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use std::ops::Range; | ||
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use crate::{BinaryReader, FromReader, Result, SectionLimited}; | ||
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/// Reader for relocation entries within a `reloc.*` section. | ||
pub type RelocationEntryReader<'a> = SectionLimited<'a, RelocationEntry>; | ||
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/// Reader for reloc.* sections as defined by | ||
/// https://github.com/WebAssembly/tool-conventions/blob/main/Linking.md#relocation-sections. | ||
#[derive(Debug, Clone)] | ||
pub struct RelocSectionReader<'a> { | ||
section: u32, | ||
range: Range<usize>, | ||
entries: SectionLimited<'a, RelocationEntry>, | ||
} | ||
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impl<'a> RelocSectionReader<'a> { | ||
/// Creates a new reader for a `reloc.*` section starting at | ||
/// `original_position` within the wasm file. | ||
pub fn new(data: &'a [u8], original_position: usize) -> Result<Self> { | ||
let mut reader = BinaryReader::new_with_offset(data, original_position); | ||
let range = reader.range().clone(); | ||
let section = reader.read_var_u32()?; | ||
Ok(Self { | ||
section, | ||
range, | ||
entries: SectionLimited::new(reader.remaining_buffer(), reader.original_position())?, | ||
}) | ||
} | ||
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/// Index of section to which the relocations apply. | ||
pub fn section_index(&self) -> u32 { | ||
self.section | ||
} | ||
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/// The byte range of the entire section. | ||
pub fn range(&self) -> Range<usize> { | ||
self.range.clone() | ||
} | ||
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/// The relocation entries. | ||
pub fn entries(&self) -> SectionLimited<'a, RelocationEntry> { | ||
self.entries.clone() | ||
} | ||
} | ||
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macro_rules! back_to_enum { | ||
($(#[$meta:meta])+ $vis:vis enum $name:ident { | ||
$($(#[$vmeta:meta])* $vname:ident $(= $val:expr)?,)* | ||
}) => { | ||
$(#[$meta])* | ||
$vis enum $name { | ||
$($(#[$vmeta])* $vname $(= $val)?,)* | ||
} | ||
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impl std::convert::TryFrom<u8> for $name { | ||
type Error = (); | ||
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fn try_from(v: u8) -> Result<Self, Self::Error> { | ||
match v { | ||
$(x if x == $name::$vname as u8 => Ok($name::$vname),)* | ||
_ => Err(()), | ||
} | ||
} | ||
} | ||
} | ||
} | ||
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back_to_enum! { | ||
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/// Relocation entry type. Each entry type corresponds to one of the | ||
/// `R_WASM_*` constants defined at | ||
/// https://github.com/llvm/llvm-project/blob/main/llvm/include/llvm/BinaryFormat/WasmRelocs.def | ||
/// and | ||
/// https://github.com/WebAssembly/tool-conventions/blob/main/Linking.md#relocation-sections. | ||
#[derive(Debug, PartialEq, Eq, Hash, Clone, Copy)] | ||
#[repr(u8)] | ||
pub enum RelocationType { | ||
/// A function index encoded as a 5-byte varuint32. Used for the | ||
/// immediate argument of a call instruction. (since LLVM 10.0) | ||
FunctionIndexLeb = 0, | ||
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/// A function table index encoded as a 5-byte varint32. Used to refer | ||
/// to the immediate argument of a i32.const instruction, e.g. taking | ||
/// the address of a function. (since LLVM 10.0) | ||
TableIndexSleb = 1, | ||
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/// A function table index encoded as a uint32, e.g. taking the address | ||
/// of a function in a static data initializer. (since LLVM 10.0) | ||
TableIndexI32 = 2, | ||
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/// A linear memory index encoded as a 5-byte varuint32. Used for the | ||
/// immediate argument of a load or store instruction, e.g. directly | ||
/// loading from or storing to a C++ global. (since LLVM 10.0) | ||
MemoryAddrLeb = 3, | ||
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/// A linear memory index encoded as a 5-byte varint32. Used for the | ||
/// immediate argument of a i32.const instruction, e.g. taking the | ||
/// address of a C++ global. (since LLVM 10.0) | ||
MemoryAddrSleb = 4, | ||
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/// A linear memory index encoded as a uint32, e.g. taking the address | ||
/// of a C++ global in a static data initializer. (since LLVM 10.0) | ||
MemoryAddrI32 = 5, | ||
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/// A type index encoded as a 5-byte varuint32, e.g. the type immediate | ||
/// in a call_indirect. (since LLVM 10.0) | ||
TypeIndexLeb = 6, | ||
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/// A global index encoded as a 5-byte varuint32, e.g. the index | ||
/// immediate in a get_global. (since LLVM 10.0) | ||
GlobalIndexLeb = 7, | ||
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/// A byte offset within code section for the specific function encoded | ||
/// as a uint32. The offsets start at the actual function code excluding | ||
/// its size field. (since LLVM 10.0) | ||
FunctionOffsetI32 = 8, | ||
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/// A byte offset from start of the specified section encoded as a | ||
/// uint32. (since LLVM 10.0) | ||
SectionOffsetI32 = 9, | ||
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/// An event index encoded as a 5-byte varuint32. Used for the immediate | ||
/// argument of a throw and if_except instruction. (since LLVM 10.0) | ||
EventIndexLeb = 10, | ||
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/// A memory address relative to the __memory_base wasm global. Used in | ||
/// position independent code (-fPIC) where absolute memory addresses | ||
/// are not known at link time. | ||
MemoryAddrRelSleb = 11, | ||
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/// A function address (table index) relative to the __table_base wasm | ||
/// global. Used in position indepenent code (-fPIC) where absolute | ||
/// function addresses are not known at link time. | ||
TableIndexRelSleb = 12, | ||
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/// A global index encoded as uint32. (since LLVM 11.0) | ||
GlobalIndexI32 = 13, | ||
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/// The 64-bit counterpart of `MemoryAddrLeb`. A 64-bit linear memory | ||
/// index encoded as a 10-byte varuint64, Used for the immediate | ||
/// argument of a load or store instruction on a 64-bit linear memory | ||
/// array. (since LLVM 11.0) | ||
MemoryAddrLeb64 = 14, | ||
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/// The 64-bit counterpart of `MemoryAddrSleb`. A 64-bit linear memory | ||
/// index encoded as a 10-byte varint64. Used for the immediate argument | ||
/// of a i64.const instruction. (since LLVM 11.0) | ||
MemoryAddrSleb64 = 15, | ||
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/// The 64-bit counterpart of `MemoryAddrI32`. A 64-bit linear memory | ||
/// index encoded as a uint64, e.g. taking the 64-bit address of a C++ | ||
/// global in a static data initializer. (since LLVM 11.0) | ||
MemoryAddrI64 = 16, | ||
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/// The 64-bit counterpart of `MemoryAddrRelSleb`. | ||
MemoryAddrRelSleb64 = 17, | ||
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/// The 64-bit counterpart of `TableIndexSleb`. A function table index | ||
/// encoded as a 10-byte varint64. Used to refer to the immediate | ||
/// argument of a i64.const instruction, e.g. taking the address of a | ||
/// function in Wasm64. (in LLVM 12.0) | ||
TableIndexSleb64 = 18, | ||
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/// The 64-bit counterpart of `TableIndexI32`. A function table index | ||
/// encoded as a uint64, e.g. taking the address of a function in a | ||
/// static data initializer. (in LLVM 12.0) | ||
TableIndexI64 = 19, | ||
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/// A table number encoded as a 5-byte varuint32. Used for the table | ||
/// immediate argument in the table.* instructions. (in LLVM 12.0) | ||
TableNumberLeb = 20, | ||
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/// An offset from the __tls_base symbol encoded as a 5-byte [varint32]. | ||
/// Used for PIC case to avoid absolute relocation. (in LLVM 12.0) | ||
MemoryAddrTlsSleb = 21, | ||
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/// The 64-bit counterpart of `FunctionOffsetI32`. A byte offset within | ||
/// code section for the specific function encoded as a uint64. (in LLVM | ||
/// 12.0) | ||
FunctionOffsetI64 = 22, | ||
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/// A byte offset between the relocating address and a linear memory | ||
/// index encoded as a uint32. Used for pointer-relative addressing. (in | ||
/// LLVM 13.0) | ||
MemoryAddrLocrelI32 = 23, | ||
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/// The 64-bit counterpart of `TableIndexRelSleb`. A function table | ||
/// index encoded as a 10-byte varint64. (in LLVM 13.0) | ||
TableIndexRelSleb64 = 24, | ||
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/// The 64-bit counterpart of `MemoryAddrTlsSleb`. (in LLVM 13.0) | ||
MemoryAddrTlsSleb64 = 25, | ||
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/// A function index encoded as a uint32. Used in custom sections for | ||
/// function annotations (__attribute__((annotate(<name>))) (in LLVM | ||
/// 17.0) | ||
FunctionIndexI32 = 26, | ||
} | ||
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} | ||
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impl<'a> FromReader<'a> for RelocationType { | ||
fn from_reader(reader: &mut BinaryReader<'a>) -> Result<Self> { | ||
let num = reader.read_u8()?; | ||
num.try_into().or_else(|_| { | ||
Err(BinaryReader::invalid_leading_byte_error( | ||
num, | ||
"RelocEntryType", | ||
reader.original_position() - 1, | ||
)) | ||
}) | ||
} | ||
} | ||
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/// Indicates the kind of addend that applies to a relocation entry. | ||
#[derive(Debug, PartialEq, Eq, Hash, Clone, Copy)] | ||
pub enum RelocAddendKind { | ||
/// Relocation entry does not include an addend. | ||
None, | ||
/// Relocation entry includes a 32-bit addend. | ||
Addend32, | ||
/// Relocation entry includes a 64-bit addend. | ||
Addend64, | ||
} | ||
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/// Single relocation entry within a `reloc.*` section, as defined at | ||
/// https://github.com/WebAssembly/tool-conventions/blob/main/Linking.md#relocation-sections. | ||
#[derive(Debug, PartialEq, Eq, Hash, Clone, Copy)] | ||
pub struct RelocationEntry { | ||
/// Relocation entry type. | ||
pub ty: RelocationType, | ||
/// Offset in bytes from the start of the section indicated by | ||
/// `RelocSectionReader::section` targetted by this relocation. | ||
pub offset: u32, | ||
/// Index in the symbol table contained in the linking section that | ||
/// corresponds to the value at `offset`. | ||
pub index: u32, | ||
/// Addend to add to the address, or `0` if not applicable. The value must | ||
/// be consistent with the `self.ty.addend_kind()`. | ||
pub addend: i64, | ||
} | ||
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impl RelocationEntry { | ||
/// Byte range relative to the start of the section indicated by | ||
/// `RelocSectionReader::section` targetted by this relocation. | ||
pub fn relocation_range(&self) -> Range<usize> { | ||
(self.offset as usize)..(self.offset as usize + self.ty.extent()) | ||
} | ||
} | ||
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impl RelocationType { | ||
/// Indicates if this relocation type has an associated `RelocEntry::addend`. | ||
pub const fn addend_kind(self: Self) -> RelocAddendKind { | ||
use RelocationType::*; | ||
match self { | ||
MemoryAddrLeb | MemoryAddrSleb | MemoryAddrI32 | FunctionOffsetI32 | ||
| SectionOffsetI32 | MemoryAddrLocrelI32 | MemoryAddrRelSleb | MemoryAddrTlsSleb => { | ||
RelocAddendKind::Addend32 | ||
} | ||
MemoryAddrRelSleb64 | MemoryAddrTlsSleb64 | MemoryAddrLeb64 | MemoryAddrSleb64 | ||
| MemoryAddrI64 | FunctionOffsetI64 => RelocAddendKind::Addend64, | ||
_ => RelocAddendKind::None, | ||
} | ||
} | ||
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/// Indicates the number of bytes that this relocation type targets. | ||
pub const fn extent(self) -> usize { | ||
use RelocationType::*; | ||
match self { | ||
FunctionIndexLeb | TableIndexSleb | MemoryAddrLeb | MemoryAddrSleb | TypeIndexLeb | ||
| GlobalIndexLeb | EventIndexLeb | MemoryAddrRelSleb | TableIndexRelSleb | ||
| TableNumberLeb | MemoryAddrTlsSleb => 5, | ||
MemoryAddrLeb64 | MemoryAddrSleb64 | TableIndexSleb64 | TableIndexRelSleb64 | ||
| MemoryAddrRelSleb64 | MemoryAddrTlsSleb64 => 10, | ||
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TableIndexI32 | MemoryAddrI32 | FunctionOffsetI32 | SectionOffsetI32 | ||
| GlobalIndexI32 | MemoryAddrLocrelI32 | FunctionIndexI32 => 4, | ||
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MemoryAddrI64 | TableIndexI64 | FunctionOffsetI64 => 8, | ||
} | ||
} | ||
} | ||
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impl<'a> FromReader<'a> for RelocationEntry { | ||
fn from_reader(reader: &mut BinaryReader<'a>) -> Result<Self> { | ||
let ty = RelocationType::from_reader(reader)?; | ||
let offset = reader.read_var_u32()?; | ||
let index = reader.read_var_u32()?; | ||
let addend = match ty.addend_kind() { | ||
RelocAddendKind::None => 0, | ||
RelocAddendKind::Addend32 => reader.read_var_i32()? as i64, | ||
RelocAddendKind::Addend64 => reader.read_var_i64()?, | ||
}; | ||
Ok(RelocationEntry { | ||
ty, | ||
offset, | ||
index, | ||
addend, | ||
}) | ||
} | ||
} |