linux-kernel - Re: [PATCH] x86: Fix location of '-plugin-opt=' flags

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Message-Id: <162161994470.2028902.331062863146834934.b4-ty@chromium.org>
Date:   Fri, 21 May 2021 10:59:10 -0700
From:   Kees Cook <keescook@...omium.org>
To:     x86@...nel.org, Sami Tolvanen <samitolvanen@...gle.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>
Cc:     Kees Cook <keescook@...omium.org>,
        clang-built-linux@...glegroups.com,
        Anthony Ruhier <aruhier@...lbox.org>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] x86: Fix location of '-plugin-opt=' flags

On Tue, 18 May 2021 12:01:06 -0700, Nathan Chancellor wrote:
> Commit b33fff07e3e3 ("x86, build: allow LTO to be selected") added a
> couple of '-plugin-opt=' flags to KBUILD_LDFLAGS because the code model
> and stack alignment are not stored in LLVM bitcode. However, these flags
> were added to KBUILD_LDFLAGS prior to the emulation flag assignment,
> which uses ':=', so they were overwritten and never added to $(LD)
> invocations. The absence of these flags caused misalignment issues in
> the AMDGPU driver when compiling with CONFIG_LTO_CLANG, resulting in
> general protection faults.
> 
> [...]

(I've slightly adjusted the title.)

Applied to for-next/clang/features, thanks!

[1/1] x86: lto: Fix location of '-plugin-opt=' flags
      https://git.kernel.org/kees/c/5d6c8592ee5f

-- 
Kees Cook