From 22f9e1ccbc9db9a1d9ecbadca972264e5ad2f169 Mon Sep 17 00:00:00 2001 From: Cherry Zhang Date: Thu, 4 Feb 2021 11:41:34 -0500 Subject: [PATCH] [dev.regabi] runtime: initialize special registers before sigpanic In case that we are panicking in ABI0 context or external code, special registers are not initialized. Initialized them in injected code before calling sigpanic. TODO: Windows, Plan 9. Change-Id: I0919b80e7cc55463f3dd94f1f63cba305717270a Reviewed-on: https://go-review.googlesource.com/c/go/+/289710 Trust: Cherry Zhang Run-TryBot: Cherry Zhang TryBot-Result: Go Bot Reviewed-by: Jeremy Faller Reviewed-by: Michael Knyszek --- src/runtime/asm.s | 5 +++++ src/runtime/asm_amd64.s | 12 ++++++++++++ src/runtime/signal_amd64.go | 7 +++++-- src/runtime/stubs.go | 4 ++++ 4 files changed, 26 insertions(+), 2 deletions(-) diff --git a/src/runtime/asm.s b/src/runtime/asm.s index 27d8df9e063ecf..72c744925d89ae 100644 --- a/src/runtime/asm.s +++ b/src/runtime/asm.s @@ -11,3 +11,8 @@ DATA runtime·no_pointers_stackmap+0x00(SB)/4, $2 DATA runtime·no_pointers_stackmap+0x04(SB)/4, $0 GLOBL runtime·no_pointers_stackmap(SB),RODATA, $8 + +#ifndef GOARCH_amd64 +TEXT ·sigpanic0(SB),NOSPLIT,$0-0 + JMP ·sigpanic(SB) +#endif diff --git a/src/runtime/asm_amd64.s b/src/runtime/asm_amd64.s index 9f15990b137cdd..83c08a52f742cf 100644 --- a/src/runtime/asm_amd64.s +++ b/src/runtime/asm_amd64.s @@ -1364,6 +1364,18 @@ TEXT runtime·addmoduledata(SB),NOSPLIT,$0-0 POPQ R15 RET +// Initialize special registers then jump to sigpanic. +// This function is injected from the signal handler for panicking +// signals. It is quite painful to set X15 in the signal context, +// so we do it here. +TEXT ·sigpanic0(SB),NOSPLIT,$0-0 +#ifdef GOEXPERIMENT_REGABI + get_tls(R14) + MOVQ g(R14), R14 + XORPS X15, X15 +#endif + JMP ·sigpanic(SB) + // gcWriteBarrier performs a heap pointer write and informs the GC. // // gcWriteBarrier does NOT follow the Go ABI. It takes two arguments: diff --git a/src/runtime/signal_amd64.go b/src/runtime/signal_amd64.go index 6ab1f758c22935..3eeb5e044ff0ff 100644 --- a/src/runtime/signal_amd64.go +++ b/src/runtime/signal_amd64.go @@ -65,11 +65,14 @@ func (c *sigctxt) preparePanic(sig uint32, gp *g) { pc := uintptr(c.rip()) sp := uintptr(c.rsp()) + // In case we are panicking from external code, we need to initialize + // Go special registers. We inject sigpanic0 (instead of sigpanic), + // which takes care of that. if shouldPushSigpanic(gp, pc, *(*uintptr)(unsafe.Pointer(sp))) { - c.pushCall(funcPC(sigpanic), pc) + c.pushCall(funcPC(sigpanic0), pc) } else { // Not safe to push the call. Just clobber the frame. - c.set_rip(uint64(funcPC(sigpanic))) + c.set_rip(uint64(funcPC(sigpanic0))) } } diff --git a/src/runtime/stubs.go b/src/runtime/stubs.go index 36bbc8991ac0f0..3d1e0c0bb4dd70 100644 --- a/src/runtime/stubs.go +++ b/src/runtime/stubs.go @@ -356,3 +356,7 @@ func duffcopy() // Called from linker-generated .initarray; declared for go vet; do NOT call from Go. func addmoduledata() + +// Injected by the signal handler for panicking signals. On many platforms it just +// jumps to sigpanic. +func sigpanic0()