ARC: [ASID] Track ASID allocation cycles/generations
This helps remove asid-to-mm reverse map
While mm->context.id contains the ASID assigned to a process, our ASID
allocator also used asid_mm_map[] reverse map. In a new allocation
cycle (mm->ASID >= @asid_cache), the Round Robin ASID allocator used this
to check if new @asid_cache belonged to some mm2 (from prev cycle).
If so, it could locate that mm using the ASID reverse map, and mark that
mm as unallocated ASID, to force it to refresh at the time of switch_mm()
However, for SMP, the reverse map has to be maintained per CPU, so
becomes 2 dimensional, hence got rid of it.
With reverse map gone, it is NOT possible to reach out to current
assignee. So we track the ASID allocation generation/cycle and
on every switch_mm(), check if the current generation of CPU ASID is
same as mm's ASID; If not it is refreshed.
(Based loosely on arch/sh implementation)
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/mm/tlb.c b/arch/arc/mm/tlb.c
index b5c5e0a..71cb26d 100644
--- a/arch/arc/mm/tlb.c
+++ b/arch/arc/mm/tlb.c
@@ -100,13 +100,7 @@
/* A copy of the ASID from the PID reg is kept in asid_cache */
-int asid_cache = FIRST_ASID;
-
-/* ASID to mm struct mapping. We have one extra entry corresponding to
- * NO_ASID to save us a compare when clearing the mm entry for old asid
- * see get_new_mmu_context (asm-arc/mmu_context.h)
- */
-struct mm_struct *asid_mm_map[NUM_ASID + 1];
+unsigned int asid_cache = MM_CTXT_FIRST_CYCLE;
/*
* Utility Routine to erase a J-TLB entry
@@ -281,7 +275,6 @@
unsigned long end)
{
unsigned long flags;
- unsigned int asid;
/* If range @start to @end is more than 32 TLB entries deep,
* its better to move to a new ASID rather than searching for
@@ -303,11 +296,10 @@
start &= PAGE_MASK;
local_irq_save(flags);
- asid = vma->vm_mm->context.asid;
- if (asid != NO_ASID) {
+ if (vma->vm_mm->context.asid != MM_CTXT_NO_ASID) {
while (start < end) {
- tlb_entry_erase(start | (asid & 0xff));
+ tlb_entry_erase(start | hw_pid(vma->vm_mm));
start += PAGE_SIZE;
}
}
@@ -361,9 +353,8 @@
*/
local_irq_save(flags);
- if (vma->vm_mm->context.asid != NO_ASID) {
- tlb_entry_erase((page & PAGE_MASK) |
- (vma->vm_mm->context.asid & 0xff));
+ if (vma->vm_mm->context.asid != MM_CTXT_NO_ASID) {
+ tlb_entry_erase((page & PAGE_MASK) | hw_pid(vma->vm_mm));
utlb_invalidate();
}
@@ -709,7 +700,8 @@
* - SW needs to have a valid ASID
*/
if (addr < 0x70000000 &&
- ((mmu_asid != mm_asid) || (mm_asid == NO_ASID)))
+ ((mm_asid == MM_CTXT_NO_ASID) ||
+ (mmu_asid != (mm_asid & MM_CTXT_ASID_MASK))))
print_asid_mismatch(mm_asid, mmu_asid, 0);
}
#endif