| From: | Nathan Bossart <nathandbossart(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Mats Kindahl <mats(at)timescale(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)lists(dot)postgresql(dot)org |
| Subject: | Re: glibc qsort() vulnerability |
| Date: | 2024-02-08 01:52:11 |
| Message-ID: | 20240208015211.GA445153@nathanxps13 |
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| Thread: | |
| Lists: | pgsql-hackers |
On Wed, Feb 07, 2024 at 04:42:07PM -0800, Andres Freund wrote:
> On 2024-02-07 16:21:24 -0600, Nathan Bossart wrote:
>> The assembly for that looks encouraging, but I still need to actually test
>> it...
>
> Possible. For 16bit upcasting to 32bit is clearly the best way. For 32 bit
> that doesn't work, given the 32bit return, so we need something more.
For the same compASC() test, I see an ~8.4% improvement with your int64
code and a ~3.4% improvement with this:
int
compASC(const void *a, const void *b)
{
int result;
if (unlikely(pg_sub_s32_overflow(*(const int32 *) a,
*(const int32 *) b,
&result)))
{
if (*(const int32 *) a > *(const int32 *) b)
return 1;
if (*(const int32 *) a < *(const int32 *) b)
return -1;
return 0;
}
return result;
}
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com
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