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cmd/link: mark holes in functab with end PC-1

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When we have multiple text sections, we need to mark holes between
the sections in the functab. A hole is marked with an entry with
the end PC of the previous section. As we now use offsets instead
of (relocated) PCs, the end offset of a section may be the same of
the start of the next one. Distinguish it by using the end address
-1.

For #48837.

Change-Id: I121aac53b32a869378632cf151cb1b6f98ad3089
Reviewed-on: https://go-review.googlesource.com/c/go/+/354636
Trust: Cherry Mui <cherryyz@google.com>
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
This commit is contained in:
Cherry Mui 2021-10-07 16:33:43 -04:00
parent 6436f5c13d
commit 1ceb72394e
1 changed files with 3 additions and 1 deletions
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4
src/cmd/link/internal/ld/pcln.go
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@ -631,9 +631,11 @@ func writePCToFunc(ctxt *Link, sb *loader.SymbolBuilder, funcs []loader.Sym, sta
if thisSect := ldr.SymSect(s); thisSect != prevSect { if thisSect := ldr.SymSect(s); thisSect != prevSect {
// With multiple text sections, there may be a hole here in the // With multiple text sections, there may be a hole here in the
// address space. We use an invalid funcoff value to mark the hole. // address space. We use an invalid funcoff value to mark the hole.
// Use the end PC - 1 to distinguish the end of a section vs. the
// start of the next.
// See also runtime/symtab.go:findfunc // See also runtime/symtab.go:findfunc
prevFuncSize := uint32(ldr.SymSize(prevFunc)) prevFuncSize := uint32(ldr.SymSize(prevFunc))
sb.SetUint32(ctxt.Arch, int64(funcIndex*2*4), pcOff(prevFunc)+prevFuncSize) sb.SetUint32(ctxt.Arch, int64(funcIndex*2*4), pcOff(prevFunc)+prevFuncSize-1)
sb.SetUint32(ctxt.Arch, int64((funcIndex*2+1)*4), ^uint32(0)) sb.SetUint32(ctxt.Arch, int64((funcIndex*2+1)*4), ^uint32(0))
funcIndex++ funcIndex++
prevSect = thisSect prevSect = thisSect