Re: [Kgdb-bugreport] module scanning in kgdb 2.x

["Amit S. Kale" <amitkale@emsyssoft.com>]

Hi,

I have checked in this kgdb change and uploaded the gdb to be used with it.
Both kgdb and gdb code for this feature has been contributed by TimeSys 
Corporation.

-Amit


On Friday 12 Mar 2004 12:30 pm, Amit S. Kale wrote:
> The gdb code for this is completely different from the one that works with
> 2.4 kernels. I'll post it at kgdb.sourceforge.net when I checkin this
> change.
>
> -Amit
>
> On Friday 12 Mar 2004 12:06 pm, Amit S. Kale wrote:
> > Hi,
> >
> > Here is code to scan modules in kgdb for 2.6 kernels. It's been
> > contributed by TimeSys Corporation.
> >
> > It does following things:
> > 1. Adds MODULE_STATE_GONE to indicate that a module was removed. This is
> > differnent from MODULE_STATE_GOING. gdb needs to be notified of a module
> > event _after_ a module has been removed. Or else it'll still find the
> > module during a module list scan and will not remove it from its core.
> >
> > 2. Defines a structure mod_section which stores module section names and
> > offsets preserved during loading of a module.
> >
> > 3. Adds a couple of fields to struct module to keep module section
> > information.
> >
> > 4. Adds a few notifications for gdb to know module related events.
> >
> > 5. Saves module section names and offsets in load_module.
> >
> > -Amit
> >
> > Index: linux-2.6.3-kgdb/include/linux/module.h
> > ===================================================================
> > --- linux-2.6.3-kgdb.orig/include/linux/module.h	2004-02-24
> > 10:44:47.000000000 +0530
> > +++ linux-2.6.3-kgdb/include/linux/module.h	2004-03-04 18:58:47.116645760
> > +0530
> > @@ -186,8 +186,17 @@
> >  	MODULE_STATE_LIVE,
> >  	MODULE_STATE_COMING,
> >  	MODULE_STATE_GOING,
> > +	MODULE_STATE_GONE,
> >  };
> >
> > +#ifdef CONFIG_KGDB
> > +#define MAX_SECTNAME 31
> > +struct mod_section {
> > +	void *address;
> > +	char name[MAX_SECTNAME + 1];
> > +};
> > +#endif
> > +
> >  struct module
> >  {
> >  	enum module_state state;
> > @@ -198,6 +207,13 @@
> >  	/* Unique handle for this module */
> >  	char name[MODULE_NAME_LEN];
> >
> > +#ifdef CONFIG_KGDB
> > +	/* keep kgdb info at the begining so that gdb doesn't have a chance to
> > +	 * miss out any fields */
> > +	unsigned long num_sections;
> > +	struct mod_section *mod_sections;
> > +#endif
> > +
> >  	/* Exported symbols */
> >  	const struct kernel_symbol *syms;
> >  	unsigned int num_syms;
> > Index: linux-2.6.3-kgdb/kernel/module.c
> > ===================================================================
> > --- linux-2.6.3-kgdb.orig/kernel/module.c	2004-02-24 10:44:56.000000000
> > +0530 +++ linux-2.6.3-kgdb/kernel/module.c	2004-03-04 18:55:59.136182672
> > +0530 @@ -727,6 +727,11 @@
> >  	mod->state = MODULE_STATE_GOING;
> >  	restart_refcounts();
> >
> > +	down(&notify_mutex);
> > +	notifier_call_chain(&module_notify_list, MODULE_STATE_GOING,
> > +				mod);
> > +	up(&notify_mutex);
> > +
> >  	/* Never wait if forced. */
> >  	if (!forced && module_refcount(mod) != 0)
> >  		wait_for_zero_refcount(mod);
> > @@ -734,6 +739,10 @@
> >  	/* Final destruction now noone is using it. */
> >  	mod->exit();
> >  	free_module(mod);
> > +	down(&notify_mutex);
> > +	notifier_call_chain(&module_notify_list, MODULE_STATE_GONE,
> > +				NULL);
> > +	up(&notify_mutex);
> >
> >   out:
> >  	up(&module_mutex);
> > @@ -1087,6 +1096,11 @@
> >  	/* Arch-specific cleanup. */
> >  	module_arch_cleanup(mod);
> >
> > +#ifdef CONFIG_KGDB
> > +	/* kgdb info */
> > +	vfree(mod->mod_sections);
> > +#endif
> > +
> >  	/* Module unload stuff */
> >  	module_unload_free(mod);
> >
> > @@ -1302,6 +1316,30 @@
> >  	return NULL;
> >  }
> >
> > +#ifdef CONFIG_KGDB
> > +int add_modsects (struct module *mod, Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
> > const +		char *secstrings)
> > +{
> > +	int i;
> > +
> > +	mod->num_sections = hdr->e_shnum - 1;
> > +	mod->mod_sections = vmalloc((hdr->e_shnum - 1)* sizeof (struct
> > mod_section));
> > +
> > +	if (mod->mod_sections == NULL) {
> > +		return -ENOMEM;
> > +	}
> > +
> > +	for (i = 1; i < hdr->e_shnum; i++) {
> > +		mod->mod_sections[i - 1].address = (void *)sechdrs[i].sh_addr;
> > +		strncpy(mod->mod_sections[i - 1].name, secstrings +
> > +				sechdrs[i].sh_name, MAX_SECTNAME);
> > +		mod->mod_sections[i - 1].name[MAX_SECTNAME] = '\0';
> > +	}
> > +
> > +	return 0;
> > +}
> > +#endif
> > +
> >  #ifdef CONFIG_KALLSYMS
> >  int is_exported(const char *name, const struct module *mod)
> >  {
> > @@ -1650,6 +1688,12 @@
> >  	percpu_modcopy(mod->percpu, (void *)sechdrs[pcpuindex].sh_addr,
> >  		       sechdrs[pcpuindex].sh_size);
> >
> > +#ifdef CONFIG_KGDB
> > +	if ((err = add_modsects(mod, hdr, sechdrs, secstrings)) < 0) {
> > +		goto nomodsectinfo;
> > +	}
> > +#endif
> > +
> >  	err = module_finalize(hdr, sechdrs, mod);
> >  	if (err < 0)
> >  		goto cleanup;
> > @@ -1688,6 +1732,11 @@
> >   arch_cleanup:
> >  	module_arch_cleanup(mod);
> >   cleanup:
> > +
> > +#ifdef CONFIG_KGDB
> > +nomodsectinfo:
> > +	vfree(mod->mod_sections);
> > +#endif
> >  	module_unload_free(mod);
> >  	module_free(mod, mod->module_init);
> >   free_core:
> > @@ -1758,7 +1807,12 @@
> >  	if (ret < 0) {
> >  		/* Init routine failed: abort.  Try to protect us from
> >                     buggy refcounters. */
> > +
> >  		mod->state = MODULE_STATE_GOING;
> > +		down(&notify_mutex);
> > +		notifier_call_chain(&module_notify_list, MODULE_STATE_GOING,
> > +					mod);
> > +		up(&notify_mutex);
> >  		synchronize_kernel();
> >  		if (mod->unsafe)
> >  			printk(KERN_ERR "%s: module is now stuck!\n",
> >
> >
> >
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