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dbefa1f31a
Commit b1fca27d384e ("kernel debug: support resetting WARN*_ONCE")
added support for clearing the state of once warnings. However,
it is not functional when CONFIG_LD_DEAD_CODE_DATA_ELIMINATION or
CONFIG_LTO_CLANG is enabled, because .data.once matches the
.data.[0-9a-zA-Z_]* pattern in the DATA_MAIN macro.
Commit cb87481ee89d ("kbuild: linker script do not match C names unless
LD_DEAD_CODE_DATA_ELIMINATION is configured") was introduced to suppress
the issue for the default CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=n case,
providing a minimal fix for stable backporting. We were aware this did
not address the issue for CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=y. The
plan was to apply correct fixes and then revert cb87481ee89d. [1]
Seven years have passed since then, yet the #ifdef workaround remains in
place. Meanwhile, commit b1fca27d384e introduced the .data.once section,
and commit dc5723b02e52 ("kbuild: add support for Clang LTO") extended
the #ifdef.
Using a ".." separator in the section name fixes the issue for
CONFIG_LD_DEAD_CODE_DATA_ELIMINATION and CONFIG_LTO_CLANG.
[1]: https://lore.kernel.org/linux-kbuild/CAK7LNASck6BfdLnESxXUeECYL26yUDm0cwRZuM4gmaWUkxjL5g@mail.gmail.com/
Fixes: b1fca27d384e ("kernel debug: support resetting WARN*_ONCE")
Fixes: dc5723b02e52 ("kbuild: add support for Clang LTO")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
37 lines
926 B
C
37 lines
926 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_ONCE_LITE_H
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#define _LINUX_ONCE_LITE_H
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#include <linux/types.h>
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/* Call a function once. Similar to DO_ONCE(), but does not use jump label
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* patching via static keys.
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*/
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#define DO_ONCE_LITE(func, ...) \
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DO_ONCE_LITE_IF(true, func, ##__VA_ARGS__)
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#define __ONCE_LITE_IF(condition) \
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({ \
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static bool __section(".data..once") __already_done; \
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bool __ret_cond = !!(condition); \
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bool __ret_once = false; \
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\
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if (unlikely(__ret_cond && !__already_done)) { \
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__already_done = true; \
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__ret_once = true; \
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} \
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unlikely(__ret_once); \
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})
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#define DO_ONCE_LITE_IF(condition, func, ...) \
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({ \
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bool __ret_do_once = !!(condition); \
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\
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if (__ONCE_LITE_IF(__ret_do_once)) \
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func(__VA_ARGS__); \
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\
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unlikely(__ret_do_once); \
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})
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#endif /* _LINUX_ONCE_LITE_H */
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