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authorRoland McGrath <roland@redhat.com>2008-07-25 19:45:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-26 12:00:09 -0700
commitfa8e26ccd485216fc45c8c2dd1ec3b7ef1a0a2f8 (patch)
treeb6c3059593d7d185aaf7f5b69c363a48b18c5bb1
parent0d094efeb1e98010c6b99923f1eb7e17bf1e3a74 (diff)
downloadop-kernel-dev-fa8e26ccd485216fc45c8c2dd1ec3b7ef1a0a2f8.zip
op-kernel-dev-fa8e26ccd485216fc45c8c2dd1ec3b7ef1a0a2f8.tar.gz
tracehook: tracehook_expect_breakpoints
This adds tracehook_expect_breakpoints() as a formal hook for the nommu code to use for its, "Is text-poking likely?" check at mmap time. This names the actual semantics the code means to test, and documents it. Signed-off-by: Roland McGrath <roland@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Reviewed-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/tracehook.h15
-rw-r--r--mm/nommu.c4
2 files changed, 17 insertions, 2 deletions
diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index 6468ca0..e113e09 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -52,6 +52,21 @@
struct linux_binprm;
/**
+ * tracehook_expect_breakpoints - guess if task memory might be touched
+ * @task: current task, making a new mapping
+ *
+ * Return nonzero if @task is expected to want breakpoint insertion in
+ * its memory at some point. A zero return is no guarantee it won't
+ * be done, but this is a hint that it's known to be likely.
+ *
+ * May be called with @task->mm->mmap_sem held for writing.
+ */
+static inline int tracehook_expect_breakpoints(struct task_struct *task)
+{
+ return (task_ptrace(task) & PT_PTRACED) != 0;
+}
+
+/**
* tracehook_unsafe_exec - check for exec declared unsafe due to tracing
* @task: current task doing exec
*
diff --git a/mm/nommu.c b/mm/nommu.c
index 4462b6a..5edccd9 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -22,7 +22,7 @@
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
-#include <linux/ptrace.h>
+#include <linux/tracehook.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/mount.h>
@@ -745,7 +745,7 @@ static unsigned long determine_vm_flags(struct file *file,
* it's being traced - otherwise breakpoints set in it may interfere
* with another untraced process
*/
- if ((flags & MAP_PRIVATE) && (current->ptrace & PT_PTRACED))
+ if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current))
vm_flags &= ~VM_MAYSHARE;
return vm_flags;
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