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From: Mark Rutland <mark.rutland@arm.com>
To: Andre Przywara <andre.przywara@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, Jaxson Han <jaxson.han@arm.com>
Subject: Re: [boot-wrapper PATCH v2 1/9] Makefile: Avoid .got section creation
Date: Fri, 7 Jan 2022 13:49:54 +0000	[thread overview]
Message-ID: <YdhFAvJoo0vt6CCT@FVFF77S0Q05N> (raw)
In-Reply-To: <20211222181607.1203191-2-andre.przywara@arm.com>

On Wed, Dec 22, 2021 at 06:15:59PM +0000, Andre Przywara wrote:
> At the moment we build the boot-wrapper with the default toolchain
> settings, which has issues if that is a toolchain targeted to Linux
> userland, for instance. Since boot-wrapper is rather simple, we get away
> with this, *mostly*, but there is at least one case where this breaks:
> Many distributions enable PIE builds by default when building GCC, so by
> just calling "gcc" we build the .o files for PIE (although we don't link
> them accordingly, since we use "ld" directly).
> When we moved the PSCI code from assembly to C, we also introduced
> global variables, which a PIE enabled GCC will put into a .got section
> (global offset table), to be able to easily relocate them at runtime
> (if needed). This section happens to be outside of the memory region
> we reserve, so can (and will be) overwritten by Linux at some point.
> Doing PSCI calls afterwards does not end well then. "memtest=1" is one
> way to trigger this.
> 
> To avoid the (in our case pointless) creation of the GOT, we specify
> -fno-pic and -fno-pie, to override any potential toolchain default.
> 
> This fixes boot-wrapper builds on many distro compilers, for instance
> as provided by Ubuntu and Arch Linux.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>

Thanks; applied.

Mark.

> ---
>  Makefile.am | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/Makefile.am b/Makefile.am
> index d0a68df..3e970a3 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -126,6 +126,7 @@ CPPFLAGS	+= $(INITRD_FLAGS)
>  CFLAGS		+= -I$(top_srcdir)/include/ -I$(top_srcdir)/$(ARCH_SRC)/include/
>  CFLAGS		+= -Wall -fomit-frame-pointer
>  CFLAGS		+= -ffunction-sections -fdata-sections
> +CFLAGS		+= -fno-pic -fno-pie
>  LDFLAGS		+= --gc-sections
>  
>  OBJ		:= $(addprefix $(ARCH_SRC),$(ARCH_OBJ)) $(addprefix $(COMMON_SRC),$(COMMON_OBJ))
> -- 
> 2.25.1
> 

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  reply	other threads:[~2022-01-07 13:51 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-22 18:15 [boot-wrapper PATCH v2 0/9] Various (build system) fixes Andre Przywara
2021-12-22 18:15 ` [boot-wrapper PATCH v2 1/9] Makefile: Avoid .got section creation Andre Przywara
2022-01-07 13:49   ` Mark Rutland [this message]
2021-12-22 18:16 ` [boot-wrapper PATCH v2 2/9] Add standard headers Andre Przywara
2022-01-07 13:49   ` Mark Rutland
2022-01-07 14:31     ` Andre Przywara
2022-01-11 11:34       ` Mark Rutland
2021-12-22 18:16 ` [boot-wrapper PATCH v2 3/9] Makefile: Tell compiler to generate bare-metal code Andre Przywara
2022-01-07 13:53   ` Mark Rutland
2022-01-07 14:38     ` Andre Przywara
2022-01-11 11:30       ` Mark Rutland
2022-01-18 12:52         ` Andre Przywara
2022-01-18 14:10           ` Ard Biesheuvel
2021-12-22 18:16 ` [boot-wrapper PATCH v2 4/9] configure: Make PSCI the default boot method Andre Przywara
2022-01-07 14:12   ` Mark Rutland
2021-12-22 18:16 ` [boot-wrapper PATCH v2 5/9] configure: Fix default DTB Andre Przywara
2022-01-07 14:13   ` Mark Rutland
2021-12-22 18:16 ` [boot-wrapper PATCH v2 6/9] configure: Use earlycon instead of earlyprintk Andre Przywara
2022-01-07 14:01   ` Mark Rutland
2022-01-07 14:14     ` Mark Rutland
2022-01-07 14:47     ` Andre Przywara
2021-12-22 18:16 ` [boot-wrapper PATCH v2 7/9] pointer auth: Document CPU feature bit mask Andre Przywara
2022-01-07 14:15   ` Mark Rutland
2021-12-22 18:16 ` [boot-wrapper PATCH v2 8/9] configure: Autodetect GICv3 Andre Przywara
2022-01-07 14:19   ` Mark Rutland
2021-12-22 18:16 ` [boot-wrapper PATCH v2 9/9] avoid dtc warnings on re-compiling DTB Andre Przywara
2022-01-07 13:59   ` Mark Rutland
2022-01-13 18:42   ` Vladimir Murzin
2022-01-13 19:50     ` Andre Przywara
2022-01-14  8:35       ` Vladimir Murzin
2022-01-14 10:44         ` Mark Rutland
2022-01-14 12:09           ` Andre Przywara
2022-01-19 12:02             ` Mark Rutland
2022-01-07 14:25 ` [boot-wrapper PATCH v2 0/9] Various (build system) fixes Mark Rutland

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