diff options
| author | Dave Cheney <dave@cheney.net> | 2014-09-30 10:03:10 +1000 |
|---|---|---|
| committer | Dave Cheney <dave@cheney.net> | 2014-09-30 10:03:10 +1000 |
| commit | d8538bea6194db2a6aa5b87fda2887dfeb9a4402 (patch) | |
| tree | 37f8b86ee64f33de795a802f68d3688e94273bc9 | |
| parent | b4dff4847461a0f8ae373ac9fad4d270b84c5772 (diff) | |
| download | go-d8538bea6194db2a6aa5b87fda2887dfeb9a4402.tar.gz | |
liblink: generate MRC replacement in liblink, not tls_arm
Fixes issue 8690.
This CL moves the save of LR around BL runtime.read_tls_fallback to liblink as it is not needed when MRC is not replaced.
LGTM=rsc, minux
R=rsc, khr, minux
CC=golang-codereviews
https://codereview.appspot.com/147310043
| -rw-r--r-- | src/liblink/obj5.c | 20 | ||||
| -rw-r--r-- | src/runtime/tls_arm.s | 11 |
2 files changed, 21 insertions, 10 deletions
diff --git a/src/liblink/obj5.c b/src/liblink/obj5.c index e192b082b..d7f2714ed 100644 --- a/src/liblink/obj5.c +++ b/src/liblink/obj5.c @@ -119,14 +119,30 @@ progedit(Link *ctxt, Prog *p) ctxt->diag("%L: TLS MRC instruction must write to R0 as it might get translated into a BL instruction", p->lineno); if(ctxt->goarm < 7) { - // Replace it with BL runtime.read_tls_fallback(SB). + // Replace it with BL runtime.read_tls_fallback(SB) for ARM CPUs that lack the tls extension. if(tlsfallback == nil) tlsfallback = linklookup(ctxt, "runtime.read_tls_fallback", 0); - // BL runtime.read_tls_fallback(SB) + // MOVW LR, R11 + p->as = AMOVW; + p->from.type = D_REG; + p->from.reg = REGLINK; + p->to.type = D_REG; + p->to.reg = REGTMP; + + // BL runtime.read_tls_fallback(SB) + p = appendp(ctxt, p); p->as = ABL; p->to.type = D_BRANCH; p->to.sym = tlsfallback; p->to.offset = 0; + + // MOVW R11, LR + p = appendp(ctxt, p); + p->as = AMOVW; + p->from.type = D_REG; + p->from.reg = REGTMP; + p->to.type = D_REG; + p->to.reg = REGLINK; break; } } diff --git a/src/runtime/tls_arm.s b/src/runtime/tls_arm.s index 039b01383..85c3940bf 100644 --- a/src/runtime/tls_arm.s +++ b/src/runtime/tls_arm.s @@ -31,11 +31,8 @@ TEXT runtime·save_g(SB),NOSPLIT,$-4 #endif // 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. - // Both functions are written to only disturb R0 so it should be safe to - // use R11 here to temporarily store LR. - MOVW LR, R11 + // The replacement function saves LR in R11 over the call to read_tls_fallback. MRC 15, 0, R0, C13, C0, 3 // fetch TLS base pointer - MOVW R11, LR // $runtime.tlsg(SB) is a special linker symbol. // It is the offset from the TLS base pointer to our // thread-local storage for g. @@ -57,10 +54,8 @@ TEXT runtime·load_g(SB),NOSPLIT,$0 // nothing to do as nacl/arm does not use TLS at all. RET #endif - // See comment in save_g. - MOVW LR, R11 - MRC 15, 0, R0, C13, C0, 3 // fetch TLS base pointer - MOVW R11, LR + // See save_g + MRC 15, 0, R0, C13, C0, 3 // fetch TLS base pointer // $runtime.tlsg(SB) is a special linker symbol. // It is the offset from the TLS base pointer to our // thread-local storage for g. |