svn commit: r187686 - head/sys/kern

Robert Watson rwatson at
Sun Jan 25 04:07:45 PST 2009

Author: rwatson
Date: Sun Jan 25 12:07:43 2009
New Revision: 187686

  When a statically linked binary is executed (or at least, one without
  an interpreter definition in its program header), set the auxiliary
  ELF argument AT_BASE to 0 rather than to the address that we would
  have mapped the interpreter at if there had been one.
  The ELF ABI specifications appear to be ambiguous as to the desired
  behavior in this situation, as they define AT_BASE as the base address
  of the interpreter, but do not mention what to do if there is none.
  On Solaris, AT_BASE will be set to the base address of the static
  binary if there is no interpreter, and on Linux, AT_BASE is set to 0.
  We go with the Linux semantics as they are of more immediate utility
  and allow the early runtime environment to know that the kernel has
  not mapped an interpreter, but because AT_PHDR points at the ELF
  header for the running binary, it is still possible to retrieve all
  required mapping information when the process starts should it be
  required.  Either approach would be preferable to our current behavior
  of passing a pointer to an unmapped region of user memory as AT_BASE.
  MFC after:	3 weeks


Modified: head/sys/kern/imgact_elf.c
--- head/sys/kern/imgact_elf.c	Sun Jan 25 10:31:45 2009	(r187685)
+++ head/sys/kern/imgact_elf.c	Sun Jan 25 12:07:43 2009	(r187686)
@@ -822,7 +822,8 @@ __CONCAT(exec_, __elfN(imgact))(struct i
 			uprintf("ELF interpreter %s not found\n", interp);
 			return (error);
-	}
+	} else
+		addr = 0;
 	 * Construct auxargs table (used by the fixup routine)

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