Hi Vincent,
On Fri, 15 Mar 2013 17:54:00 +0100, Vincent Stehlé
wrote:
> The _start symbol is already relocated, so do not add the relocation the
> second
> time in c_runtime_cpu_setup.
>
> This fixes e.g. the abort exception handling path, which ended in double fault
> due to bad address in VBAR.
>
> Signed-off-by: Vincent Stehlé
> Reported-by: Lubomir Popov
> ---
>
>
> Hello,
>
> Here is a fix for a bug reported by Lubomir. He noticed that exceptions were
> not handled correctly anymore. This can be seen with e.g. the 'dhcp' command
> on
> some OMAP platforms.
>
> Looking at the code, I would says the fix applies to all armv7 platforms
> except
> Tegra but I did only test on OMAP5. On this platform at least the abort is now
> handled:
>
> OMAP5430 EVM # dhcp
> data abort
>
> MAYBE you should read doc/README.arm-unaligned-accesses
>
> pc : [] lr : []
> sp : feef9dc4 ip : fefed0f8 fp :
> r10: 0001 r9 : 0001 r8 : feef9f48
> r7 : feef9fe0 r6 : r5 : r4 : 0014
> r3 : r2 : 0002 r1 : 0014 r0 : fefed0f4
> Flags: Nzcv IRQs off FIQs off Mode SVC_32
> Resetting CPU ...
>
> resetting ...
>
> It would be appreciated if folks could verify on other ARMv7 platforms, when
> running from flash for example (where relocation may differ?)
>
>
> arch/arm/cpu/armv7/start.S |1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
> index 6b59529d..d06b35f 100644
> --- a/arch/arm/cpu/armv7/start.S
> +++ b/arch/arm/cpu/armv7/start.S
> @@ -254,7 +254,6 @@ ENTRY(c_runtime_cpu_setup)
> #if !defined(CONFIG_TEGRA)
> /* Set vector address in CP15 VBAR register */
> ldr r0, =_start
> - add r0, r0, r9
> mcr p15, 0, r0, c12, c0, 0 @Set VBAR
> #endif /* !Tegra */
That's a very good catch!
For the record, the issue crept in when I applied the patch set to
remove all R_ARM_ABS32 relocation record types; after that, the only
manual relocations that should have remained were the three ones in each
relocate_code() routine, yet in armv7 there was this fourth one which
had totally escaped my attention.
I have verified in the ELF dump of omap5_evm that the "=_start"
reference is indeed relocated as part of relocate_code() execution.
As this is a bugfix, applied to u-boot-arm/master,
thanks!
Amicalement,
--
Albert.
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