Messages in this thread | | | Date | Tue, 2 Jun 2015 09:41:12 +0200 | From | Ingo Molnar <> | Subject | Re: [committed, PATCH] Add -mshared option to x86 ELF assembler |
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* Andy Lutomirski <luto@amacapital.net> wrote:
> On Mon, Jun 1, 2015 at 4:05 AM, H.J. Lu <hjl.tools@gmail.com> wrote: > > On Mon, Jun 1, 2015 at 1:32 AM, Markus Trippelsdorf > > <markus@trippelsdorf.de> wrote: > >> On 2015.05.15 at 03:34 -0700, H.J. Lu wrote: > >>> This patch adds -mshared option to x86 ELF assembler. By default, > >>> assembler will optimize out non-PLT relocations against defined non-weak > >>> global branch targets with default visibility. The -mshared option tells > >>> the assembler to generate code which may go into a shared library > >>> where all non-weak global branch targets with default visibility can > >>> be preempted. The resulting code is slightly bigger. This option > >>> only affects the handling of branch instructions. > >>> > >>> This Linux kernel patch is needed to create a working x86 Linux kernel if > >>> it hasn't been applied: > >>> > >>> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S > >>> index ae6588b..b91a00c 100644 > >>> --- a/arch/x86/kernel/head_64.S > >>> +++ b/arch/x86/kernel/head_64.S > >>> @@ -339,8 +339,8 @@ early_idt_handlers: > >>> i = i + 1 > >>> .endr > >>> > >>> -/* This is global to keep gas from relaxing the jumps */ > >>> -ENTRY(early_idt_handler) > >>> +/* This is weak to keep gas from relaxing the jumps */ > >>> +WEAK(early_idt_handler) > >>> cld > >> > >> Have you posted the patch to LKML already? > >> (I hit this issue today and it took me a while to figure out the cause.) > > > > A kernel patch will be checked in soon. > > > > It already is: > > https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/commit/?h=x86/asm&id=cdeb6048940fa4bfb429e2f1cba0d28a11e20cd5 > > It's currently queued for 4.2. > > Ingo, would it make sense to promote this to 4.1? It's definitely a violation > of the "no development after the merge window" rule, but it's sort of a build > fix. [...]
Yeah, agreed - the commit was problem-free in testing, so I've cherry-picked it over into tip:x86/urgent and will push it to Linus for v4.1.
Thanks,
Ingo
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