From: Kees Cook <keescook@chromium.org>
To: Jarmo Tiitto <jarmo.tiitto@gmail.com>
Cc: Sami Tolvanen <samitolvanen@google.com>,
Bill Wendling <wcw@google.com>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
clang-built-linux@googlegroups.com, linux-kernel@vger.kernel.org,
morbo@google.com
Subject: Re: [PATCH v3 1/1] pgo: Fix allocate_node() v2
Date: Fri, 4 Jun 2021 11:06:37 -0700 [thread overview]
Message-ID: <202106041104.929FFB3@keescook> (raw)
In-Reply-To: <20210604165819.7947-1-jarmo.tiitto@gmail.com>
On Fri, Jun 04, 2021 at 07:58:20PM +0300, Jarmo Tiitto wrote:
> When clang instrumentation eventually calls allocate_node()
> the struct llvm_prf_data *p argument tells us from what section
> we should reserve the vnode: It either points into vmlinux's
> core __llvm_prf_data section or some loaded module's
> __llvm_prf_data section.
>
> But since we don't have access to corresponding
> __llvm_prf_vnds section(s) for any module, the function
> should return just NULL and ignore any profiling attempts
> from modules for now.
>
> Signed-off-by: Jarmo Tiitto <jarmo.tiitto@gmail.com>
> ---
> Based on Kees and others feedback here is v3 patch
> that clarifies why the current checks in allocate_node()
> are flawed. I did fair amount of KGDB time on it.
>
> The commit is based on kees/for-next/clang/features tree,
> hopefully this is ok. Should I have based it on linux-next
> instead?
>
> I grep -R'd where the memory_contains() can be found and it is only
> found in #include <asm-generic/sections.h>
That's true, but the way to use "asm-generic" is to include the
top-level "asm" file, so that architectures can override things as
needed.
> I cross my fingers and await if this is my first accepted patch. :-)
I tweaked it a bit and applied it (see the separate email).
Thank you!
-Kees
--
Kees Cook
next prev parent reply other threads:[~2021-06-04 18:07 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-04 16:58 [PATCH v3 1/1] pgo: Fix allocate_node() v2 Jarmo Tiitto
2021-06-04 17:04 ` Nathan Chancellor
2021-06-04 17:28 ` Nick Desaulniers
2021-06-04 17:58 ` Kees Cook
2021-06-04 18:06 ` Kees Cook [this message]
2021-06-05 17:15 ` Jarmo Tiitto
2021-06-05 23:45 ` Fangrui Song
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