[go] cmd/link: move pclntab out of relro section
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Ian Lance Taylor (Gerrit)
Nov 5, 2025, 7:15:00 PM (5 days ago) Nov 5
to goph...@pubsubhelper.golang.org, Ian Lance Taylor, golang-co...@googlegroups.com
Ian Lance Taylor has uploaded the change for review![]( "Open in Gerrit")
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cmd/link: move pclntab out of relro section
The .gopclntab section should not have any relocations.
Move it out of relro to regular rodata.
Note that this is tested by tests like TestNoTextrel in
cmd/cgo/internal/testshared.
For #76038
Change-Id: I7f837e423bf1e802509277f5dc7fdd1ed0228e32
Change diff
diff --git a/src/cmd/link/internal/ld/data.go b/src/cmd/link/internal/ld/data.go
index fcc3272..e7e202f 100644
--- a/src/cmd/link/internal/ld/data.go
+++ b/src/cmd/link/internal/ld/data.go
@@ -1581,7 +1581,7 @@
// the relro data.
isRelro = true
}
- case sym.SGOFUNC:
+ case sym.SGOFUNC, sym.SPCLNTAB:
// The only SGOFUNC symbols that contain relocations are .stkobj,
// and their relocations are of type objabi.R_ADDROFF,
// which always get resolved during linking.
@@ -2119,6 +2119,21 @@
}
}
+ /* gopclntab */
+ sect = state.allocateNamedSectionAndAssignSyms(segro, ".gopclntab", sym.SPCLNTAB, sym.SRODATA, 04)
+ ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.pclntab", 0), sect)
+ ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.pcheader", 0), sect)
+ ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.funcnametab", 0), sect)
+ ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.cutab", 0), sect)
+ ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.filetab", 0), sect)
+ ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.pctab", 0), sect)
+ ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.functab", 0), sect)
+ ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.epclntab", 0), sect)
+ setCarrierSize(sym.SPCLNTAB, int64(sect.Length))
+ if ctxt.HeadType == objabi.Haix {
+ xcoffUpdateOuterSize(ctxt, int64(sect.Length), sym.SPCLNTAB)
+ }
+
/* read-only ELF, Mach-O sections */
state.allocateSingleSymSections(segro, sym.SELFROSECT, sym.SRODATA, 04)
@@ -2238,21 +2253,6 @@
state.checkdatsize(sym.SITABLINK)
sect.Length = uint64(state.datsize) - sect.Vaddr
- /* gopclntab */
- sect = state.allocateNamedSectionAndAssignSyms(seg, genrelrosecname(".gopclntab"), sym.SPCLNTAB, sym.SRODATA, relroSecPerm)
- ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.pclntab", 0), sect)
- ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.pcheader", 0), sect)
- ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.funcnametab", 0), sect)
- ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.cutab", 0), sect)
- ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.filetab", 0), sect)
- ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.pctab", 0), sect)
- ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.functab", 0), sect)
- ldr.SetSymSect(ldr.LookupOrCreateSym("runtime.epclntab", 0), sect)
- setCarrierSize(sym.SPCLNTAB, int64(sect.Length))
- if ctxt.HeadType == objabi.Haix {
- xcoffUpdateOuterSize(ctxt, int64(sect.Length), sym.SPCLNTAB)
- }
-
// 6g uses 4-byte relocation offsets, so the entire segment must fit in 32 bits.
if state.datsize != int64(uint32(state.datsize)) {
Errorf("read-only data segment too large: %d", state.datsize)
diff --git a/src/cmd/link/internal/ld/elf.go b/src/cmd/link/internal/ld/elf.go
index 8981f1c..90f9388 100644
--- a/src/cmd/link/internal/ld/elf.go
+++ b/src/cmd/link/internal/ld/elf.go
@@ -1250,11 +1250,12 @@
func elfshreloc(arch *sys.Arch, sect *sym.Section) *ElfShdr {
// If main section is SHT_NOBITS, nothing to relocate.
- // Also nothing to relocate in .shstrtab or notes.
+ // Also nothing to relocate in .shstrtab or notes or .gopclntab.
if sect.Vaddr >= sect.Seg.Vaddr+sect.Seg.Filelen {
return nil
}
- if sect.Name == ".shstrtab" || sect.Name == ".tbss" {
+ switch sect.Name {
+ case ".shstrtab", ".tbss", ".gopclntab":
return nil
}
if sect.Elfsect.(*ElfShdr).Type == uint32(elf.SHT_NOTE) {
@@ -1469,6 +1470,7 @@
}
shstrtabAddstring(".elfdata")
shstrtabAddstring(".rodata")
+ shstrtabAddstring(".gopclntab")
// See the comment about data.rel.ro.FOO section names in data.go.
relro_prefix := ""
if ctxt.UseRelro() {
@@ -1477,7 +1479,6 @@
}
shstrtabAddstring(relro_prefix + ".typelink")
shstrtabAddstring(relro_prefix + ".itablink")
- shstrtabAddstring(relro_prefix + ".gopclntab")
if ctxt.IsExternal() {
*FlagD = true
@@ -1486,7 +1487,6 @@
shstrtabAddstring(elfRelType + ".rodata")
shstrtabAddstring(elfRelType + relro_prefix + ".typelink")
shstrtabAddstring(elfRelType + relro_prefix + ".itablink")
- shstrtabAddstring(elfRelType + relro_prefix + ".gopclntab")
shstrtabAddstring(elfRelType + ".noptrdata")
shstrtabAddstring(elfRelType + ".data")
if ctxt.UseRelro() {
diff --git a/src/cmd/link/internal/ld/elf_test.go b/src/cmd/link/internal/ld/elf_test.go
index c2a1bc0..c56d27f 100644
--- a/src/cmd/link/internal/ld/elf_test.go
+++ b/src/cmd/link/internal/ld/elf_test.go
@@ -408,7 +408,7 @@
}
// This program is intended to be just big/complicated enough that
-// we wind up with decent-sized .data.rel.ro.{typelink,itablink,gopclntab}
+// we wind up with decent-sized .data.rel.ro.{typelink,itablink}
// sections.
const ifacecallsProg = `
package main
diff --git a/src/cmd/link/internal/sym/symkind.go b/src/cmd/link/internal/sym/symkind.go
index 9f62e80..8709e7b 100644
--- a/src/cmd/link/internal/sym/symkind.go
+++ b/src/cmd/link/internal/sym/symkind.go
@@ -64,6 +64,7 @@
SRODATAFIPSEND // End of FIPS read-only data.
SRODATAEND // End of read-only data.
SFUNCTAB // Appears to be unused, except for runtime.etypes.
+ SPCLNTAB // Pclntab data.
SELFROSECT // ELF read-only data: relocs, dynamic linking info.
// Read-only, non-executable, dynamically relocatable segment.
@@ -91,7 +92,6 @@
STYPELINK // Type links.
SITABLINK // Itab links.
- SPCLNTAB // Pclntab data.
// Allocated writable segment.
SFirstWritable
diff --git a/src/cmd/link/internal/sym/symkind_string.go b/src/cmd/link/internal/sym/symkind_string.go
index 4e3a0a3..019e7c7 100644
--- a/src/cmd/link/internal/sym/symkind_string.go
+++ b/src/cmd/link/internal/sym/symkind_string.go
@@ -27,19 +27,19 @@
_ = x[SRODATAFIPSEND-16]
_ = x[SRODATAEND-17]
_ = x[SFUNCTAB-18]
- _ = x[SELFROSECT-19]
- _ = x[STYPERELRO-20]
- _ = x[SSTRINGRELRO-21]
- _ = x[SGOSTRINGRELRO-22]
- _ = x[SGOFUNCRELRO-23]
- _ = x[SGCBITSRELRO-24]
- _ = x[SRODATARELRO-25]
- _ = x[SFUNCTABRELRO-26]
- _ = x[SELFRELROSECT-27]
- _ = x[SMACHORELROSECT-28]
- _ = x[STYPELINK-29]
- _ = x[SITABLINK-30]
- _ = x[SPCLNTAB-31]
+ _ = x[SPCLNTAB-19]
+ _ = x[SELFROSECT-20]
+ _ = x[STYPERELRO-21]
+ _ = x[SSTRINGRELRO-22]
+ _ = x[SGOSTRINGRELRO-23]
+ _ = x[SGOFUNCRELRO-24]
+ _ = x[SGCBITSRELRO-25]
+ _ = x[SRODATARELRO-26]
+ _ = x[SFUNCTABRELRO-27]
+ _ = x[SELFRELROSECT-28]
+ _ = x[SMACHORELROSECT-29]
+ _ = x[STYPELINK-30]
+ _ = x[SITABLINK-31]
_ = x[SFirstWritable-32]
_ = x[SBUILDINFO-33]
_ = x[SFIPSINFO-34]
@@ -90,9 +90,9 @@
_ = x[SSEHSECT-79]
}
-const _SymKind_name = "SxxxSTEXTSTEXTFIPSSTARTSTEXTFIPSSTEXTFIPSENDSTEXTENDSELFRXSECTSMACHOPLTSTYPESSTRINGSGOSTRINGSGOFUNCSGCBITSSRODATASRODATAFIPSSTARTSRODATAFIPSSRODATAFIPSENDSRODATAENDSFUNCTABSELFROSECTSTYPERELROSSTRINGRELROSGOSTRINGRELROSGOFUNCRELROSGCBITSRELROSRODATARELROSFUNCTABRELROSELFRELROSECTSMACHORELROSECTSTYPELINKSITABLINKSPCLNTABSFirstWritableSBUILDINFOSFIPSINFOSELFSECTSMACHOSMACHOGOTSWINDOWSSELFGOTSNOPTRDATASNOPTRDATAFIPSSTARTSNOPTRDATAFIPSSNOPTRDATAFIPSENDSNOPTRDATAENDSINITARRSDATASDATAFIPSSTARTSDATAFIPSSDATAFIPSENDSDATAENDSXCOFFTOCSBSSSNOPTRBSSSLIBFUZZER_8BIT_COUNTERSCOVERAGE_COUNTERSCOVERAGE_AUXVARSTLSBSSSFirstUnallocatedSXREFSMACHOSYMSTRSMACHOSYMTABSMACHOINDIRECTPLTSMACHOINDIRECTGOTSDYNIMPORTSHOSTOBJSUNDEFEXTSDWARFSECTSDWARFCUINFOSDWARFCONSTSDWARFFCNSDWARFABSFCNSDWARFTYPESDWARFVARSDWARFRANGESDWARFLOCSDWARFLINESSDWARFADDRSSEHUNWINDINFOSSEHSECT"
+const _SymKind_name = "SxxxSTEXTSTEXTFIPSSTARTSTEXTFIPSSTEXTFIPSENDSTEXTENDSELFRXSECTSMACHOPLTSTYPESSTRINGSGOSTRINGSGOFUNCSGCBITSSRODATASRODATAFIPSSTARTSRODATAFIPSSRODATAFIPSENDSRODATAENDSFUNCTABSPCLNTABSELFROSECTSTYPERELROSSTRINGRELROSGOSTRINGRELROSGOFUNCRELROSGCBITSRELROSRODATARELROSFUNCTABRELROSELFRELROSECTSMACHORELROSECTSTYPELINKSITABLINKSFirstWritableSBUILDINFOSFIPSINFOSELFSECTSMACHOSMACHOGOTSWINDOWSSELFGOTSNOPTRDATASNOPTRDATAFIPSSTARTSNOPTRDATAFIPSSNOPTRDATAFIPSENDSNOPTRDATAENDSINITARRSDATASDATAFIPSSTARTSDATAFIPSSDATAFIPSENDSDATAENDSXCOFFTOCSBSSSNOPTRBSSSLIBFUZZER_8BIT_COUNTERSCOVERAGE_COUNTERSCOVERAGE_AUXVARSTLSBSSSFirstUnallocatedSXREFSMACHOSYMSTRSMACHOSYMTABSMACHOINDIRECTPLTSMACHOINDIRECTGOTSDYNIMPORTSHOSTOBJSUNDEFEXTSDWARFSECTSDWARFCUINFOSDWARFCONSTSDWARFFCNSDWARFABSFCNSDWARFTYPESDWARFVARSDWARFRANGESDWARFLOCSDWARFLINESSDWARFADDRSSEHUNWINDINFOSSEHSECT"
-var _SymKind_index = [...]uint16{0, 4, 9, 23, 32, 44, 52, 62, 71, 76, 83, 92, 99, 106, 113, 129, 140, 154, 164, 172, 182, 192, 204, 218, 230, 242, 254, 267, 280, 295, 304, 313, 321, 335, 345, 354, 362, 368, 377, 385, 392, 402, 421, 435, 452, 465, 473, 478, 492, 501, 513, 521, 530, 534, 543, 566, 583, 599, 606, 623, 628, 640, 652, 669, 686, 696, 704, 713, 723, 735, 746, 755, 767, 777, 786, 797, 806, 817, 827, 841, 849}
+var _SymKind_index = [...]uint16{0, 4, 9, 23, 32, 44, 52, 62, 71, 76, 83, 92, 99, 106, 113, 129, 140, 154, 164, 172, 180, 190, 200, 212, 226, 238, 250, 262, 275, 288, 303, 312, 321, 335, 345, 354, 362, 368, 377, 385, 392, 402, 421, 435, 452, 465, 473, 478, 492, 501, 513, 521, 530, 534, 543, 566, 583, 599, 606, 623, 628, 640, 652, 669, 686, 696, 704, 713, 723, 735, 746, 755, 767, 777, 786, 797, 806, 817, 827, 841, 849}
func (i SymKind) String() string {
if i >= SymKind(len(_SymKind_index)-1) {
Change information
Files:
- M src/cmd/link/internal/ld/data.go
- M src/cmd/link/internal/ld/elf.go
- M src/cmd/link/internal/ld/elf_test.go
- M src/cmd/link/internal/sym/symkind.go
- M src/cmd/link/internal/sym/symkind_string.go
Change size: M
Delta: 5 files changed, 37 insertions(+), 37 deletions(-)
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Ian Lance Taylor (Gerrit)
Nov 5, 2025, 7:15:37 PM (5 days ago) Nov 5
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Ian Lance Taylor (Gerrit)
Nov 5, 2025, 10:59:46 PM (5 days ago) Nov 5
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Ian Lance Taylor uploaded patch set #2 to this change.
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Ian Lance Taylor (Gerrit)
Nov 5, 2025, 11:00:27 PM (5 days ago) Nov 5
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Russ Cox (Gerrit)
Nov 6, 2025, 5:30:16 AM (5 days ago) Nov 6
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File-level comment, Patchset 2 (Latest):
Russ Cox . resolved
I think being in relro is left over from when functab contained actual pointers.
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Ian Lance Taylor (Gerrit)
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Change information
Commit message:
cmd/link: move pclntab out of relro section
The .gopclntab section should not have any relocations.
Move it out of relro to regular rodata.
Note that this is tested by tests like TestNoTextrel in
cmd/cgo/internal/testshared.
The existing test TestMachoSectionsReadOnly looks for sections in a
Mach-O file that are read-only after relocations are applied
(this is marked by a segment with a flags field set to 0x10).
We remove the __gopclntab section, as that section is now read-only
at all times, not only after relocating.
For #76038
Change-Id: I7f837e423bf1e802509277f5dc7fdd1ed0228e32
Reviewed-on: https://go-review.googlesource.com/c/go/+/718065
Reviewed-by: Russ Cox <r...@golang.org>
Reviewed-by: Cherry Mui <cher...@google.com>
LUCI-TryBot-Result: Go LUCI <golang...@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Ian Lance Taylor <ia...@golang.org>
Files:
- M src/cmd/link/internal/ld/data.go
- M src/cmd/link/internal/ld/elf.go
- M src/cmd/link/internal/ld/elf_test.go
- M src/cmd/link/internal/ld/macho_test.go
- M src/cmd/link/internal/sym/symkind.go
- M src/cmd/link/internal/sym/symkind_string.go
Change size: M
Delta: 6 files changed, 43 insertions(+), 42 deletions(-)
Branch: refs/heads/master
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Code-Review: +2 by Cherry Mui, +2 by Russ Cox
TryBots-Pass: LUCI-TryBot-Result+1 by Go LUCI
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