On Fri, Jul 24, 2015 at 07:52:15PM +0200, Peter Zijlstra wrote:
> --- a/arch/sparc/include/asm/jump_label.h
> +++ b/arch/sparc/include/asm/jump_label.h
> @@ -7,16 +7,32 @@
>
> #define JUMP_LABEL_NOP_SIZE 4
>
> -static __always_inline bool arch_static_branch(struct static_key *key)
> +static __always_inline bool arch_static_branch(struct static_key *key, bool
> branch)
> {
> - asm_volatile_goto("1:\n\t"
> - "nop\n\t"
> - "nop\n\t"
It just occurred to me that this second nop is a branch delay slot, and
therefore..
> - ".pushsection __jump_table, \"aw\"\n\t"
> - ".align 4\n\t"
> - ".word 1b, %l[l_yes], %c0\n\t"
> - ".popsection \n\t"
> - : : "i" (key) : : l_yes);
> + asm_volatile_goto("1:\n\t"
> + "nop\n\t"
> + "nop\n\t"
> + ".pushsection __jump_table, \"aw\"\n\t"
> + ".align 4\n\t"
> + ".word 1b, %l[l_yes], %c0\n\t"
> + ".popsection \n\t"
> + : : "i" (&((char *)key)[branch]) : : l_yes);
> +
> + return false;
> +l_yes:
> + return true;
> +}
> +
> +static __always_inline bool arch_static_branch_jump(struct static_key *key,
> bool branch)
> +{
> + asm_volatile_goto("1:\n\t"
> + "b %l[l_yes]\n\t"
should very much be here too:
"nop\n\t"
> + ".pushsection __jump_table, \"aw\"\n\t"
> + ".align 4\n\t"
> + ".word 1b, %l[l_yes], %c0\n\t"
> + ".popsection \n\t"
> + : : "i" (&((char *)key)[branch]) : : l_yes);
> +
> return false;
> l_yes:
> return true;
--
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