[PATCH] uml: add skas0 command-line option

This adds the "skas0" parameter to force skas0 operation on SKAS3 host and
shows which operating mode has been selected.

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

1 files changed, 25 insertions, 10 deletions

diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index c45a60e9c92d..8b01a5584e80 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -212,12 +212,26 @@ static int stop_ptraced_child(int pid, int exitcode, int mustexit)
 
 static int force_sysemu_disabled = 0;
 
+int ptrace_faultinfo = 1;
+int proc_mm = 1;
+
+static int __init skas0_cmd_param(char *str, int* add)
+{
+        ptrace_faultinfo = proc_mm = 0;
+        return 0;
+}
+
 static int __init nosysemu_cmd_param(char *str, int* add)
 {
         force_sysemu_disabled = 1;
         return 0;
 }
 
+__uml_setup("skas0", skas0_cmd_param,
+                "skas0\n"
+                "    Disables SKAS3 usage, so that SKAS0 is used, unless you \n"
+                "    specify mode=tt.\n\n");
+
 __uml_setup("nosysemu", nosysemu_cmd_param,
                 "nosysemu\n"
                 "    Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
@@ -359,12 +373,10 @@ void forward_pending_sigio(int target)
                 kill(target, SIGIO);
 }
 
-int ptrace_faultinfo = 0;
-int proc_mm = 1;
-
 extern void *__syscall_stub_start, __syscall_stub_end;
 
 #ifdef UML_CONFIG_MODE_SKAS
+
 static inline void check_skas3_ptrace_support(void)
 {
         struct ptrace_faultinfo fi;
@@ -375,6 +387,7 @@ static inline void check_skas3_ptrace_support(void)
 
         n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
         if (n < 0) {
+                ptrace_faultinfo = 0;
                 if(errno == EIO)
                         printf("not found\n");
                 else {
@@ -382,8 +395,10 @@ static inline void check_skas3_ptrace_support(void)
                 }
         }
         else {
-                ptrace_faultinfo = 1;
-                printf("found\n");
+                if (!ptrace_faultinfo)
+                        printf("found but disabled on command line\n");
+                else
+                        printf("found\n");
         }
 
         init_registers(pid);
@@ -396,13 +411,13 @@ int can_do_skas(void)
         if (os_access("/proc/mm", OS_ACC_W_OK) < 0) {
                 proc_mm = 0;
                 printf("not found\n");
-                goto out;
-        }
-        else {
-                printf("found\n");
+        } else {
+                if (!proc_mm)
+                        printf("found but disabled on command line\n");
+                else
+                        printf("found\n");
         }
 
-out:
         check_skas3_ptrace_support();
         return 1;
 }