* [PATCH LP-BUILD-TOOLS] Allow patching files compiled multiple times
@ 2018-02-23 17:08 Ross Lagerwall
2018-03-05 10:32 ` Ross Lagerwall
0 siblings, 1 reply; 3+ messages in thread
From: Ross Lagerwall @ 2018-02-23 17:08 UTC (permalink / raw)
To: xen-devel; +Cc: Ross Lagerwall
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 */
} else if (curfile)
curfile = NULL; /* end hint file symbols */
}
+ last_type = other;
if (!curfile)
continue;
if (sym->bind == STB_LOCAL && !strcmp(sym->name, name)) {
--
2.9.5
_______________________________________________
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Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH LP-BUILD-TOOLS] Allow patching files compiled multiple times
2018-02-23 17:08 [PATCH LP-BUILD-TOOLS] Allow patching files compiled multiple times Ross Lagerwall
@ 2018-03-05 10:32 ` Ross Lagerwall
2018-03-05 20:01 ` Konrad Rzeszutek Wilk
0 siblings, 1 reply; 3+ messages in thread
From: Ross Lagerwall @ 2018-03-05 10:32 UTC (permalink / raw)
To: xen-devel
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 */
> } 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?
--
Ross Lagerwall
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH LP-BUILD-TOOLS] Allow patching files compiled multiple times
2018-03-05 10:32 ` Ross Lagerwall
@ 2018-03-05 20:01 ` Konrad Rzeszutek Wilk
0 siblings, 0 replies; 3+ messages in thread
From: Konrad Rzeszutek Wilk @ 2018-03-05 20:01 UTC (permalink / raw)
To: Ross Lagerwall; +Cc: xen-devel
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
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
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2018-02-23 17:08 [PATCH LP-BUILD-TOOLS] Allow patching files compiled multiple times Ross Lagerwall
2018-03-05 10:32 ` Ross Lagerwall
2018-03-05 20:01 ` Konrad Rzeszutek Wilk
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