master
6 Commits
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Simon Glass
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a603e20179 |
doc: malloc: Add a section on finding memory leaks
Document the practical workflow for detecting and diagnosing memory leaks in U-Boot, particularly in sandbox builds. This covers: - Using ut_check_delta() in unit tests for leak detection - Comparing heap dumps with malloc_dump_to_file() - Using malloc traffic logging to trace allocations - Verifying debug functions don't affect heap state - A step-by-step practical workflow Co-developed-by: Claude <noreply@anthropic.com> Signed-off-by: Simon Glass <simon.glass@canonical.com> |
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Simon Glass
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1d306039ce |
malloc: Add an option to disable mcheck-backtrace collection
Backtrace collection is relatively expensive and can significantly slow down malloc()-heavy code when mcheck is enabled. Add a new CONFIG_MCHECK_BACKTRACE option (default y) to allow disabling backtrace collection while keeping the other mcheck features (canaries, double-free detection, etc.) enabled. This allows using mcheck with less overhead when caller information is not needed. Co-developed-by: Claude <noreply@anthropic.com> Signed-off-by: Simon Glass <simon.glass@canonical.com> |
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Simon Glass
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7856369dc2 |
cmd: malloc: Add a command to show the malloc log
Add a command interface for the malloc-traffic log:
- malloc log start: Start recording allocations
- malloc log stop: Stop recording
- malloc log: Dump the recorded entries
Example output:
=> malloc log
Malloc log: 29 entries (max 524288, total 29)
Seq Type Ptr Size Caller
---- -------- ---------------- -------- ------
0 free 16a016e0 0 free_pipe_list:2001
<-parse_stream_outer:3208 <-parse_file_outer:3300
1 alloc 16a01b90 20 hush_file_init:3277
<-parse_file_outer:3295 <-run_pipe_real:1986
Co-developed-by: Claude <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>
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Simon Glass
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1d0df266dc |
malloc: Add a log for malloc() traffic
Add a malloc()-traffic log that records all malloc()-related calls with their addresses, sizes, and caller information. This is useful for debugging allocation patterns and finding the source of allocations that lack caller info in heap dumps. Each entry stores: - Operation type (alloc/free/realloc/memalign) - Pointer address - Size (and old size for realloc) - Full caller backtrace string On sandbox, the log buffer is allocated from host memory using os_malloc(), so it does not affect U-Boot's heap. The size is controlled by CONFIG_MCHECK_LOG_SIZE (default 512K entries). If the log fills up, it wraps around (circular buffer) and a warning is shown when dumping to indicate how many entries were lost. Co-developed-by: Claude <noreply@anthropic.com> Signed-off-by: Simon Glass <simon.glass@canonical.com> |
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Simon Glass
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48e4d58cc0 |
doc: malloc: Document debugging features
Update the malloc() with more info about the debugging features:
- CONFIG_MALLOC_DEBUG and CONFIG_MCHECK_HEAP_PROTECTION Kconfig options
- The malloc command with info and dump subcommands
- Caller backtrace display when mcheck is enabled
Series-to: concept
Series-cc: heinrich
Series-version: 2
Cover-letter:
malloc: Add heap debugging commands and mcheck caller tracking
This series adds improved heap-debugging capabilities.
As part of this, the recently added backtrace feature is reworked to
avoid itself using malloc(), which makes it difficult for malloc() to
use.
A new 'malloc' command with 'info' and 'dump' subcommands allows
inspecting the heap state at runtime.
The mcheck heap-protection feature is integrated into Kconfig and can be
used to to track caller information for each allocation, showing the
function name and line number.
The caller info can be seen with 'malloc dump', including for freed
chunks where possible.
The 'malloc info' command shows a few more heap statistics:
=> malloc info
total bytes = 96 MiB
in use bytes = 700.9 KiB
malloc count = 1234
free count = 567
realloc count = 89
The 'malloc dump' command walks the heap showing each chunk:
=> malloc dump
Heap dump: 19a0e000 - 1fa10000
Address Size Status
----------------------------------
19a0e000 10 (chunk header)
19a0e010 a0 log_init:453 <-board_init_r:774 <-sandbox_flow:
19a0e0b0 20070 membuf_new:420 <-console_record_init:880 <-boar
19a2e120 170 membuf_new:420 <-console_record_init:886 <-boar
19a2e290 150 unflatten_device_tree:299 <-of_live_build:328 <
19a2e3e0 a0 uclass_get:157 <-device_bind_common:59 <-device
...
19a4b080 70 free done_word:2489 <-parse_stream_outer:3190 <-pars
...
This is useful for debugging memory leaks, understanding allocation
patterns, and tracking down heap corruption issues.
Some additional patches are included to make all this work:
- format_size() for human-readable size formatting
- ut_asserteq_regex() for flexible test assertions
- backtrace_str() for condensed backtrace output
Finally, this series includes a few patches for some of the more obvious
memory leaks (scmi and some test drivers), plus a reduction in truetype
memory allocations and a fix for a watchdog crash with 'ut dm'.
END
Co-developed-by: Claude <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>
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Simon Glass
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4096d43361 |
doc: Add malloc documentation
Add doc/develop/malloc.rst documenting U-Boot's dynamic memory
allocation implementation:
- Overview of pre/post-relocation malloc phases
- dlmalloc 2.8.6 version and features
- Data structure sizes (~500 bytes vs 1032 bytes in 2.6.6)
- Configuration options for code-size optimization
- Debugging features (mcheck, valgrind, malloc testing)
- API reference
Also add an introductory comment to dlmalloc.c summarising the
U-Boot configuration.
Series-to: concept
Series-cc: heinrich
Cover-letter:
malloc: Import dlmalloc 2.8.6
This series imports dlmalloc 2.8.6 from Doug Lea, replacing the old
version 2.6.6 that U-Boot has been using since 2002.
The new version provides:
- Better memory efficiency with improved binning algorithms
- More robust overflow checking via MAX_REQUEST
- Somewhat cleaner codebase
All U-Boot-specific modifications from the historical commits have been
ported to the new implementation, including:
- Pre-relocation malloc via malloc_simple
- Valgrind annotations
- Malloc testing infrastructure
- mcheck heap protection support
- Sandbox USE_DL_PREFIX support
The approach here is to leave the upstream code unchanged, so much as
possible, clearly marking U-Boot-specific changes with an #ifdef
Unfortunately the code size is not great out-of-the-box, so the final
part of the series includes some options to remove in-place realloc(),
provide a simplified init, remove the tree stucture for large blocks
and a few other things.
With these adjustments the new version is about 1K less code on Thumb2
(firefly-rk3288).
The new free() algorithm is more sophisticated but also larger. If
needed we might be able to shrink by a few hundred bytes. Of course SPL
doesn't normally use free() so the benefit might be minimal.
Another point worth mentioning is that the pre-inited av_[] array has
been replaced replaced with a BSS _sm_ struct which reduces the image
size by about 1.5K. One patch adjusts some imx8mp boards to deal with
the larger BSS.
Some code-size stats:
$ buildman -b mala imx8mp_venice firefly-rk3288 firefly-rk3399 -sS --step 0
Summary of 2 commits for 3 boards (3 threads, 11 jobs per thread)
01: backtrace: Strip the source tree prefix from filenames
aarch64: w+ imx8mp_venice firefly-rk3399
40: doc: Add malloc documentation
aarch64: (for 2/2 boards) all -3904.0 bss +864.0 data -2076.0
spl/u-boot-spl:all -654.0 spl/u-boot-spl:bss +316.0
spl/u-boot-spl:data -1034.0 spl/u-boot-spl:text +64.0 text -2692.0
arm: (for 1/1 boards) all -1436.0 data -1040.0 text -396.0
For the new malloc.h I have avoided including string.h so have added
that to various places that need it.
The existing common/dlmalloc.src file is left alone.
In order to bring this in without losing functionality, I went through
the patches applied to the original implementation over time. Where
these commits were added, they are added as a cherry-pick, with the
original commit hash.
Here is a list of what was done with each U-Boot commit on top of the
new common/dlmalloc.c and include/malloc.h:
1.
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