[RISCV] Support RISC-V TLSDESC in LLD #77516
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Created using spr 1.3.4
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@llvm/pr-subscribers-lld @llvm/pr-subscribers-lld-elf Author: Paul Kirth (ilovepi) ChangesThis patch adds support for RISC-V TLSDESC relocations, as described in It does not attempt to handle relaxation for these cases, which will be Full diff: https://github.com/llvm/llvm-project/pull/77516.diff 6 Files Affected:
diff --git a/lld/ELF/Arch/RISCV.cpp b/lld/ELF/Arch/RISCV.cpp
index 1d3d179e5d6fb5..460cccbabdb002 100644
--- a/lld/ELF/Arch/RISCV.cpp
+++ b/lld/ELF/Arch/RISCV.cpp
@@ -44,6 +44,7 @@ class RISCV final : public TargetInfo {
void relocate(uint8_t *loc, const Relocation &rel,
uint64_t val) const override;
void relocateAlloc(InputSectionBase &sec, uint8_t *buf) const override;
+ RelExpr adjustTlsExpr(RelType type, RelExpr expr) const override;
bool relaxOnce(int pass) const override;
};
@@ -120,6 +121,8 @@ RISCV::RISCV() {
}
gotRel = symbolicRel;
+ tlsDescRel = R_RISCV_TLSDESC_CALL;
+
// .got[0] = _DYNAMIC
gotHeaderEntriesNum = 1;
@@ -298,6 +301,13 @@ RelExpr RISCV::getRelExpr(const RelType type, const Symbol &s,
return R_TLSGD_PC;
case R_RISCV_TLS_GOT_HI20:
return R_GOT_PC;
+ case R_RISCV_TLSDESC_HI20:
+ return R_TLSDESC_PC;
+ case R_RISCV_TLSDESC_LOAD_LO12:
+ case R_RISCV_TLSDESC_ADD_LO12:
+ return R_TLSDESC;
+ case R_RISCV_TLSDESC_CALL:
+ return R_TLSDESC_CALL;
case R_RISCV_TPREL_HI20:
case R_RISCV_TPREL_LO12_I:
case R_RISCV_TPREL_LO12_S:
@@ -420,6 +430,7 @@ void RISCV::relocate(uint8_t *loc, const Relocation &rel, uint64_t val) const {
case R_RISCV_PCREL_HI20:
case R_RISCV_TLS_GD_HI20:
case R_RISCV_TLS_GOT_HI20:
+ case R_RISCV_TLSDESC_HI20:
case R_RISCV_TPREL_HI20:
case R_RISCV_HI20: {
uint64_t hi = val + 0x800;
@@ -430,6 +441,8 @@ void RISCV::relocate(uint8_t *loc, const Relocation &rel, uint64_t val) const {
case R_RISCV_PCREL_LO12_I:
case R_RISCV_TPREL_LO12_I:
+ case R_RISCV_TLSDESC_LOAD_LO12:
+ case R_RISCV_TLSDESC_ADD_LO12:
case R_RISCV_LO12_I: {
uint64_t hi = (val + 0x800) >> 12;
uint64_t lo = val - (hi << 12);
@@ -557,6 +570,13 @@ void RISCV::relocateAlloc(InputSectionBase &sec, uint8_t *buf) const {
}
}
+RelExpr RISCV::adjustTlsExpr(RelType type, RelExpr expr) const {
+ if (expr == R_RELAX_TLS_GD_TO_IE) {
+ return R_RELAX_TLS_GD_TO_IE_ABS;
+ }
+ return expr;
+}
+
namespace {
struct SymbolAnchor {
uint64_t offset;
diff --git a/lld/ELF/InputSection.cpp b/lld/ELF/InputSection.cpp
index 53b496bd084258..90f55c4b8a6b1c 100644
--- a/lld/ELF/InputSection.cpp
+++ b/lld/ELF/InputSection.cpp
@@ -851,6 +851,7 @@ uint64_t InputSectionBase::getRelocTargetVA(const InputFile *file, RelType type,
return sym.getSize() + a;
case R_TLSDESC:
return in.got->getTlsDescAddr(sym) + a;
+ case R_RISCV_TLSDESC_HI:
case R_TLSDESC_PC:
return in.got->getTlsDescAddr(sym) + a - p;
case R_TLSDESC_GOTPLT:
diff --git a/lld/ELF/Relocations.cpp b/lld/ELF/Relocations.cpp
index 20eb02b8798447..6e67a13731fea8 100644
--- a/lld/ELF/Relocations.cpp
+++ b/lld/ELF/Relocations.cpp
@@ -1269,7 +1269,7 @@ static unsigned handleTlsRelocation(RelType type, Symbol &sym,
return handleMipsTlsRelocation(type, sym, c, offset, addend, expr);
if (oneof<R_AARCH64_TLSDESC_PAGE, R_TLSDESC, R_TLSDESC_CALL, R_TLSDESC_PC,
- R_TLSDESC_GOTPLT>(expr) &&
+ R_TLSDESC_GOTPLT, R_RISCV_TLSDESC_HI>(expr) &&
config->shared) {
if (expr != R_TLSDESC_CALL) {
sym.setFlags(NEEDS_TLSDESC);
@@ -1333,7 +1333,7 @@ static unsigned handleTlsRelocation(RelType type, Symbol &sym,
if (oneof<R_AARCH64_TLSDESC_PAGE, R_TLSDESC, R_TLSDESC_CALL, R_TLSDESC_PC,
R_TLSDESC_GOTPLT, R_TLSGD_GOT, R_TLSGD_GOTPLT, R_TLSGD_PC,
- R_LOONGARCH_TLSGD_PAGE_PC>(expr)) {
+ R_LOONGARCH_TLSGD_PAGE_PC, R_RISCV_TLSDESC_HI>(expr)) {
if (!toExecRelax) {
sym.setFlags(NEEDS_TLSGD);
c.addReloc({expr, type, offset, addend, &sym});
diff --git a/lld/ELF/Relocations.h b/lld/ELF/Relocations.h
index cfb9092149f3e0..9a24fe8a219dab 100644
--- a/lld/ELF/Relocations.h
+++ b/lld/ELF/Relocations.h
@@ -103,6 +103,10 @@ enum RelExpr {
R_RISCV_ADD,
R_RISCV_LEB128,
R_RISCV_PC_INDIRECT,
+ R_RISCV_TLSDESC_HI,
+ R_RISCV_TLSDESC_LOAD_LO,
+ R_RISCV_TLSDESC_ADD_LO,
+ R_RISCV_TLSDESC_CALLER,
// Same as R_PC but with page-aligned semantics.
R_LOONGARCH_PAGE_PC,
// Same as R_PLT_PC but with page-aligned semantics.
diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index dfec5e07301a74..34bb3da2a1c343 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -1950,7 +1950,8 @@ template <class ELFT> void Writer<ELFT>::finalizeSections() {
}
}
- if (config->emachine == EM_386 || config->emachine == EM_X86_64) {
+ if (config->emachine == EM_386 || config->emachine == EM_X86_64 ||
+ config->emachine == EM_RISCV) {
// On targets that support TLSDESC, _TLS_MODULE_BASE_ is defined in such a
// way that:
//
diff --git a/lld/test/ELF/riscv-tlsdesc-le.s b/lld/test/ELF/riscv-tlsdesc-le.s
new file mode 100644
index 00000000000000..6aa670cffb59b8
--- /dev/null
+++ b/lld/test/ELF/riscv-tlsdesc-le.s
@@ -0,0 +1,43 @@
+// RUN: llvm-mc -filetype=obj -triple=riscv64-pc-linux %s -o %t.o
+// RUN: ld.lld -shared %t.o -o %t.so
+// RUN: llvm-objdump --no-print-imm-hex -d --no-show-raw-insn %t.so | FileCheck %s
+// RUN: llvm-readelf -r %t.so | FileCheck --check-prefix=REL %s
+
+// CHECK: 00000000000012d8 <_start>:
+// CHECK-NEXT: 12d8: auipc a0, 1
+// CHECK-NEXT: 12dc: ld a1, 920(a0)
+// CHECK-NEXT: 12e0: addi a0, a0, 920
+// CHECK-NEXT: 12e4: jalr t0, a1
+// CHECK-NEXT: 12e8: add a0, a0, tp
+// CHECK-NEXT: 12ec: ret
+
+// REL: Relocation section '.rela.dyn' at offset 0x{{[0-9a-f]+}} contains 2 entries
+// REL: R_RISCV_TLSDESC_CALL ffffffffffffffe8
+// REL-NEXT: R_RISCV_TLSDESC_CALL 0
+
+ .text
+ .attribute 4, 16
+ .attribute 5, "rv64i2p1"
+ .file "<stdin>"
+ .globl _start # -- Begin function _start
+ .p2align 2
+ .type _start,@function
+_start: # @_start
+# %bb.0: # %entry
+.Ltlsdesc_hi0:
+ auipc a0, %tlsdesc_hi(unspecified)
+ ld a1, %tlsdesc_load_lo(.Ltlsdesc_hi0)(a0)
+ addi a0, a0, %tlsdesc_add_lo(.Ltlsdesc_hi0)
+ jalr t0, 0(a1), %tlsdesc_call(.Ltlsdesc_hi0)
+ add a0, a0, tp
+ ret
+.Lfunc_end0:
+ .size _start, .Lfunc_end0-_start
+ # -- End function
+ .section ".note.GNU-stack","",@progbits
+
+ .section .tbss,"awT",@nobits
+ .p2align 2
+
+unspecified:
+ .zero 4
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Created using spr 1.3.4
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The patch does not need address TLSDESC to TLS LE and IE optimizations, which is pretty important. I think we don't need linker relaxation, but we do need TLS optimization for correctness. The changes are pretty subtle, I'll probably create patch based on this with you as a co-author. |
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I have found several issues.
#79099 reuses an old revision of the LLVM part but otherwise is a rewrite and should fix these issues as well as implement linker relaxation. |
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Abandon in favor of #79239 |
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This patch adds support for RISC-V TLSDESC relocations, as described in
riscv-non-isa/riscv-elf-psabi-doc#373.
It does not attempt to handle relaxation for these cases, which will be
handled separately.