From 1e3c19f3fee12e5e2b7802a54908a4d4d03960da Mon Sep 17 00:00:00 2001
From: Dmitry Vyukov <dvyukov@google.com>
Date: Fri, 27 May 2022 18:55:35 +0200
Subject: [PATCH] runtime: support riscv64 SV57 mode
riscv64 has SV57 mode when user-space VA is 56 bits.
Linux kernel recently got support for this mode and Go binaries started crashing as:
runtime: lfstack.push invalid packing: node=0xffffff5908a940 cnt=0x1
packed=0xffff5908a9400001 -> node=0xffff5908a940
Adjust lfstack code to use only 8 top bits of pointers on riscv64.
For context see:
https://groups.google.com/g/syzkaller-bugs/c/lU0GQTZoNQQ/m/O_c3vmE3AAAJ
Update #54104
Change-Id: Ib5d3d6a79c0c6eddf11618d73fcc8bc1832a9c25
Reviewed-on: https://go-review.googlesource.com/c/go/+/409055
Reviewed-by: Joel Sing <joel@sing.id.au>
Reviewed-by: Meng Zhuo <mzh@golangcn.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
---
src/runtime/lfstack_64bit.go | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/src/runtime/lfstack_64bit.go b/src/runtime/lfstack_64bit.go
index 154130cf63b..88cbd3bcc7e 100644
--- a/src/runtime/lfstack_64bit.go
+++ b/src/runtime/lfstack_64bit.go
@@ -36,12 +36,21 @@ const (
// We use one bit to distinguish between the two ranges.
aixAddrBits = 57
aixCntBits = 64 - aixAddrBits + 3
+
+ // riscv64 SV57 mode gives 56 bits of userspace VA.
+ // lfstack code supports it, but broader support for SV57 mode is incomplete,
+ // and there may be other issues (see #54104).
+ riscv64AddrBits = 56
+ riscv64CntBits = 64 - riscv64AddrBits + 3
)
func lfstackPack(node *lfnode, cnt uintptr) uint64 {
if GOARCH == "ppc64" && GOOS == "aix" {
return uint64(uintptr(unsafe.Pointer(node)))<<(64-aixAddrBits) | uint64(cnt&(1<<aixCntBits-1))
}
+ if GOARCH == "riscv64" {
+ return uint64(uintptr(unsafe.Pointer(node)))<<(64-riscv64AddrBits) | uint64(cnt&(1<<riscv64CntBits-1))
+ }
return uint64(uintptr(unsafe.Pointer(node)))<<(64-addrBits) | uint64(cnt&(1<<cntBits-1))
}
@@ -54,5 +63,8 @@ func lfstackUnpack(val uint64) *lfnode {
if GOARCH == "ppc64" && GOOS == "aix" {
return (*lfnode)(unsafe.Pointer(uintptr((val >> aixCntBits << 3) | 0xa<<56)))
}
+ if GOARCH == "riscv64" {
+ return (*lfnode)(unsafe.Pointer(uintptr(val >> riscv64CntBits << 3)))
+ }
return (*lfnode)(unsafe.Pointer(uintptr(val >> cntBits << 3)))
}
--
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