0.9.5.15:

[sbcl.git] / src / runtime / linux-os.c

diff --git a/src/runtime/linux-os.c b/src/runtime/linux-os.c
index 25fd433..2e4e126 100644 (file)
--- a/src/runtime/linux-os.c
+++ b/src/runtime/linux-os.c
@@ -52,10 +52,17 @@
 #include "gencgc-internal.h"
 #endif
 
+#ifdef LISP_FEATURE_X86
+/* Prototype for personality(2). Done inline here since the header file
+ * for this isn't available on old versions of glibc. */
+int personality (unsigned long);
+#endif
+
 size_t os_vm_page_size;
 
 #ifdef LISP_FEATURE_SB_THREAD
-#include <linux/unistd.h>
+#include <sys/syscall.h>
+#include <unistd.h>
 #include <errno.h>
 
 /* values taken from the kernel's linux/futex.h.  This header file
@@ -66,13 +73,11 @@ size_t os_vm_page_size;
 #define FUTEX_FD (2)
 #define FUTEX_REQUEUE (3)
 
-#define __NR_sys_futex __NR_futex
-
-_syscall4(int,sys_futex,
-          int *, futex,
-          int, op,
-          int, val,
-          struct timespec *, rel);
+#define sys_futex sbcl_sys_futex
+static inline int sys_futex (void *futex, int op, int val, struct timespec *rel)
+{
+    return syscall (SYS_futex, futex, op, val, rel);
+}
 
 int
 futex_wait(int *lock_word, int oldval)
@@ -92,8 +97,24 @@ futex_wake(int *lock_word, int n)
 int linux_sparc_siginfo_bug = 0;
 int linux_no_threads_p = 0;
 
+#ifdef LISP_FEATURE_SB_THREAD
+int
+isnptl (void)
+{
+  size_t n = confstr (_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
+  if (n > 0) {
+      char *buf = alloca (n);
+      confstr (_CS_GNU_LIBPTHREAD_VERSION, buf, n);
+      if (strstr (buf, "NPTL")) {
+          return 1;
+      }
+  }
+  return 0;
+}
+#endif
+
 void
-os_init(void)
+os_init(char *argv[], char *envp[])
 {
     /* Conduct various version checks: do we have enough mmap(), is
      * this a sparc running 2.2, can we do threads? */
@@ -121,11 +142,63 @@ os_init(void)
     }
 #ifdef LISP_FEATURE_SB_THREAD
     futex_wait(futex,-1);
-    if(errno==ENOSYS)  linux_no_threads_p = 1;
-    if(linux_no_threads_p)
-        fprintf(stderr,"Linux with NPTL support (e.g. kernel 2.6 or newer) required for \nthread-enabled SBCL.  Disabling thread support.\n\n");
+    if(errno==ENOSYS) {
+       lose("This version of SBCL is compiled with threading support, but your kernel is too old to support this.\n\
+Please use a more recent kernel or a version of SBCL without threading support.\n");
+    }
+    if(! isnptl()) {
+       lose("This version of SBCL only works correctly with the NPTL threading library. Please use a newer glibc, use an older SBCL, or stop using LD_ASSUME_KERNEL");
+    }
 #endif
     os_vm_page_size = getpagesize();
+
+    /* KLUDGE: Disable memory randomization on new Linux kernels
+     * by setting a personality flag and re-executing. (We need
+     * to re-execute, since the memory maps that can conflict with
+     * the SBCL spaces have already been done at this point).
+     *
+     * Since randomization is currently implemented only on x86 kernels,
+     * don't do this trick on other platforms.
+     */
+#ifdef LISP_FEATURE_X86
+    if ((major_version == 2 && minor_version >= 6)
+        || major_version >= 3)
+    {
+        int pers = personality(0xffffffffUL);
+        /* 0x40000 aka. ADDR_NO_RANDOMIZE */
+        if (!(pers & 0x40000)) {
+            int retval = personality(pers | 0x40000);
+            /* Allegedly some Linux kernels (the reported case was
+             * "hardened Linux 2.6.7") won't set the new personality,
+             * but nor will they return -1 for an error. So as a
+             * workaround query the new personality...
+             */
+            int newpers = personality(0xffffffffUL);
+            /* ... and don't re-execute if either the setting resulted
+             * in an error or if the value didn't change. Otherwise
+             * this might result in an infinite loop.
+             */
+            if (retval != -1 && newpers != pers) {
+                /* Use /proc/self/exe instead of trying to figure out
+                 * the executable path from PATH and argv[0], since
+                 * that's unreliable. We follow the symlink instead of
+                 * executing the file directly in order to prevent top
+                 * from displaying the name of the process as "exe". */
+                char runtime[PATH_MAX+1];
+                int i = readlink("/proc/self/exe", runtime, PATH_MAX);
+                if (i != -1) {
+                    runtime[i] = '\0';
+                    execve(runtime, argv, envp);
+                }
+            }
+            /* Either changing the personality or execve() failed. Either
+             * way we might as well continue, and hope that the random
+             * memory maps are ok this time around.
+             */
+            fprintf(stderr, "WARNING: Couldn't re-execute SBCL with the proper personality flags (maybe /proc isn't mounted?). Trying to continue anyway.\n");
+        }
+    }
+#endif
 }
 
 
@@ -150,11 +223,17 @@ os_validate(os_vm_address_t addr, os_vm_size_t len)
     }
 #endif
     actual = mmap(addr, len, OS_VM_PROT_ALL, flags, -1, 0);
-    if (actual == MAP_FAILED || (addr && (addr!=actual))) {
+    if (actual == MAP_FAILED) {
         perror("mmap");
         return 0;               /* caller should check this */
     }
 
+    if (addr && (addr!=actual)) {
+        fprintf(stderr, "mmap: wanted %lu bytes at %p, actually mapped at %p\n",
+                (unsigned long) len, addr, actual);
+        return 0;
+    }
+    
 #ifdef LISP_FEATURE_ALPHA
 
     len=(len+(os_vm_page_size-1))&(~(os_vm_page_size-1));