From: Madhavan Srinivasan <maddy@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org,
Thibault Ferrante <thibault.ferrante@canonical.com>
Cc: mpe@ellerman.id.au, npiggin@gmail.com, shuah@kernel.org,
chleroy@kernel.org, linux-kselftest@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] selftests/powerpc/tm: Fix tcheck() reading uninitialised CR value
Date: Mon, 14 Sep 2026 12:51:13 +0530 [thread overview]
Message-ID: <178919368037.441103.6444951061225387886.b4-ty@linux.ibm.com> (raw)
In-Reply-To: <20260907215420.1258678-1-thibault.ferrante@canonical.com>
On Mon, 07 Sep 2026 23:54:20 +0200, Thibault Ferrante wrote:
> tcheck() is used to check the current transaction state (active,
> suspended, doomed) via the "tcheck" instruction, which writes its
> result into CR field 0. The inline asm declared a GPR output operand
> for this result but never actually moved the CR into it.
>
> Every caller (tcheck_doomed(), tcheck_active(), tcheck_suspended(),
> tcheck_transactional()) has effectively been testing bits of an unrelated,
> arbitrary register value since this helper was introduced.
> The "& 4" mask discards the TDOOMED and TS_lsb (suspended) bits before
> they ever reach the callers, so tcheck_doomed() and tcheck_suspended()
> can never return true, and tcheck_transactional() degrades to being
> equivalent to tcheck_active().
>
> [...]
Applied to powerpc/fixes.
[1/1] selftests/powerpc/tm: Fix tcheck() reading uninitialised CR value
https://git.kernel.org/powerpc/c/ed28b16eab705071d28edaace47189c2eb3aa108
cheers
prev parent reply other threads:[~2026-09-14 7:21 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-07 21:54 [PATCH] selftests/powerpc/tm: Fix tcheck() reading uninitialised CR value Thibault Ferrante
2026-09-09 5:28 ` Venkat
2026-09-09 8:56 ` Christophe Leroy (CS GROUP)
2026-09-09 10:05 ` Thibault Ferrante
2026-09-14 7:21 ` Madhavan Srinivasan [this message]
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