kernel.git/arch/s390/kernel/early.c, branch linux-5.13.y

s390: make PCI mio support a machine flag

2021-09-18T11:42:04Z

[ Upstream commit 3322ba0d7bea1e24ae464418626f6a15b69533ab ] Kernel support for the newer PCI mio instructions can be toggled off with the pci=nomio command line option which needs to integrate with common code PCI option parsing. However this option then toggles static branches which can't be toggled yet in an early_param() call. Thus commit 9964f396f1d0 ("s390: fix setting of mio addressing control") moved toggling the static branches to the PCI init routine. With this setup however we can't check for mio support outside the PCI code during early boot, i.e. before switching the static branches, which we need to be able to export this as an ELF HWCAP. Improve on this by turning mio availability into a machine flag that gets initially set based on CONFIG_PCI and the facility bit and gets toggled off if pci=nomio is found during PCI option parsing allowing simple access to this machine flag after early init. Reviewed-by: Heiko Carstens Signed-off-by: Niklas Schnelle Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin

s390/time: convert tod_clock_base to union

2021-02-13T16:17:54Z

Convert tod_clock_base to union tod_clock. This simplifies quite a bit of code and also fixes a bug in read_persistent_clock64(); void read_persistent_clock64(struct timespec64 *ts) { __u64 delta; delta = initial_leap_seconds + TOD_UNIX_EPOCH; get_tod_clock_ext(clk); *(__u64 *) &clk[1] -= delta; if (*(__u64 *) &clk[1] > delta) clk[0]--; ext_to_timespec64(clk, ts); } Assume &clk[1] == 3 and delta == 2; then after the substraction the if condition becomes true and the epoch part of the clock is decremented by one because of an assumed overflow, even though there is none. Fix this by using 128 bit arithmetics and let the compiler do the right thing: void read_persistent_clock64(struct timespec64 *ts) { union tod_clock clk; u64 delta; delta = initial_leap_seconds + TOD_UNIX_EPOCH; store_tod_clock_ext(&clk); clk.eitod -= delta; ext_to_timespec64(&clk, ts); } Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/time: rename store_tod_clock_ext() and use union tod_clock

2021-02-13T16:17:54Z

Rename store_tod_clock_ext() to store_tod_clock_ext_cc() to reflect that it returns a condition code and also use union tod_clock as parameter. Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/time: use stcke instead of stck

2021-02-09T14:57:05Z

Use STORE CLOCK EXTENDED instead of STORE CLOCK in early tod clock setup. This is just to remove another usage of stck, trying to remove all usages of STORE CLOCK. This doesn't fix anything. Reviewed-by: Christian Borntraeger Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: remove unused s390_base_ext_handler

2020-11-09T10:20:58Z

s390_base_ext_handler_fn haven't been used since its introduction in commit ab14de6c37fa ("[S390] Convert memory detection into C code."). s390_base_ext_handler itself is currently falsely storing 16 registers at __LC_SAVE_AREA_ASYNC rewriting several following lowcore values: cpu_flags, return_psw, return_mcck_psw, sync_enter_timer and async_enter_timer. Besides that s390_base_ext_handler itself is only potentially hiding EXT interrupts which should not have happen in the first place. Any piece of code which requires EXT interrupts before fully functional ext_int_handler is enabled has to do it on its own, like this is done by sclp_early_cmd() which is doing EXT interrupts handling synchronously in sclp_early_wait_irq(). With s390_base_ext_handler removed unexpected EXT interrupt leads to disabled wait with the address 0x1b0 (__LC_EXT_NEW_PSW), which is currently setup in the decompressor. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens

s390: remove cad commandline option

2020-09-30T10:09:54Z

remove the cad command line option as the instruction was never published and never used by userspace. Signed-off-by: Sven Schnelle Reviewed-by: Vasily Gorbik Acked-by: Christian Borntraeger Signed-off-by: Vasily Gorbik

s390/kasan: fix early pgm check handler execution

2020-06-23T12:05:50Z

Currently if early_pgm_check_handler is called it ends up in pgm check loop. The problem is that early_pgm_check_handler is instrumented by KASAN but executed without DAT flag enabled which leads to addressing exception when KASAN checks try to access shadow memory. Fix that by executing early handlers with DAT flag on under KASAN as expected. Reported-and-tested-by: Alexander Egorenkov Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens

s390: remove last diag 0x44 caller

2019-12-11T18:53:24Z

diag 0x44 is a voluntary undirected yield of a virtual CPU. This has caused a lot of performance issues in the past. There is only one caller left, and that one is only executed if diag 0x9c (directed yield) is not present. Given that all hypervisors implement diag 0x9c anyway, remove the last diag 0x44 to avoid that more callers will be added. Worst case that could happen now, if diag 0x9c is not present, is that a virtual CPU would loop a bit instead of giving its time slice up. diag 0x44 statistics in debugfs are kept and will always be zero, so that user space can tell that there are no calls. Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/early: move access registers setup in C code

2019-11-20T11:58:13Z

Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/early: move control registers setup in C code

2019-11-20T11:58:12Z

Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik