lkml.org 
[lkml]   [2018]   [Nov]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH RFC 0/3] Static calls
On 11 November 2018 at 00:20, Peter Zijlstra <peterz@infradead.org> wrote:
> On Fri, Nov 09, 2018 at 02:50:27PM +0100, Ard Biesheuvel wrote:
>> On 9 November 2018 at 08:28, Ingo Molnar <mingo@kernel.org> wrote:
>> >> - I'm not sure about the objtool approach. Objtool is (currently)
>> >> x86-64 only, which means we have to use the "unoptimized" version
>> >> everywhere else. I may experiment with a GCC plugin instead.
>> >
>> > I'd prefer the objtool approach. It's a pretty reliable first-principles
>> > approach while GCC plugin would have to be replicated for Clang and any
>> > other compilers, etc.
>> >
>>
>> I implemented the GCC plugin approach here for arm64
>
> I'm confused; I though we only needed objtool for variable instruction
> length architectures, because we can't reliably decode our instruction
> stream. Otherwise we can fairly trivially use the DWARF relocation data,
> no?

How would that work? We could build vmlinux with --emit-relocs, filter
out the static jump/call relocations and resolve the symbol names to
filter the ones associated with calls to trampolines. But then, we
have to build the static_call_sites section and reinject it back into
the image in some way, which is essentially objtool, no?

\
 
 \ /
  Last update: 2018-11-11 14:43    [W:0.096 / U:0.940 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site