From: Michael Ellerman <mpe@ellerman.id.au>
To: Nicholas Miehlbradt <nicholas@linux.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org,
Nicholas Miehlbradt <nicholas@linux.ibm.com>
Subject: Re: [PATCH v2] Add static_key_feature_checks_initialized flag
Date: Mon, 08 Apr 2024 21:10:43 +1000 [thread overview]
Message-ID: <87msq4az4c.fsf@mail.lhotse> (raw)
In-Reply-To: <20240408052358.5030-1-nicholas@linux.ibm.com>
Nicholas Miehlbradt <nicholas@linux.ibm.com> writes:
> JUMP_LABEL_FEATURE_CHECK_DEBUG used static_key_intialized to determine
> whether {cpu,mmu}_has_feature() is used before static keys were
> initialized. However, {cpu,mmu}_has_feature() should not be used before
> setup_feature_keys() is called but static_key_initialized is set well
> before this by the call to jump_label_init() in early_init_devtree().
> This creates a window in which JUMP_LABEL_FEATURE_CHECK_DEBUG will not
> detect misuse and report errors. Add a flag specifically to indicate
> when {cpu,mmu}_has_feature() is safe to use.
I'm not sure it warrants a Fixes: tag, but it was commit
ca829e05d3d4 ("powerpc/64: Init jump labels before parse_early_param()")
which added the earlier call to jump_label_init() and created the window
where the debug checks don't fire.
cheers
next prev parent reply other threads:[~2024-04-08 11:11 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-08 5:23 [PATCH v2] Add static_key_feature_checks_initialized flag Nicholas Miehlbradt
2024-04-08 11:10 ` Michael Ellerman [this message]
2024-04-22 8:16 ` Michael Ellerman
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