[PATCH] UML - Fix vsyscall brokenness

From: Jeff Dike
Date: Fri Jul 29 2005 - 10:28:48 EST

The #if/#ifdef cleanup exposed a bug in UML's ELF header processing. With
this bug fixed, UML recognizes the vsyscall info coming from the host. On
FC4, there is a vsyscall page low in the address space, which UML doesn't
provide. This causes an infinite page fault loop and a hang on boot.

This patch works around that by making this look like a no-vsyscall system.

Signed-off-by: Jeff Dike <jdike@xxxxxxxxxxx>

Index: linux-2.6.12-rc3-mm2/arch/um/os-Linux/elf_aux.c
--- linux-2.6.12-rc3-mm2.orig/arch/um/os-Linux/elf_aux.c 2005-07-28 12:08:54.000000000 -0400
+++ linux-2.6.12-rc3-mm2/arch/um/os-Linux/elf_aux.c 2005-07-28 18:47:31.000000000 -0400
@@ -9,9 +9,10 @@
#include <elf.h>
#include <stddef.h>
+#include <asm/elf.h>
#include "init.h"
#include "elf_user.h"
-#include <asm/elf.h>
+#include "mem_user.h"

typedef Elf32_auxv_t elf_auxv_t;
@@ -41,6 +42,9 @@
vsyscall_ehdr = auxv->a_un.a_val;
+ /* See if the page is under TASK_SIZE */
+ if (vsyscall_ehdr < (unsigned long) envp)
+ vsyscall_ehdr = 0;
case AT_HWCAP:
elf_aux_hwcap = auxv->a_un.a_val;

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