Re: [kvm-unit-tests PATCH v4 05/13] s390x: Add BSS clearing for non ELF boot

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 03.01.19 11:07, Janosch Frank wrote:
> When doing an IPL normal the memory will not be zeroed and hence the
> BSS section can have any value. We need to clear it by ourselves.
> 
> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> Reviewed-by: Thomas Huth <thuth@xxxxxxxxxx>
> ---
>  s390x/cstart64.S | 22 ++++++++++++++++++++--
>  s390x/flat.lds   |  2 ++
>  2 files changed, 22 insertions(+), 2 deletions(-)
> 
> diff --git a/s390x/cstart64.S b/s390x/cstart64.S
> index 6622633..dedfe80 100644
> --- a/s390x/cstart64.S
> +++ b/s390x/cstart64.S
> @@ -39,7 +39,22 @@ start:
>  	/* setup initial PSW mask + control registers*/
>  	larl	%r1, initial_psw
>  	lpswe	0(%r1)
> -init_psw_cont:
> +clear_bss_start:
> +	larl 	%r2, __bss_start
> +	larl 	%r3, __bss_end
> +	slgr 	%r3, %r2		# Get sizeof bss
> +	aghi 	%r3,-1
> +	srlg 	%r4,%r3,8		# Calc number of 256 byte chunks
> +	ltgr 	%r4,%r4
> +	lgr 	%r1,%r2
> +	jz	clear_bss_remainder		# If none, clear remaining bytes
> +clear_bss_loop:
> +	xc	0(256,%r1), 0(%r1)	# Clear 256 byte chunks via xor
> +	la	%r1, 256(%r1)
> +	brctg 	%r4, clear_bss_loop
> +clear_bss_remainder:
> +	larl	%r2, memsetxc
> +	ex 	%r3, 0(%r2)
>  	/* setup pgm interrupt handler */
>  	larl	%r1, pgm_int_psw
>  	mvc	GEN_LC_PGM_NEW_PSW(16), 0(%r1)
> @@ -71,6 +86,9 @@ init_psw_cont:
>  	/* call exit() */
>  	j exit
>  
> +memsetxc:
> +	xc 0(1,%r1),0(%r1)
> +
>  	.macro SAVE_REGS
>  	/* save grs 0-15 */
>  	stmg	%r0, %r15, GEN_LC_SW_INT_GRS
> @@ -159,7 +177,7 @@ svc_int:
>  
>  	.align	8
>  initial_psw:
> -	.quad	0x0000000180000000, init_psw_cont
> +	.quad	0x0000000180000000, clear_bss_start
>  pgm_int_psw:
>  	.quad	0x0000000180000000, pgm_int
>  ext_int_psw:
> diff --git a/s390x/flat.lds b/s390x/flat.lds
> index 977af7c..403d967 100644
> --- a/s390x/flat.lds
> +++ b/s390x/flat.lds
> @@ -40,7 +40,9 @@ SECTIONS
>  	. = ALIGN(16);
>  	.rodata : { *(.rodata) *(.rodata.*) }
>  	. = ALIGN(16);
> +	__bss_start = .;
>  	.bss : { *(.bss) }
> +	__bss_end = .;
>  	. = ALIGN(64K);
>  	edata = .;
>  	. += 64K;
> 

Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>

-- 

Thanks,

David / dhildenb



[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Kernel Development]     [Kernel Newbies]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite Info]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Samba]     [Linux Media]     [Device Mapper]

  Powered by Linux