Re: [PATCH LP-BUILD-TOOLS] Allow patching files compiled multiple times

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Mon, Mar 05, 2018 at 10:32:51AM +0000, Ross Lagerwall wrote:
> On 02/23/2018 05:08 PM, Ross Lagerwall wrote:
> > gas prior to binutils commit fbdf9406b0 (appears in 2.27) outputs symbol
> > table entries resulting from .file in reverse order. If we get two
> > consecutive file symbols, prefer the first one if that names an object
> > file or has a directory component (to cover multiply compiled files).
> > 
> > This is the same workaround that was applied in Xen commit d37d63d4b548
> > ("symbols: prefix static symbols with their source file names") for
> > Xen's internal symbol table.
> > 
> > This fixes building a livepatch for XSA-243.
> > ---
> >   lookup.c | 18 ++++++++++++++++++
> >   1 file changed, 18 insertions(+)
> > 
> > diff --git a/lookup.c b/lookup.c
> > index 39125c6..645b91a 100644
> > --- a/lookup.c
> > +++ b/lookup.c
> > @@ -149,16 +149,34 @@ int lookup_local_symbol(struct lookup_table *table, char *name, char *hint,
> >   	struct symbol *sym, *match = NULL;
> >   	int i;
> >   	char *curfile = NULL;
> > +	enum { other, multi_source } last_type = other;
> >   	memset(result, 0, sizeof(*result));
> >   	for_each_symbol(i, sym, table) {
> >   		if (sym->type == STT_FILE) {
> > +			const char *ext = strrchr(sym->name, '.');
> > +			int multi = strchr(sym->name, '/') ||
> > +				    (ext && ext[1] == 'o');
> > +
> > +			/*
> > +			 * gas prior to binutils commit fbdf9406b0 (appears in
> > +			 * 2.27) outputs symbol table entries resulting from
> > +			 * .file in reverse order. If we get two consecutive
> > +			 * file symbols, prefer the first one if that names an
> > +			 * object file or has a directory component (to cover
> > +			 * multiply compiled files).
> > +			 */
> > +			if (last_type == multi_source)
> > +				continue;
> > +
> >   			if (!strcmp(sym->name, hint)) {
> >   				curfile = sym->name;
> > +				last_type = multi ? multi_source : other;
> >   				continue; /* begin hint file symbols */

Perhaps add some logging as well?
> >   			} else if (curfile)
> >   				curfile = NULL; /* end hint file symbols */
> >   		}
> > +		last_type = other;
> >   		if (!curfile)
> >   			continue;
> >   		if (sym->bind == STB_LOCAL && !strcmp(sym->name, name)) {
> > 
> 
> Ping, Konrad?

This looks familiar, but how come it has no SoB?

> 
> -- 
> Ross Lagerwall

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