This is the mail archive of the
mailing list for the glibc project.
Re: [PATCH] x86-64: Implement strcpy family IFUNC selectors in C
- From: Zack Weinberg <zackw at panix dot com>
- To: libc-alpha at sourceware dot org
- Date: Sun, 11 Jun 2017 10:01:42 -0400
- Subject: Re: [PATCH] x86-64: Implement strcpy family IFUNC selectors in C
- Authentication-results: sourceware.org; auth=none
- References: <20170611135042.GA22931@gmail.com>
On 06/11/2017 09:50 AM, H.J. Lu wrote:
> Implement strcpy family IFUNC selectors in C.
> All internal calls within libc.so can use IFUNC on x86-64 since unlike
> x86, x86-64 doesn't need to reserve a register to make a PLT call. For
> libc,a, we can't use IFUNC for functions which are called before IFUNC
> has been initialized. Use IFUNC internally reduces the icache footprint
> since libc.so and other codes in the process use the same implementations.
> The patch uses IFUNC for strcpy family functions within libc.
> Any comments?
I like the idea, but I don't understand ifuncs nearly well enough to
comment on your code. I recall _strenuous_ objections to this concept
in the past; please post some performance numbers or something.