diff options
| author | Elias Naur <elias.naur@gmail.com> | 2014-02-03 14:07:54 -0800 |
|---|---|---|
| committer | Ian Lance Taylor <iant@golang.org> | 2014-02-03 14:07:54 -0800 |
| commit | 1dd4da14591a25748f90a42ef35fa360ff8edde2 (patch) | |
| tree | 2d1c3e79d0afb5fc12f2ff4a5208b7b5a1c7838a /src/liblink/obj5.c | |
| parent | e6d8bfe218a5f387d7aceddcaee5067a59181838 (diff) | |
| download | go-1dd4da14591a25748f90a42ef35fa360ff8edde2.tar.xz | |
liblink, cmd/5a, cmd/5l: restore cgo on older ARM processors
CL 56120043 fixed TLS handling on ARM after the introduction of
liblink but left older ARM processors broken.
Before liblink, the MRC instruction was replaced with a fallback
on older ARMs. CL 56120043 removed that, because the rewrite matched
bit patterns on the AWORD pseudo-instruction and could therefore change
unrelated AWORDs that happened to match.
This CL adds an AMRC instruction to encode both MRC and MCR previously
encoded as AWORDs. Then, in liblink, the AMRC instructions are either
rewritten to AWORD, or, on goarm < 7, replaced with a branch to the
fallback.
./all.bash completes successfully on an ARMv7 with either GOARM=7 or
GOARM=5. I have verified that the fallback is indeed present in both
runtime.save_gm and runtime.load_gm when GOARM=5 but not when GOARM=7.
If all goes well, this should fix the armv5 builders.
LGTM=iant
R=iant, rsc
CC=golang-codereviews
https://golang.org/cl/55540044
Diffstat (limited to 'src/liblink/obj5.c')
| -rw-r--r-- | src/liblink/obj5.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/src/liblink/obj5.c b/src/liblink/obj5.c index da688066a6..cda00b6432 100644 --- a/src/liblink/obj5.c +++ b/src/liblink/obj5.c @@ -92,6 +92,7 @@ progedit(Link *ctxt, Prog *p) { char literal[64]; LSym *s; + LSym *tlsfallback; p->from.class = 0; p->to.class = 0; @@ -105,6 +106,25 @@ progedit(Link *ctxt, Prog *p) break; } + // Replace TLS register fetches on older ARM procesors. + switch(p->as) { + case AMRC: + // If the instruction matches MRC 15, 0, <reg>, C13, C0, 3, replace it. + if(ctxt->goarm < 7 && (p->to.offset & 0xffff0fff) == 0xee1d0f70) { + tlsfallback = linklookup(ctxt, "runtime.read_tls_fallback", 0); + + // BL runtime.read_tls_fallback(SB) + p->as = ABL; + p->to.type = D_BRANCH; + p->to.sym = tlsfallback; + p->to.offset = 0; + } else { + // Otherwise, MRC/MCR instructions need no further treatment. + p->as = AWORD; + } + break; + } + // Rewrite float constants to values stored in memory. switch(p->as) { case AMOVF: |