debug/buildinfo: remove macho/elf DataStart fallback code

The go version code can't read pre-1.13 go versions, but in 1.13 we
always write the go version info to the .go.buildinfo section. Remove
the fallback code because it won't be used.

See https://github.com/rsc/goversion/blob/v1.2.0/version/read.go for the
original rsc.io/goversion code that could read pre-1.13 data and
CL 173343 for the code added to go1.13 which would look for a writable
section rather than a read only section as rsc.io/goversion did.

Fixes #73060

Change-Id: I5d593d5724323351aef3ff04e04f7df96a6a6964
Reviewed-on: https://go-review.googlesource.com/c/go/+/756421
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Michael Matloob <matloob@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

1 files changed, 0 insertions, 13 deletions

diff --git a/src/debug/buildinfo/buildinfo.go b/src/debug/buildinfo/buildinfo.go
index d202d5050a..d943d0abe2 100644
--- a/src/debug/buildinfo/buildinfo.go
+++ b/src/debug/buildinfo/buildinfo.go
@@ -458,11 +458,6 @@ func (x *elfExe) DataStart() (uint64, uint64) {
 			return s.Addr, s.Size
 		}
 	}
-	for _, p := range x.f.Progs {
-		if p.Type == elf.PT_LOAD && p.Flags&(elf.PF_X|elf.PF_W) == elf.PF_W {
-			return p.Vaddr, p.Memsz
-		}
-	}
 	return 0, 0
 }
 
@@ -543,14 +538,6 @@ func (x *machoExe) DataStart() (uint64, uint64) {
 			return sec.Addr, sec.Size
 		}
 	}
-	// Try the first non-empty writable segment.
-	const RW = 3
-	for _, load := range x.f.Loads {
-		seg, ok := load.(*macho.Segment)
-		if ok && seg.Addr != 0 && seg.Filesz != 0 && seg.Prot == RW && seg.Maxprot == RW {
-			return seg.Addr, seg.Memsz
-		}
-	}
 	return 0, 0
 }