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gdb: make structured core file mappings processing global

Browse source 
In corelow.c, within core_target::build_file_mappings, we have code
that wraps around a call to gdbarch_read_core_file_mappings and
provides more structure to the results.

Specifically, gdbarch_read_core_file_mappings calls a callback once
for every region of every mapped file.  The wrapper code groups all of
the mappings for one file into an instance of 'struct mapped_file',
this allows all of the mapped regions to be associated with the
build-id and filename of a file.

In the next commit I plan to make this information available via the
Python API, and so I need to allow access to this structured wrapping
outside of corelow.c.

This commit renames 'struct mapped_file' to 'struct core_mapped_file'
and moves the struct into gdbcore.h.  Then a new global function
gdb_read_core_file_mappings is created into which I move the code to
build the structured data.

Then corelow.c is updated to call gdb_read_core_file_mappings.

This commit does not extend the Python API, that is for the next
commit.

There should be no user visible changes after this commit.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32844

Approved-By: Tom Tromey <tom@tromey.com>
This commit is contained in:
Andrew Burgess 2025-08-25 16:47:20 +01:00
parent 7862554bcf
commit fc8e5a565b
2 changed files with 160 additions and 101 deletions
Download patch file Download diff file Expand all files Collapse all files

218
gdb/corelow.c
View file

@ -366,108 +366,27 @@ core_target::core_target ()
void
core_target::build_file_mappings ()
{
/* Type holding information about a single file mapped into the inferior
at the point when the core file was created. Associates a build-id
with the list of regions the file is mapped into. */
struct mapped_file
{
/* Type for a region of a file that was mapped into the inferior when
the core file was generated. */
struct region
{
/* Constructor. See member variables for argument descriptions. */
region (CORE_ADDR start_, CORE_ADDR end_, CORE_ADDR file_ofs_)
: start (start_),
end (end_),
file_ofs (file_ofs_)
{ /* Nothing. */ }
/* The inferior address for the start of the mapped region. */
CORE_ADDR start;
/* The inferior address immediately after the mapped region. */
CORE_ADDR end;
/* The offset within the mapped file for this content. */
CORE_ADDR file_ofs;
};
/* If not nullptr, then this is the build-id associated with this
file. */
const bfd_build_id *build_id = nullptr;
/* If true then we have seen multiple different build-ids associated
with the same filename. The build_id field will have been set back
to nullptr, and we should not set build_id in future. */
bool ignore_build_id_p = false;
/* All the mapped regions of this file. */
std::vector<region> regions;
};
gdb::unordered_map<std::string, struct bfd *> bfd_map;
gdb::unordered_set<std::string> unavailable_paths;
/* All files mapped into the core file. The key is the filename. */
gdb::unordered_map<std::string, mapped_file> mapped_files;
std::vector<core_mapped_file> mapped_files
= gdb_read_core_file_mappings (m_core_gdbarch,
current_program_space->core_bfd ());
/* See linux_read_core_file_mappings() in linux-tdep.c for an example
read_core_file_mappings method. */
gdbarch_read_core_file_mappings (m_core_gdbarch,
current_program_space->core_bfd (),
/* After determining the number of mappings, read_core_file_mappings
will invoke this lambda. */
[&] (ULONGEST)
{
},
/* read_core_file_mappings will invoke this lambda for each mapping
that it finds. */
[&] (int num, ULONGEST start, ULONGEST end, ULONGEST file_ofs,
const char *filename, const bfd_build_id *build_id)
{
/* Architecture-specific read_core_mapping methods are expected to
weed out non-file-backed mappings. */
gdb_assert (filename != nullptr);
/* Add this mapped region to the data for FILENAME. */
mapped_file &file_data = mapped_files[filename];
file_data.regions.emplace_back (start, end, file_ofs);
if (build_id != nullptr && !file_data.ignore_build_id_p)
{
if (file_data.build_id == nullptr)
file_data.build_id = build_id;
else if (!build_id_equal (build_id, file_data.build_id))
{
warning (_("Multiple build-ids found for %ps"),
styled_string (file_name_style.style (), filename));
file_data.build_id = nullptr;
file_data.ignore_build_id_p = true;
}
}
});
/* Get the build-id of the core file. */
const bfd_build_id *core_build_id
= build_id_bfd_get (current_program_space->core_bfd ());
for (const auto &[filename, file_data] : mapped_files)
for (const core_mapped_file &file_data : mapped_files)
{
/* If this mapped file has the same build-id as was discovered for
the core-file itself, then we assume this is the main
executable. Record the filename as we can use this later. */
if (file_data.build_id != nullptr
&& m_expected_exec_filename.empty ()
&& build_id_equal (file_data.build_id, core_build_id))
m_expected_exec_filename = filename;
/* If this mapped file is marked as the main executable then record
the filename as we can use this later. */
if (file_data.is_main_exec && m_expected_exec_filename.empty ())
m_expected_exec_filename = file_data.filename;
/* Use exec_file_find() to do sysroot expansion. It'll
also strip the potential sysroot "target:" prefix. If
there is no sysroot, an equivalent (possibly more
canonical) pathname will be provided. */
gdb::unique_xmalloc_ptr<char> expanded_fname
= exec_file_find (filename.c_str (), nullptr);
= exec_file_find (file_data.filename.c_str (), nullptr);
bool build_id_mismatch = false;
if (expanded_fname != nullptr && file_data.build_id != nullptr)
@ -509,7 +428,7 @@ core_target::build_file_mappings ()
{
abfd = find_objfile_by_build_id (current_program_space,
file_data.build_id,
filename.c_str ());
file_data.filename.c_str ());
if (abfd != nullptr)
{
@ -527,7 +446,7 @@ core_target::build_file_mappings ()
}
std::vector<mem_range> ranges;
for (const mapped_file::region &region : file_data.regions)
for (const core_mapped_file::region &region : file_data.regions)
ranges.emplace_back (region.start, region.end - region.start);
if (expanded_fname == nullptr
@ -545,7 +464,7 @@ core_target::build_file_mappings ()
bool content_is_in_core_file_p = true;
/* Record all regions for this file as unavailable. */
for (const mapped_file::region &region : file_data.regions)
for (const core_mapped_file::region &region : file_data.regions)
{
/* Check to see if the region is available within the core
file. */
@ -577,33 +496,33 @@ core_target::build_file_mappings ()
if (build_id_mismatch)
{
if (expanded_fname == nullptr
|| filename == expanded_fname.get ())
|| file_data.filename == expanded_fname.get ())
warning (_("File %ps doesn't match build-id from core-file "
"during file-backed mapping processing"),
styled_string (file_name_style.style (),
filename.c_str ()));
file_data.filename.c_str ()));
else
warning (_("File %ps which was expanded to %ps, doesn't match "
"build-id from core-file during file-backed "
"mapping processing"),
styled_string (file_name_style.style (),
filename.c_str ()),
file_data.filename.c_str ()),
styled_string (file_name_style.style (),
expanded_fname.get ()));
}
else if (!content_is_in_core_file_p)
{
if (expanded_fname == nullptr
|| filename == expanded_fname.get ())
|| file_data.filename == expanded_fname.get ())
warning (_("Can't open file %ps during file-backed mapping "
"note processing"),
styled_string (file_name_style.style (),
filename.c_str ()));
file_data.filename.c_str ()));
else
warning (_("Can't open file %ps which was expanded to %ps "
"during file-backed mapping note processing"),
styled_string (file_name_style.style (),
filename.c_str ()),
file_data.filename.c_str ()),
styled_string (file_name_style.style (),
expanded_fname.get ()));
}
@ -617,7 +536,7 @@ core_target::build_file_mappings ()
abfd.get ());
/* Create sections for each mapped region. */
for (const mapped_file::region &region : file_data.regions)
for (const core_mapped_file::region &region : file_data.regions)
{
/* Make new BFD section. All sections have the same name,
which is permitted by bfd_make_section_anyway(). */
@ -653,7 +572,7 @@ core_target::build_file_mappings ()
soname = gdb_bfd_read_elf_soname (actual_filename);
}
m_mapped_file_info.add (soname.get (), filename.c_str (),
m_mapped_file_info.add (soname.get (), file_data.filename.c_str (),
actual_filename, std::move (ranges),
file_data.build_id);
}
@ -2163,6 +2082,103 @@ mapped_file_info::lookup (const char *filename,
/* See gdbcore.h. */
std::vector<core_mapped_file>
gdb_read_core_file_mappings (struct gdbarch *gdbarch, struct bfd *cbfd)
{
std::vector<core_mapped_file> results;
/* A map entry used while building RESULTS. */
struct map_entry
{
explicit map_entry (core_mapped_file *ptr)
: file_data (ptr)
{ /* Nothing. */ }
/* Points to an entry in RESULTS, this allows entries to be quickly
looked up and updated as new mappings are read. */
core_mapped_file *file_data = nullptr;
/* If true then we have seen multiple different build-ids associated
with the filename of FILE_DATA. The FILE_DATA->build_id field will
have been set to nullptr, and we should not set FILE_DATA->build_id
in future. */
bool ignore_build_id_p = false;
};
/* All files mapped into the core file. The key is the filename. */
gdb::unordered_map<std::string, map_entry> mapped_files;
/* Get the build-id of the core file. At least on Linux, this will be
the build-id for the main executable. If other targets add the
gdbarch_read_core_file_mappings method, then it might turn out that
this logic is no longer true, in which case this might need to move
into the gdbarch_read_core_file_mappings method. */
const bfd_build_id *core_build_id = build_id_bfd_get (cbfd);
/* See linux_read_core_file_mappings() in linux-tdep.c for an example
read_core_file_mappings method. */
gdbarch_read_core_file_mappings (gdbarch, cbfd,
/* After determining the number of mappings, read_core_file_mappings
will invoke this lambda. */
[&] (ULONGEST)
{
},
/* read_core_file_mappings will invoke this lambda for each mapping
that it finds. */
[&] (int num, ULONGEST start, ULONGEST end, ULONGEST file_ofs,
const char *filename, const bfd_build_id *build_id)
{
/* Architecture-specific read_core_mapping methods are expected to
weed out non-file-backed mappings. */
gdb_assert (filename != nullptr);
/* Add this mapped region to the data for FILENAME. */
auto iter = mapped_files.find (filename);
if (iter == mapped_files.end ())
{
/* Create entry in results list. */
results.emplace_back ();
/* The entry to be added to the lookup map. */
map_entry entry (&results.back ());
entry.file_data->filename = filename;
/* Add entry to the quick lookup map and update ITER. */
auto inserted_result
= mapped_files.insert ({filename, std::move (entry)});
gdb_assert (inserted_result.second);
iter = inserted_result.first;
}
core_mapped_file &file_data = *iter->second.file_data;
bool &ignore_build_id_p = iter->second.ignore_build_id_p;
file_data.regions.emplace_back (start, end, file_ofs);
if (build_id != nullptr && !ignore_build_id_p)
{
if (file_data.build_id == nullptr)
file_data.build_id = build_id;
else if (!build_id_equal (build_id, file_data.build_id))
{
warning (_("Multiple build-ids found for %ps"),
styled_string (file_name_style.style (), filename));
file_data.build_id = nullptr;
ignore_build_id_p = true;
}
}
if (build_id != nullptr
&& core_build_id != nullptr
&& build_id_equal (build_id, core_build_id))
file_data.is_main_exec = true;
});
return results;
}
/* See gdbcore.h. */
std::optional <core_target_mapped_file_info>
core_target_find_mapped_file (const char *filename,
std::optional<CORE_ADDR> addr)

43
gdb/gdbcore.h
View file

@ -258,4 +258,47 @@ std::optional<core_target_mapped_file_info>
core_target_find_mapped_file (const char *filename,
std::optional<CORE_ADDR> addr);
/* Type holding information about a single file mapped into the inferior
at the point when the core file was created. Associates a build-id
with the list of regions the file is mapped into. */
struct core_mapped_file
{
/* Type for a region of a file that was mapped into the inferior when
the core file was generated. */
struct region
{
/* Constructor. See member variables for argument descriptions. */
region (CORE_ADDR start_, CORE_ADDR end_, CORE_ADDR file_ofs_)
: start (start_),
end (end_),
file_ofs (file_ofs_)
{ /* Nothing. */ }
/* The inferior address for the start of the mapped region. */
CORE_ADDR start;
/* The inferior address immediately after the mapped region. */
CORE_ADDR end;
/* The offset within the mapped file for this content. */
CORE_ADDR file_ofs;
};
/* The filename as recorded in the core file. */
std::string filename;
/* If not nullptr, then this is the build-id associated with this
file. */
const bfd_build_id *build_id = nullptr;
/* All the mapped regions of this file. */
std::vector<region> regions;
/* True if this is the main executable. */
bool is_main_exec = false;
};
extern std::vector<core_mapped_file> gdb_read_core_file_mappings
(struct gdbarch *gdbarch, struct bfd *cbfd);
#endif /* GDB_GDBCORE_H */