On 6/24/21 5:49 PM, Thomas Huth wrote:
> On 24/06/2021 14.01, Janosch Frank wrote:
>> Snippets are small guests That can be run under a unit test as the
>> hypervisor. They can be written in C or assembly. The C code needs a
>> linker script and a start assembly file that jumps to main to work
>> properly. So let's add that as well as a gitignore entry for the new
>> files.
>>
>> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
>> ---
>> .gitignore | 1 +
>> s390x/snippets/c/cstart.S | 15 ++++++++++++
>> s390x/snippets/c/flat.lds | 51 +++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 67 insertions(+)
>> create mode 100644 s390x/snippets/c/cstart.S
>> create mode 100644 s390x/snippets/c/flat.lds
>>
>> diff --git a/.gitignore b/.gitignore
>> index 8534fb7..b3cf2cb 100644
>> --- a/.gitignore
>> +++ b/.gitignore
>> @@ -23,3 +23,4 @@ cscope.*
>> /api/dirty-log
>> /api/dirty-log-perf
>> /s390x/*.bin
>> +/s390x/snippets/*/*.gbin
>> diff --git a/s390x/snippets/c/cstart.S b/s390x/snippets/c/cstart.S
>> new file mode 100644
>> index 0000000..d7f6525
>> --- /dev/null
>> +++ b/s390x/snippets/c/cstart.S
>> @@ -0,0 +1,15 @@
>> +#include <asm/sigp.h>
>> +
>> +.section .init
>> + .globl start
>> +start:
>> + /* XOR all registers with themselves to clear them fully. */
>> + .irp i, 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
>> + xgr \i,\i
>> + .endr
>> + /* 0x3000 is the stack page for now */
>> + lghi %r15, 0x4000 - 160
>> + brasl %r14, main
>> + /* For now let's only use cpu 0 in snippets so this will always work. */
>> + xgr %r0, %r0
>> + sigp %r2, %r0, SIGP_STOP
>> diff --git a/s390x/snippets/c/flat.lds b/s390x/snippets/c/flat.lds
>> new file mode 100644
>> index 0000000..5e70732
>> --- /dev/null
>> +++ b/s390x/snippets/c/flat.lds
>> @@ -0,0 +1,51 @@
>> +SECTIONS
>> +{
>> + .lowcore : {
>> + /*
>> + * Initial short psw for disk boot, with 31 bit addressing for
>> + * non z/Arch environment compatibility and the instruction
>> + * address 0x10000 (cstart64.S .init).
>
> I think this comment needs some adjustments (0x10000 => 0x4000 and do not
> talk about cstart64.S)?
Right, will do
>
> Also, what about switching to 64-bit mode in the snippets?
I thought about that for some time a while ago.
It's not really necessary since the host test can also decide which
guest PSW is used to start the snippet but it also doesn't hurt so I
just added a sam64.
>
> Thomas
>
>
>> + */
>> + . = 0;
>> + LONG(0x00080000)
>> + LONG(0x80004000)
>> + /* Restart new PSW for booting via PSW restart. */
>> + . = 0x1a0;
>> + QUAD(0x0000000180000000)
>> + QUAD(0x0000000000004000)
>> + }
>> + . = 0x4000;
>> + .text : {
>> + *(.init)
>> + *(.text)
>> + *(.text.*)
>> + }
>> + . = ALIGN(64K);
>> + etext = .;
>> + .opd : { *(.opd) }
>> + . = ALIGN(16);
>> + .dynamic : {
>> + dynamic_start = .;
>> + *(.dynamic)
>> + }
>> + .dynsym : {
>> + dynsym_start = .;
>> + *(.dynsym)
>> + }
>> + .rela.dyn : { *(.rela*) }
>> + . = ALIGN(16);
>> + .data : {
>> + *(.data)
>> + *(.data.rel*)
>> + }
>> + . = ALIGN(16);
>> + .rodata : { *(.rodata) *(.rodata.*) }
>> + . = ALIGN(16);
>> + __bss_start = .;
>> + .bss : { *(.bss) }
>> + __bss_end = .;
>> + . = ALIGN(64K);
>> + edata = .;
>> + . += 64K;
>> + . = ALIGN(64K);
>> +}
>>
>
