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https://github.com/JakeHillion/drgn.git
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04d2dee964
There's a lot more context here that we should write down. It's also
worth noting that it appears that GDB always zero fills the range
between p_filesz and p_memsz, so if we end up having any other issues
because of this, we might have to concede and go back to the behavior
before commit 02912ca7d0 ("libdrgn: fix handling of p_filesz < p_memsz
in core dumps").
Signed-off-by: Omar Sandoval <osandov@osandov.com>
127 lines
3.6 KiB
C
127 lines
3.6 KiB
C
// Copyright (c) Meta Platforms, Inc. and affiliates.
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// SPDX-License-Identifier: GPL-3.0-or-later
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/**
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* @file
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*
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* Memory reading interface.
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*
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* See @ref MemoryReader.
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*/
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#ifndef DRGN_MEMORY_READER_H
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#define DRGN_MEMORY_READER_H
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#include "binary_search_tree.h"
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#include "drgn.h"
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/**
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* @ingroup Internals
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*
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* @defgroup MemoryReader Memory reader
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*
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* Memory reading interface.
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*
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* @ref drgn_memory_reader provides a common interface for registering regions
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* of memory in a program and reading from memory.
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*
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* @ref drgn_memory_reader does not have a notion of the maximum address or
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* address overflow/wrap-around. Those must be handled at a higher layer.
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*
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* @{
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*/
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DEFINE_BINARY_SEARCH_TREE_TYPE(drgn_memory_segment_tree,
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struct drgn_memory_segment)
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/**
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* Memory reader.
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*
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* A memory reader maps the segments of memory in an address space to callbacks
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* which can be used to read memory from those segments.
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*/
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struct drgn_memory_reader {
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/** Virtual memory segments. */
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struct drgn_memory_segment_tree virtual_segments;
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/** Physical memory segments. */
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struct drgn_memory_segment_tree physical_segments;
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};
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/**
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* Initialize a @ref drgn_memory_reader.
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*
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* The reader is initialized with no segments.
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*/
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void drgn_memory_reader_init(struct drgn_memory_reader *reader);
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/** Deinitialize a @ref drgn_memory_reader. */
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void drgn_memory_reader_deinit(struct drgn_memory_reader *reader);
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/** Return whether a @ref drgn_memory_reader has no segments. */
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bool drgn_memory_reader_empty(struct drgn_memory_reader *reader);
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/**
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* Add a segment to a @ref drgn_memory_reader.
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*
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* @param[in] reader Memory reader.
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* @param[in] min_address Start address (inclusive).
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* @param[in] max_address End address (inclusive). Must be `>= min_address`.
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* @param[in] read_fn Callback to read from segment.
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* @param[in] arg Argument to pass to @p read_fn.
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* @param[in] physical Whether to add a physical memory segment.
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* @return @c NULL on success, non-@c NULL on error.
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*/
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struct drgn_error *
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drgn_memory_reader_add_segment(struct drgn_memory_reader *reader,
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uint64_t min_address, uint64_t max_address,
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drgn_memory_read_fn read_fn, void *arg,
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bool physical);
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/**
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* Read from a @ref drgn_memory_reader.
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*
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* @param[in] reader Memory reader.
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* @param[out] buf Buffer to read into.
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* @param[in] address Starting address in memory to read.
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* @param[in] count Number of bytes to read. `address + count - 1` must be
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* `<= UINT64_MAX`
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* @param[in] physical Whether @c address is physical.
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* @return @c NULL on success, non-@c NULL on error.
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*/
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struct drgn_error *drgn_memory_reader_read(struct drgn_memory_reader *reader,
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void *buf, uint64_t address,
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size_t count, bool physical);
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/** Argument for @ref drgn_read_memory_file(). */
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struct drgn_memory_file_segment {
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/** Offset in the file where the segment starts. */
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uint64_t file_offset;
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/**
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* Size of the segment in the file. This may be less than the size of
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* the segment in memory.
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*/
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uint64_t file_size;
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/** File descriptor. */
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int fd;
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/**
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* If @c true, EIO is treated as a fault. Otherwise, it is treated as an
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* OS error.
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*/
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bool eio_is_fault;
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/**
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* If @c true, reads between @ref file_size and the size of the segment
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* in memory will be returned as zeroes. Otherwise, such reads will
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* result in a fault.
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*/
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bool zerofill;
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};
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/** @ref drgn_memory_read_fn which reads from a file. */
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struct drgn_error *drgn_read_memory_file(void *buf, uint64_t address,
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size_t count, uint64_t offset,
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void *arg, bool physical);
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/** @} */
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#endif /* DRGN_MEMORY_READER_H */
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