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Date:   Thu, 28 Apr 2022 18:42:12 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Cc:     Michael Ellerman <mpe@ellerman.id.au>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        <linux-kernel@vger.kernel.org>, <linuxppc-dev@lists.ozlabs.org>,
        llvm@lists.linux.dev
Subject: Re: [PATCH v2 2/2] ftrace: recordmcount: Handle sections with no
 non-weak symbols
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        <126aca34935cf1c7168e17970c706e36577094e7.1651166001.git.naveen.n.rao@linux.vnet.ibm.com>
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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