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Merge pull request #731 from dave-tucker/noclone-btf
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aya-obj: Mutate BTF in-place without clone
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@dave-tucker
dave-tucker authored Aug 9, 2023
2 parents cb42d02 + 098d436 commit e210012
Showing 1 changed file with 39 additions and 38 deletions.
77 changes: 39 additions & 38 deletions aya-obj/src/btf/btf.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -475,17 +475,15 @@ impl Btf {
) -> Result<(), BtfError> {
let mut types = mem::take(&mut self.types);
for i in 0..types.types.len() {
let t = &types.types[i];
let t = &mut types.types[i];
let kind = t.kind();
match t {
// Fixup PTR for Rust
// LLVM emits names for Rust pointer types, which the kernel doesn't like
// While I figure out if this needs fixing in the Kernel or LLVM, we'll
// do a fixup here
BtfType::Ptr(ptr) => {
let mut fixed_ty = ptr.clone();
fixed_ty.name_offset = 0;
types.types[i] = BtfType::Ptr(fixed_ty)
ptr.name_offset = 0;
}
// Sanitize VAR if they are not supported
BtfType::Var(v) if !features.btf_datasec => {
Expand All @@ -496,7 +494,7 @@ impl Btf {
debug!("{}: not supported. replacing with STRUCT", kind);

// STRUCT aren't allowed to have "." in their name, fixup this if needed.
let mut name_offset = t.name_offset();
let mut name_offset = d.name_offset;
let name = self.string_at(name_offset)?;

// Handle any "." characters in struct names
Expand All @@ -506,18 +504,22 @@ impl Btf {
name_offset = self.add_string(&fixed_name);
}

let mut members = vec![];
for member in d.entries.iter() {
let mt = types.type_by_id(member.btf_type).unwrap();
members.push(BtfMember {
name_offset: mt.name_offset(),
btf_type: member.btf_type,
offset: member.offset * 8,
let entries = std::mem::take(&mut d.entries);

let members = entries
.iter()
.map(|e| {
let mt = types.type_by_id(e.btf_type).unwrap();
BtfMember {
name_offset: mt.name_offset(),
btf_type: e.btf_type,
offset: e.offset * 8,
}
})
}
.collect();

types.types[i] =
BtfType::Struct(Struct::new(name_offset, members, d.entries.len() as u32));
BtfType::Struct(Struct::new(name_offset, members, entries.len() as u32));
}
// Fixup DATASEC
// DATASEC sizes aren't always set by LLVM
Expand All @@ -527,18 +529,16 @@ impl Btf {
let name = self.string_at(d.name_offset)?;
let name = name.into_owned();

let mut fixed_ty = d.clone();

// Handle any "/" characters in section names
// Example: "maps/hashmap"
let fixed_name = name.replace('/', ".");
if fixed_name != name {
fixed_ty.name_offset = self.add_string(&fixed_name);
d.name_offset = self.add_string(&fixed_name);
}

// There are some cases when the compiler does indeed populate the
// size
if t.size().unwrap() > 0 {
if d.size > 0 {
debug!("{} {}: size fixup not required", kind, name);
} else {
// We need to get the size of the section from the ELF file
Expand All @@ -551,22 +551,23 @@ impl Btf {
}
};
debug!("{} {}: fixup size to {}", kind, name, size);
fixed_ty.size = *size as u32;
d.size = *size as u32;

// The Vec<btf_var_secinfo> contains BTF_KIND_VAR sections
// that need to have their offsets adjusted. To do this,
// we need to get the offset from the ELF file.
// This was also cached during initial parsing and
// we can query by name in symbol_offsets
for d in &mut fixed_ty.entries.iter_mut() {
let var_type = types.type_by_id(d.btf_type)?;
let var_kind = var_type.kind();
if let BtfType::Var(var) = var_type {
let mut entries = mem::take(&mut d.entries);
let mut fixed_section = d.clone();

for e in entries.iter_mut() {
if let BtfType::Var(var) = types.type_by_id(e.btf_type)? {
let var_name = self.string_at(var.name_offset)?;
if var.linkage == VarLinkage::Static {
debug!(
"{} {}: {} {}: fixup not required",
kind, name, var_kind, var_name
"{} {}: VAR {}: fixup not required",
kind, name, var_name
);
continue;
}
Expand All @@ -579,27 +580,26 @@ impl Btf {
});
}
};
d.offset = *offset as u32;
e.offset = *offset as u32;
debug!(
"{} {}: {} {}: fixup offset {}",
kind, name, var_kind, var_name, offset
"{} {}: VAR {}: fixup offset {}",
kind, name, var_name, offset
);
} else {
return Err(BtfError::InvalidDatasec);
}
}
fixed_section.entries = entries;
types.types[i] = BtfType::DataSec(fixed_section);
}
types.types[i] = BtfType::DataSec(fixed_ty);
}
// Fixup FUNC_PROTO
BtfType::FuncProto(ty) if features.btf_func => {
let mut ty = ty.clone();
for (i, param) in ty.params.iter_mut().enumerate() {
if param.name_offset == 0 && param.btf_type != 0 {
param.name_offset = self.add_string(&format!("param{i}"));
}
}
types.types[i] = BtfType::FuncProto(ty);
}
// Sanitize FUNC_PROTO
BtfType::FuncProto(ty) if !features.btf_func => {
Expand Down Expand Up @@ -635,7 +635,6 @@ impl Btf {
// and verified separately from their callers, while instead we
// want tracking info (eg bound checks) to be propagated to the
// memory builtins.
let mut fixed_ty = ty.clone();
if ty.linkage() == FuncLinkage::Global {
if !features.btf_func_global {
debug!(
Expand All @@ -645,9 +644,8 @@ impl Btf {
} else {
debug!("changing FUNC {name} linkage to BTF_FUNC_STATIC");
}
fixed_ty.set_linkage(FuncLinkage::Static);
ty.set_linkage(FuncLinkage::Static);
}
types.types[i] = BtfType::Func(fixed_ty);
}
}
// Sanitize FLOAT
Expand Down Expand Up @@ -1244,9 +1242,9 @@ mod tests {
0,
)));

let name_offset = btf.add_string("foo");
let var_name_offset = btf.add_string("foo");
let var_type_id = btf.add_type(BtfType::Var(Var::new(
name_offset,
var_name_offset,
int_type_id,
VarLinkage::Static,
)));
Expand All @@ -1271,11 +1269,14 @@ mod tests {
assert_eq!(fixed.name_offset , name_offset);
assert_matches!(*fixed.members, [
BtfMember {
name_offset: _,
name_offset: name_offset1,
btf_type,
offset: 0,
},
] => assert_eq!(btf_type, var_type_id));
] => {
assert_eq!(name_offset1, var_name_offset);
assert_eq!(btf_type, var_type_id);
})
});
// Ensure we can convert to bytes and back again
let raw = btf.to_bytes();
Expand Down

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