runtime: remove sys.HugePageSize

sys.HugePageSize was superceded in the last commit by physHugePageSize
which is determined dynamically by querying the operating system.

For #30333.

Change-Id: I827bfca8bdb347e989cead31564a8fffe56c66ff
Reviewed-on: https://go-review.googlesource.com/c/go/+/173757
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

src/runtime/internal/sys/arch_386.go

@@ -10,7 +10,6 @@ const (
 	DefaultPhysPageSize = GoosNacl*65536 + (1-GoosNacl)*4096 // 4k normally; 64k on NaCl
 	PCQuantum           = 1
 	Int64Align          = 4
-	HugePageSize        = 1 << 21
 	MinFrameSize        = 0
 )
 

src/runtime/internal/sys/arch_amd64.go

@@ -10,7 +10,6 @@ const (
 	DefaultPhysPageSize = 4096
 	PCQuantum           = 1
 	Int64Align          = 8
-	HugePageSize        = 1 << 21
 	MinFrameSize        = 0
 )
 

src/runtime/internal/sys/arch_amd64p32.go

@@ -10,7 +10,6 @@ const (
 	DefaultPhysPageSize = 65536*GoosNacl + 4096*(1-GoosNacl)
 	PCQuantum           = 1
 	Int64Align          = 8
-	HugePageSize        = 1 << 21
 	MinFrameSize        = 0
 )
 

src/runtime/internal/sys/arch_arm.go

@@ -10,7 +10,6 @@ const (
 	DefaultPhysPageSize = 65536
 	PCQuantum           = 4
 	Int64Align          = 4
-	HugePageSize        = 0
 	MinFrameSize        = 4
 )
 

src/runtime/internal/sys/arch_arm64.go

@@ -10,7 +10,6 @@ const (
 	DefaultPhysPageSize = 65536
 	PCQuantum           = 4
 	Int64Align          = 8
-	HugePageSize        = 0
 	MinFrameSize        = 8
 )
 

src/runtime/internal/sys/arch_mips.go

@@ -10,7 +10,6 @@ const (
 	DefaultPhysPageSize = 65536
 	PCQuantum           = 4
 	Int64Align          = 4
-	HugePageSize        = 0
 	MinFrameSize        = 4
 )
 

src/runtime/internal/sys/arch_mips64.go

@@ -10,7 +10,6 @@ const (
 	DefaultPhysPageSize = 16384
 	PCQuantum           = 4
 	Int64Align          = 8
-	HugePageSize        = 0
 	MinFrameSize        = 8
 )
 

src/runtime/internal/sys/arch_mips64le.go

@@ -10,7 +10,6 @@ const (
 	DefaultPhysPageSize = 16384
 	PCQuantum           = 4
 	Int64Align          = 8
-	HugePageSize        = 0
 	MinFrameSize        = 8
 )
 

src/runtime/internal/sys/arch_mipsle.go

@@ -10,7 +10,6 @@ const (
 	DefaultPhysPageSize = 65536
 	PCQuantum           = 4
 	Int64Align          = 4
-	HugePageSize        = 0
 	MinFrameSize        = 4
 )
 

src/runtime/internal/sys/arch_ppc64.go

@@ -10,7 +10,6 @@ const (
 	DefaultPhysPageSize = 65536
 	PCQuantum           = 4
 	Int64Align          = 8
-	HugePageSize        = 0
 	MinFrameSize        = 32
 )
 

src/runtime/internal/sys/arch_ppc64le.go

@@ -10,7 +10,6 @@ const (
 	DefaultPhysPageSize = 65536
 	PCQuantum           = 4
 	Int64Align          = 8
-	HugePageSize        = 0
 	MinFrameSize        = 32
 )
 

src/runtime/internal/sys/arch_s390x.go

@@ -10,7 +10,6 @@ const (
 	DefaultPhysPageSize = 4096
 	PCQuantum           = 2
 	Int64Align          = 8
-	HugePageSize        = 0
 	MinFrameSize        = 8
 )
 

src/runtime/internal/sys/arch_wasm.go

@@ -10,7 +10,6 @@ const (
 	DefaultPhysPageSize = 65536
 	PCQuantum           = 1
 	Int64Align          = 8
-	HugePageSize        = 0
 	MinFrameSize        = 0
 )
 

src/runtime/mem_linux.go

@@ -6,7 +6,6 @@ package runtime
 
 import (
 	"runtime/internal/atomic"
-	"runtime/internal/sys"
 	"unsafe"
 )
 
@@ -63,37 +62,35 @@ func sysUnused(v unsafe.Pointer, n uintptr) {
 	// gets most of the benefit of huge pages while keeping the
 	// number of VMAs under control. With hugePageSize = 2MB, even
 	// a pessimal heap can reach 128GB before running out of VMAs.
-	if sys.HugePageSize != 0 {
-		var s uintptr = sys.HugePageSize // division by constant 0 is a compile-time error :(
-
+	if physHugePageSize != 0 {
 		// If it's a large allocation, we want to leave huge
 		// pages enabled. Hence, we only adjust the huge page
 		// flag on the huge pages containing v and v+n-1, and
 		// only if those aren't aligned.
 		var head, tail uintptr
-		if uintptr(v)%s != 0 {
+		if uintptr(v)%physHugePageSize != 0 {
 			// Compute huge page containing v.
-			head = uintptr(v) &^ (s - 1)
+			head = uintptr(v) &^ (physHugePageSize - 1)
 		}
-		if (uintptr(v)+n)%s != 0 {
+		if (uintptr(v)+n)%physHugePageSize != 0 {
 			// Compute huge page containing v+n-1.
-			tail = (uintptr(v) + n - 1) &^ (s - 1)
+			tail = (uintptr(v) + n - 1) &^ (physHugePageSize - 1)
 		}
 
 		// Note that madvise will return EINVAL if the flag is
 		// already set, which is quite likely. We ignore
 		// errors.
-		if head != 0 && head+sys.HugePageSize == tail {
+		if head != 0 && head+physHugePageSize == tail {
 			// head and tail are different but adjacent,
 			// so do this in one call.
-			madvise(unsafe.Pointer(head), 2*sys.HugePageSize, _MADV_NOHUGEPAGE)
+			madvise(unsafe.Pointer(head), 2*physHugePageSize, _MADV_NOHUGEPAGE)
 		} else {
 			// Advise the huge pages containing v and v+n-1.
 			if head != 0 {
-				madvise(unsafe.Pointer(head), sys.HugePageSize, _MADV_NOHUGEPAGE)
+				madvise(unsafe.Pointer(head), physHugePageSize, _MADV_NOHUGEPAGE)
 			}
 			if tail != 0 && tail != head {
-				madvise(unsafe.Pointer(tail), sys.HugePageSize, _MADV_NOHUGEPAGE)
+				madvise(unsafe.Pointer(tail), physHugePageSize, _MADV_NOHUGEPAGE)
 			}
 		}
 	}
@@ -120,7 +117,7 @@ func sysUnused(v unsafe.Pointer, n uintptr) {
 }
 
 func sysUsed(v unsafe.Pointer, n uintptr) {
-	if sys.HugePageSize != 0 {
+	if physHugePageSize != 0 {
 		// Partially undo the NOHUGEPAGE marks from sysUnused
 		// for whole huge pages between v and v+n. This may
 		// leave huge pages off at the end points v and v+n
@@ -129,12 +126,11 @@ func sysUsed(v unsafe.Pointer, n uintptr) {
 		// the end points as well, but it's probably not worth
 		// the cost because when neighboring allocations are
 		// freed sysUnused will just set NOHUGEPAGE again.
-		var s uintptr = sys.HugePageSize
 
 		// Round v up to a huge page boundary.
-		beg := (uintptr(v) + (s - 1)) &^ (s - 1)
+		beg := (uintptr(v) + (physHugePageSize - 1)) &^ (physHugePageSize - 1)
 		// Round v+n down to a huge page boundary.
-		end := (uintptr(v) + n) &^ (s - 1)
+		end := (uintptr(v) + n) &^ (physHugePageSize - 1)
 
 		if beg < end {
 			madvise(unsafe.Pointer(beg), end-beg, _MADV_HUGEPAGE)