[[PATCH 1/2] MIPS: Replace some magic numbers with symbolic values in tlbex.c] On 13/05/2009 (Wed 13:48) David Daney wrote:
> The logic used to split the r4000 refill handler is liberally
> sprinkled with magic numbers. We attempt to explain what they are and
> normalize them against a new symbolic value (MIPS64_REFILL_INSNS).
>
> CC: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
> CC: David VomLehn <dvomlehn@xxxxxxxxx>
> Signed-off-by: David Daney <ddaney@xxxxxxxxxxxxxxxxxx>
> ---
> arch/mips/mm/tlbex.c | 34 ++++++++++++++++++++++++++--------
> 1 files changed, 26 insertions(+), 8 deletions(-)
>
> diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
> index 4dc4f3e..d99ed78 100644
> --- a/arch/mips/mm/tlbex.c
> +++ b/arch/mips/mm/tlbex.c
> @@ -649,6 +649,14 @@ static void __cpuinit build_update_entries(u32 **p, unsigned int tmp,
> #endif
> }
>
> +/*
> + * For a 64-bit kernel, we are using the 64-bit XTLB refill execption
"exception"
-- aside from that, I've double checked that the changes should be inert
(excluding the improved readability). You can add a:
Reviewed-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
if you want, or given that it really isn't a complex patch, feel free
to reduce the clutter and no need to mention me at all. Your choice.
Thanks for the cleanup,
Paul.
> + * because EXL == 0. If we wrap, we can also use the 32 instruction
> + * slots before the XTLB refill exception handler which belong to the
> + * unused TLB refill exception.
> + */
> +#define MIPS64_REFILL_INSNS 32
> +
> static void __cpuinit build_r4000_tlb_refill_handler(void)
> {
> u32 *p = tlb_handler;
> @@ -702,9 +710,10 @@ static void __cpuinit build_r4000_tlb_refill_handler(void)
> if ((p - tlb_handler) > 64)
> panic("TLB refill handler space exceeded");
> #else
> - if (((p - tlb_handler) > 63)
> - || (((p - tlb_handler) > 61)
> - && uasm_insn_has_bdelay(relocs, tlb_handler + 29)))
> + if (((p - tlb_handler) > (MIPS64_REFILL_INSNS * 2) - 1)
> + || (((p - tlb_handler) > (MIPS64_REFILL_INSNS * 2) - 3)
> + && uasm_insn_has_bdelay(relocs,
> + tlb_handler + MIPS64_REFILL_INSNS - 3)))
> panic("TLB refill handler space exceeded");
> #endif
>
> @@ -717,16 +726,24 @@ static void __cpuinit build_r4000_tlb_refill_handler(void)
> uasm_copy_handler(relocs, labels, tlb_handler, p, f);
> final_len = p - tlb_handler;
> #else /* CONFIG_64BIT */
> - f = final_handler + 32;
> - if ((p - tlb_handler) <= 32) {
> + f = final_handler + MIPS64_REFILL_INSNS;
> + if ((p - tlb_handler) <= MIPS64_REFILL_INSNS) {
> /* Just copy the handler. */
> uasm_copy_handler(relocs, labels, tlb_handler, p, f);
> final_len = p - tlb_handler;
> } else {
> - u32 *split = tlb_handler + 30;
> + /*
> + * Split two instructions before the end. One for the
> + * branch and one for the instruction in the delay
> + * slot.
> + */
> + u32 *split = tlb_handler + MIPS64_REFILL_INSNS - 2;
>
> /*
> - * Find the split point.
> + * Find the split point. If the branch would fall in
> + * a delay slot, we must back up an additional
> + * instruction so that it is no longer in a delay
> + * slot.
> */
> if (uasm_insn_has_bdelay(relocs, split - 1))
> split--;
> @@ -749,7 +766,8 @@ static void __cpuinit build_r4000_tlb_refill_handler(void)
>
> /* Copy the rest of the handler. */
> uasm_copy_handler(relocs, labels, split, p, final_handler);
> - final_len = (f - (final_handler + 32)) + (p - split);
> + final_len = (f - (final_handler + MIPS64_REFILL_INSNS)) +
> + (p - split);
> }
> #endif /* CONFIG_64BIT */
>
> --
> 1.6.0.6
>
