Messages in this thread | | | From | Andy Lutomirski <> | Date | Mon, 1 Jun 2015 08:48:48 -0700 | Subject | Re: [committed, PATCH] Add -mshared option to x86 ELF assembler |
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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. Alternatively, we could ask Greg et al to backport it.
--Andy
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