(resend with complete cc)
On 9 March 2015 at 20:09, Russell King - ARM Linux
<linux@xxxxxxxxxxxxxxxx> wrote:
> On Fri, Mar 06, 2015 at 03:34:40PM +0100, Ard Biesheuvel wrote:
>> From: Arnd Bergmann <arnd@xxxxxxxx>
>>
>> When building large kernels, the linker will emit lots of veneers
>> into the .hyp.idmap.text section, which causes it to grow beyond
>> one page, and that triggers the build error.
>>
>> This moves the section into .rodata instead, which avoids the
>> veneers and is safe because the code is not executed directly
>> but remapped by the hypervisor into its own executable address
>> space.
>>
>> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
>> [ardb: move the ALIGN() to .rodata as well, update log s/copied/remapped/]
>> Tested-by: Marc Zyngier <marc.zyngier@xxxxxxx>
>> Reviewed-by: Marc Zyngier <marc.zyngier@xxxxxxx>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
>> ---
>> arch/arm/kernel/vmlinux.lds.S | 9 +++++++--
>> 1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
>> index b31aa73e8076..2787eb8d3616 100644
>> --- a/arch/arm/kernel/vmlinux.lds.S
>> +++ b/arch/arm/kernel/vmlinux.lds.S
>> @@ -22,11 +22,15 @@
>> ALIGN_FUNCTION(); \
>> VMLINUX_SYMBOL(__idmap_text_start) = .; \
>> *(.idmap.text) \
>> - VMLINUX_SYMBOL(__idmap_text_end) = .; \
>> + VMLINUX_SYMBOL(__idmap_text_end) = .;
>> +
>> +#define IDMAP_RODATA \
>> + .rodata : { \
>
> We already have a .rodata section defined by RO_DATA(). Quite how this
> interacts with the existing .rodata section, I don't know, but it
> probably won't be right. Have you checked what effect this has?
>
Here's just the rodata lines from 'readelf -S vmlinux', with and
without the patch applied
[ 4] .rodata PROGBITS c0752000 552000 310620 00 A 0 0 64
[ 4] .rodata PROGBITS c0752000 552000 3106c0 00 AX 0 0 64
and there is only a single one, so it appears binutils is quite happy with this.
If the A -> AX bothers you, we could fold in the following hunk as well.
--- a/arch/arm/kvm/init.S
+++ b/arch/arm/kvm/init.S
@@ -52,7 +52,7 @@
*/
.text
- .pushsection .hyp.idmap.text,"ax"
+ .pushsection .hyp.idmap.text,"a"
.align 5
__kvm_hyp_init:
.globl __kvm_hyp_init
which takes care of that.
_______________________________________________
kvmarm mailing list
kvmarm@xxxxxxxxxxxxxxxxxxxxx
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
