| Message ID | 20230626132138.87668-4-thuth@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | pc-bios/s390-ccw: Fixes and improvements for start.S | expand |
Am 26.06.23 um 15:21 schrieb Thomas Huth: > diff --git a/pc-bios/s390-ccw/start.S b/pc-bios/s390-ccw/start.S > index 29b0a9ece0..47ef6e8aa8 100644 > --- a/pc-bios/s390-ccw/start.S > +++ b/pc-bios/s390-ccw/start.S > @@ -120,3 +120,8 @@ external_new_mask: > .quad 0x0000000180000000 > io_new_mask: > .quad 0x0000000180000000 > + > +.bss > + > + .align 16 > + .lcomm stack,STACK_SIZE IIRC, the ELF ABI defines the stack to be 8 byte aligned, but 16 certainly does not hurt. Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
On 6/26/23 16:54, Christian Borntraeger wrote: > > Am 26.06.23 um 15:21 schrieb Thomas Huth: > >> diff --git a/pc-bios/s390-ccw/start.S b/pc-bios/s390-ccw/start.S >> index 29b0a9ece0..47ef6e8aa8 100644 >> --- a/pc-bios/s390-ccw/start.S >> +++ b/pc-bios/s390-ccw/start.S >> @@ -120,3 +120,8 @@ external_new_mask: >> .quad 0x0000000180000000 >> io_new_mask: >> .quad 0x0000000180000000 >> + >> +.bss >> + >> + .align 16 >> + .lcomm stack,STACK_SIZE > > IIRC, the ELF ABI defines the stack to be 8 byte aligned, but 16 certainly does not hurt. This doesn't do what you think it does. .lcomm produces a COMMON symbol, which is merged with .bss at link time. Thus the .align does nothing. Even switching to .bss section does nothing here. You want .bss .align 16 stack: .space STACK_SIZE .size stack, STACK_SIZE r~
On 26/06/2023 17.25, Richard Henderson wrote: > On 6/26/23 16:54, Christian Borntraeger wrote: >> >> Am 26.06.23 um 15:21 schrieb Thomas Huth: >> >>> diff --git a/pc-bios/s390-ccw/start.S b/pc-bios/s390-ccw/start.S >>> index 29b0a9ece0..47ef6e8aa8 100644 >>> --- a/pc-bios/s390-ccw/start.S >>> +++ b/pc-bios/s390-ccw/start.S >>> @@ -120,3 +120,8 @@ external_new_mask: >>> .quad 0x0000000180000000 >>> io_new_mask: >>> .quad 0x0000000180000000 >>> + >>> +.bss >>> + >>> + .align 16 >>> + .lcomm stack,STACK_SIZE >> >> IIRC, the ELF ABI defines the stack to be 8 byte aligned, but 16 certainly >> does not hurt. > > This doesn't do what you think it does. > > .lcomm produces a COMMON symbol, which is merged with .bss at link time. > Thus the .align does nothing. Even switching to .bss section does nothing > here. > > You want > > .bss > .align 16 > stack: > .space STACK_SIZE > .size stack, STACK_SIZE Oh, thanks! I'll fix it in v2. Thomas
diff --git a/pc-bios/s390-ccw/s390-ccw.h b/pc-bios/s390-ccw/s390-ccw.h index b88e0550ab..91afcbbca9 100644 --- a/pc-bios/s390-ccw/s390-ccw.h +++ b/pc-bios/s390-ccw/s390-ccw.h @@ -55,7 +55,6 @@ void consume_io_int(void); /* main.c */ void write_subsystem_identification(void); void write_iplb_location(void); -extern char stack[PAGE_SIZE * 8] __attribute__((__aligned__(PAGE_SIZE))); unsigned int get_loadparm_index(void); void main(void); diff --git a/pc-bios/s390-ccw/main.c b/pc-bios/s390-ccw/main.c index a2def83e82..5506798098 100644 --- a/pc-bios/s390-ccw/main.c +++ b/pc-bios/s390-ccw/main.c @@ -17,7 +17,6 @@ #include "virtio-scsi.h" #include "dasd-ipl.h" -char stack[PAGE_SIZE * 8] __attribute__((__aligned__(PAGE_SIZE))); static SubChannelId blk_schid = { .one = 1 }; static char loadparm_str[LOADPARM_LEN + 1]; QemuIplParameters qipl; diff --git a/pc-bios/s390-ccw/netmain.c b/pc-bios/s390-ccw/netmain.c index 056e93a818..5cd619b2d6 100644 --- a/pc-bios/s390-ccw/netmain.c +++ b/pc-bios/s390-ccw/netmain.c @@ -50,7 +50,6 @@ void write_iplb_location(void) {} /* STSI 3.2.2 offset of first vmdb + offset of uuid inside vmdb */ #define STSI322_VMDB_UUID_OFFSET ((8 + 12) * 4) -char stack[PAGE_SIZE * 8] __attribute__((aligned(PAGE_SIZE))); IplParameterBlock iplb __attribute__((aligned(PAGE_SIZE))); static char cfgbuf[2048]; diff --git a/pc-bios/s390-ccw/start.S b/pc-bios/s390-ccw/start.S index 29b0a9ece0..47ef6e8aa8 100644 --- a/pc-bios/s390-ccw/start.S +++ b/pc-bios/s390-ccw/start.S @@ -120,3 +120,8 @@ external_new_mask: .quad 0x0000000180000000 io_new_mask: .quad 0x0000000180000000 + +.bss + + .align 16 + .lcomm stack,STACK_SIZE
The stack array is only referenced from the start-up code (which is shared between the s390-ccw.img and the s390-netboot.img), but it is currently declared twice, once in main.c and once in netmain.c. It makes more sense to declare this in start.S instead - which will also be helpful in the next patch, since we need to mention the .bss section in start.S in that patch. While we're at it, let's also drop the huge alignment of the stack, since there is no technical requirement for aligning it to page boundaries. Signed-off-by: Thomas Huth <thuth@redhat.com> --- pc-bios/s390-ccw/s390-ccw.h | 1 - pc-bios/s390-ccw/main.c | 1 - pc-bios/s390-ccw/netmain.c | 1 - pc-bios/s390-ccw/start.S | 5 +++++ 4 files changed, 5 insertions(+), 3 deletions(-)