[PATCH 3.16 243/366] ARC: Fix CONFIG_SWAP

Ben Hutchings
2018-11-11T20:32:45Z

From: Alexey Brodkin <abrodkin@synopsys.com>

commit 6e3761145a9ba3ce267c330b6bff51cf6a057b06 upstream.

swap was broken on ARC due to silly copy-paste issue.

We encode offset from swapcache page in __swp_entry() as (off << 13) but
were not decoding back in __swp_offset() as (off >> 13) - it was still
(off << 13).

This finally fixes swap usage on ARC.

| # mkswap /dev/sda2
|
| # swapon -a -e /dev/sda2
| Adding 500728k swap on /dev/sda2. Priority:-2 extents:1 across:500728k
|
| # free
| total used free shared buffers cached
| Mem: 765104 13456 751648 4736 8 4736
| -/+ buffers/cache: 8712 756392
| Swap: 500728 0 500728

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/arc/include/asm/pgtable.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arc/include/asm/pgtable.h
+++ b/arch/arc/include/asm/pgtable.h
@@ -361,7 +361,7 @@ void update_mmu_cache(struct vm_area_str

/* Decode a PTE containing swap "identifier "into constituents */
#define __swp_type(pte_lookalike) (((pte_lookalike).val) & 0x1f)
-#define __swp_offset(pte_lookalike) ((pte_lookalike).val << 13)
+#define __swp_offset(pte_lookalike) ((pte_lookalike).val >> 13)

/* NOPs, to keep generic kernel happy */
#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })