggested modifications, have a look

This one looks pretty good.  I made a couple minor tweaks for the unhandled
command entry error-handling, the minimal commands message, and for a clean
compile.  Other than that, it's queued for the next release.

Thanks,
   Dave


>>
>> I haven't walked through all the restricted command list code paths to
>> verify that they can work properly for all architectures without, say,
>> kernel_init(), the 3 machdep_init() calls, vm_init() etc. having run.
>> Certainly trying to rd or dis vmalloc addresses would display garbage
>> data or just fail, but that's to be expected.
>>
>> I quickly tried this on a x86 and x86_64 -- but have you tried this on
>> an ia64 or ppc64?
> I tested on ppc64 and on corrupted dump and it worked fine
>>
>> The only thing I'm not excited about is all the re-tinkering with the
>> help screen output.  Why bother?  I'd prefer to keep things simple.
>> During initialization, display a WARNING message that lists the supported
>> commands just prior to the first prompt.  And then just leave the help
>> screen alone, and let your command-restriction mechanism display the
>> per-command message:
>>
>>   error(INFO, "command: %s not available in minimal mode\n", args[0]);
>> ...and then perhaps followed up immediately with the acceptable command
>> list again.
> I have done this code change
>>
>> Another minor suggestion -- I think you can put the "eval" command in
>> the supported list.  I use it all the time, and in this minimal 
>> environment
>> it may come in very handy.  (There may be others, but they're probably 
>> not
>> worth having...)
> allowed eval to be executed in minimal mode
> 
> Thanks
> Yeehaw
> 
> 
> 
> 
> ------------------------------------------------------------------------
> 
> Signed-off-by: Sharyathi Nagesh  <sharyath at in.ibm.com>
> Signed-off-by: Sachin P Sant 	 <sachinp at in.ibm.com>
> ---
> 
> diff -Naurp crash-old/cmdline.c crash-new/cmdline.c
> --- crash-old/cmdline.c	2008-03-31 22:58:31.000000000 +0530
> +++ crash-new/cmdline.c	2008-08-18 09:25:21.000000000 +0530
> @@ -2137,3 +2137,11 @@ wait_for_children(ulong waitflag)
>  		stall(1000);
>  	}
>  }
> +
> +int minimal_functions(char *name)
> +{
> +	return  STREQ("log", name) || STREQ("help",name) || \
> +		STREQ("dis", name) || STREQ("q", name)   || \
> +		STREQ("sym", name) || STREQ("exit", name)|| \
> +		STREQ("rd", name)  || STREQ("eval", name) ; 
> +}
> diff -Naurp crash-old/defs.h crash-new/defs.h
> --- crash-old/defs.h	2008-03-31 22:58:31.000000000 +0530
> +++ crash-new/defs.h	2008-08-04 13:36:23.000000000 +0530
> @@ -183,6 +183,7 @@ struct number_option {
>  #define PLEASE_WAIT   (0x200000000000000ULL)
>  #define IFILE_ERROR   (0x400000000000000ULL)
>  #define KERNTYPES     (0x800000000000000ULL)
> +#define MINIMAL_MODE (0x1000000000000000ULL)
>  
>  #define ACTIVE()            (pc->flags & LIVE_SYSTEM)
>  #define DUMPFILE()          (!(pc->flags & LIVE_SYSTEM))
> @@ -3129,6 +3130,7 @@ int received_SIGINT(void);
>  void debug_redirect(char *);
>  int CRASHPAGER_valid(void);
>  char *setup_scroll_command(void);
> +int minimal_functions(char *);
>  
>  /*
>   *  tools.c
> diff -Naurp crash-old/main.c crash-new/main.c
> --- crash-old/main.c	2008-08-18 11:50:38.000000000 +0530
> +++ crash-new/main.c	2008-08-18 11:54:31.000000000 +0530
> @@ -56,6 +56,7 @@ static struct option long_options[] = {
>          {"no_scroll", 0, 0, 0},
>          {"reloc", required_argument, 0, 0},
>  	{"active", 0, 0, 0},
> +	{"minimal", 0, 0, 0},
>          {0, 0, 0, 0}
>  };
>  
> @@ -197,6 +198,9 @@ main(int argc, char **argv)
>  				kt->flags |= RELOC_SET;
>  			}
>  
> +			else if (STREQ(long_options[option_index].name, "minimal")) 
> +				pc->flags |= MINIMAL_MODE;
> +
>  			else {
>  				error(INFO, "internal error: option %s unhandled\n",
>  					long_options[option_index].name);
> @@ -492,7 +496,7 @@ main_loop(void)
>  #else
>          		error(FATAL, XEN_HYPERVISOR_NOT_SUPPORTED);
>  #endif
> -		} else {
> +		} else if(!(pc->flags & MINIMAL_MODE)){
>  			read_in_kernel_config(IKCFG_INIT);
>  			kernel_init();
>  			machdep_init(POST_GDB);
> @@ -520,7 +524,7 @@ main_loop(void)
>  #else
>          		error(FATAL, XEN_HYPERVISOR_NOT_SUPPORTED);
>  #endif
> -		} else {
> +		} else if(!(pc->flags & MINIMAL_MODE)){
>  			display_sys_stats();
>  			show_context(CURRENT_CONTEXT());
>  		}
> @@ -528,6 +532,11 @@ main_loop(void)
>          }
>  
>          pc->flags |= RUNTIME;
> +	
> +	if(pc->flags & MINIMAL_MODE){
> +            error(WARNING, "In minimal mode you have access to only these \n \ 
> +		commands: 'log', 'dis', 'rd','sym', 'eval' and 'exit' \n");
> +	}
>  
>  	/*
>  	 *  Return here if a non-recoverable error occurs
> @@ -610,7 +619,14 @@ reattempt:
>  		return;
>  
>  	pc->curcmd = pc->program_name;
> -	error(INFO, "command not found: %s\n", args[0]);
> +	if (!(pc->flags & MINIMAL_MODE)) 
> +		error(INFO, "command not found: %s\n", args[0]);
> +	else{
> +		error(INFO, 
> +		"command: %s not available in minimal mode\n", args[0]);
> +		error(INFO, 
> +		"supported commands:'log', 'dis', 'rd', 'sym', 'eval', 'exit' \n");
> +	}
>  
>  	if (pc->curcmd_flags & REPEAT)
>  		pc->curcmd_flags &= ~REPEAT;
> @@ -625,6 +641,9 @@ get_command_table_entry(char *name)
>  {       
>          struct command_table_entry *cp;
>          struct extension_table *ext;
> +	
> +	if ((pc->flags & MINIMAL_MODE) && !minimal_functions(name)) 
> +		return NULL;
>    
>  	for (cp = pc->cmd_table; cp->name; cp++) {
>                  if (STREQ(cp->name, name))