From 7a8bc7172b17e219b3603e99c8da44efb283e652 Mon Sep 17 00:00:00 2001 From: David Goldblatt Date: Fri, 29 Sep 2017 13:54:08 -0700 Subject: [PATCH] ARM: Don't extend bit LG_VADDR to compute high address bits. In userspace ARM on Linux, zero-ing the high bits is the correct way to do this. This doesn't fix the fact that we currently set LG_VADDR to 48 on ARM, when in fact larger virtual address sizes are coming soon. We'll cross that bridge when we come to it. --- include/jemalloc/internal/rtree.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/include/jemalloc/internal/rtree.h b/include/jemalloc/internal/rtree.h index b5d4db39..4563db23 100644 --- a/include/jemalloc/internal/rtree.h +++ b/include/jemalloc/internal/rtree.h @@ -178,9 +178,21 @@ rtree_leaf_elm_bits_read(tsdn_t *tsdn, rtree_t *rtree, rtree_leaf_elm_t *elm, JEMALLOC_ALWAYS_INLINE extent_t * rtree_leaf_elm_bits_extent_get(uintptr_t bits) { +# ifdef __aarch64__ + /* + * aarch64 doesn't sign extend the highest virtual address bit to set + * the higher ones. Instead, the high bits gets zeroed. + */ + uintptr_t high_bit_mask = ((uintptr_t)1 << LG_VADDR) - 1; + /* Mask off the slab bit. */ + uintptr_t low_bit_mask = ~(uintptr_t)1; + uintptr_t mask = high_bit_mask & low_bit_mask; + return (extent_t *)(bits & mask); +# else /* Restore sign-extended high bits, mask slab bit. */ return (extent_t *)((uintptr_t)((intptr_t)(bits << RTREE_NHIB) >> RTREE_NHIB) & ~((uintptr_t)0x1)); +# endif } JEMALLOC_ALWAYS_INLINE szind_t