runtime: reduce syscall when call runtime.clone
Change-Id: I3ea398fd86aae4c86557dd6fff65d90a6f756890
GitHub-Last-Rev: 4c295388f7b5e6768ffd2530337f78b4c75a9310
GitHub-Pull-Request: golang/go#40392
Reviewed-on: https://go-review.googlesource.com/c/go/+/244626
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/src/runtime/sys_linux_amd64.s b/src/runtime/sys_linux_amd64.s
index 621c01b..8d90813 100644
--- a/src/runtime/sys_linux_amd64.s
+++ b/src/runtime/sys_linux_amd64.s
@@ -592,13 +592,25 @@
MOVQ stk+8(FP), SI
MOVQ $0, DX
MOVQ $0, R10
-
+ MOVQ $0, R8
// Copy mp, gp, fn off parent stack for use by child.
// Careful: Linux system call clobbers CX and R11.
- MOVQ mp+16(FP), R8
+ MOVQ mp+16(FP), R13
MOVQ gp+24(FP), R9
MOVQ fn+32(FP), R12
-
+ CMPQ R13, $0 // m
+ JEQ nog1
+ CMPQ R9, $0 // g
+ JEQ nog1
+ LEAQ m_tls(R13), R8
+#ifdef GOOS_android
+ // Android stores the TLS offset in runtime·tls_g.
+ SUBQ runtime·tls_g(SB), R8
+#else
+ ADDQ $8, R8 // ELF wants to use -8(FS)
+#endif
+ ORQ $0x00080000, DI //add flag CLONE_SETTLS(0x00080000) to call clone
+nog1:
MOVL $SYS_clone, AX
SYSCALL
@@ -612,27 +624,23 @@
MOVQ SI, SP
// If g or m are nil, skip Go-related setup.
- CMPQ R8, $0 // m
- JEQ nog
+ CMPQ R13, $0 // m
+ JEQ nog2
CMPQ R9, $0 // g
- JEQ nog
+ JEQ nog2
// Initialize m->procid to Linux tid
MOVL $SYS_gettid, AX
SYSCALL
- MOVQ AX, m_procid(R8)
-
- // Set FS to point at m->tls.
- LEAQ m_tls(R8), DI
- CALL runtime·settls(SB)
+ MOVQ AX, m_procid(R13)
// In child, set up new stack
get_tls(CX)
- MOVQ R8, g_m(R9)
+ MOVQ R13, g_m(R9)
MOVQ R9, g(CX)
CALL runtime·stackcheck(SB)
-nog:
+nog2:
// Call fn
CALL R12
