From: Rich Felker <dalias@libc.org>
To: musl@lists.openwall.com
Subject: Re: another armv7-m exception handling problem
Date: Mon, 21 Oct 2019 01:04:11 -0400 [thread overview]
Message-ID: <20191021050411.GE16318@brightrain.aerifal.cx> (raw)
In-Reply-To: <CAEg67GnC-DMqkMOUs+3uEnetac_L52ehpALxq8oyS_9kg9RJtw@mail.gmail.com>
On Mon, Oct 21, 2019 at 03:43:40PM +1100, Patrick Oppenlander wrote:
> Not sure if this is a musl, gcc or ld bug.
>
> Running gcc-8.3.0 musl 1.1.24 static pie.
>
> Simple test case:
>
> int main()
> {
> try {
> throw 1;
> } catch (int d) {
> return d;
> }
> return 0;
> }
>
> Expected:
> % ./a.out
> % echo $?
> 1
>
> Actual:
> % ./a.out
> terminate called after throwing an instance of 'int'
> terminate called recursively
> Aborted (core dumped)
>
> The problem is that get_eit_entry is returning _URC_FAILURE here:
>
> if (__gnu_Unwind_Find_exidx)
> {
> eitp = (const __EIT_entry *) __gnu_Unwind_Find_exidx (return_address,
> &nrec);
> if (!eitp)
> {
> UCB_PR_ADDR (ucbp) = 0;
> return _URC_FAILURE; <----- !!!!
> }
> }
>
> Looks like a linker or program load problem to me -- the GOT entry for
> __gnu_Unwind_Find_exidx is correctly set to 0, but after program load
> it's been offset to some non-zero value. There's an R_ARM_RELATIVE
> relocation on the GOT entry.
>
> Not sure where this is going wrong.
OK, this is almost surely a bug in the tooling -- a weak reference has
to use a GOT slot in PIC since it might be undefined and need to
evaluate to 0, and the GOT slot should not have a relocation on it if
it ends up evaluating to 0. Pretty sure it's ld's fault.
Rich
next prev parent reply other threads:[~2019-10-21 5:04 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-21 4:43 Patrick Oppenlander
2019-10-21 5:04 ` Rich Felker [this message]
2019-10-21 5:20 ` Rich Felker
2019-10-21 5:34 ` Patrick Oppenlander
2019-10-21 5:38 ` Rich Felker
2019-10-21 5:51 ` Patrick Oppenlander
2019-10-21 18:09 ` Szabolcs Nagy
2019-10-21 19:03 ` Rich Felker
2019-10-21 19:08 ` Szabolcs Nagy
2019-10-21 19:29 ` Rich Felker
2020-01-10 10:22 ` Szabolcs Nagy
2020-01-11 6:20 ` Patrick Oppenlander
2019-10-21 21:17 ` Patrick Oppenlander
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