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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Tue, 29 Sep 2020 12:22:50 -0700
Message-ID: <CAKwvOd=s+N4+X94sTams_hKn8uV5Hc6QyCc7OHyOGC-JFesS8A@mail.gmail.com>
Subject: Re: [PATCH] srcu: avoid escaped section names
To:     "Paul E . McKenney" <paulmck@kernel.org>
Cc:     Steven Rostedt <rostedt@goodmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        Josh Triplett <josh@joshtriplett.org>,
        Kees Cook <keescook@chromium.org>,
        LKML <linux-kernel@vger.kernel.org>, rcu@vger.kernel.org,
        clang-built-linux <clang-built-linux@googlegroups.com>
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Precedence: bulk

gah, must have had a `-a` in my `git commit --amend`...sorry, will send a v2...

On Tue, Sep 29, 2020 at 12:22 PM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> The stringification operator, `#`, in the preprocessor escapes strings.
> For example, `# "foo"` becomes `"\"foo\""`.  GCC and Clang differ in how
> they treat section names that contain \".
>
> The portable solution is to not use a string literal with the
> preprocessor stringification operator.
>
> Link: https://bugs.llvm.org/show_bug.cgi?id=42950
> Fixes: commit fe15b50cdeee ("srcu: Allocate per-CPU data for DEFINE_SRCU() in modules")
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
>  arch/arm/Kconfig         |  1 +
>  arch/arm/mm/Kconfig      | 11 +++++++++++
>  include/linux/srcutree.h |  2 +-
>  3 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index fe2f17eb2b50..51200e371faf 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -358,6 +358,7 @@ config ARCH_EBSA110
>
>  config ARCH_EP93XX
>         bool "EP93xx-based"
> +       depends on !LD_IS_LLD
>         select ARCH_SPARSEMEM_ENABLE
>         select ARM_AMBA
>         imply ARM_PATCH_PHYS_VIRT
> diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
> index 65e4482e3849..c06787c9bb48 100644
> --- a/arch/arm/mm/Kconfig
> +++ b/arch/arm/mm/Kconfig
> @@ -9,6 +9,7 @@ comment "Processor Type"
>  config CPU_ARM7TDMI
>         bool
>         depends on !MMU
> +       depends on !LD_IS_LLD
>         select CPU_32v4T
>         select CPU_ABRT_LV4T
>         select CPU_CACHE_V4
> @@ -23,6 +24,7 @@ config CPU_ARM7TDMI
>  # ARM720T
>  config CPU_ARM720T
>         bool
> +       depends on !LD_IS_LLD
>         select CPU_32v4T
>         select CPU_ABRT_LV4T
>         select CPU_CACHE_V4
> @@ -43,6 +45,7 @@ config CPU_ARM720T
>  config CPU_ARM740T
>         bool
>         depends on !MMU
> +       depends on !LD_IS_LLD
>         select CPU_32v4T
>         select CPU_ABRT_LV4T
>         select CPU_CACHE_V4
> @@ -61,6 +64,7 @@ config CPU_ARM740T
>  config CPU_ARM9TDMI
>         bool
>         depends on !MMU
> +       depends on !LD_IS_LLD
>         select CPU_32v4T
>         select CPU_ABRT_NOMMU
>         select CPU_CACHE_V4
> @@ -75,6 +79,7 @@ config CPU_ARM9TDMI
>  # ARM920T
>  config CPU_ARM920T
>         bool
> +       depends on !LD_IS_LLD
>         select CPU_32v4T
>         select CPU_ABRT_EV4T
>         select CPU_CACHE_V4WT
> @@ -94,6 +99,7 @@ config CPU_ARM920T
>  # ARM922T
>  config CPU_ARM922T
>         bool
> +       depends on !LD_IS_LLD
>         select CPU_32v4T
>         select CPU_ABRT_EV4T
>         select CPU_CACHE_V4WT
> @@ -114,6 +120,7 @@ config CPU_ARM922T
>  # ARM925T
>  config CPU_ARM925T
>         bool
> +       depends on !LD_IS_LLD
>         select CPU_32v4T
>         select CPU_ABRT_EV4T
>         select CPU_CACHE_V4WT
> @@ -153,6 +160,7 @@ config CPU_ARM926T
>  # FA526
>  config CPU_FA526
>         bool
> +       depends on !LD_IS_LLD
>         select CPU_32v4
>         select CPU_ABRT_EV4
>         select CPU_CACHE_FA
> @@ -172,6 +180,7 @@ config CPU_FA526
>  config CPU_ARM940T
>         bool
>         depends on !MMU
> +       depends on !LD_IS_LLD
>         select CPU_32v4T
>         select CPU_ABRT_NOMMU
>         select CPU_CACHE_VIVT
> @@ -278,6 +287,7 @@ config CPU_ARM1026
>  # SA110
>  config CPU_SA110
>         bool
> +       depends on !LD_IS_LLD
>         select CPU_32v3 if ARCH_RPC
>         select CPU_32v4 if !ARCH_RPC
>         select CPU_ABRT_EV4
> @@ -299,6 +309,7 @@ config CPU_SA110
>  # SA1100
>  config CPU_SA1100
>         bool
> +       depends on !LD_IS_LLD
>         select CPU_32v4
>         select CPU_ABRT_EV4
>         select CPU_CACHE_V4WB
> diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
> index 9cfcc8a756ae..9de652f4e1bd 100644
> --- a/include/linux/srcutree.h
> +++ b/include/linux/srcutree.h
> @@ -124,7 +124,7 @@ struct srcu_struct {
>  # define __DEFINE_SRCU(name, is_static)                                        \
>         is_static struct srcu_struct name;                              \
>         struct srcu_struct * const __srcu_struct_##name                 \
> -               __section("___srcu_struct_ptrs") = &name
> +               __section(___srcu_struct_ptrs) = &name
>  #else
>  # define __DEFINE_SRCU(name, is_static)                                        \
>         static DEFINE_PER_CPU(struct srcu_data, name##_srcu_data);      \
> --
> 2.28.0.709.gb0816b6eb0-goog
>


-- 
Thanks,
~Nick Desaulniers