runtime/cgo: store M for C-created thread in pthread key

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

diff --git a/src/runtime/asm_arm.s b/src/runtime/asm_arm.s
index 569165ed19ada58661b825e4d20d5c6524a88aa7..01906dff4a5eb723574e0947981264470a962b1c 100644 (file)
--- a/src/runtime/asm_arm.s
+++ b/src/runtime/asm_arm.s
@@ -630,6 +630,16 @@ nosave:
 TEXT   ·cgocallback(SB),NOSPLIT,$12-12
        NO_LOCAL_POINTERS
 
+       // Skip cgocallbackg, just dropm when fn is nil, and frame is the saved g.
+       // It is used to dropm while thread is exiting.
+       MOVW    fn+0(FP), R1
+       CMP     $0, R1
+       B.NE    loadg
+       // Restore the g from frame.
+       MOVW    frame+4(FP), g
+       B       dropm
+
+loadg:
        // Load m and g from thread-local storage.
 #ifdef GOOS_openbsd
        BL      runtime·load_g(SB)
@@ -639,7 +649,8 @@ TEXT        ·cgocallback(SB),NOSPLIT,$12-12
        BL.NE   runtime·load_g(SB)
 #endif
 
-       // If g is nil, Go did not create the current thread.
+       // If g is nil, Go did not create the current thread,
+       // or if this thread never called into Go on pthread platforms.
        // Call needm to obtain one for temporary use.
        // In this case, we're running on the thread stack, so there's
        // lots of space, but the linker doesn't know. Hide the call from
@@ -653,7 +664,7 @@ TEXT        ·cgocallback(SB),NOSPLIT,$12-12
 
 needm:
        MOVW    g, savedm-4(SP) // g is zero, so is m.
-       MOVW    $runtime·needm(SB), R0
+       MOVW    $runtime·needAndBindM(SB), R0
        BL      (R0)
 
        // Set m->g0->sched.sp = SP, so that if a panic happens
@@ -724,14 +735,31 @@ havem:
        MOVW    savedsp-12(SP), R4      // must match frame size
        MOVW    R4, (g_sched+gobuf_sp)(g)
 
-       // If the m on entry was nil, we called needm above to borrow an m
-       // for the duration of the call. Since the call is over, return it with dropm.
+       // If the m on entry was nil, we called needm above to borrow an m,
+       // 1. for the duration of the call on non-pthread platforms,
+       // 2. or the duration of the C thread alive on pthread platforms.
+       // If the m on entry wasn't nil,
+       // 1. the thread might be a Go thread,
+       // 2. or it's wasn't the first call from a C thread on pthread platforms,
+       //    since the we skip dropm to resue the m in the first call.
        MOVW    savedm-4(SP), R6
        CMP     $0, R6
-       B.NE    3(PC)
+       B.NE    done
+
+       // Skip dropm to reuse it in the next call, when a pthread key has been created.
+       MOVW    _cgo_pthread_key_created(SB), R6
+       // It means cgo is disabled when _cgo_pthread_key_created is a nil pointer, need dropm.
+       CMP     $0, R6
+       B.EQ    dropm
+       MOVW    (R6), R6
+       CMP     $0, R6
+       B.NE    done
+
+dropm:
        MOVW    $runtime·dropm(SB), R0
        BL      (R0)
 
+done:
        // Done!
        RET