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Documentation: livepatch: document reliable stacktrace Add documentation for reliable stacktrace. This is intended to describe the semantics and to be an aid for implementing architecture support for HAVE_RELIABLE_STACKTRACE. Unwinding is a subtle area, and architectures vary greatly in both implementation and the set of concerns that affect them, so I've tried to avoid making this too specific to any given architecture. I've used examples from both x86_64 and arm64 to explain corner cases in more detail, but I've tried to keep the descriptions sufficient for those who are unfamiliar with the particular architecture. This document aims to give rationale for all the recommendations and requirements, since that makes it easier to spot nearby issues, or when a check happens to catch a few things at once. Signed-off-by: Mark Rutland <mark.rutland@arm.com> [Updates following review -- broonie] Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Mark Brown <broonie@kernel.org> Signed-off-by: Jiri Kosina <jkosina@suse.cz> 2021-01-20 16:47:14 +00:00









































Documentation: Fix typos Fix typos in Documentation. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Link: https://lore.kernel.org/r/20230814212822.193684-4-helgaas@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net> 2023-08-14 16:28:22 -05:00
Documentation: livepatch: document reliable stacktrace Add documentation for reliable stacktrace. This is intended to describe the semantics and to be an aid for implementing architecture support for HAVE_RELIABLE_STACKTRACE. Unwinding is a subtle area, and architectures vary greatly in both implementation and the set of concerns that affect them, so I've tried to avoid making this too specific to any given architecture. I've used examples from both x86_64 and arm64 to explain corner cases in more detail, but I've tried to keep the descriptions sufficient for those who are unfamiliar with the particular architecture. This document aims to give rationale for all the recommendations and requirements, since that makes it easier to spot nearby issues, or when a check happens to catch a few things at once. Signed-off-by: Mark Rutland <mark.rutland@arm.com> [Updates following review -- broonie] Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Mark Brown <broonie@kernel.org> Signed-off-by: Jiri Kosina <jkosina@suse.cz> 2021-01-20 16:47:14 +00:00













































































































































x86,objtool: Split UNWIND_HINT_EMPTY in two Mark reported that the ORC unwinder incorrectly marks an unwind as reliable when the unwind terminates prematurely in the dark corners of return_to_handler() due to lack of information about the next frame. The problem is UNWIND_HINT_EMPTY is used in two different situations: 1) The end of the kernel stack unwind before hitting user entry, boot code, or fork entry 2) A blind spot in ORC coverage where the unwinder has to bail due to lack of information about the next frame The ORC unwinder has no way to tell the difference between the two. When it encounters an undefined stack state with 'end=1', it blindly marks the stack reliable, which can break the livepatch consistency model. Fix it by splitting UNWIND_HINT_EMPTY into UNWIND_HINT_UNDEFINED and UNWIND_HINT_END_OF_STACK. Reported-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/fd6212c8b450d3564b855e1cb48404d6277b4d9f.1677683419.git.jpoimboe@kernel.org 2023-03-01 07:13:12 -08:00
Documentation: livepatch: document reliable stacktrace Add documentation for reliable stacktrace. This is intended to describe the semantics and to be an aid for implementing architecture support for HAVE_RELIABLE_STACKTRACE. Unwinding is a subtle area, and architectures vary greatly in both implementation and the set of concerns that affect them, so I've tried to avoid making this too specific to any given architecture. I've used examples from both x86_64 and arm64 to explain corner cases in more detail, but I've tried to keep the descriptions sufficient for those who are unfamiliar with the particular architecture. This document aims to give rationale for all the recommendations and requirements, since that makes it easier to spot nearby issues, or when a check happens to catch a few things at once. Signed-off-by: Mark Rutland <mark.rutland@arm.com> [Updates following review -- broonie] Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Mark Brown <broonie@kernel.org> Signed-off-by: Jiri Kosina <jkosina@suse.cz> 2021-01-20 16:47:14 +00:00

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309 lines

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