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Re: glibc 2.19 - asyn-signal safe TLS and ASan.
- From: Kostya Serebryany <kcc at google dot com>
- To: Paul Pluzhnikov <ppluzhnikov at google dot com>
- Cc: OndÅej BÃlka <neleai at seznam dot cz>, "Joseph S. Myers" <joseph at codesourcery dot com>, Andrew Hunter <ahh at google dot com>, "Carlos O'Donell" <carlos at redhat dot com>, GNU C Library <libc-alpha at sourceware dot org>, Roland McGrath <roland at hack dot frob dot com>, address-sanitizer at googlegroups dot com
- Date: Mon, 27 Jan 2014 19:47:31 +0400
- Subject: Re: glibc 2.19 - asyn-signal safe TLS and ASan.
- Authentication-results: sourceware.org; auth=none
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On Mon, Jan 27, 2014 at 7:37 PM, Paul Pluzhnikov <ppluzhnikov@google.com> wrote:
> On Mon, Jan 27, 2014 at 5:37 AM, Kostya Serebryany <kcc@google.com> wrote:
>
>>> > How do I "export" __signal_safe_memalign? (I/d like to experiment myself)
>>> You'll need this snippet of above patch: (line 61,5):
>>
>> Paul, I tried this:
>>
>> --- a/elf/Versions
>> +++ b/elf/Versions
>> @@ -62,5 +62,8 @@ ld {
>>
>> # Pointer protection.
>> __pointer_chk_guard;
>> + # for signal safe TLS
>> + __signal_safe_malloc; __signal_safe_free; __signal_safe_memalign;
>> + __signal_safe_realloc; __signal_safe_calloc;
>> }
>> }
>>
>> it did not help: "nm libc.so | grep signal_safe_memalign" is empty.
>
> It probably did. I believe these functions are defined and used in
> 'ld.so', so try 'nm ld.so | grep signal_safe'.
Indeed so, thanks!
So, exporting __signal_safe_memalign&co will allow us to extend the
existing hack to 2.19.
If this simple change can not be done for 2.19, can *anything* be done at all?
(Long term we'd still prefer something less hackish)
--kcc
>
>
> --
> Paul Pluzhnikov