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| author | Cherry Mui <cherryyz@google.com> | 2022-08-24 18:33:21 -0400 |
|---|---|---|
| committer | Cherry Mui <cherryyz@google.com> | 2022-08-25 14:56:18 +0000 |
| commit | e4be2ac79f3cc7219ae1cf8334463d11cae24e01 (patch) | |
| tree | a736f32c9b83bbd44694f1e3e508dfd504dd2e6e /src/runtime/asm_arm.s | |
| parent | d4ff25ac69c90bb0e6a92aff7650d0bf3d41d29e (diff) | |
| download | go-e4be2ac79f3cc7219ae1cf8334463d11cae24e01.tar.xz | |
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.
Fixes #54332.
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>
Diffstat (limited to 'src/runtime/asm_arm.s')
| -rw-r--r-- | src/runtime/asm_arm.s | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/src/runtime/asm_arm.s b/src/runtime/asm_arm.s index b47184e36b..591ef2a399 100644 --- a/src/runtime/asm_arm.s +++ b/src/runtime/asm_arm.s @@ -387,6 +387,13 @@ TEXT runtime·morestack(SB),NOSPLIT|NOFRAME,$0-0 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) |