uprobes/x86: Allow to probe a NOP instruction with 0x66 prefix

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[ Upstream commit cefa72129e ]

Intel ICC -hotpatch inserts 2-byte "0x66 0x90" NOP at the start of each
function to reserve extra space for hot-patching, and currently it is not
possible to probe these functions because branch_setup_xol_ops() wrongly
rejects NOP with REP prefix as it treats them like word-sized branch
instructions.

Fixes: 250bbd12c2 ("uprobes/x86: Refuse to attach uprobe to "word-sized" branch insns")
Reported-by: Seiji Nishikawa <snishika@redhat.com>
Suggested-by: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20221204173933.GA31544@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

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Oleg Nesterov 2022-12-04 18:39:33 +01:00 • committed by Greg Kroah-Hartman

parent 01f2c2052e

commit daea9a0647

1 changed files with 3 additions and 1 deletions

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arch/x86/kernel/uprobes.c

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