Attachment 377732 Details for Bug 545307 – patch to fix the bug

[patch] patch to fix the bug

xen-detect.patch (text/plain), 1.73 KB, created by Paolo Bonzini on 2009-12-11 13:34:16 UTC

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Creator: Paolo Bonzini

Created: 2009-12-11 13:34:16 UTC

Size: 1.73 KB

patch

obsolete

>diff --git a/tools/misc/xen-detect.c b/tools/misc/xen-detect.c
>--- a/tools/misc/xen-detect.c
>+++ b/tools/misc/xen-detect.c
>@@ -29,9 +29,11 @@
> #include <stdlib.h>
> #include <string.h>
> #include <sys/types.h>
>-#include <sys/wait.h>
>+#include <setjmp.h>
>+#include <signal.h>
> #include <unistd.h>
> 
>+jmp_buf j;
> static int pv_context;
> 
> static void cpuid(uint32_t idx,
>@@ -74,6 +76,11 @@
>     return 1;
> }
> 
>+void sigill_handler (int sig)
>+{
>+    longjmp(j, 1);
>+}
>+
> int main(void)
> {
>     pid_t pid;
>@@ -84,33 +91,18 @@
>     if ( check_for_xen() )
>         return 0;
> 
>-    /* Now we check for execution in PV context. */
>-    pv_context = 1;
>-
>     /*
>-     * Fork a child to test the paravirtualised CPUID instruction.
>-     * If executed outside Xen PV context, the extended opcode will fault.
>+     * Setup a signal handler to test the paravirtualised CPUID instruction.
>+     * If executed outside Xen PV context, the extended opcode will fault
>+     * and we'll print "Not running on Xen".
>      */
>-    pid = fork();
>-    switch ( pid )
>-    {
>-    case 0:
>-        /* Child: test paravirtualised CPUID opcode and then exit cleanly. */
>-        cpuid(0x40000000, &dummy, &dummy, &dummy, &dummy);
>-        exit(0);
>-    case -1:
>-        fprintf(stderr, "Fork failed.\n");
>-        return 0;
>+    signal(SIGILL, sigill_handler);
>+    if (setjmp(j) == 0) {
>+        pv_context = 1;
>+        if ( check_for_xen() )
>+            return 0;
>     }
> 
>-    /*
>-     * Parent waits for child to terminate and checks for clean exit.
>-     * Only if the exit is clean is it safe for us to try the extended CPUID.
>-     */
>-    waitpid(pid, &status, 0);
>-    if ( WIFEXITED(status) && check_for_xen() )
>-        return 0;
>-
>     printf("Not running on Xen.\n");
>     return 0;
> }

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Attachments on bug 545307: 376838 | 377732