From 0020b8a2572a953b8521ce75367779255c5a1436 Mon Sep 17 00:00:00 2001 From: Cherry Zhang Date: Sat, 8 Apr 2017 14:27:33 -0400 Subject: [PATCH] runtime: prevent TLS fetching instructions from being assembled on NaCl/ARM They are dead code already, but the verifier is still not happy. Don't assemble them at all. Looks like it has been like that for long. I don't know why it was ok. Maybe the verifier is now more picky? Fixes #19884. Change-Id: Ib806fb73ca469789dec56f52d484cf8baf7a245c Reviewed-on: https://go-review.googlesource.com/40111 Run-TryBot: Cherry Zhang TryBot-Result: Gobot Gobot Reviewed-by: Josh Bleecher Snyder Reviewed-by: Dave Cheney --- src/runtime/tls_arm.s | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/src/runtime/tls_arm.s b/src/runtime/tls_arm.s index 32bfcf88f0..a5f5003ea8 100644 --- a/src/runtime/tls_arm.s +++ b/src/runtime/tls_arm.s @@ -35,7 +35,7 @@ TEXT runtime·save_g(SB),NOSPLIT,$-4 // nothing to do as nacl/arm does not use TLS at all. MOVW g, R0 // preserve R0 across call to setg<> RET -#endif +#else // If the host does not support MRC the linker will replace it with // a call to runtime.read_tls_fallback which jumps to __kuser_get_tls. // The replacement function saves LR in R11 over the call to read_tls_fallback. @@ -46,6 +46,7 @@ TEXT runtime·save_g(SB),NOSPLIT,$-4 MOVW g, 0(R0) MOVW g, R0 // preserve R0 across call to setg<> RET +#endif // load_g loads the g register from pthread-provided // thread-local memory, for use after calling externally compiled @@ -54,7 +55,7 @@ TEXT runtime·load_g(SB),NOSPLIT,$0 #ifdef GOOS_nacl // nothing to do as nacl/arm does not use TLS at all. RET -#endif +#else // See save_g MRC 15, 0, R0, C13, C0, 3 // fetch TLS base pointer BIC $3, R0 // Darwin/ARM might return unaligned pointer @@ -62,6 +63,7 @@ TEXT runtime·load_g(SB),NOSPLIT,$0 ADD R11, R0 MOVW 0(R0), g RET +#endif // This is called from rt0_go, which runs on the system stack // using the initial stack allocated by the OS. -- 2.50.0