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 <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

1 files changed, 32 insertions, 20 deletions

diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index 2058a435add4..fa67b66bf144 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -38,6 +38,11 @@
 #include <asm/runtime_instr.h>
 #include <asm/fpu/types.h>
 #include <asm/fpu/internal.h>
+#include <asm/irqflags.h>
+
+typedef long (*sys_call_ptr_t)(unsigned long, unsigned long,
+			       unsigned long, unsigned long,
+			       unsigned long, unsigned long);
 
 static inline void set_cpu_flag(int flag)
 {
@@ -101,31 +106,32 @@ extern void __bpon(void);
  */
 struct thread_struct {
 	unsigned int  acrs[NUM_ACRS];
-        unsigned long ksp;              /* kernel stack pointer             */
-	unsigned long user_timer;	/* task cputime in user space */
-	unsigned long guest_timer;	/* task cputime in kvm guest */
-	unsigned long system_timer;	/* task cputime in kernel space */
-	unsigned long hardirq_timer;	/* task cputime in hardirq context */
-	unsigned long softirq_timer;	/* task cputime in softirq context */
-	unsigned long sys_call_table;	/* system call table address */
-	unsigned long gmap_addr;	/* address of last gmap fault. */
-	unsigned int gmap_write_flag;	/* gmap fault write indication */
-	unsigned int gmap_int_code;	/* int code of last gmap fault */
-	unsigned int gmap_pfault;	/* signal of a pending guest pfault */
+	unsigned long ksp;			/* kernel stack pointer */
+	unsigned long user_timer;		/* task cputime in user space */
+	unsigned long guest_timer;		/* task cputime in kvm guest */
+	unsigned long system_timer;		/* task cputime in kernel space */
+	unsigned long hardirq_timer;		/* task cputime in hardirq context */
+	unsigned long softirq_timer;		/* task cputime in softirq context */
+	const sys_call_ptr_t *sys_call_table;	/* system call table address */
+	unsigned long gmap_addr;		/* address of last gmap fault. */
+	unsigned int gmap_write_flag;		/* gmap fault write indication */
+	unsigned int gmap_int_code;		/* int code of last gmap fault */
+	unsigned int gmap_pfault;		/* signal of a pending guest pfault */
+
 	/* Per-thread information related to debugging */
-	struct per_regs per_user;	/* User specified PER registers */
-	struct per_event per_event;	/* Cause of the last PER trap */
-	unsigned long per_flags;	/* Flags to control debug behavior */
-	unsigned int system_call;	/* system call number in signal */
-	unsigned long last_break;	/* last breaking-event-address. */
-        /* pfault_wait is used to block the process on a pfault event */
+	struct per_regs per_user;		/* User specified PER registers */
+	struct per_event per_event;		/* Cause of the last PER trap */
+	unsigned long per_flags;		/* Flags to control debug behavior */
+	unsigned int system_call;		/* system call number in signal */
+	unsigned long last_break;		/* last breaking-event-address. */
+	/* pfault_wait is used to block the process on a pfault event */
 	unsigned long pfault_wait;
 	struct list_head list;
 	/* cpu runtime instrumentation */
 	struct runtime_instr_cb *ri_cb;
-	struct gs_cb *gs_cb;		/* Current guarded storage cb */
-	struct gs_cb *gs_bc_cb;		/* Broadcast guarded storage cb */
-	unsigned char trap_tdb[256];	/* Transaction abort diagnose block */
+	struct gs_cb *gs_cb;			/* Current guarded storage cb */
+	struct gs_cb *gs_bc_cb;			/* Broadcast guarded storage cb */
+	unsigned char trap_tdb[256];		/* Transaction abort diagnose block */
 	/*
 	 * Warning: 'fpu' is dynamically-sized. It *MUST* be at
 	 * the end.
@@ -184,6 +190,7 @@ static inline void release_thread(struct task_struct *tsk) { }
 
 /* Free guarded storage control block */
 void guarded_storage_release(struct task_struct *tsk);
+void gs_load_bc_cb(struct pt_regs *regs);
 
 unsigned long get_wchan(struct task_struct *p);
 #define task_pt_regs(tsk) ((struct pt_regs *) \
@@ -324,6 +331,11 @@ extern void memcpy_absolute(void *, void *, size_t);
 extern int s390_isolate_bp(void);
 extern int s390_isolate_bp_guest(void);
 
+static __always_inline bool regs_irqs_disabled(struct pt_regs *regs)
+{
+	return arch_irqs_disabled_flags(regs->psw.mask);
+}
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* __ASM_S390_PROCESSOR_H */