| From c845aa2d070d96885f4f2c57c0de35ff291a09f3 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Mon, 14 Jun 2021 22:09:20 +0200 |
| Subject: s390/mem_detect: fix tprot() program check new psw handling |
| |
| From: Heiko Carstens <hca@linux.ibm.com> |
| |
| [ Upstream commit da9057576785aaab52e706e76c0475c85b77ec14 ] |
| |
| The tprot() 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/mem_detect.c | 28 +++++++++++++++++----------- |
| 1 file changed, 17 insertions(+), 11 deletions(-) |
| |
| diff --git a/arch/s390/boot/mem_detect.c b/arch/s390/boot/mem_detect.c |
| index 3f093556dc3b..a0e980f57c02 100644 |
| --- a/arch/s390/boot/mem_detect.c |
| +++ b/arch/s390/boot/mem_detect.c |
| @@ -114,24 +114,30 @@ static int diag260(void) |
| |
| static int tprot(unsigned long addr) |
| { |
| - unsigned long pgm_addr; |
| + unsigned long reg1, reg2; |
| int rc = -EFAULT; |
| - psw_t old = S390_lowcore.program_new_psw; |
| + psw_t old; |
| |
| - S390_lowcore.program_new_psw.mask = __extract_psw(); |
| asm volatile( |
| - " larl %[pgm_addr],1f\n" |
| - " stg %[pgm_addr],%[psw_pgm_addr]\n" |
| + " mvc 0(16,%[psw_old]),0(%[psw_pgm])\n" |
| + " epsw %[reg1],%[reg2]\n" |
| + " st %[reg1],0(%[psw_pgm])\n" |
| + " st %[reg2],4(%[psw_pgm])\n" |
| + " larl %[reg1],1f\n" |
| + " stg %[reg1],8(%[psw_pgm])\n" |
| " tprot 0(%[addr]),0\n" |
| " ipm %[rc]\n" |
| " srl %[rc],28\n" |
| - "1:\n" |
| - : [pgm_addr] "=&d"(pgm_addr), |
| - [psw_pgm_addr] "=Q"(S390_lowcore.program_new_psw.addr), |
| - [rc] "+&d"(rc) |
| - : [addr] "a"(addr) |
| + "1: mvc 0(16,%[psw_pgm]),0(%[psw_old])\n" |
| + : [reg1] "=&d" (reg1), |
| + [reg2] "=&a" (reg2), |
| + [rc] "+&d" (rc), |
| + "=Q" (S390_lowcore.program_new_psw.addr), |
| + "=Q" (old) |
| + : [psw_old] "a" (&old), |
| + [psw_pgm] "a" (&S390_lowcore.program_new_psw), |
| + [addr] "a" (addr) |
| : "cc", "memory"); |
| - S390_lowcore.program_new_psw = old; |
| return rc; |
| } |
| |
| -- |
| 2.30.2 |
| |
