[PATCH] s390: memory detection > 32GB (e9b9a047) · Commits · e / devices / android_kernel_xiaomi_markw

The kernel takes a very long time to boot if the memory size is bigger then 32767 MB. The memory size is contained in a structure created by an sclp call. The kernel accesses the field with a LH instrution which performs a sign extension of a 16 bit word. In the case of a memory size with bit 2^15 set this results in a very large value and the memory detection just loops for a long time. In addition if more then 64 GB are used on a 64 bit system the memory size is read from an incorrect storage location. Use zero-extention to read the 16 bit memory size and the correct offset to read the 4 byte memory size on 64 bit. Signed-off-by:

Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by:

Andrew Morton <akpm@osdl.org> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

arch/s390/kernel/head.S

+4 −4

Original line number	Diff line number	Diff line
		@@ -517,10 +517,10 @@ startup:basr %r13,0 # get base
		l %r2, .Lrcp2-.LPG1(%r13) # try with Read SCP
		b .Lservicecall-.LPG1(%r13)
		.Lprocsccb:
		lh %r1,.Lscpincr1-PARMAREA(%r4) # use this one if != 0
		chi %r1,0x00
		jne .Lscnd
		l %r1,.Lscpincr2-PARMAREA(%r4) # otherwise use this one
		lhi %r1,0
		icm %r1,3,.Lscpincr1-PARMAREA(%r4) # use this one if != 0
		jnz .Lscnd
		l %r1,.Lscpincr2-PARMAREA+4(%r4) # otherwise use this one
		.Lscnd:
		xr %r3,%r3 # same logic
		ic %r3,.Lscpa1-PARMAREA(%r4)

arch/s390/kernel/head64.S

+3 −3

Original line number	Diff line number	Diff line
		@@ -518,9 +518,9 @@ startup:basr %r13,0 # get base
		l %r2,.Lrcp2-.LPG1(%r13) # try with Read SCP
		b .Lservicecall-.LPG1(%r13)
		.Lprocsccb:
		lh %r1,.Lscpincr1-PARMAREA(%r4) # use this one if != 0
		chi %r1,0x00
		jne .Lscnd
		lghi %r1,0
		icm %r1,3,.Lscpincr1-PARMAREA(%r4) # use this one if != 0
		jnz .Lscnd
		lg %r1,.Lscpincr2-PARMAREA(%r4) # otherwise use this one
		.Lscnd:
		xr %r3,%r3 # same logic