Skip to content

Commit

Permalink
cleanup reading kcore blocks (#102)
Browse files Browse the repository at this point in the history
  • Loading branch information
@bmc-msft
bmc-msft authored Jun 16, 2022
1 parent 7398475 commit 0979236
Show file tree
Hide file tree
Showing 4 changed files with 313 additions and 54 deletions.
1 change: 1 addition & 0 deletions src/image.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,7 @@ pub struct Header {
pub version: u32,
}

#[derive(PartialEq, Eq, Debug, Clone)]
pub struct Block {
pub offset: u64,
pub range: Range<u64>,
Expand Down
104 changes: 66 additions & 38 deletions src/iomem.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,7 @@ fn parse_file(path: &Path) -> Result<Vec<Range<u64>>, Error> {
ranges.push(start..end);
}

Ok(ranges)
Ok(merge_ranges(ranges))
}

#[must_use]
Expand Down Expand Up @@ -122,43 +122,71 @@ mod tests {

#[test]
fn test_parse_iomem() -> Result<(), Error> {
let ranges = parse_file(Path::new("test/iomem.txt"))?;
let expected = [
4096..654_335,
1_048_576..1_073_676_287,
4_294_967_296..6_979_321_855,
];
assert_eq!(ranges, expected);

let ranges = parse_file(Path::new("test/iomem-2.txt"))?;
let expected = [
4096..655_359,
1_048_576..1_055_838_207,
1_056_026_624..1_073_328_127,
1_073_737_728..1_073_741_823,
4_294_967_296..6_979_321_855,
];
assert_eq!(ranges, expected);

let ranges = parse_file(Path::new("test/iomem-3.txt"))?;
let expected = [
65_536..649_215,
1_048_576..2_146_303_999,
2_146_435_072..2_147_483_647,
];
assert_eq!(ranges, expected);

let ranges = parse_file(Path::new("test/iomem-4.txt"))?;
let expected = [
4_096..655_359,
1_048_576..1_423_523_839,
1_423_585_280..1_511_186_431,
1_780_150_272..1_818_623_999,
1_818_828_800..1_843_613_695,
2_071_535_616..2_071_986_175,
4_294_967_296..414_464_344_063,
];
assert_eq!(ranges, expected);
for (filename, expected) in [
(
Path::new("test/iomem.txt"),
vec![
4096..654_335,
1_048_576..1_073_676_287,
4_294_967_296..6_979_321_855,
],
),
(
Path::new("test/iomem-2.txt"),
vec![
4096..655_359,
1_048_576..1_055_838_207,
1_056_026_624..1_073_328_127,
1_073_737_728..1_073_741_823,
4_294_967_296..6_979_321_855,
],
),
(
Path::new("test/iomem-3.txt"),
vec![
65_536..649_215,
1_048_576..2_146_303_999,
2_146_435_072..2_147_483_647,
],
),
(
Path::new("test/iomem-4.txt"),
vec![
4_096..655_359,
1_048_576..1_423_523_839,
1_423_585_280..1_511_186_431,
1_780_150_272..1_818_623_999,
1_818_828_800..1_843_613_695,
2_071_535_616..2_071_986_175,
4_294_967_296..414_464_344_063,
],
),
(
Path::new("test/iomem-5.txt"),
vec![
4_096..655_359,
1_048_576..175_058_967,
175_058_968..175_067_223,
175_067_224..175_071_255,
175_071_256..175_077_463,
175_077_464..175_079_447,
175_079_448..175_087_703,
175_087_704..175_091_735,
175_091_736..175_124_567,
175_124_568..241_524_735,
241_643_520..251_310_079,
251_326_464..251_383_807,
251_424_768..264_671_231,
264_675_328..267_280_383,
267_739_136..267_866_111,
267_870_208..3_221_225_471,
4_294_967296..13_958_643_711,
],
),
] {
let ranges = parse_file(filename)?;
assert_eq!(ranges, expected);
}

Ok(())
}
Expand Down
123 changes: 107 additions & 16 deletions src/snapshot.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -20,9 +20,6 @@ pub enum Error {
#[error("locked down /proc/kcore")]
LockedDownKcore,

#[error("unable to find memory range: {0:?}")]
UnableToFindMemoryRange(Range<u64>),

#[error("unable to create memory snapshot")]
UnableToCreateMemorySnapshot(#[from] crate::image::Error),

Expand Down Expand Up @@ -194,6 +191,50 @@ impl<'a, 'b> Snapshot<'a, 'b> {
Ok(())
}

// given a set of ranges from iomem and a set of Blocks derived from the
// psuedo-elf phys section headers, derive a set of ranges that can be used
// to create a snapshot.
fn find_kcore_blocks(ranges: &[Range<u64>], headers: &[Block]) -> Vec<Block> {
let mut result = vec![];

'outer: for range in ranges {
let mut range = range.clone();

'inner: for header in headers {
match (
header.range.contains(&range.start),
// TODO: ranges is currently inclusive, but not a
// RangeInclusive. this should be adjusted.
header.range.contains(&(range.end - 1)),
) {
(true, true) => {
let block = Block {
offset: header.offset + range.start - header.range.start,
range: range.clone(),
};

result.push(block);
continue 'outer;
}
(true, false) => {
let block = Block {
offset: header.offset + range.start - header.range.start,
range: range.start..header.range.end,
};

result.push(block);
range.start = header.range.end;
}
_ => {
continue 'inner;
}
};
}
}

result
}

fn kcore(&self) -> Result<()> {
if !is_kcore_ok() {
return Err(Error::LockedDownKcore);
Expand All @@ -206,21 +247,19 @@ impl<'a, 'b> Snapshot<'a, 'b> {
file.phdrs.sort_by(|a, b| a.vaddr.cmp(&b.vaddr));
let start = file.phdrs[0].vaddr - self.memory_ranges[0].start;

let mut blocks = vec![];
'outer: for range in &self.memory_ranges {
for phdr in &file.phdrs {
if range.start == phdr.vaddr - start {
let size = u64::min(phdr.memsz, range.end - range.start);
blocks.push(Block {
offset: phdr.offset,
range: range.start..range.start + size,
});
continue 'outer;
}
}
return Err(Error::UnableToFindMemoryRange(range.clone()));
let mut physical_ranges = vec![];

for phdr in file.phdrs {
let entry_start = phdr.vaddr - start;
let entry_end = entry_start + phdr.memsz;

physical_ranges.push(Block {
range: entry_start..entry_end,
offset: phdr.offset,
});
}

let blocks = Self::find_kcore_blocks(&self.memory_ranges, &physical_ranges);
image.write_blocks(&blocks)?;
Ok(())
}
Expand All @@ -247,3 +286,55 @@ impl<'a, 'b> Snapshot<'a, 'b> {
Ok(())
}
}

#[cfg(test)]
mod tests {
use super::*;

#[test]
fn translate_ranges() {
let ranges = [10..20, 30..35, 45..55];

let core_ranges = [
Block {
range: 10..20,
offset: 0,
},
Block {
range: 25..35,
offset: 10,
},
Block {
range: 40..50,
offset: 20,
},
Block {
range: 50..55,
offset: 35,
},
];

let expected = vec![
Block {
offset: 0,
range: 10..20,
},
Block {
offset: 10 + 5,
range: 30..35,
},
Block {
offset: 25,
range: 45..50,
},
Block {
offset: 35,
range: 50..55,
},
];

let result = Snapshot::find_kcore_blocks(&ranges, &core_ranges);

assert_eq!(result, expected);
}
}
Loading

0 comments on commit 0979236

Please sign in to comment.