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btf: Replace / in DATASEC before load to kernel

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This replaces the / character with a . which is allowed in the kernel
names. Not allowing a forward slash is perhaps a kernel bug, but lets
fix it up here as it's commonly used for Aya

Signed-off-by: Dave Tucker <dave@dtucker.co.uk>
pull/179/head
Dave Tucker 3 years ago
parent 1904aeaef9
commit 825bb3ad20
1 changed files with 56 additions and 48 deletions
Show Stats Download Patch File Download Diff File

104
aya/src/obj/btf/btf.rs
Unescape Escape View File

@ -453,57 +453,64 @@ impl Btf {
// Start DataSec Fixups
let sec_name = self.string_at(ty.name_off)?;
let name = sec_name.to_string();
// There are some cases when the compiler does indeed populate the
// size
if unsafe { ty.__bindgen_anon_1.size > 0 } {
debug!("{} {}: fixup not required", kind, name);
continue;
}
let mut fixed_ty = *ty;
let mut fixed_data = data.clone();
// We need to get the size of the section from the ELF file
// Fortunately, we cached these when parsing it initially
// and we can this up by name in section_sizes
let size =
section_sizes
.get(&name)
.ok_or_else(|| BtfError::UnknownSectionSize {
// Handle any "/" characters in section names
// Example: "maps/hashmap"
let fixed_name = name.replace('/', ".");
if fixed_name != name {
fixed_ty.name_off = self.add_string(fixed_name);
}
// There are some cases when the compiler does indeed populate the
// size
if unsafe { ty.__bindgen_anon_1.size > 0 } {
debug!("{} {}: size fixup not required", kind, name);
} else {
// We need to get the size of the section from the ELF file
// Fortunately, we cached these when parsing it initially
// and we can this up by name in section_sizes
let size = section_sizes.get(&name).ok_or_else(|| {
BtfError::UnknownSectionSize {
section_name: name.clone(),
})?;
debug!("{} {}: fixup size to {}", kind, name, size);
fixed_ty.__bindgen_anon_1.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_data {
let var_type = types.type_by_id(d.type_)?;
let var_kind = var_type.kind()?.unwrap();
if let BtfType::Var(vty, var) = var_type {
let var_name = self.string_at(vty.name_off)?.to_string();
if var.linkage == btf_func_linkage::BTF_FUNC_STATIC as u32 {
}
})?;
debug!("{} {}: fixup size to {}", kind, name, size);
fixed_ty.__bindgen_anon_1.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_data {
let var_type = types.type_by_id(d.type_)?;
let var_kind = var_type.kind()?.unwrap();
if let BtfType::Var(vty, var) = var_type {
let var_name = self.string_at(vty.name_off)?.to_string();
if var.linkage == btf_func_linkage::BTF_FUNC_STATIC as u32 {
debug!(
"{} {}: {} {}: fixup not required",
kind, name, var_kind, var_name
);
continue;
}
let offset = symbol_offsets.get(&var_name).ok_or(
BtfError::SymbolOffsetNotFound {
symbol_name: var_name.clone(),
},
)?;
d.offset = *offset as u32;
debug!(
"{} {}: {} {}: fixup not required",
kind, name, var_kind, var_name
"{} {}: {} {}: fixup offset {}",
kind, name, var_kind, var_name, offset
);
continue;
} else {
return Err(BtfError::InvalidDatasec);
}
let offset = symbol_offsets.get(&var_name).ok_or(
BtfError::SymbolOffsetNotFound {
symbol_name: var_name.clone(),
},
)?;
d.offset = *offset as u32;
debug!(
"{} {}: {} {}: fixup offset {}",
kind, name, var_kind, var_name, offset
);
} else {
return Err(BtfError::InvalidDatasec);
}
}
types.types[i] = BtfType::DataSec(fixed_ty, fixed_data);
@ -1097,7 +1104,7 @@ mod tests {
BTF_VAR_GLOBAL_EXTERN,
));
let name_offset = btf.add_string(".data".to_string());
let name_offset = btf.add_string(".data/foo".to_string());
let variables = vec![btf_var_secinfo {
type_: var_type_id,
offset: 0,
@ -1111,14 +1118,14 @@ mod tests {
};
btf.fixup_and_sanitize(
&HashMap::from([(".data".to_string(), 32u64)]),
&HashMap::from([(".data/foo".to_string(), 32u64)]),
&HashMap::from([("foo".to_string(), 64u64)]),
&features,
)
.unwrap();
if let BtfType::DataSec(fixed, sec_info) = btf.type_by_id(datasec_type_id).unwrap() {
assert!(fixed.name_off == name_offset);
assert!(fixed.name_off != name_offset);
assert!(unsafe { fixed.__bindgen_anon_1.size } == 32);
assert!(sec_info.len() == 1);
assert!(sec_info[0].type_ == var_type_id);
@ -1126,7 +1133,8 @@ mod tests {
sec_info[0].offset == 64,
"expected 64, got {}",
sec_info[0].offset
)
);
assert!(btf.string_at(fixed.name_off).unwrap() == ".data.foo")
} else {
panic!("not a datasec")
}

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