When UML is unable to reuse the host's vDSO FIXADDR_USER_START
is zero.
To handle this special case correclty we have to implement custom
gate area helper methods.
Signed-off-by: Richard Weinberger <rich...@nod.at>
---
arch/um/sys-i386/Makefile | 2 +-
arch/um/sys-i386/asm/elf.h | 2 +
arch/um/sys-i386/mem.c | 62 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 65 insertions(+), 1 deletions(-)
create mode 100644 arch/um/sys-i386/mem.c
diff --git a/arch/um/sys-i386/Makefile b/arch/um/sys-i386/Makefile
index b1da91c..daaea15 100644
--- a/arch/um/sys-i386/Makefile
+++ b/arch/um/sys-i386/Makefile
@@ -4,7 +4,7 @@
obj-y = bug.o bugs.o checksum.o delay.o fault.o ksyms.o ldt.o ptrace.o \
ptrace_user.o setjmp.o signal.o stub.o stub_segv.o syscalls.o sysrq.o \
- sys_call_table.o tls.o atomic64_cx8_32.o
+ sys_call_table.o tls.o atomic64_cx8_32.o mem.o
obj-$(CONFIG_BINFMT_ELF) += elfcore.o
diff --git a/arch/um/sys-i386/asm/elf.h b/arch/um/sys-i386/asm/elf.h
index d964a41..4230555 100644
--- a/arch/um/sys-i386/asm/elf.h
+++ b/arch/um/sys-i386/asm/elf.h
@@ -105,6 +105,8 @@ extern unsigned long __kernel_vsyscall;
#define FIXADDR_USER_START VSYSCALL_BASE
#define FIXADDR_USER_END VSYSCALL_END
+#define __HAVE_ARCH_GATE_AREA 1
+
/*
* Architecture-neutral AT_ values in 0-17, leave some room
* for more of them, start the x86-specific ones at 32.
diff --git a/arch/um/sys-i386/mem.c b/arch/um/sys-i386/mem.c
new file mode 100644
index 0000000..639900a
--- /dev/null
+++ b/arch/um/sys-i386/mem.c
@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2011 Richard Weinberger <ric...@nod.at>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/mm.h>
+#include <asm/page.h>
+#include <asm/mman.h>
+
+static struct vm_area_struct gate_vma;
+
+static int __init gate_vma_init(void)
+{
+ if (!FIXADDR_USER_START)
+ return 0;
+
+ gate_vma.vm_mm = NULL;
+ gate_vma.vm_start = FIXADDR_USER_START;
+ gate_vma.vm_end = FIXADDR_USER_END;
+ gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
+ gate_vma.vm_page_prot = __P101;
+
+ /*
+ * Make sure the vDSO gets into every core dump.
+ * Dumping its contents makes post-mortem fully interpretable later
+ * without matching up the same kernel and hardware config to see
+ * what PC values meant.
+ */
+ gate_vma.vm_flags |= VM_ALWAYSDUMP;
+
+ return 0;
+}
+__initcall(gate_vma_init);
+
+struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
+{
+ return FIXADDR_USER_START ? &gate_vma : NULL;
+}
+
+int in_gate_area_no_mm(unsigned long addr)
+{
+ if (!FIXADDR_USER_START)
+ return 0;
+
+ if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
+ return 1;
+
+ return 0;
+}
+
+int in_gate_area(struct mm_struct *mm, unsigned long addr)
+{
+ struct vm_area_struct *vma = get_gate_vma(mm);
+
+ if (!vma)
+ return 0;
+
+ return (addr >= vma->vm_start) && (addr < vma->vm_end);
+}
--
1.7.6
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