904646 - GDB doesn't see shared libraries from custom linker on Android 4.3

Status: RESOLVED FIXED

(Core :: mozglue, defect)

Description

[(inactive) Jim Chen [:jchen] [:darchons]]

On Android 4.3, the envp/auxv stack layout is slightly different: there are two NULLs between the envp pointers and the auxv pointers. As a result, the custom linker fails to insert its shared libraries into the DT_DEBUG list, and GDB doesn't see them.

Comment 1

[(inactive) Jim Chen [:jchen] [:darchons]]

Attachment: Skip second NULL when traversing envp/auxv pointers to let GDB work on Android 4.3 (v1)

This patch fixes the bug for me.

Comment 2

[Mike Hommey [:glandium]]

Comment on attachment 789619 [details] [diff] [review]
Skip second NULL when traversing envp/auxv pointers to let GDB work on Android 4.3 (v1)

Review of attachment 789619 [details] [diff] [review]:
-----------------------------------------------------------------

::: mozglue/linker/ElfLoader.cpp
@@ +589,5 @@
>     * thus the first auxiliary vector. */
>    while (*scan++);
> +
> +  /* Some platforms have a second NULL here, so skip it if we encounter it */
> +  if (!*scan)

How about while(!*scan++); ? (in case we end up with even more NULLs)

Comment 3

[(inactive) Jim Chen [:jchen] [:darchons]]

Attachment: Skip NULLs when traversing envp/auxv pointers to let GDB work on Android 4.3 (v2)

Okay, this will skip over all NUlls (if any).

Comment 4

[(inactive) Jim Chen [:jchen] [:darchons]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/c218913f49b2

Comment 5

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/c218913f49b2