| From b856855222b90044781dfdd6c36bb267c2850221 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Mon, 14 Jun 2021 14:49:31 +0200 |
| Subject: s390/ipl_parm: fix program check new psw handling |
| |
| From: Heiko Carstens <hca@linux.ibm.com> |
| |
| [ Upstream commit 88c2510cecb7e2b518e3c4fdf3cf0e13ebe9377c ] |
| |
| The __diag308() inline asm temporarily changes the program check new |
| psw to redirect a potential program check on the diag instruction. |
| Restoring of the program check new psw is done in C code behind the |
| inline asm. |
| |
| This can be problematic, especially if the function is inlined, since |
| the compiler can reorder instructions in such a way that a different |
| instruction, which may result in a program check, might be executed |
| before the program check new psw has been restored. |
| |
| To avoid such a scenario move restoring into the inline asm. For |
| consistency reasons move also saving of the original program check new |
| psw into the inline asm. |
| |
| Signed-off-by: Heiko Carstens <hca@linux.ibm.com> |
| Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| arch/s390/boot/ipl_parm.c | 19 +++++++++++-------- |
| 1 file changed, 11 insertions(+), 8 deletions(-) |
| |
| diff --git a/arch/s390/boot/ipl_parm.c b/arch/s390/boot/ipl_parm.c |
| index d372a45fe10e..dd92092e3eec 100644 |
| --- a/arch/s390/boot/ipl_parm.c |
| +++ b/arch/s390/boot/ipl_parm.c |
| @@ -28,22 +28,25 @@ static inline int __diag308(unsigned long subcode, void *addr) |
| register unsigned long _addr asm("0") = (unsigned long)addr; |
| register unsigned long _rc asm("1") = 0; |
| unsigned long reg1, reg2; |
| - psw_t old = S390_lowcore.program_new_psw; |
| + psw_t old; |
| |
| asm volatile( |
| + " mvc 0(16,%[psw_old]),0(%[psw_pgm])\n" |
| " epsw %0,%1\n" |
| - " st %0,%[psw_pgm]\n" |
| - " st %1,%[psw_pgm]+4\n" |
| + " st %0,0(%[psw_pgm])\n" |
| + " st %1,4(%[psw_pgm])\n" |
| " larl %0,1f\n" |
| - " stg %0,%[psw_pgm]+8\n" |
| + " stg %0,8(%[psw_pgm])\n" |
| " diag %[addr],%[subcode],0x308\n" |
| - "1: nopr %%r7\n" |
| + "1: mvc 0(16,%[psw_pgm]),0(%[psw_old])\n" |
| : "=&d" (reg1), "=&a" (reg2), |
| - [psw_pgm] "=Q" (S390_lowcore.program_new_psw), |
| + "+Q" (S390_lowcore.program_new_psw), |
| + "=Q" (old), |
| [addr] "+d" (_addr), "+d" (_rc) |
| - : [subcode] "d" (subcode) |
| + : [subcode] "d" (subcode), |
| + [psw_old] "a" (&old), |
| + [psw_pgm] "a" (&S390_lowcore.program_new_psw) |
| : "cc", "memory"); |
| - S390_lowcore.program_new_psw = old; |
| return _rc; |
| } |
| |
| -- |
| 2.30.2 |
| |