On 2019-04-17 5:01 p.m., Helge Deller wrote: > On 17.04.19 22:58, Helge Deller wrote: >> On 17.04.19 22:55, Sven Schnelle wrote: >>> On Fri, Apr 12, 2019 at 07:12:04PM -0400, John David Anglin wrote: >>>> TLB operations only need to be serialized on machines with the Merced (Stretch) bus. >>>> The only machines in this category are L and N class, and they require a 64-bit PA 2.0 >>>> kernel. On these machines, we use local TLB purges in the tmpalias routines. We don't >>>> need to serialize TLB purges on all other machines. Thus, the lock/unlock code can be >>>> removed when CONFIG_PA20 is not defined. Further, when CONFIG_PA20 is not defined, >>>> alternative patching converts the TLB purges to local purges when PA 2.0 hardware has >>>> been detected. >>>> >>>> Signed-off-by: John David Anglin <dave.anglin@xxxxxxxx> >>> I had this patch running on my C8000 and J5000 for a few days, and haven't >>> encountered any issues. >> Nah... >> I do have one of the critical machines (rp5470), and I tried >> to add the necessary code to detect and handle the TLB serialization. >> Until now the patch sadly doesn't work yet (hangs at boot), it still needs more work. >> You can find it in my git tree: >> https://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux.git/commit/?h=tlb-flush-merced-bus&id=fc6044f83cb9828ec6ebecb23a46549d9ebc518f > Please ignore my comments. > Dave's patch is OK. > > I mixed it up with the Mikulas Patocka's patch: "use per-pagetable spinlock" > https://patchwork.kernel.org/patch/10888249/ I think this hunk needs fixing to handle merced case: diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S index 5796524a3137..3e11fdd9d3af 100644 --- a/arch/parisc/kernel/entry.S +++ b/arch/parisc/kernel/entry.S @@ -48,14 +48,9 @@ .level 2.0 #endif - .import pa_tlb_lock,data - .macro load_pa_tlb_lock reg -#if __PA_LDCW_ALIGNMENT > 4 - load32 PA(pa_tlb_lock) + __PA_LDCW_ALIGNMENT-1, \reg - depi 0,31,__PA_LDCW_ALIGN_ORDER, \reg -#else - load32 PA(pa_tlb_lock), \reg -#endif + .macro load_process_pte_lock reg + mfctl %cr25,\reg + addil L%((PAGE_SIZE << PGD_ALLOC_ORDER) - PAGE_SIZE),\reg .endm /* space_to_prot macro creates a prot id from a space id */ -- John David Anglin dave.anglin@xxxxxxxx
