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/kernel/process.c | 30 +++++++++++++++++++++++------- 1 file changed, 23 insertions(+), 7 deletions(-) (limited to 'arch/s390/kernel/process.c') diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c index bc3ca54edfb4..367bd000f6d1 100644 --- a/arch/s390/kernel/process.c +++ b/arch/s390/kernel/process.c @@ -29,6 +29,7 @@ #include #include #include +#include #include #include #include @@ -43,9 +44,22 @@ #include #include "entry.h" -asmlinkage void ret_from_fork(void) asm ("ret_from_fork"); +void ret_from_fork(void) asm("ret_from_fork"); -extern void kernel_thread_starter(void); +void __ret_from_fork(struct task_struct *prev, struct pt_regs *regs) +{ + void (*func)(void *arg); + + schedule_tail(prev); + + if (!user_mode(regs)) { + /* Kernel thread */ + func = (void *)regs->gprs[9]; + func((void *)regs->gprs[10]); + } + clear_pt_regs_flag(regs, PIF_SYSCALL); + syscall_exit_to_user_mode(regs); +} void flush_thread(void) { @@ -108,10 +122,12 @@ int copy_thread(unsigned long clone_flags, unsigned long new_stackp, p->thread.last_break = 1; frame->sf.back_chain = 0; + frame->sf.gprs[5] = (unsigned long)frame + sizeof(struct stack_frame); + frame->sf.gprs[6] = (unsigned long)p; /* new return point is ret_from_fork */ - frame->sf.gprs[8] = (unsigned long) ret_from_fork; + frame->sf.gprs[8] = (unsigned long)ret_from_fork; /* fake return stack for resume(), don't go back to schedule */ - frame->sf.gprs[9] = (unsigned long) frame; + frame->sf.gprs[9] = (unsigned long)frame; /* Store access registers to kernel stack of new process. */ if (unlikely(p->flags & PF_KTHREAD)) { @@ -120,10 +136,10 @@ int copy_thread(unsigned long clone_flags, unsigned long new_stackp, frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK; frame->childregs.psw.addr = - (unsigned long) kernel_thread_starter; + (unsigned long)__ret_from_fork; frame->childregs.gprs[9] = new_stackp; /* function */ frame->childregs.gprs[10] = arg; - frame->childregs.gprs[11] = (unsigned long) do_exit; + frame->childregs.gprs[11] = (unsigned long)do_exit; frame->childregs.orig_gpr2 = -1; return 0; @@ -153,7 +169,7 @@ int copy_thread(unsigned long clone_flags, unsigned long new_stackp, return 0; } -asmlinkage void execve_tail(void) +void execve_tail(void) { current->thread.fpu.fpc = 0; asm volatile("sfpc %0" : : "d" (0)); -- cgit