[lld][WebAssembly] Error on unexpected relocation types in -pie/-shared data sections
#162117
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sbc100
changed the title
-pie/-s…-pie/-shared` data sections
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@llvm/pr-subscribers-lld @llvm/pr-subscribers-lld-wasm Author: Sam Clegg (sbc100) ChangesMost likely we do want to support R_WASM_FUNCTION_INDEX_I32 at some point but this relocation types (along with many others) is not currently supported by See #146923 Full diff: https://github.com/llvm/llvm-project/pull/162117.diff 2 Files Affected:
diff --git a/lld/test/wasm/bad-data-relocs.s b/lld/test/wasm/bad-data-relocs.s
new file mode 100644
index 0000000000000..4292d67eee0c8
--- /dev/null
+++ b/lld/test/wasm/bad-data-relocs.s
@@ -0,0 +1,27 @@
+## Certain relocations types are not supported by runtime relocation code
+## generated in `-shared/`-pie` binaries.
+
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t.o %s
+# RUN: not wasm-ld -pie --experimental-pic %t.o -o %t.wasm 2>&1 | FileCheck %s
+
+# CHECK: wasm-ld: error: invalid relocation type in data section: R_WASM_FUNCTION_INDEX_I32
+
+foo:
+ .functype foo (i32) -> ()
+ end_function
+
+.globl _start
+_start:
+ .functype _start () -> ()
+ i32.const bar@GOT
+ call foo@GOT
+ end_function
+
+# data section containing relocation type that is not valid in a data section
+.section .data,"",@
+.globl bar
+bar:
+ .int32 0
+ .size bar, 4
+
+.reloc bar, R_WASM_FUNCTION_INDEX_I32, foo
diff --git a/lld/wasm/InputChunks.cpp b/lld/wasm/InputChunks.cpp
index 181221a77b106..f5e9c4a04a48f 100644
--- a/lld/wasm/InputChunks.cpp
+++ b/lld/wasm/InputChunks.cpp
@@ -406,6 +406,16 @@ uint64_t InputChunk::getVA(uint64_t offset) const {
return (outputSeg ? outputSeg->startVA : 0) + getChunkOffset(offset);
}
+bool isValidRuntimeRelocation(WasmRelocType type) {
+ // TODO(https://github.com/llvm/llvm-project/issues/146923): Add
+ // R_WASM_FUNCTION_INDEX_I32 to this list
+ return type == R_WASM_TABLE_INDEX_I32 ||
+ type == R_WASM_TABLE_INDEX_I64 ||
+ type == R_WASM_MEMORY_ADDR_LOCREL_I32 ||
+ type == R_WASM_MEMORY_ADDR_I32 ||
+ type == R_WASM_MEMORY_ADDR_I64;
+}
+
// Generate code to apply relocations to the data section at runtime.
// This is only called when generating shared libraries (PIC) where address are
// not known at static link time.
@@ -426,6 +436,11 @@ bool InputChunk::generateRelocationCode(raw_ostream &os) const {
for (const WasmRelocation &rel : relocations) {
uint64_t offset = getVA(rel.Offset) - getInputSectionOffset();
+ if (!isValidRuntimeRelocation(rel.getType())) {
+ error("invalid relocation type in data section: " + relocTypetoString(rel.Type));
+ }
+
+
Symbol *sym = file->getSymbol(rel);
// Runtime relocations are needed when we don't know the address of
// a symbol statically.
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✅ With the latest revision this PR passed the C/C++ code formatter. |
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dschuff
reviewed
Oct 6, 2025
…hared` data sections Most likely we do want to support R_WASM_FUNCTION_INDEX_I32 at some point but this relocation types (along with many others) is not currently supported by `InputChunk::generateRelocationCode`. See llvm#146923
sbc100
changed the title
-pie/-shared` data sections-pie/-shared data sections
sbc100
changed the title
-pie/-shared data sections-pie/-shared data sections
|
Can we land this? I think it would be good first step in fixing #146923 since it turns that crash into an error. |
dschuff
approved these changes
Oct 6, 2025
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/25/builds/12106 Here is the relevant piece of the build log for the reference |
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Most likely we do want to support R_WASM_FUNCTION_INDEX_I32 at some point but this relocation types (along with many others) is not currently supported by
InputChunk::generateRelocationCode.See #146923