linux-dev/arch/s390/include/asm/vdso.h, branch linus/master

s390/vdso: add minimal compat vdso

2021-07-08T13:37:28Z

Add a small vdso for 31 bit compat application that provides trampolines for calls to sigreturn,rt_sigreturn,syscall_restart. This is requird for moving these syscalls away from the signal frame to the vdso. Note that this patch effectively disables CONFIG_COMPAT when using clang to compile the kernel. clang doesn't support 31 bit mode. We want to redirect sigreturn and restart_syscall to the vdso. However, the kernel cannot parse the ELF vdso file, so we need to generate header files which contain the offsets of the syscall instructions in the vdso page. Signed-off-by: Sven Schnelle Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/vdso: rename VDSO64_LBASE to VDSO_LBASE

2021-07-08T13:37:28Z

Will be used by both vdso32 and vdso64, so change the name. Signed-off-by: Sven Schnelle Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/vdso: implement generic vdso time namespace support

2021-02-09T14:57:05Z

Implement generic vdso time namespace support which also enables time namespaces for s390. This is quite similar to what arm64 has. Reviewed-by: Alexander Gordeev Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/vdso: convert vdso_init() to arch_initcall

2021-02-09T14:57:05Z

Convert vdso_init() to arch_initcall like it is on all other architectures. This requires to remove the vdso_getcpu_init() call from vdso_init() since it must be called before smp is enabled. vdso_getcpu_init() is now an early_initcall like on powerpc. Reviewed-by: Alexander Gordeev Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/vdso: remove VDSO32_LBASE compat leftover

2021-02-09T14:57:04Z

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

s390/vdso: reimplement getcpu vdso syscall

2020-11-23T11:01:13Z

Implement the previously removed getcpu vdso syscall by using the TOD programmable field to pass the cpu number to user space. Reviewed-by: Sven Schnelle Signed-off-by: Heiko Carstens

s390/mm: remove set_fs / rework address space handling

2020-11-23T11:01:12Z

Remove set_fs support from s390. With doing this rework address space handling and simplify it. As a result address spaces are now setup like this: CPU running in | %cr1 ASCE | %cr7 ASCE | %cr13 ASCE ----------------------------|-----------|-----------|----------- user space | user | user | kernel kernel, normal execution | kernel | user | kernel kernel, kvm guest execution | gmap | user | kernel To achieve this the getcpu vdso syscall is removed in order to avoid secondary address mode and a separate vdso address space in for user space. The getcpu vdso syscall will be implemented differently with a subsequent patch. The kernel accesses user space always via secondary address space. This happens in different ways: - with mvcos in home space mode and directly read/write to secondary address space - with mvcs/mvcp in primary space mode and copy from primary space to secondary space or vice versa - with e.g. cs in secondary space mode and access secondary space Switching translation modes happens with sacf before and after instructions which access user space, like before. Lazy handling of control register reloading is removed in the hope to make everything simpler, but at the cost of making kernel entry and exit a bit slower. That is: on kernel entry the primary asce is always changed to contain the kernel asce, and on kernel exit the primary asce is changed again so it contains the user asce. In kernel mode there is only one exception to the primary asce: when kvm guests are executed the primary asce contains the gmap asce (which describes the guest address space). The primary asce is reset to kernel asce whenever kvm guest execution is interrupted, so that this doesn't has to be taken into account for any user space accesses. Reviewed-by: Sven Schnelle Signed-off-by: Heiko Carstens

s390/vdso: remove orphaned declarations

2020-09-30T10:09:54Z

Remove couple of declarations which are unused since commit 4bff8cb54502 ("s390: convert to GENERIC_VDSO"). Acked-by: Sven Schnelle Signed-off-by: Vasily Gorbik

s390: convert to GENERIC_VDSO

2020-08-26T16:47:21Z

Convert s390 to generic vDSO. There are a few special things on s390: - vDSO can be called without a stack frame - glibc did this in the past. So we need to allocate a stackframe on our own. - The former assembly code used stcke to get the TOD clock and applied time steering to it. We need to do the same in the new code. This is done in the architecture specific __arch_get_hw_counter function. The steering information is stored in an architecure specific area in the vDSO data. - CPUCLOCK_VIRT is now handled with a syscall fallback, which might be slower/less accurate than the old implementation. The getcpu() function stays as an assembly function because there is no generic implementation and the code is just a few lines. Performance number from my system do 100 mio gettimeofday() calls: Plain syscall: 8.6s Generic VDSO: 1.3s old ASM VDSO: 1s So it's a bit slower but still much faster than syscalls. Signed-off-by: Sven Schnelle Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/vdso: fix vDSO clock_getres()

2020-06-16T11:44:05Z

clock_getres in the vDSO library has to preserve the same behaviour of posix_get_hrtimer_res(). In particular, posix_get_hrtimer_res() does: sec = 0; ns = hrtimer_resolution; and hrtimer_resolution depends on the enablement of the high resolution timers that can happen either at compile or at run time. Fix the s390 vdso implementation of clock_getres keeping a copy of hrtimer_resolution in vdso data and using that directly. Link: https://lkml.kernel.org/r/20200324121027.21665-1-vincenzo.frascino@arm.com Signed-off-by: Vincenzo Frascino Acked-by: Martin Schwidefsky [heiko.carstens@de.ibm.com: use llgf for proper zero extension] Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik