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 032d68165216..85049541c191 100644 --- a/arch/s390/boot/mem_detect.c +++ b/arch/s390/boot/mem_detect.c @@ -115,24 +115,30 @@ 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; }