forked from mirrors/linux
dbefa1f31a
Commitb1fca27d38("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. Commitcb87481ee8("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 revertcb87481ee8. [1] Seven years have passed since then, yet the #ifdef workaround remains in place. Meanwhile, commitb1fca27d38introduced the .data.once section, and commitdc5723b02e("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:b1fca27d38("kernel debug: support resetting WARN*_ONCE") Fixes:dc5723b02e("kbuild: add support for Clang LTO") Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
36 lines
926 B
C
36 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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