Commit:     14251809b1921b1216568700f1be2f91a1cbb5c7
Parent:     cf2775f175128fc9fd7ffb88981e068d27bc85db
Author:     Jeff Dike <[EMAIL PROTECTED]>
AuthorDate: Wed Feb 28 20:13:31 2007 -0800
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Thu Mar 1 14:53:38 2007 -0800

    [PATCH] uml: host VDSO fix
    This fixes a problem seen by a number of people running UML on newer host
    kernels.  init would hang with an infinite segfault loop.
    It turns out that the host kernel was providing a AT_SYSINFO_EHDR of
    0xffffe000, which faked UML into believing that the host VDSO page could be
    reused.  However, AT_SYSINFO pointed into the middle of the address space, 
    was unmapped as a result.  Because UML was providing AT_SYSINFO_EHDR and
    AT_SYSINFO to its own processes, these would branch to nowhere when trying 
    use the VDSO.
    The fix is to also check the location of AT_SYSINFO when deciding whether to
    use the host's VDSO.
    Signed-off-by: Jeff Dike <[EMAIL PROTECTED]>
    Cc: Paolo 'Blaisorblade' Giarrusso <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
 arch/um/os-Linux/elf_aux.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/arch/um/os-Linux/elf_aux.c b/arch/um/os-Linux/elf_aux.c
index 3a8d7e3..608784d 100644
--- a/arch/um/os-Linux/elf_aux.c
+++ b/arch/um/os-Linux/elf_aux.c
@@ -39,6 +39,9 @@ __init void scan_elf_aux( char **envp)
                switch ( auxv->a_type ) {
                        case AT_SYSINFO:
                                __kernel_vsyscall = auxv->a_un.a_val;
+                               /* See if the page is under TASK_SIZE */
+                               if (__kernel_vsyscall < (unsigned long) envp)
+                                       __kernel_vsyscall = 0;
                        case AT_SYSINFO_EHDR:
                                vsyscall_ehdr = auxv->a_un.a_val;
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