| Message ID | 871qioapgh.fsf@oldenburg3.str.redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | libgcc: Fix eh_frame fast path in find_fde_tail | expand |
On Tue, Jun 6, 2023 at 11:53 AM Florian Weimer via Gcc-patches <gcc-patches@gcc.gnu.org> wrote: > > The eh_frame value is only used by linear_search_fdes, not the binary > search directly in find_fde_tail, so the bug is not immediately > apparent with most programs. > > Fixes commit e724b0480bfa5ec04f39be8c7290330b495c59de ("libgcc: > Special-case BFD ld unwind table encodings in find_fde_tail"). OK. > [I'd appreciate suggestions how I could add a test for this. BFD ld > does not seem to allow ommitting the binary search table.] > > libgcc/ > > PR libgcc/109712 > * unwind-dw2-fde-dip.c (find_fde_tail): Correct fast path for > parsing eh_frame. > > --- > libgcc/unwind-dw2-fde-dip.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/libgcc/unwind-dw2-fde-dip.c b/libgcc/unwind-dw2-fde-dip.c > index 6223f5f18a2..4e0b880513f 100644 > --- a/libgcc/unwind-dw2-fde-dip.c > +++ b/libgcc/unwind-dw2-fde-dip.c > @@ -403,8 +403,8 @@ find_fde_tail (_Unwind_Ptr pc, > BFD ld generates. */ > signed value __attribute__ ((mode (SI))); > memcpy (&value, p, sizeof (value)); > + eh_frame = p + value; > p += sizeof (value); > - dbase = value; /* No adjustment because pcrel has base 0. */ > } > else > p = read_encoded_value_with_base (hdr->eh_frame_ptr_enc, > > base-commit: b327cbe8f4eefc91ee2bea49a1da7128adf30281 >
diff --git a/libgcc/unwind-dw2-fde-dip.c b/libgcc/unwind-dw2-fde-dip.c index 6223f5f18a2..4e0b880513f 100644 --- a/libgcc/unwind-dw2-fde-dip.c +++ b/libgcc/unwind-dw2-fde-dip.c @@ -403,8 +403,8 @@ find_fde_tail (_Unwind_Ptr pc, BFD ld generates. */ signed value __attribute__ ((mode (SI))); memcpy (&value, p, sizeof (value)); + eh_frame = p + value; p += sizeof (value); - dbase = value; /* No adjustment because pcrel has base 0. */ } else p = read_encoded_value_with_base (hdr->eh_frame_ptr_enc,
The eh_frame value is only used by linear_search_fdes, not the binary search directly in find_fde_tail, so the bug is not immediately apparent with most programs. Fixes commit e724b0480bfa5ec04f39be8c7290330b495c59de ("libgcc: Special-case BFD ld unwind table encodings in find_fde_tail"). [I'd appreciate suggestions how I could add a test for this. BFD ld does not seem to allow ommitting the binary search table.] libgcc/ PR libgcc/109712 * unwind-dw2-fde-dip.c (find_fde_tail): Correct fast path for parsing eh_frame. --- libgcc/unwind-dw2-fde-dip.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) base-commit: b327cbe8f4eefc91ee2bea49a1da7128adf30281