From 6a18122614608c597511c2cc188ef771e393f1fb Mon Sep 17 00:00:00 2001 From: David Crawshaw Date: Tue, 15 Sep 2015 13:40:24 -0400 Subject: [PATCH] [release-branch.go1.5] runtime: preserve R11 in darwin/arm entrypoint The _rt0_arm_darwin_lib entrypoint has to conform to the darwin ARMv7 calling convention, which requires functions to preserve the value of R11. Go uses R11 as the liblink REGTMP register, so save it manually. Also avoid using R4, which is also callee-save. Fixes #12590 Change-Id: I9c3b374e330f81ff8fc9c01fa20505a33ddcf39a Reviewed-on: https://go-review.googlesource.com/14603 Reviewed-by: Ian Lance Taylor Reviewed-on: https://go-review.googlesource.com/16968 Run-TryBot: Austin Clements Reviewed-by: Russ Cox --- src/runtime/rt0_darwin_arm.s | 29 ++++++++++++++++++----------- 1 file changed, 18 insertions(+), 11 deletions(-) diff --git a/src/runtime/rt0_darwin_arm.s b/src/runtime/rt0_darwin_arm.s index 95a2b179c4424..d60985060d4a0 100644 --- a/src/runtime/rt0_darwin_arm.s +++ b/src/runtime/rt0_darwin_arm.s @@ -16,27 +16,34 @@ TEXT _rt0_arm_darwin(SB),7,$-4 // // Note that all currently shipping darwin/arm platforms require // cgo and do not support c-shared. -TEXT _rt0_arm_darwin_lib(SB),NOSPLIT,$12 +TEXT _rt0_arm_darwin_lib(SB),NOSPLIT,$0 + // R11 is REGTMP, reserved for liblink. It is used below to + // move R0/R1 into globals. However in the darwin ARMv7 calling + // convention, it is a callee-saved register. So we save it to a + // temporary register. + MOVW R11, R2 MOVW R0, _rt0_arm_darwin_lib_argc<>(SB) MOVW R1, _rt0_arm_darwin_lib_argv<>(SB) // Create a new thread to do the runtime initialization and return. - MOVW _cgo_sys_thread_create(SB), R4 - CMP $0, R4 + MOVW _cgo_sys_thread_create(SB), R3 + CMP $0, R3 B.EQ nocgo MOVW $_rt0_arm_darwin_lib_go(SB), R0 MOVW $0, R1 - BL (R4) + MOVW R2, R11 + BL (R3) RET nocgo: MOVW $0x400000, R0 - MOVW $_rt0_arm_darwin_lib_go(SB), R1 - MOVW $0, R2 - MOVW R0, (R13) // stacksize - MOVW R1, 4(R13) // fn - MOVW R2, 8(R13) // fnarg - MOVW $runtime·newosproc0(SB), R4 - BL (R4) + MOVW R0, (R13) // stacksize + MOVW $_rt0_arm_darwin_lib_go(SB), R0 + MOVW R0, 4(R13) // fn + MOVW $0, R0 + MOVW R0, 8(R13) // fnarg + MOVW $runtime·newosproc0(SB), R3 + MOVW R2, R11 + BL (R3) RET TEXT _rt0_arm_darwin_lib_go(SB),NOSPLIT,$0