Commit 2b6eff59 authored Jun 21, 2018 by Christian Borntraeger Committed by Greg Kroah-Hartman Jul 11, 2018

s390: Correct register corruption in critical section cleanup



commit 891f6a726cacbb87e5b06076693ffab53bd378d7 upstream.

In the critical section cleanup we must not mess with r1.  For march=z9
or older, larl + ex (instead of exrl) are used with r1 as a temporary
register. This can clobber r1 in several interrupt handlers. Fix this by
using r11 as a temp register.  r11 is being saved by all callers of
cleanup_critical.

Fixes: 6dd85fbb87 ("s390: move expoline assembler macros to a header")
Cc: stable@vger.kernel.org #v4.16
Reported-by: Oliver Kurz <okurz@suse.com>
Reported-by: Petr Tesařík <ptesarik@suse.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent e6cf7e68

arch/s390/kernel/entry.S

+2 −2

Original line number	Diff line number	Diff line
		@@ -1244,7 +1244,7 @@ cleanup_critical:
		jl 0f
		clg %r9,BASED(.Lcleanup_table+104) # .Lload_fpu_regs_end
		jl .Lcleanup_load_fpu_regs
		0: BR_EX %r14
		0: BR_EX %r14,%r11

		.align 8
		.Lcleanup_table:
		@@ -1280,7 +1280,7 @@ cleanup_critical:
		ni __SIE_PROG0C+3(%r9),0xfe # no longer in SIE
		lctlg %c1,%c1,__LC_USER_ASCE # load primary asce
		larl %r9,sie_exit # skip forward to sie_exit
		BR_EX %r14
		BR_EX %r14,%r11
		#endif

		.Lcleanup_system_call: