On 2018-12-18 10:26, 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> > --- > s390x/cstart64.S | 21 ++++++++++++++++++++- > s390x/flat.lds | 2 ++ > 2 files changed, 22 insertions(+), 1 deletion(-) > > diff --git a/s390x/cstart64.S b/s390x/cstart64.S > index 7886f35..aba11f4 100644 > --- a/s390x/cstart64.S > +++ b/s390x/cstart64.S > @@ -37,6 +37,22 @@ start: > /* setup initial PSW mask + control registers*/ > larl %r1, initial_psw > lpswe 0(%r1) > +init_clear_bss: > + 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 remainder # If none, clear remaining bytes > +loop: > + xc 0(256,%r1), 0(%r1) # Clear 256 byte chunks via xor > + la %r1, 256(%r1) > + brctg %r4, loop > +remainder: > + larl %r2, memsetxc > + ex %r3, 0(%r2) Looks similar to the kernel's memset function, so I think this is fine. Reviewed-by: Thomas Huth <thuth@xxxxxxxxxx>
