6.13-stable review patch. If anyone has any objections, please let me know.
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From: Heiko Carstens hca@linux.ibm.com
commit c3a589fd9fcbf295a7402a4b188dc9277d505f4f upstream.
The cmma_test_essa() inline assembly uses tmp as input and output, however tmp is specified as output only, which allows the compiler to optimize the initialization of tmp away.
Therefore the ESSA detection may or may not work depending on previous contents of the register that the compiler selected for tmp.
Fix this by using the correct constraint modifier.
Fixes: 468a3bc2b7b9 ("s390/cmma: move parsing of cmma kernel parameter to early boot code") Cc: stable@vger.kernel.org Signed-off-by: Heiko Carstens hca@linux.ibm.com Reviewed-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/s390/boot/startup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/s390/boot/startup.c +++ b/arch/s390/boot/startup.c @@ -75,7 +75,7 @@ static int cmma_test_essa(void) : [reg1] "=&d" (reg1), [reg2] "=&a" (reg2), [rc] "+&d" (rc), - [tmp] "=&d" (tmp), + [tmp] "+&d" (tmp), "+Q" (get_lowcore()->program_new_psw), "=Q" (old) : [psw_old] "a" (&old),