[go] cmd/link: propagate Mach-O section alignment to symbol in loadmacho
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Commit message
cmd/link: propagate Mach-O section alignment to symbol in loadmacho
The Mach-O object file loader reads the section alignment from the section header into ldMachoSect.align, but never calls SetAlign on the symbol builder when converting sections to linker symbols. This causes all Mach-O .syso sections to fall back to Funcalign (16 bytes on ARM64) regardless of the alignment declared in the section header.
For .syso files containing C-compiled code with ADRP instructions on ARM64, the lack of page alignment (4096 bytes) leads to incorrect PC-relative address computation and runtime crashes.
The ELF loader already correctly propagates section alignment via sb.SetAlign (ldelf.go:543). Apply the same treatment to the Mach-O loader. Note that Mach-O stores alignment as log2 (e.g. 12 for 4096), so we use 1 << sect.align.
Fixes #78192
Change diff
diff --git a/src/cmd/link/internal/loadmacho/ldmacho.go b/src/cmd/link/internal/loadmacho/ldmacho.go
index ecd0150..41d99b8 100644
--- a/src/cmd/link/internal/loadmacho/ldmacho.go
+++ b/src/cmd/link/internal/loadmacho/ldmacho.go
@@ -570,6 +570,9 @@
bld.SetData(dat[sect.addr-c.seg.vmaddr:][:sect.size])
}
bld.SetSize(int64(len(bld.Data())))
+ if sect.align != 0 {
+ bld.SetAlign(1 << sect.align)
+ }
if sect.segname == "__TEXT" {
if sect.name == "__text" {
Change information
- M src/cmd/link/internal/loadmacho/ldmacho.go
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Gopher Robot (Gerrit)
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I spotted some possible problems with your PR:
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penglei (fixpoint) (Gerrit)
penglei (fixpoint) added 1 comment![]( "Open in Gerrit")
I spotted some possible problems with your PR:
1. You have a long 340 character line in the commit message body. Please add line breaks to long lines that should be wrapped. Lines in the commit message body should be wrapped at ~76 characters unless needed for things like URLs or tables. (Note: GitHub might render long lines as soft-wrapped, so double-check in the Gerrit commit message shown above.)Please address any problems by updating the GitHub PR.
When complete, mark this comment as 'Done' and click the [blue 'Reply' button](https://go.dev/wiki/GerritBot#i-left-a-reply-to-a-comment-in-gerrit-but-no-one-but-me-can-see-it) above. These findings are based on heuristics; if a finding does not apply, briefly reply here saying so.
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