* Re: [committed, PATCH] Add -mshared option to x86 ELF assembler [not found] ` <CAMe9rOrdqc1v7Dzm3T=CO2a7mVNypOXkAZMFxRMJwwcu61jxGQ@mail.gmail.com> @ 2015-06-01 15:48 ` Andy Lutomirski 2015-06-02 7:41 ` Ingo Molnar 0 siblings, 1 reply; 2+ messages in thread From: Andy Lutomirski @ 2015-06-01 15:48 UTC (permalink / raw) To: H.J. Lu, X86 ML, linux-kernel Cc: Markus Trippelsdorf, Binutils, Andy Lutomirski 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 ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [committed, PATCH] Add -mshared option to x86 ELF assembler 2015-06-01 15:48 ` [committed, PATCH] Add -mshared option to x86 ELF assembler Andy Lutomirski @ 2015-06-02 7:41 ` Ingo Molnar 0 siblings, 0 replies; 2+ messages in thread From: Ingo Molnar @ 2015-06-02 7:41 UTC (permalink / raw) To: Andy Lutomirski Cc: H.J. Lu, X86 ML, linux-kernel, Markus Trippelsdorf, Binutils, Andy Lutomirski, Linus Torvalds, Greg Kroah-Hartman * 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 ^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2015-06-02 7:41 UTC | newest] Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- [not found] <20150515103414.GA20518@intel.com> [not found] ` <20150601083214.GA381@x4> [not found] ` <CAMe9rOrdqc1v7Dzm3T=CO2a7mVNypOXkAZMFxRMJwwcu61jxGQ@mail.gmail.com> 2015-06-01 15:48 ` [committed, PATCH] Add -mshared option to x86 ELF assembler Andy Lutomirski 2015-06-02 7:41 ` Ingo Molnar
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.