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Re: [Xen-devel] [PATCH v5 09/14] jump_label: port __jump_table to linker tables
- To: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
- From: "Luis R. Rodriguez" <mcgrof@xxxxxxxxxx>
- Date: Tue, 3 Jan 2017 22:27:44 +0100
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- Delivery-date: Tue, 03 Jan 2017 21:28:00 +0000
- List-id: Xen developer discussion <xen-devel.lists.xen.org>
On Thu, Dec 22, 2016 at 04:08:22PM +0200, Andy Shevchenko wrote:
> On Wed, 2016-12-21 at 18:38 -0800, Luis R. Rodriguez wrote:
> > Move the __jump_table from the a custom section solution
> > to a generic solution, this avoiding extra vmlinux.lds.h
> > customizations.
> >
> > This also demos the use of the .data linker table and of
> > the shared asm call push_section_tbl().
> >
>
> > {
> > asm_volatile_goto("1:\n\t"
> > WASM(nop) "\n\t"
> > - ".pushsection __jump_table, \"aw\"\n\t"
> > + push_section_tbl_any(.data, __jump_table, aw)
> > ".word 1b, %l[l_yes], %c0\n\t"
> > ".popsection\n\t"
> > : : "i" (&((char *)key)[branch]) : : l_yes);
> > @@ -26,7 +28,7 @@ static __always_inline bool
> > arch_static_branch_jump(struct static_key *key, bool
> > {
> > asm_volatile_goto("1:\n\t"
> > WASM(b) " %l[l_yes]\n\t"
> > - ".pushsection __jump_table, \"aw\"\n\t"
> > + push_section_tbl_any(.data, __jump_table, aw)
> > ".word 1b, %l[l_yes], %c0\n\t"
> > ".popsection\n\t"
>
> Does it make sense to introduce something like
>
> #define pop_section_tbl ".popsection\n\t"
> #define pop_section_tbl_any pop_section_tbl
Absolutely ! However this would be an evolution, and I would much
prefer to add this later as an atomic step later to enable other
users to also be using this shared macro. I did not have an immediate
need for a pop_section_tbl() macro as its not section specific.
Luis
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