uml: more page fault path trimming

More trimming of the page fault path.

Permissions are passed around in a single int rather than one bit per
int.  The permission values are copied from libc so that they can be
passed to mmap and mprotect without any further conversion.

The register sets used by do_syscall_stub and copy_context_skas0 are
initialized once, at boot time, rather than once per call.

wait_stub_done checks whether it is getting the signals it expects by
comparing the wait status to a mask containing bits for the signals of
interest rather than comparing individually to the signal numbers.  It
also has one check for a wait failure instead of two.  The caller is
expected to do the initial continue of the stub.  This gets rid of an
argument and some logic.  The fname argument is gone, as that can be
had from a stack trace.

user_signal() is collapsed into userspace() as it is basically one or
two lines of code afterwards.

The physical memory remapping stuff is gone, as it is unused.

flush_tlb_page is inlined.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 29 insertions, 22 deletions

diff --git a/arch/um/os-Linux/skas/mem.c b/arch/um/os-Linux/skas/mem.c
index af0790719b77..8e490fff3d47 100644
--- a/arch/um/os-Linux/skas/mem.c
+++ b/arch/um/os-Linux/skas/mem.c
@@ -24,10 +24,11 @@
 #include "uml-config.h"
 #include "sysdep/ptrace.h"
 #include "sysdep/stub.h"
+#include "init.h"
 
 extern unsigned long batch_syscall_stub, __syscall_stub_start;
 
-extern void wait_stub_done(int pid, int sig, char * fname);
+extern void wait_stub_done(int pid);
 
 static inline unsigned long *check_init_stack(struct mm_id * mm_idp,
                                               unsigned long *stack)
@@ -39,6 +40,19 @@ static inline unsigned long *check_init_stack(struct mm_id * mm_idp,
         return stack;
 }
 
+static unsigned long syscall_regs[MAX_REG_NR];
+
+static int __init init_syscall_regs(void)
+{
+        get_safe_registers(syscall_regs, NULL);
+        syscall_regs[REGS_IP_INDEX] = UML_CONFIG_STUB_CODE +
+                ((unsigned long) &batch_syscall_stub -
+                 (unsigned long) &__syscall_stub_start);
+        return 0;
+}
+
+__initcall(init_syscall_regs);
+
 extern int proc_mm;
 
 int single_count = 0;
@@ -47,12 +61,11 @@ int multi_op_count = 0;
 
 static inline long do_syscall_stub(struct mm_id * mm_idp, void **addr)
 {
-        unsigned long regs[MAX_REG_NR];
         int n, i;
         long ret, offset;
         unsigned long * data;
         unsigned long * syscall;
-        int pid = mm_idp->u.pid;
+        int err, pid = mm_idp->u.pid;
 
         if(proc_mm)
 #warning Need to look up userspace_pid by cpu
@@ -60,21 +73,21 @@ static inline long do_syscall_stub(struct mm_id * mm_idp, void **addr)
 
         multi_count++;
 
-        get_safe_registers(regs, NULL);
-        regs[REGS_IP_INDEX] = UML_CONFIG_STUB_CODE +
-                ((unsigned long) &batch_syscall_stub -
-                 (unsigned long) &__syscall_stub_start);
-
-        n = ptrace_setregs(pid, regs);
+        n = ptrace_setregs(pid, syscall_regs);
         if(n < 0){
                 printk("Registers - \n");
                 for(i = 0; i < MAX_REG_NR; i++)
-                        printk("\t%d\t0x%lx\n", i, regs[i]);
+                        printk("\t%d\t0x%lx\n", i, syscall_regs[i]);
                 panic("do_syscall_stub : PTRACE_SETREGS failed, errno = %d\n",
                       -n);
         }
 
-        wait_stub_done(pid, 0, "do_syscall_stub");
+        err = ptrace(PTRACE_CONT, pid, 0, 0);
+        if(err)
+                panic("Failed to continue stub, pid = %d, errno = %d\n", pid,
+                      errno);
+
+        wait_stub_done(pid);
 
         /* When the stub stops, we find the following values on the
          * beginning of the stack:
@@ -176,14 +189,10 @@ long syscall_stub_data(struct mm_id * mm_idp,
         return 0;
 }
 
-int map(struct mm_id * mm_idp, unsigned long virt, unsigned long len,
-        int r, int w, int x, int phys_fd, unsigned long long offset,
-        int done, void **data)
+int map(struct mm_id * mm_idp, unsigned long virt, unsigned long len, int prot,
+        int phys_fd, unsigned long long offset, int done, void **data)
 {
-        int prot, ret;
-
-        prot = (r ? PROT_READ : 0) | (w ? PROT_WRITE : 0) |
-                (x ? PROT_EXEC : 0);
+        int ret;
 
         if(proc_mm){
                 struct proc_mm_op map;
@@ -253,13 +262,11 @@ int unmap(struct mm_id * mm_idp, unsigned long addr, unsigned long len,
 }
 
 int protect(struct mm_id * mm_idp, unsigned long addr, unsigned long len,
-            int r, int w, int x, int done, void **data)
+            unsigned int prot, int done, void **data)
 {
         struct proc_mm_op protect;
-        int prot, ret;
+        int ret;
 
-        prot = (r ? PROT_READ : 0) | (w ? PROT_WRITE : 0) |
-                (x ? PROT_EXEC : 0);
         if(proc_mm){
                 int fd = mm_idp->u.mm_fd;