[PATCH] uml: S390 preparation, abstract host page fault data

This patch removes the arch-specific fault/trap-infos from thread and
skas-regs.

It adds a new struct faultinfo, that is arch-specific defined in
sysdep/faultinfo.h.

The structure is inserted in thread.arch and thread.regs.skas and
thread.regs.tt

Now, segv and other trap-handlers can copy the contents from regs.X.faultinfo
to thread.arch.faultinfo with one simple assignment.

Also, the number of macros necessary is reduced to

FAULT_ADDRESS(struct faultinfo)
    extracts the faulting address from faultinfo

FAULT_WRITE(struct faultinfo)
    extracts the "is_write" flag

SEGV_IS_FIXABLE(struct faultinfo)
    is true for the fixable segvs, i.e. (TRAP == 14)
    on i386

UPT_FAULTINFO(regs)
    result is (struct faultinfo *) to the faultinfo
    in regs->skas.faultinfo

GET_FAULTINFO_FROM_SC(struct faultinfo, struct sigcontext *)
    copies the relevant parts of the sigcontext to
    struct faultinfo.

On SIGSEGV, call user_signal() instead of handle_segv(), if the architecture
provides the information needed in PTRACE_FAULTINFO, or if PTRACE_FAULTINFO is
missing, because segv-stub will provide the info.

The benefit of the change is, that in case of a non-fixable SIGSEGV, we can
give user processes a SIGSEGV, instead of possibly looping on pagefault
handling.

Since handle_segv() sikked arch_fixup() implicitly by passing ip==0 to segv(),
I changed segv() to call arch_fixup() only, if !is_user.

Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

8 files changed, 76 insertions, 41 deletions

diff --git a/arch/um/kernel/ptrace.c b/arch/um/kernel/ptrace.c
index ffc599bd85c..ec19fed7c64 100644
--- a/arch/um/kernel/ptrace.c
+++ b/arch/um/kernel/ptrace.c
@@ -252,13 +252,13 @@ long sys_ptrace(long request, long pid, long addr, long data)
 		break;
 #endif
 	case PTRACE_FAULTINFO: {
-		struct ptrace_faultinfo fault;
-
-		fault = ((struct ptrace_faultinfo) 
-			{ .is_write	= child->thread.err,
-			  .addr		= child->thread.cr2 });
-		ret = copy_to_user((unsigned long __user *) data, &fault,
-				   sizeof(fault));
+                /* Take the info from thread->arch->faultinfo,
+                 * but transfer max. sizeof(struct ptrace_faultinfo).
+                 * On i386, ptrace_faultinfo is smaller!
+                 */
+                ret = copy_to_user((unsigned long __user *) data,
+                                   &child->thread.arch.faultinfo,
+                                   sizeof(struct ptrace_faultinfo));
 		if(ret)
 			break;
 		break;
@@ -269,6 +269,7 @@ long sys_ptrace(long request, long pid, long addr, long data)
 				   sizeof(child->pending.signal));
 		break;
 
+#ifdef PTRACE_LDT
 	case PTRACE_LDT: {
 		struct ptrace_ldt ldt;
 
@@ -284,6 +285,7 @@ long sys_ptrace(long request, long pid, long addr, long data)
 		ret = -EIO;
 		break;
 	}
+#endif
 #ifdef CONFIG_PROC_MM
 	case PTRACE_SWITCH_MM: {
 		struct mm_struct *old = child->mm;
diff --git a/arch/um/kernel/skas/include/skas.h b/arch/um/kernel/skas/include/skas.h
index f0702c2c720..96b51dba347 100644
--- a/arch/um/kernel/skas/include/skas.h
+++ b/arch/um/kernel/skas/include/skas.h
@@ -27,9 +27,10 @@ extern void map(int fd, unsigned long virt, unsigned long len, int r, int w,
 extern int unmap(int fd, void *addr, unsigned long len);
 extern int protect(int fd, unsigned long addr, unsigned long len, 
 		   int r, int w, int x);
-extern void user_signal(int sig, union uml_pt_regs *regs);
+extern void user_signal(int sig, union uml_pt_regs *regs, int pid);
 extern int new_mm(int from);
 extern void start_userspace(int cpu);
+extern void get_skas_faultinfo(int pid, struct faultinfo * fi);
 extern long execute_syscall_skas(void *r);
 
 #endif
diff --git a/arch/um/kernel/skas/process.c b/arch/um/kernel/skas/process.c
index b4ffaaa8124..c0b30515dfb 100644
--- a/arch/um/kernel/skas/process.c
+++ b/arch/um/kernel/skas/process.c
@@ -4,6 +4,7 @@
  */
 
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 #include <errno.h>
 #include <signal.h>
@@ -37,17 +38,26 @@ int is_skas_winch(int pid, int fd, void *data)
 	return(1);
 }
 
-static void handle_segv(int pid)
+void get_skas_faultinfo(int pid, struct faultinfo * fi)
 {
-	struct ptrace_faultinfo fault;
 	int err;
 
-	err = ptrace(PTRACE_FAULTINFO, pid, 0, &fault);
+        err = ptrace(PTRACE_FAULTINFO, pid, 0, fi);
 	if(err)
-		panic("handle_segv - PTRACE_FAULTINFO failed, errno = %d\n",
-		      errno);
+                panic("get_skas_faultinfo - PTRACE_FAULTINFO failed, "
+                      "errno = %d\n", errno);
+
+        /* Special handling for i386, which has different structs */
+        if (sizeof(struct ptrace_faultinfo) < sizeof(struct faultinfo))
+                memset((char *)fi + sizeof(struct ptrace_faultinfo), 0,
+                       sizeof(struct faultinfo) -
+                       sizeof(struct ptrace_faultinfo));
+}
 
-	segv(fault.addr, 0, FAULT_WRITE(fault.is_write), 1, NULL);
+static void handle_segv(int pid, union uml_pt_regs * regs)
+{
+        get_skas_faultinfo(pid, &regs->skas.faultinfo);
+        segv(regs->skas.faultinfo, 0, 1, NULL);
 }
 
 /*To use the same value of using_sysemu as the caller, ask it that value (in local_using_sysemu)*/
@@ -163,7 +173,7 @@ void userspace(union uml_pt_regs *regs)
 		if(WIFSTOPPED(status)){
 		  	switch(WSTOPSIG(status)){
 			case SIGSEGV:
-				handle_segv(pid);
+                                handle_segv(pid, regs);
 				break;
 			case SIGTRAP + 0x80:
 			        handle_trap(pid, regs, local_using_sysemu);
@@ -177,7 +187,7 @@ void userspace(union uml_pt_regs *regs)
 			case SIGBUS:
 			case SIGFPE:
 			case SIGWINCH:
-				user_signal(WSTOPSIG(status), regs);
+                                user_signal(WSTOPSIG(status), regs, pid);
 				break;
 			default:
 			        printk("userspace - child stopped with signal "
diff --git a/arch/um/kernel/skas/trap_user.c b/arch/um/kernel/skas/trap_user.c
index 8e9b46d4702..0dee1d95c80 100644
--- a/arch/um/kernel/skas/trap_user.c
+++ b/arch/um/kernel/skas/trap_user.c
@@ -5,12 +5,15 @@
 
 #include <signal.h>
 #include <errno.h>
-#include "sysdep/ptrace.h"
 #include "signal_user.h"
 #include "user_util.h"
 #include "kern_util.h"
 #include "task.h"
 #include "sigcontext.h"
+#include "skas.h"
+#include "ptrace_user.h"
+#include "sysdep/ptrace.h"
+#include "sysdep/ptrace_user.h"
 
 void sig_handler_common_skas(int sig, void *sc_ptr)
 {
@@ -31,9 +34,11 @@ void sig_handler_common_skas(int sig, void *sc_ptr)
 	r = &TASK_REGS(get_current())->skas;
 	save_user = r->is_user;
 	r->is_user = 0;
-	r->fault_addr = SC_FAULT_ADDR(sc);
-	r->fault_type = SC_FAULT_TYPE(sc);
-	r->trap_type = SC_TRAP_TYPE(sc);
+        if ( sig == SIGFPE || sig == SIGSEGV ||
+             sig == SIGBUS || sig == SIGILL ||
+             sig == SIGTRAP ) {
+                GET_FAULTINFO_FROM_SC(r->faultinfo, sc);
+        }
 
 	change_sig(SIGUSR1, 1);
 	info = &sig_info[sig];
@@ -45,14 +50,17 @@ void sig_handler_common_skas(int sig, void *sc_ptr)
 	r->is_user = save_user;
 }
 
-void user_signal(int sig, union uml_pt_regs *regs)
+extern int ptrace_faultinfo;
+
+void user_signal(int sig, union uml_pt_regs *regs, int pid)
 {
 	struct signal_info *info;
+        int segv = ((sig == SIGFPE) || (sig == SIGSEGV) || (sig == SIGBUS) ||
+                    (sig == SIGILL) || (sig == SIGTRAP));
 
 	regs->skas.is_user = 1;
-	regs->skas.fault_addr = 0;
-	regs->skas.fault_type = 0;
-	regs->skas.trap_type = 0;
+	if (segv)
+		get_skas_faultinfo(pid, &regs->skas.faultinfo);
 	info = &sig_info[sig];
 	(*info->handler)(sig, regs);
 
diff --git a/arch/um/kernel/trap_kern.c b/arch/um/kernel/trap_kern.c
index 47e766e6ba1..54e2ec33a43 100644
--- a/arch/um/kernel/trap_kern.c
+++ b/arch/um/kernel/trap_kern.c
@@ -133,12 +133,19 @@ static int check_remapped_addr(unsigned long address, int is_write)
 	return(0);
 }
 
-unsigned long segv(unsigned long address, unsigned long ip, int is_write, 
-		   int is_user, void *sc)
+/*
+ * We give a *copy* of the faultinfo in the regs to segv.
+ * This must be done, since nesting SEGVs could overwrite
+ * the info in the regs. A pointer to the info then would
+ * give us bad data!
+ */
+unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, void *sc)
 {
 	struct siginfo si;
 	void *catcher;
 	int err;
+        int is_write = FAULT_WRITE(fi);
+        unsigned long address = FAULT_ADDRESS(fi);
 
         if(!is_user && (address >= start_vm) && (address < end_vm)){
                 flush_tlb_kernel_vm();
@@ -159,7 +166,7 @@ unsigned long segv(unsigned long address, unsigned long ip, int is_write,
 	} 
 	else if(current->thread.fault_addr != NULL)
 		panic("fault_addr set but no fault catcher");
-	else if(arch_fixup(ip, sc))
+        else if(!is_user && arch_fixup(ip, sc))
 		return(0);
 
  	if(!is_user) 
@@ -171,6 +178,7 @@ unsigned long segv(unsigned long address, unsigned long ip, int is_write,
 		si.si_errno = 0;
 		si.si_code = BUS_ADRERR;
 		si.si_addr = (void *)address;
+                current->thread.arch.faultinfo = fi;
 		force_sig_info(SIGBUS, &si, current);
 	}
 	else if(err == -ENOMEM){
@@ -180,22 +188,20 @@ unsigned long segv(unsigned long address, unsigned long ip, int is_write,
 	else {
 		si.si_signo = SIGSEGV;
 		si.si_addr = (void *) address;
-		current->thread.cr2 = address;
-		current->thread.err = is_write;
+                current->thread.arch.faultinfo = fi;
 		force_sig_info(SIGSEGV, &si, current);
 	}
 	return(0);
 }
 
-void bad_segv(unsigned long address, unsigned long ip, int is_write)
+void bad_segv(struct faultinfo fi, unsigned long ip)
 {
 	struct siginfo si;
 
 	si.si_signo = SIGSEGV;
 	si.si_code = SEGV_ACCERR;
-	si.si_addr = (void *) address;
-	current->thread.cr2 = address;
-	current->thread.err = is_write;
+        si.si_addr = (void *) FAULT_ADDRESS(fi);
+        current->thread.arch.faultinfo = fi;
 	force_sig_info(SIGSEGV, &si, current);
 }
 
@@ -204,6 +210,7 @@ void relay_signal(int sig, union uml_pt_regs *regs)
 	if(arch_handle_signal(sig, regs)) return;
 	if(!UPT_IS_USER(regs))
 		panic("Kernel mode signal %d", sig);
+        current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
 	force_sig(sig, current);
 }
 
diff --git a/arch/um/kernel/trap_user.c b/arch/um/kernel/trap_user.c
index 50a4042a509..f825a6eda3f 100644
--- a/arch/um/kernel/trap_user.c
+++ b/arch/um/kernel/trap_user.c
@@ -54,23 +54,22 @@ struct {
 void segv_handler(int sig, union uml_pt_regs *regs)
 {
 	int index, max;
+        struct faultinfo * fi = UPT_FAULTINFO(regs);
 
-	if(UPT_IS_USER(regs) && !UPT_SEGV_IS_FIXABLE(regs)){
-		bad_segv(UPT_FAULT_ADDR(regs), UPT_IP(regs), 
-			 UPT_FAULT_WRITE(regs));
+        if(UPT_IS_USER(regs) && !SEGV_IS_FIXABLE(fi)){
+                bad_segv(*fi, UPT_IP(regs));
 		return;
 	}
 	max = sizeof(segfault_record)/sizeof(segfault_record[0]);
 	index = next_trap_index(max);
 
 	nsegfaults++;
-	segfault_record[index].address = UPT_FAULT_ADDR(regs);
+        segfault_record[index].address = FAULT_ADDRESS(*fi);
 	segfault_record[index].pid = os_getpid();
-	segfault_record[index].is_write = UPT_FAULT_WRITE(regs);
+        segfault_record[index].is_write = FAULT_WRITE(*fi);
 	segfault_record[index].sp = UPT_SP(regs);
 	segfault_record[index].is_user = UPT_IS_USER(regs);
-	segv(UPT_FAULT_ADDR(regs), UPT_IP(regs), UPT_FAULT_WRITE(regs),
-	     UPT_IS_USER(regs), regs);
+        segv(*fi, UPT_IP(regs), UPT_IS_USER(regs), regs);
 }
 
 void usr2_handler(int sig, union uml_pt_regs *regs)
diff --git a/arch/um/kernel/tt/tracer.c b/arch/um/kernel/tt/tracer.c
index 7b5d937e595..f7b1753a025 100644
--- a/arch/um/kernel/tt/tracer.c
+++ b/arch/um/kernel/tt/tracer.c
@@ -89,8 +89,10 @@ void tracer_panic(char *format, ...)
 
 static void tracer_segv(int sig, struct sigcontext sc)
 {
+        struct faultinfo fi;
+        GET_FAULTINFO_FROM_SC(fi, &sc);
 	printf("Tracing thread segfault at address 0x%lx, ip 0x%lx\n",
-	       SC_FAULT_ADDR(&sc), SC_IP(&sc));
+               FAULT_ADDRESS(fi), SC_IP(&sc));
 	while(1)
 		pause();
 }
diff --git a/arch/um/kernel/tt/trap_user.c b/arch/um/kernel/tt/trap_user.c
index 92a3820ca54..fc108615bea 100644
--- a/arch/um/kernel/tt/trap_user.c
+++ b/arch/um/kernel/tt/trap_user.c
@@ -7,6 +7,7 @@
 #include <errno.h>
 #include <signal.h>
 #include "sysdep/ptrace.h"
+#include "sysdep/sigcontext.h"
 #include "signal_user.h"
 #include "user_util.h"
 #include "kern_util.h"
@@ -28,6 +29,11 @@ void sig_handler_common_tt(int sig, void *sc_ptr)
 		change_sig(SIGSEGV, 1);
 
 	r = &TASK_REGS(get_current())->tt;
+        if ( sig == SIGFPE || sig == SIGSEGV ||
+             sig == SIGBUS || sig == SIGILL ||
+             sig == SIGTRAP ) {
+                GET_FAULTINFO_FROM_SC(r->faultinfo, sc);
+        }
 	save_regs = *r;
 	is_user = user_context(SC_SP(sc));
 	r->sc = sc;