diff options
Diffstat (limited to 'src/runtime/lfstack_64bit.go')
| -rw-r--r-- | src/runtime/lfstack_64bit.go | 32 |
1 files changed, 19 insertions, 13 deletions
diff --git a/src/runtime/lfstack_64bit.go b/src/runtime/lfstack_64bit.go index 07c2a141f0..8180b0a248 100644 --- a/src/runtime/lfstack_64bit.go +++ b/src/runtime/lfstack_64bit.go @@ -2,26 +2,32 @@ // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. -// +build arm64 mips64 mips64le ppc64 ppc64le +// +build arm64 mips64 mips64le ppc64 ppc64le s390x package runtime import "unsafe" -// On ppc64, Linux limits the user address space to 46 bits (see -// TASK_SIZE_USER64 in the Linux kernel). This has grown over time, -// so here we allow 48 bit addresses. -// -// On mips64, Linux limits the user address space to 40 bits (see -// TASK_SIZE64 in the Linux kernel). This has grown over time, -// so here we allow 48 bit addresses. -// -// In addition to the 16 bits taken from the top, we can take 3 from the -// bottom, because node must be pointer-aligned, giving a total of 19 bits -// of count. const ( + // addrBits is the number of bits needed to represent a virtual address. + // + // In Linux the user address space for each architecture is limited as + // follows (taken from the processor.h file for the architecture): + // + // Architecture Name Maximum Value (exclusive) + // --------------------------------------------------------------------- + // arm64 TASK_SIZE_64 Depends on configuration. + // ppc64{,le} TASK_SIZE_USER64 0x400000000000UL (46 bit addresses) + // mips64{,le} TASK_SIZE64 0x010000000000UL (40 bit addresses) + // s390x TASK_SIZE 0x020000000000UL (41 bit addresses) + // + // These values may increase over time. addrBits = 48 - cntBits = 64 - addrBits + 3 + + // In addition to the 16 bits taken from the top, we can take 3 from the + // bottom, because node must be pointer-aligned, giving a total of 19 bits + // of count. + cntBits = 64 - addrBits + 3 ) func lfstackPack(node *lfnode, cnt uintptr) uint64 { |