Commit f9c87a6f authored Jul 06, 2015 by Martin Schwidefsky

s390/sclp: clear upper register halves in _sclp_print_early



If the kernel is compiled with gcc 5.1 and the XZ compression option
the decompress_kernel function calls _sclp_print_early in 64-bit mode
while the content of the upper register half of %r6 is non-zero.
This causes a specification exception on the servc instruction in
_sclp_servc.

The _sclp_print_early function saves and restores the upper registers
halves but it fails to clear them for the 31-bit code of the mini sclp
driver.

Cc: <stable@vger.kernel.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

parent a215c8fb

arch/s390/kernel/sclp.S

+4 −0

Original line number	Diff line number	Diff line
		@@ -270,6 +270,8 @@ ENTRY(_sclp_print_early)
		jno .Lesa2
		ahi %r15,-80
		stmh %r6,%r15,96(%r15) # store upper register halves
		basr %r13,0
		lmh %r0,%r15,.Lzeroes-.(%r13) # clear upper register halves
		.Lesa2:
		lr %r10,%r2 # save string pointer
		lhi %r2,0
		@@ -291,6 +293,8 @@ ENTRY(_sclp_print_early)
		.Lesa3:
		lm %r6,%r15,120(%r15) # restore registers
		br %r14
		.Lzeroes:
		.fill 64,4,0

		.LwritedataS4:
		.long 0x00760005 # SCLP command for write data

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