From 56e62a73702836017564eaacd5212e4d0fa1c01d Mon Sep 17 00:00:00 2001 From: Sven Schnelle Date: Sat, 21 Nov 2020 11:14:56 +0100 Subject: s390: convert to generic entry This patch converts s390 to use the generic entry infrastructure from kernel/entry/*. There are a few special things on s390: - PIF_PER_TRAP is moved to TIF_PER_TRAP as the generic code doesn't know about our PIF flags in exit_to_user_mode_loop(). - The old code had several ways to restart syscalls: a) PIF_SYSCALL_RESTART, which was only set during execve to force a restart after upgrading a process (usually qemu-kvm) to pgste page table extensions. b) PIF_SYSCALL, which is set by do_signal() to indicate that the current syscall should be restarted. This is changed so that do_signal() now also uses PIF_SYSCALL_RESTART. Continuing to use PIF_SYSCALL doesn't work with the generic code, and changing it to PIF_SYSCALL_RESTART makes PIF_SYSCALL and PIF_SYSCALL_RESTART more unique. - On s390 calling sys_sigreturn or sys_rt_sigreturn is implemented by executing a svc instruction on the process stack which causes a fault. While handling that fault the fault code sets PIF_SYSCALL to hand over processing to the syscall code on exit to usermode. The patch introduces PIF_SYSCALL_RET_SET, which is set if ptrace sets a return value for a syscall. The s390x ptrace ABI uses r2 both for the syscall number and return value, so ptrace cannot set the syscall number + return value at the same time. The flag makes handling that a bit easier. do_syscall() will just skip executing the syscall if PIF_SYSCALL_RET_SET is set. CONFIG_DEBUG_ASCE was removd in favour of the generic CONFIG_DEBUG_ENTRY. CR1/7/13 will be checked both on kernel entry and exit to contain the correct asces. Signed-off-by: Sven Schnelle Signed-off-by: Vasily Gorbik --- arch/s390/Kconfig.debug | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'arch/s390/Kconfig.debug') diff --git a/arch/s390/Kconfig.debug b/arch/s390/Kconfig.debug index 6bfaceebbbc0..ef96c25fa921 100644 --- a/arch/s390/Kconfig.debug +++ b/arch/s390/Kconfig.debug @@ -6,10 +6,12 @@ config TRACE_IRQFLAGS_SUPPORT config EARLY_PRINTK def_bool y -config DEBUG_USER_ASCE - bool "Debug User ASCE" +config DEBUG_ENTRY + bool "Debug low-level entry code" + depends on DEBUG_KERNEL help - Check on exit to user space that address space control - elements are setup correctly. + This option enables sanity checks in s390 low-level entry code. + Some of these sanity checks may slow down kernel entries and + exits or otherwise impact performance. If unsure, say N. -- cgit v1.2.3