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author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2013-10-15 16:08:34 +0200 |
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committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2013-10-24 17:17:11 +0200 |
commit | 4725c86055f5bbdcdfe47199c0715881893a2c79 (patch) | |
tree | e201bd8d8a11e58117e9ecf360f3fab43c6267e9 /arch/s390/kernel/signal.c | |
parent | 01a7cfa24afd8e18ce691d3c2f1e1f093cf3a900 (diff) | |
download | op-kernel-dev-4725c86055f5bbdcdfe47199c0715881893a2c79.zip op-kernel-dev-4725c86055f5bbdcdfe47199c0715881893a2c79.tar.gz |
s390: fix save and restore of the floating-point-control register
The FPC_VALID_MASK has been used to check the validity of the value
to be loaded into the floating-point-control register. With the
introduction of the floating-point extension facility and the
decimal-floating-point additional bits have been defined which need
to be checked in a non straight forward way. So far these bits have
been ignored which can cause an incorrect results for decimal-
floating-point operations, e.g. an incorrect rounding mode to be
set after signal return.
The static check with the FPC_VALID_MASK is replaced with a trial
load of the floating-point-control value, see test_fp_ctl.
In addition an information leak with the padding word between the
floating-point-control word and the floating-point registers in
the s390_fp_regs is fixed.
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/signal.c')
-rw-r--r-- | arch/s390/kernel/signal.c | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c index 5c0ce01..4c28c39 100644 --- a/arch/s390/kernel/signal.c +++ b/arch/s390/kernel/signal.c @@ -62,14 +62,15 @@ static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs) user_sregs.regs.psw.addr = regs->psw.addr; memcpy(&user_sregs.regs.gprs, ®s->gprs, sizeof(sregs->regs.gprs)); memcpy(&user_sregs.regs.acrs, current->thread.acrs, - sizeof(sregs->regs.acrs)); + sizeof(user_sregs.regs.acrs)); /* * We have to store the fp registers to current->thread.fp_regs * to merge them with the emulated registers. */ - save_fp_regs(¤t->thread.fp_regs); + save_fp_ctl(¤t->thread.fp_regs.fpc); + save_fp_regs(current->thread.fp_regs.fprs); memcpy(&user_sregs.fpregs, ¤t->thread.fp_regs, - sizeof(s390_fp_regs)); + sizeof(user_sregs.fpregs)); if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs))) return -EFAULT; return 0; @@ -82,8 +83,13 @@ static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs) /* Alwys make any pending restarted system call return -EINTR */ current_thread_info()->restart_block.fn = do_no_restart_syscall; - if (__copy_from_user(&user_sregs, sregs, sizeof(_sigregs))) + if (__copy_from_user(&user_sregs, sregs, sizeof(user_sregs))) return -EFAULT; + + /* Loading the floating-point-control word can fail. Do that first. */ + if (restore_fp_ctl(&user_sregs.fpregs.fpc)) + return -EINVAL; + /* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */ regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) | (user_sregs.regs.psw.mask & PSW_MASK_USER); @@ -97,14 +103,13 @@ static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs) regs->psw.addr = user_sregs.regs.psw.addr; memcpy(®s->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs)); memcpy(¤t->thread.acrs, &user_sregs.regs.acrs, - sizeof(sregs->regs.acrs)); + sizeof(current->thread.acrs)); restore_access_regs(current->thread.acrs); memcpy(¤t->thread.fp_regs, &user_sregs.fpregs, - sizeof(s390_fp_regs)); - current->thread.fp_regs.fpc &= FPC_VALID_MASK; + sizeof(current->thread.fp_regs)); - restore_fp_regs(¤t->thread.fp_regs); + restore_fp_regs(current->thread.fp_regs.fprs); clear_thread_flag(TIF_SYSCALL); /* No longer in a system call */ return 0; } |