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

[Albert ARIBAUD]

Hi Albert,

On Fri, 19 Sep 2014 18:04:14 +0200, Albert ARIBAUD
<albert.u.boot at aribaud.net> wrote:

> 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?

Ping.

> > Thanks,
> > 
> > 	M.
> 
> Amicalement,

Amicalement,
-- 
Albert.