[release-branch.go1.19] runtime: mark morestack_noctxt SPWRITE on LR architectures On LR architectures, morestack (and morestack_noctxt) are called with a special calling convention, where the caller doesn't save LR on stack but passes it as a register, which morestack will save to g.sched.lr. The stack unwinder currently doesn't understand it, and would fail to unwind from it. morestack already writes SP (as it switches stack), but morestack_noctxt (which tailcalls morestack) doesn't. If a profiling signal lands right in morestack_noctxt, the unwinder will try to unwind the stack and go off, and possibly crash. Marking morestack_noctxt SPWRITE stops the unwinding. Ideally we could teach the unwinder about the special calling convention, or change the calling convention to be less special (so the unwinder doesn't need to fetch a register from the signal context). This is a stop-gap solution, to stop the unwinder from crashing. Updates #54332. Fixes #54675. Change-Id: I75295f2e27ddcf05f1ea0b541aedcb9000ae7576 Reviewed-on: https://go-review.googlesource.com/c/go/+/425396 TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: Cherry Mui <cherryyz@google.com> Reviewed-by: Michael Pratt <mpratt@google.com> (cherry picked from commit e4be2ac79f3cc7219ae1cf8334463d11cae24e01) Reviewed-on: https://go-review.googlesource.com/c/go/+/425615
diff --git a/src/runtime/asm_arm.s b/src/runtime/asm_arm.s index b47184e..591ef2a 100644 --- a/src/runtime/asm_arm.s +++ b/src/runtime/asm_arm.s
@@ -387,6 +387,13 @@ RET TEXT runtime·morestack_noctxt(SB),NOSPLIT|NOFRAME,$0-0 + // Force SPWRITE. This function doesn't actually write SP, + // but it is called with a special calling convention where + // the caller doesn't save LR on stack but passes it as a + // register (R3), and the unwinder currently doesn't understand. + // Make it SPWRITE to stop unwinding. (See issue 54332) + MOVW R13, R13 + MOVW $0, R7 B runtime·morestack(SB)
diff --git a/src/runtime/asm_arm64.s b/src/runtime/asm_arm64.s index 7836ba1..7eb5bcf 100644 --- a/src/runtime/asm_arm64.s +++ b/src/runtime/asm_arm64.s
@@ -320,6 +320,13 @@ UNDEF TEXT runtime·morestack_noctxt(SB),NOSPLIT|NOFRAME,$0-0 + // Force SPWRITE. This function doesn't actually write SP, + // but it is called with a special calling convention where + // the caller doesn't save LR on stack but passes it as a + // register (R3), and the unwinder currently doesn't understand. + // Make it SPWRITE to stop unwinding. (See issue 54332) + MOVD RSP, RSP + MOVW $0, R26 B runtime·morestack(SB)
diff --git a/src/runtime/asm_mips64x.s b/src/runtime/asm_mips64x.s index 3597ebe..1abadb9 100644 --- a/src/runtime/asm_mips64x.s +++ b/src/runtime/asm_mips64x.s
@@ -258,6 +258,13 @@ UNDEF TEXT runtime·morestack_noctxt(SB),NOSPLIT|NOFRAME,$0-0 + // Force SPWRITE. This function doesn't actually write SP, + // but it is called with a special calling convention where + // the caller doesn't save LR on stack but passes it as a + // register (R3), and the unwinder currently doesn't understand. + // Make it SPWRITE to stop unwinding. (See issue 54332) + MOVV R29, R29 + MOVV R0, REGCTXT JMP runtime·morestack(SB)
diff --git a/src/runtime/asm_mipsx.s b/src/runtime/asm_mipsx.s index 4a086b8..877c1bb 100644 --- a/src/runtime/asm_mipsx.s +++ b/src/runtime/asm_mipsx.s
@@ -257,6 +257,13 @@ UNDEF TEXT runtime·morestack_noctxt(SB),NOSPLIT,$0-0 + // Force SPWRITE. This function doesn't actually write SP, + // but it is called with a special calling convention where + // the caller doesn't save LR on stack but passes it as a + // register (R3), and the unwinder currently doesn't understand. + // Make it SPWRITE to stop unwinding. (See issue 54332) + MOVW R29, R29 + MOVW R0, REGCTXT JMP runtime·morestack(SB)
diff --git a/src/runtime/asm_ppc64x.s b/src/runtime/asm_ppc64x.s index c6bcf82..6a162ef 100644 --- a/src/runtime/asm_ppc64x.s +++ b/src/runtime/asm_ppc64x.s
@@ -334,6 +334,13 @@ UNDEF TEXT runtime·morestack_noctxt(SB),NOSPLIT|NOFRAME,$0-0 + // Force SPWRITE. This function doesn't actually write SP, + // but it is called with a special calling convention where + // the caller doesn't save LR on stack but passes it as a + // register (R5), and the unwinder currently doesn't understand. + // Make it SPWRITE to stop unwinding. (See issue 54332) + MOVD R1, R1 + MOVD R0, R11 BR runtime·morestack(SB)
diff --git a/src/runtime/asm_riscv64.s b/src/runtime/asm_riscv64.s index 00caa9f..389851b 100644 --- a/src/runtime/asm_riscv64.s +++ b/src/runtime/asm_riscv64.s
@@ -158,8 +158,8 @@ */ // Called during function prolog when more stack is needed. -// Caller has already loaded: -// R1: framesize, R2: argsize, R3: LR +// Called with return address (i.e. caller's PC) in X5 (aka T0), +// and the LR register contains the caller's LR. // // The traceback routines see morestack on a g0 as being // the top of a stack (for example, morestack calling newstack @@ -209,6 +209,13 @@ // func morestack_noctxt() TEXT runtime·morestack_noctxt(SB),NOSPLIT|NOFRAME,$0-0 + // Force SPWRITE. This function doesn't actually write SP, + // but it is called with a special calling convention where + // the caller doesn't save LR on stack but passes it as a + // register, and the unwinder currently doesn't understand. + // Make it SPWRITE to stop unwinding. (See issue 54332) + MOV X2, X2 + MOV ZERO, CTXT JMP runtime·morestack(SB)
diff --git a/src/runtime/asm_s390x.s b/src/runtime/asm_s390x.s index 9159a67..334e1aa 100644 --- a/src/runtime/asm_s390x.s +++ b/src/runtime/asm_s390x.s
@@ -346,6 +346,13 @@ UNDEF TEXT runtime·morestack_noctxt(SB),NOSPLIT|NOFRAME,$0-0 + // Force SPWRITE. This function doesn't actually write SP, + // but it is called with a special calling convention where + // the caller doesn't save LR on stack but passes it as a + // register (R5), and the unwinder currently doesn't understand. + // Make it SPWRITE to stop unwinding. (See issue 54332) + MOVD R15, R15 + MOVD $0, R12 BR runtime·morestack(SB)