[U-Boot] [PATCH 4/8] ARMv8: PSCI: Add linker section to hold PSCI code

[Albert ARIBAUD]

Hi Marc,

On Thu, 18 Sep 2014 16:28:52 +0100, Marc Zyngier <marc.zyngier at arm.com>
wrote:

> On Thu, Sep 18 2014 at 10:12:17 AM, Albert ARIBAUD <albert.u.boot at aribaud.net> wrote:
> > Hi Arnab,
> >
> > On Thu, 28 Aug 2014 01:59:57 +0530, Arnab Basu
> > <arnab.basu at freescale.com> wrote:
> >
> >> A separate linker section makes it possible to keep this code either
> >> in DDR or in some secure memory location provided specifically for the
> >> purpose.
> >> 
> >> So far no one is using this section.
> >> 
> >> Signed-off-by: Arnab Basu <arnab.basu at freescale.com>
> >> Reviewed-by: Bhupesh Sharma <bhupesh.sharma at freescale.com>
> >> Cc: Marc Zyngier <marc.zyngier at arm.com>
> >> ---
> >>  arch/arm/config.mk            |    2 +-
> >>  arch/arm/cpu/armv8/u-boot.lds |   30 ++++++++++++++++++++++++++++++
> >>  2 files changed, 31 insertions(+), 1 deletions(-)
> >> 
> >> diff --git a/arch/arm/config.mk b/arch/arm/config.mk
> >> index c339e6d..9272e9c 100644
> >> --- a/arch/arm/config.mk
> >> +++ b/arch/arm/config.mk
> >> @@ -111,7 +111,7 @@ endif
> >>  
> >>  # limit ourselves to the sections we want in the .bin.
> >>  ifdef CONFIG_ARM64
> >> -OBJCOPYFLAGS += -j .text -j .rodata -j .data -j .u_boot_list -j .rela.dyn
> >> +OBJCOPYFLAGS += -j .text -j .secure_text -j .rodata -j .data -j .u_boot_list -j .rela.dyn
> >>  else
> >>  OBJCOPYFLAGS += -j .text -j .secure_text -j .rodata -j .hash -j .data -j .got.plt -j .u_boot_list -j .rel.dyn
> >>  endif
> >> diff --git a/arch/arm/cpu/armv8/u-boot.lds b/arch/arm/cpu/armv8/u-boot.lds
> >> index 4c12222..bd95fff 100644
> >> --- a/arch/arm/cpu/armv8/u-boot.lds
> >> +++ b/arch/arm/cpu/armv8/u-boot.lds
> >> @@ -8,6 +8,8 @@
> >>   * SPDX-License-Identifier:	GPL-2.0+
> >>   */
> >>  
> >> +#include <config.h>
> >> +
> >>  OUTPUT_FORMAT("elf64-littleaarch64", "elf64-littleaarch64", "elf64-littleaarch64")
> >>  OUTPUT_ARCH(aarch64)
> >>  ENTRY(_start)
> >> @@ -23,6 +25,34 @@ SECTIONS
> >>  		*(.text*)
> >>  	}
> >>  
> >> +#ifdef CONFIG_ARMV8_PSCI
> >> +
> >> +#ifndef CONFIG_ARMV8_SECURE_BASE
> >> +#define CONFIG_ARMV8_SECURE_BASE
> >> +#endif
> >> +
> >> +	.__secure_start : {
> >> +		. = ALIGN(0x1000);
> >> +		*(.__secure_start)
> >> +	}
> >> +
> >> +	.secure_text CONFIG_ARMV8_SECURE_BASE :
> >> +		AT(ADDR(.__secure_start) + SIZEOF(.__secure_start))
> >> +	{
> >> +		*(._secure.text)
> >> +	}
> >> +
> >> +	. = LOADADDR(.__secure_start) +
> >> +		SIZEOF(.__secure_start) +
> >> +		SIZEOF(.secure_text);
> >> +
> >> +	__secure_end_lma = .;
> >> +	.__secure_end : AT(__secure_end_lma) {
> >> +		*(.__secure_end)
> >> +		LONG(0x1d1071c);	/* Must output something to reset LMA */
> >
> > Can you explain in more detail what issue this fixes?
> 
> If you use AT to force a new load address (LMA), you must ensure that
> you actually output something at this address. Here, if *(.__secure_end)
> ends up being empty, whatever follows would be as if the AT never
> happened, ending up at the wrong LMA.
>
> The workaround is to force the output of a dummy value in all
> cases, ensuring that the rest of the text is at a sensible LMA. This is
> an issue that has been in GNU ld for years, and this workaround is a
> copy/paste of the same one in the ARMv7 ld script.

I see. Does the ld bug have an identifier that we could mention in a
comment in the linker script as a reference?

> Thanks,
> 
> 	M.

Amicalement,
-- 
Albert.