From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Nick Desaulniers <ndesaulniers@google.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>,
Joe Lawrence <joe.lawrence@redhat.com>,
Kees Cook <keescook@chromium.org>,
Fangrui Song <maskray@google.com>,
linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
Paul Mackerras <paulus@samba.org>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 1/2] powerpc/vdso64: link vdso64 with linker
Date: Wed, 2 Mar 2022 17:48:00 +0100 [thread overview]
Message-ID: <a120fa0c-4d00-ed4c-cffa-0df1fb5abb2b@csgroup.eu> (raw)
In-Reply-To: <20200901222523.1941988-2-ndesaulniers@google.com>
Le 02/09/2020 à 00:25, Nick Desaulniers a écrit :
> Rather than invoke the compiler as the driver, use the linker. That way
> we can check --orphan-handling=warn support correctly, as cc-ldoption
> was removed in
> commit 055efab3120b ("kbuild: drop support for cc-ldoption").
>
> Painstakingly compared the output between `objdump -a` before and after
> this change. Now function symbols have the correct type of FUNC rather
> than NONE, and the entry is slightly different (which doesn't matter for
> the vdso). Binary size is the same.
>
> Fixes: commit f2af201002a8 ("powerpc/build: vdso linker warning for orphan sections")
> Link: https://lore.kernel.org/lkml/CAKwvOdnn3wxYdJomvnveyD_njwRku3fABWT_bS92duihhywLJQ@mail.gmail.com/
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Is this change still necessary ? If so please rebase as we have changed
the structure of VDSO source files (Only one directory common to 32 and 64).
Christophe
> ---
> arch/powerpc/include/asm/vdso.h | 17 ++---------------
> arch/powerpc/kernel/vdso64/Makefile | 8 ++++++--
> arch/powerpc/kernel/vdso64/vdso64.lds.S | 1 -
> 3 files changed, 8 insertions(+), 18 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/vdso.h b/arch/powerpc/include/asm/vdso.h
> index 2ff884853f97..11b2ecf49f79 100644
> --- a/arch/powerpc/include/asm/vdso.h
> +++ b/arch/powerpc/include/asm/vdso.h
> @@ -24,19 +24,7 @@ int vdso_getcpu_init(void);
>
> #else /* __ASSEMBLY__ */
>
> -#ifdef __VDSO64__
> -#define V_FUNCTION_BEGIN(name) \
> - .globl name; \
> - name: \
> -
> -#define V_FUNCTION_END(name) \
> - .size name,.-name;
> -
> -#define V_LOCAL_FUNC(name) (name)
> -#endif /* __VDSO64__ */
> -
> -#ifdef __VDSO32__
> -
> +#if defined(__VDSO32__) || defined (__VDSO64__)
> #define V_FUNCTION_BEGIN(name) \
> .globl name; \
> .type name,@function; \
> @@ -46,8 +34,7 @@ int vdso_getcpu_init(void);
> .size name,.-name;
>
> #define V_LOCAL_FUNC(name) (name)
> -
> -#endif /* __VDSO32__ */
> +#endif /* __VDSO{32|64}__ */
>
> #endif /* __ASSEMBLY__ */
>
> diff --git a/arch/powerpc/kernel/vdso64/Makefile b/arch/powerpc/kernel/vdso64/Makefile
> index 38c317f25141..7ea3ce537d0a 100644
> --- a/arch/powerpc/kernel/vdso64/Makefile
> +++ b/arch/powerpc/kernel/vdso64/Makefile
> @@ -32,9 +32,13 @@ $(obj)/%.so: OBJCOPYFLAGS := -S
> $(obj)/%.so: $(obj)/%.so.dbg FORCE
> $(call if_changed,objcopy)
>
> +ldflags-y := -shared -soname linux-vdso64.so.1 \
> + $(call ld-option, --eh-frame-hdr) \
> + $(call ld-option, --orphan-handling=warn) -T
> +
> # actual build commands
> -quiet_cmd_vdso64ld = VDSO64L $@
> - cmd_vdso64ld = $(CC) $(c_flags) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^) $(call cc-ldoption, -Wl$(comma)--orphan-handling=warn)
> +quiet_cmd_vdso64ld = LD $@
> + cmd_vdso64ld = $(cmd_ld)
>
> # install commands for the unstripped file
> quiet_cmd_vdso_install = INSTALL $@
> diff --git a/arch/powerpc/kernel/vdso64/vdso64.lds.S b/arch/powerpc/kernel/vdso64/vdso64.lds.S
> index 4e3a8d4ee614..58c33b704b6a 100644
> --- a/arch/powerpc/kernel/vdso64/vdso64.lds.S
> +++ b/arch/powerpc/kernel/vdso64/vdso64.lds.S
> @@ -11,7 +11,6 @@ OUTPUT_FORMAT("elf64-powerpcle", "elf64-powerpcle", "elf64-powerpcle")
> OUTPUT_FORMAT("elf64-powerpc", "elf64-powerpc", "elf64-powerpc")
> #endif
> OUTPUT_ARCH(powerpc:common64)
> -ENTRY(_start)
>
> SECTIONS
> {
next prev parent reply other threads:[~2022-03-02 16:48 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-01 22:25 [PATCH 0/2] link vdso with linker Nick Desaulniers
2020-09-01 22:25 ` [PATCH 1/2] powerpc/vdso64: link vdso64 " Nick Desaulniers
2020-09-02 12:14 ` Michael Ellerman
2020-09-02 17:41 ` Nick Desaulniers
2020-09-02 18:02 ` Christophe Leroy
2021-04-22 22:44 ` Nick Desaulniers
2021-04-23 7:40 ` Christophe Leroy
2021-04-23 17:18 ` Christophe Leroy
2022-03-02 16:48 ` Christophe Leroy [this message]
2020-09-01 22:25 ` [PATCH 2/2] powerpc/vdso32: " Nick Desaulniers
2020-09-02 2:58 ` Kees Cook
2020-09-02 6:46 ` Christophe Leroy
2020-09-02 14:14 ` Segher Boessenkool
2020-09-02 15:43 ` Christophe Leroy
2020-09-02 16:57 ` Segher Boessenkool
2020-09-02 7:56 ` Christophe Leroy
2020-09-02 10:16 ` Christophe Leroy
2020-09-02 5:21 ` [PATCH 0/2] link vdso " Nathan Chancellor
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