diff options
Diffstat (limited to 'src/runtime/asm_386.s')
| -rw-r--r-- | src/runtime/asm_386.s | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/src/runtime/asm_386.s b/src/runtime/asm_386.s index 20d3c47c9..0d46a9eff 100644 --- a/src/runtime/asm_386.s +++ b/src/runtime/asm_386.s @@ -732,6 +732,20 @@ needm: MOVL g(CX), BP MOVL g_m(BP), BP + // 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. + MOVL m_g0(BP), SI + MOVL SP, (g_sched+gobuf_sp)(SI) + havem: // Now there's a valid m, and we're running on its m->g0. // Save current m->g0->sched.sp on stack and then set it to SP. |