LGTM!
On Fri, Aug 18, 2017 at 8:16 AM, Dave Watson <davejwat...@fb.com> wrote:
> Repro for a multilib binary on host x86_64:
>
> CFLAGS="-m32" LDFLAGS="-m32" ./configure --enable-debug --
> host=i686-pc-linux-gnu --target=i686-pc-linux-gnu --libdur=/usr/lib32
> --prefix=/usr --disable-documentation
>
> make check
>
> Gtest-init function fails trying to step through libc_start_main. The CFA
> function is:
>
> DW_CFA_def_cfa_offset: 112
> DW_CFA_advance_loc: 5 to ...643
> DW_CFA_restore state
>
> Where the return address is 643.
>
> Generally, it appears we apply all ip <= end_ip, which is incorrect in
> some circumstances.
>
> libgcc only applies ip < end_ip + is_signal_frame, but that seems to break
> async signal handling
> tests in libunwind for unknown reasons.
>
> This is somewhat simlar to the fix in e9e8ed73e for GNU_args_size,
> where the same ip check was added.
> ---
> src/dwarf/Gparser.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/src/dwarf/Gparser.c b/src/dwarf/Gparser.c
> index e8eaeac8..9d405e76 100644
> --- a/src/dwarf/Gparser.c
> +++ b/src/dwarf/Gparser.c
> @@ -289,8 +289,10 @@ run_cfi_program (struct dwarf_cursor *c,
> dwarf_state_record_t *sr,
> ret = -UNW_EINVAL;
> break;
> }
> - memcpy (&sr->rs_current, &(*rs_stack)->state, sizeof
> (sr->rs_current));
> - pop_rstate_stack(rs_stack);
> + if (*ip < end_ip) {
> + memcpy (&sr->rs_current, &(*rs_stack)->state, sizeof
> (sr->rs_current));
> + pop_rstate_stack(rs_stack);
> + }
> Debug (15, "CFA_restore_state\n");
> break;
>
> --
> 2.13.5
>
>
--
Saleem Abdulrasool
compnerd (at) compnerd (dot) org
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