[dev.power64] all: merge default (dd5014ed9b01) into dev.power64

[gostls13.git] / src / runtime / asm_arm.s

diff --git a/src/runtime/asm_arm.s b/src/runtime/asm_arm.s
index 8942b11acb1025d13eae253e3a51cf7ae41f00c5..9a58fdc51e25a1d4e9853c6d0a47f68fd6933cd1 100644 (file)
--- a/src/runtime/asm_arm.s
+++ b/src/runtime/asm_arm.s
@@ -556,6 +556,21 @@ TEXT       ·cgocallback_gofunc(SB),NOSPLIT,$8-12
        MOVW    $runtime·needm(SB), R0
        BL      (R0)
 
+       // Set m->sched.sp = SP, so that if a panic happens
+       // during the function we are about to execute, it will
+       // have a valid SP to run on the g0 stack.
+       // The next few lines (after the havem label)
+       // will save this SP onto the stack and then write
+       // the same SP back to m->sched.sp. That seems redundant,
+       // but if an unrecovered panic happens, unwindm will
+       // restore the g->sched.sp from the stack location
+       // and then onM will try to use it. If we don't set it here,
+       // that restored SP will be uninitialized (typically 0) and
+       // will not be usable.
+       MOVW    g_m(g), R8
+       MOVW    m_g0(R8), R3
+       MOVW    R13, (g_sched+gobuf_sp)(R3)
+
 havem:
        MOVW    g_m(g), R8
        MOVW    R8, savedm-4(SP)