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cranelift: Add COFF TLS Support (#4546)

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* cranelift: Implement COFF TLS Relocations

* cranelift: Emit SecRel relocations

* cranelift: Handle _tls_index symbol in backend
This commit is contained in:
Afonso Bordado
2022-08-11 17:33:40 +01:00
committed by GitHub
parent a40b253792
commit c5bc368cfe
10 changed files with 153 additions and 29 deletions
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48
cranelift/codegen/src/isa/x64/inst/emit.rs
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@@ -1,7 +1,7 @@
use crate::binemit::{Addend, Reloc};
use crate::ir::immediates::{Ieee32, Ieee64};
use crate::ir::LibCall;
use crate::ir::TrapCode;
use crate::ir::{KnownSymbol, LibCall};
use crate::isa::x64::encoding::evex::{EvexInstruction, EvexVectorLength};
use crate::isa::x64::encoding::rex::{
emit_simm, emit_std_enc_enc, emit_std_enc_mem, emit_std_reg_mem, emit_std_reg_reg, int_reg_enc,
@@ -2952,6 +2952,52 @@ pub(crate) fn emit(
sink.put1(0x17);
}
Inst::CoffTlsGetAddr { ref symbol } => {
// See: https://gcc.godbolt.org/z/M8or9x6ss
// And: https://github.com/bjorn3/rustc_codegen_cranelift/issues/388#issuecomment-532930282
// Emit the following sequence
// movl (%rip), %eax ; IMAGE_REL_AMD64_REL32 _tls_index
// movq %gs:88, %rcx
// movq (%rcx,%rax,8), %rax
// leaq (%rax), %rax ; Reloc: IMAGE_REL_AMD64_SECREL symbol
// Load TLS index for current thread
// movl (%rip), %eax
sink.put1(0x8b); // mov
sink.put1(0x05);
emit_reloc(
sink,
Reloc::X86PCRel4,
&ExternalName::KnownSymbol(KnownSymbol::CoffTlsIndex),
-4,
);
sink.put4(0); // offset
// movq %gs:88, %rcx
// Load the TLS Storage Array pointer
// The gs segment register refers to the base address of the TEB on x64.
// 0x58 is the offset in the TEB for the ThreadLocalStoragePointer member on x64:
sink.put_data(&[
0x65, 0x48, // REX.W
0x8b, // MOV
0x0c, 0x25, 0x58, // 0x58 - ThreadLocalStoragePointer offset
0x00, 0x00, 0x00,
]);
// movq (%rcx,%rax,8), %rax
// Load the actual TLS entry for this thread.
// Computes ThreadLocalStoragePointer + _tls_index*8
sink.put_data(&[0x48, 0x8b, 0x04, 0xc1]);
// leaq (%rax), %rax
sink.put1(0x48);
sink.put1(0x8d);
sink.put1(0x80);
emit_reloc(sink, Reloc::X86SecRel, symbol, 0);
sink.put4(0); // offset
}
Inst::Unwind { ref inst } => {
sink.add_unwind(inst.clone());
}