Greg Kroah-Hartman
598cf27219
Link: https://lore.kernel.org/r/20260217200002.683975158@linuxfoundation.org Tested-by: Florian Fainelli <florian.fainelli@broadcom.com> Tested-by: Takeshi Ogasawara <takeshi.ogasawara@futuring-girl.com> Tested-by: Peter Schneider <pschneider1968@googlemail.com> Tested-by: Jon Hunter <jonathanh@nvidia.com> Tested-by: Salvatore Bonaccorso <carnil@debian.org> Tested-by: Brett A C Sheffield <bacs@librecast.net> Tested-by: Mark Brown <broonie@kernel.org> Tested-by: Luna Jernberg <droidbittin@gmail.com> Tested-by: Ronald Warsow <rwarsow@gmx.de> Tested-by: Justin M. Forbes <jforbes@fedoraproject.org> Tested-by: Ron Economos <re@w6rz.net> Tested-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
61 lines
1.9 KiB
C
61 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_INSTRUMENTATION_H
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#define __LINUX_INSTRUMENTATION_H
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#ifdef CONFIG_NOINSTR_VALIDATION
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#include <linux/objtool.h>
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#include <linux/stringify.h>
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/* Begin/end of an instrumentation safe region */
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#define __instrumentation_begin(c) ({ \
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asm volatile(__stringify(c) ": nop\n\t" \
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ANNOTATE_INSTR_BEGIN(__ASM_BREF(c)) \
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: : "i" (c)); \
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})
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#define instrumentation_begin() __instrumentation_begin(__COUNTER__)
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/*
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* Because instrumentation_{begin,end}() can nest, objtool validation considers
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* _begin() a +1 and _end() a -1 and computes a sum over the instructions.
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* When the value is greater than 0, we consider instrumentation allowed.
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*
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* There is a problem with code like:
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*
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* noinstr void foo()
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* {
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* instrumentation_begin();
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* ...
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* if (cond) {
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* instrumentation_begin();
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* ...
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* instrumentation_end();
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* }
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* bar();
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* instrumentation_end();
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* }
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*
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* If instrumentation_end() would be an empty label, like all the other
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* annotations, the inner _end(), which is at the end of a conditional block,
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* would land on the instruction after the block.
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*
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* If we then consider the sum of the !cond path, we'll see that the call to
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* bar() is with a 0-value, even though, we meant it to happen with a positive
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* value.
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*
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* To avoid this, have _end() be a NOP instruction, this ensures it will be
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* part of the condition block and does not escape.
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*/
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#define __instrumentation_end(c) ({ \
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asm volatile(__stringify(c) ": nop\n\t" \
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ANNOTATE_INSTR_END(__ASM_BREF(c)) \
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: : "i" (c)); \
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})
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#define instrumentation_end() __instrumentation_end(__COUNTER__)
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#else /* !CONFIG_NOINSTR_VALIDATION */
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# define instrumentation_begin() do { } while(0)
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# define instrumentation_end() do { } while(0)
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#endif /* CONFIG_NOINSTR_VALIDATION */
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#endif /* __LINUX_INSTRUMENTATION_H */
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