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x86: Check PT_GNU_PROPERTY early

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The PT_GNU_PROPERTY segment is scanned before PT_NOTE.  For binaries
with the PT_GNU_PROPERTY segment, we can check it to avoid scan of
the PT_NOTE segment.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
This commit is contained in:
H.J. Lu 2023-12-07 13:05:39 -08:00
parent 7e03e0de7e
commit 4753e92868
1 changed files with 80 additions and 40 deletions
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120
sysdeps/x86/dl-prop.h
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@ -81,6 +81,60 @@ _dl_open_check (struct link_map *m)
#endif
}
/* Check the GNU property and return its value. It returns:
-1: Skip this note.
0: Stop checking.
1: Continue to check.
*/
static inline int
_dl_check_gnu_property (unsigned int type, unsigned int datasz,
void *ptr, unsigned int *feature_1_and,
unsigned int *needed_1,
unsigned int *isa_1_needed)
{
if (type == GNU_PROPERTY_X86_FEATURE_1_AND
|| type == GNU_PROPERTY_X86_ISA_1_NEEDED
|| type == GNU_PROPERTY_1_NEEDED)
{
/* The sizes of types which we are searching for are
4 bytes. There is no point to continue if this
note is ill-formed. */
if (datasz != 4)
return -1;
/* NB: Stop the scan only after seeing all types which
we are searching for. */
_Static_assert (((GNU_PROPERTY_X86_ISA_1_NEEDED
> GNU_PROPERTY_X86_FEATURE_1_AND)
&& (GNU_PROPERTY_X86_FEATURE_1_AND
> GNU_PROPERTY_1_NEEDED)),
"GNU_PROPERTY_X86_ISA_1_NEEDED > "
"GNU_PROPERTY_X86_FEATURE_1_AND && "
"GNU_PROPERTY_X86_FEATURE_1_AND > "
"GNU_PROPERTY_1_NEEDED");
if (type == GNU_PROPERTY_X86_FEATURE_1_AND)
*feature_1_and = *(unsigned int *) ptr;
else if (type == GNU_PROPERTY_1_NEEDED)
*needed_1 = *(unsigned int *) ptr;
else
{
*isa_1_needed = *(unsigned int *) ptr;
/* Keep searching for the next GNU property note
generated by the older linker. */
return 0;
}
}
else if (type > GNU_PROPERTY_X86_ISA_1_NEEDED)
{
/* Stop the scan since property type is in ascending
order. */
return 0;
}
return 1;
}
static inline void __attribute__ ((unused))
_dl_process_property_note (struct link_map *l, const ElfW(Nhdr) *note,
const ElfW(Addr) size, const ElfW(Addr) align)
@ -141,45 +195,14 @@ _dl_process_property_note (struct link_map *l, const ElfW(Nhdr) *note,
last_type = type;
if (type == GNU_PROPERTY_X86_FEATURE_1_AND
|| type == GNU_PROPERTY_X86_ISA_1_NEEDED
|| type == GNU_PROPERTY_1_NEEDED)
{
/* The sizes of types which we are searching for are
4 bytes. There is no point to continue if this
note is ill-formed. */
if (datasz != 4)
return;
/* NB: Stop the scan only after seeing all types which
we are searching for. */
_Static_assert (((GNU_PROPERTY_X86_ISA_1_NEEDED
> GNU_PROPERTY_X86_FEATURE_1_AND)
&& (GNU_PROPERTY_X86_FEATURE_1_AND
> GNU_PROPERTY_1_NEEDED)),
"GNU_PROPERTY_X86_ISA_1_NEEDED > "
"GNU_PROPERTY_X86_FEATURE_1_AND && "
"GNU_PROPERTY_X86_FEATURE_1_AND > "
"GNU_PROPERTY_1_NEEDED");
if (type == GNU_PROPERTY_X86_FEATURE_1_AND)
feature_1_and = *(unsigned int *) ptr;
else if (type == GNU_PROPERTY_1_NEEDED)
needed_1 = *(unsigned int *) ptr;
else
{
isa_1_needed = *(unsigned int *) ptr;
/* Keep searching for the next GNU property note
generated by the older linker. */
break;
}
}
else if (type > GNU_PROPERTY_X86_ISA_1_NEEDED)
{
/* Stop the scan since property type is in ascending
order. */
break;
}
int result = _dl_check_gnu_property (type, datasz, ptr,
&feature_1_and,
&needed_1,
&isa_1_needed);
if (result == -1)
return; /* Skip this note. */
else if (result == 0)
break; /* Stop checking. */
/* Check the next property item. */
ptr += ALIGN_UP (datasz, sizeof (ElfW(Addr)));
@ -217,7 +240,24 @@ static inline int __attribute__ ((always_inline))
_dl_process_gnu_property (struct link_map *l, int fd, uint32_t type,
uint32_t datasz, void *data)
{
return 0;
/* This is called on each GNU property. */
unsigned int needed_1 = 0;
unsigned int feature_1_and = 0;
unsigned int isa_1_needed = 0;
int result = _dl_check_gnu_property (type, datasz, data,
&feature_1_and, &needed_1,
&isa_1_needed);
if (needed_1 != 0)
l->l_1_needed = needed_1;
if (isa_1_needed != 0)
l->l_x86_isa_1_needed = isa_1_needed;
if (feature_1_and != 0)
l->l_x86_feature_1_and = feature_1_and;
if ((needed_1 | isa_1_needed | feature_1_and) != 0)
l->l_property = lc_property_valid;
else if (l->l_property == lc_property_unknown)
l->l_property = lc_property_none;
return result <= 0 ? 0 : result;
}
#endif /* _DL_PROP_H */