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From: Steven Rostedt <rostedt@goodmis.org>
To: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Cc: llvm@lists.linux.dev, Nick Desaulniers <ndesaulniers@google.com>,
	linux-kernel@vger.kernel.org,
	Nathan Chancellor <nathan@kernel.org>,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2 2/2] ftrace: recordmcount: Handle sections with no non-weak symbols
Date: Thu, 28 Apr 2022 18:42:12 -0400	[thread overview]
Message-ID: <20220428184212.18fbf438@gandalf.local.home> (raw)
In-Reply-To: <126aca34935cf1c7168e17970c706e36577094e7.1651166001.git.naveen.n.rao@linux.vnet.ibm.com>

On Thu, 28 Apr 2022 22:49:52 +0530
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:

> But, with ppc64 elf abi v1 which only supports the old -pg flag, mcount
> location can differ between the weak and non-weak variants of a
> function. In such scenarios, one of the two mcount entries will be
> invalid. Such architectures need to validate mcount locations by
> ensuring that the instruction(s) at those locations are as expected. On
> powerpc, this can be a simple check to ensure that the instruction is a
> 'bl'. This check can be further tightened as necessary.

I was thinking about this more, and I was thinking that we could create
another section; Perhaps __mcount_loc_weak. And place these in that
section. That way, we could check if these symbols to see if there's
already a symbol for it, and if there is, then drop it.

-- Steve

  reply	other threads:[~2022-04-28 22:42 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-28 17:19 [PATCH v2 0/2] ftrace/recordmcount: Handle object files without section symbols Naveen N. Rao
2022-04-28 17:19 ` [PATCH v2 1/2] ftrace: Drop duplicate mcount locations Naveen N. Rao
2022-04-28 17:19 ` [PATCH v2 2/2] ftrace: recordmcount: Handle sections with no non-weak symbols Naveen N. Rao
2022-04-28 22:42   ` Steven Rostedt [this message]
2022-04-29 17:39     ` Naveen N. Rao
2022-04-29 17:59       ` Steven Rostedt
2022-04-29 19:33         ` Naveen N. Rao
2022-04-29 19:47           ` Steven Rostedt

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