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RISC-V: Special handling for 0000 #7998

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RISC-V: Special handling for 0000 #7998

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38 changes: 38 additions & 0 deletions arch/riscv/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -637,6 +637,20 @@ struct RiscVArch<D: RiscVDisassembler> {
_dis: PhantomData<D>,
}

impl<D: RiscVDisassembler> RiscVArch<D> {
fn decode_zero(data: &[u8]) -> Option<usize> {
if <D::CompressedExtension as riscv_dis::StandardExtension>::supported()
&& data.len() >= 2
&& data[0] == 0
&& data[1] == 0
{
Some(2)
} else {
None
}
}
}

impl<D: RiscVDisassembler> Architecture for RiscVArch<D> {
type Handle = CustomArchitectureHandle<Self>;

Expand Down Expand Up @@ -687,6 +701,14 @@ impl<D: RiscVDisassembler> Architecture for RiscVArch<D> {
}

fn instruction_info(&self, data: &[u8], addr: u64) -> Option<InstructionInfo> {
// Special handling for 0000, which is often used by compilers
// after jumps/calls in noreturn functions to trap execution
if let Some(inst_len) = Self::decode_zero(data) {
let mut res = InstructionInfo::new(inst_len, 0);
res.add_branch(BranchKind::Unresolved);
return Some(res);
}

let (inst_len, op) = match D::decode(addr, data) {
Ok(Instr::Rv16(op)) => (2, op),
Ok(Instr::Rv32(op)) => (4, op),
Expand Down Expand Up @@ -752,6 +774,15 @@ impl<D: RiscVDisassembler> Architecture for RiscVArch<D> {
use riscv_dis::Operand;
use InstructionTextTokenKind::*;

// Special handling for 0000, which is often used by compilers
// after jumps/calls in noreturn functions to trap execution
if let Some(inst_len) = Self::decode_zero(data) {
return Some((
inst_len,
vec![InstructionTextToken::new("trap", Instruction)],
));
}

let inst = match D::decode(addr, data) {
Ok(i) => i,
_ => return None,
Expand Down Expand Up @@ -1065,6 +1096,13 @@ impl<D: RiscVDisassembler> Architecture for RiscVArch<D> {
addr: u64,
il: &LowLevelILMutableFunction,
) -> Option<(usize, bool)> {
// Special handling for 0000, which is often used by compilers
// after jumps/calls in noreturn functions to trap execution
if let Some(inst_len) = Self::decode_zero(data) {
il.trap(0).append();
return Some((inst_len, true));
}

let max_width = self.default_integer_size();

let (inst_len, op) = match D::decode(addr, data) {
Expand Down
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