Re: [RFC PATCH v3 6/7] scripts/sorttable: Add ORC unwind tables sort concurrently

[Shile Zhang]

On 2019/11/15 17:19, Peter Zijlstra wrote:
> On Fri, Nov 15, 2019 at 02:47:49PM +0800, Shile Zhang wrote:
>
> > @@ -141,21 +306,44 @@ static int do_sort(Elf_Ehdr *ehdr,
> >   		if (r(&s->sh_type) == SHT_SYMTAB_SHNDX)
> >   			symtab_shndx = (Elf32_Word *)((const char *)ehdr +
> >   						      _r(&s->sh_offset));
> > -	}
> >   
> > +#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
> > +		/* locate the ORC unwind tables */
> > +		if (!strcmp(secstrings + idx, ".orc_unwind_ip")) {
> > +			orctable.orc_ip_size = s->sh_size;
> > +			g_orc_ip_table = (int *)((void *)ehdr +
> > +						   s->sh_offset);
> > +		}
> > +		if (!strcmp(secstrings + idx, ".orc_unwind")) {
> > +			orctable.orc_size = s->sh_size;
> > +			g_orc_table = (struct orc_entry *)((void *)ehdr +
> > +							     s->sh_offset);
> > +		}
> > +#endif
> > +	} /* for loop */
> > +
> > +#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
> Maybe something like:
>
> 	if (g_orc_table && g_orc_ip_table) {
> 		 if (pthread_create(...))
> 		...
> 	} else if (g_orc_table || g_orc_up_table) {
> 		fprintf(stderr, "incomplete ORC tables...\n");
> 	}
>
> > +	/* create thread to sort ORC unwind tables concurrently */
> > +	if (pthread_create(&orc_sort_thread, NULL, sort_orctable, &orctable)) {
> > +		fprintf(stderr,
> > +			"pthread_create orc_sort_thread failed '%s': %s\n",
> > +			strerror(errno), fname);
> > +		goto out;
> > +	}
> > +#endif
> >   	if (!extab_sec) {
> >   		fprintf(stderr,	"no __ex_table in file: %s\n", fname);
> > -		return -1;
> > +		goto out;
> >   	}
> >   
> >   	if (!symtab_sec) {
> >   		fprintf(stderr,	"no .symtab in file: %s\n", fname);
> > -		return -1;
> > +		goto out;
> >   	}
> >   
> >   	if (!strtab_sec) {
> >   		fprintf(stderr,	"no .strtab in file: %s\n", fname);
> > -		return -1;
> > +		goto out;
> >   	}
> >   
> >   	extab_image = (void *)ehdr + _r(&extab_sec->sh_offset);
> > @@ -192,7 +380,7 @@ static int do_sort(Elf_Ehdr *ehdr,
> >   		fprintf(stderr,
> >   			"no main_extable_sort_needed symbol in file: %s\n",
> >   			fname);
> > -		return -1;
> > +		goto out;
> >   	}
> >   
> >   	sort_needed_sec = &shdr[get_secindex(r2(&sym->st_shndx),
> > @@ -205,6 +393,20 @@ static int do_sort(Elf_Ehdr *ehdr,
> >   
> >   	/* extable has been sorted, clear the flag */
> >   	w(0, sort_needed_loc);
> > +	rc = 0;
> >   
> > -	return 0;
> > +out:
> > +#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
> > +	{ /* to avoid gcc warning about declaration */
> > +	void *retval = NULL;
> and then here:
>
> 	if (orc_sort_thread) {
> 		void *retval = NULL;
> 		pthread_join(...);
> 		...
> 	}


Thank you for your kindly advice! I'll change it in next version.

> > +
> > +	/* wait for ORC tables sort done */
> > +	pthread_join(orc_sort_thread, &retval);
> > +	if (retval) {
> > +		fprintf(stderr, "%s in file: %s\n", (char *)retval, fname);
> > +		rc = -1;
> > +	}
> > +	}
> > +#endif
> > +	return rc;
> >   }