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Commit 548f0a4e authored by Richard Weinberger's avatar Richard Weinberger Committed by Linus Torvalds
Browse files

um: Set __HAVE_ARCH_GATE_AREA for i386 



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: default avatarRichard Weinberger <richard@nod.at>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b743ac54

arch/um/sys-i386/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/um/sys-i386/asm/elf.h

+2 −0
Original line number Diff line number Diff line
@@ -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.

arch/um/sys-i386/mem.c

0 → 100644
+62 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2011 Richard Weinberger <richrd@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);

}